Spring-AOP

探秘 Spring AOP

AOP 是什么？

是一种编程范式，不是编程语言
解决特定问题，不能解决所有问题
是 OOP 的补充，不是替代

编程范式：

面向过程编程
面向对象编程
函数式编程
事件驱动编程
面向切面编程
...

AOP 的初衷：

DRY: Don't Repeat yourself
SoC: Separation of concerns
- 水平分离：展示层->服务层->持久层
- 垂直分离：模块划分订单、库存等）
- 切面分离：分离功能性需求与非功能性需求

使用 AOP 的好处：

集中处理某一关注点/横切逻辑
可以很方便地添加/删除关注点
侵入性少，增强代码可读性及可维护性
...

AOP 的应用场景：

权限控制
缓存控制
事务控制
审计日志
性能监控
分布式追踪
异常处理
...

支持 AOP 的编程语言：

Java
.NET
C/C++
Ruby
Python
PHP
....

1. 实现一个权限控制

实现权限切换

public class CurrentUserHolder {
    public static final ThreadLocal<String> holder = new ThreadLocal<>();
    public static String get() {
        return holder.get() == null ? "unknown" : holder.get();
    }
    public static void set(String user) {
        holder.set(user);
    }
}

实现认证逻辑

@Service
public class AuthService {
    public void checkAccess() {
        System.out.println("执行了checkAccess...");
        String user = CurrentUserHolder.get();
        if (!"admin".equals(user)) {
            throw new RuntimeException("operation not allow");
        }
    }
}

实现业务逻辑

public class ProductService {
    public void insert(Product product) {
        System.out.println("insert product");
    }
    public void delete(Long id) {
        System.out.println("delete product");
    }
}

1.1. 传统方式

@SpringBootConfiguration
@ComponentScan("org.example.spring_aop.prepare")
public class PrepareApplication {
}

@Service
public class AuthService {
    // ...
}

@Service
public class ProductService {
    @Autowired
    AuthService authService;
    public void insert(Product product) {
        authService.checkAccess();
        // ...
    }
    public void delete(Long id) {
        authService.checkAccess();
        // ...
    }
}

1.2. AOP 方式

@SpringBootConfiguration
@ComponentScan("org.example.spring_aop.teach")
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class TeachApplication {
}

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface AdminOnly {
}

@Aspect
@Component
public class SecurityAspect {
    @Autowired
    AuthService authService;
    @Pointcut("@annotation(AdminOnly)")
    public void adminOnly() {
    }
    @Before("adminOnly()")
    public void check() {
        authService.checkAccess();
    }
}

@Service
public class AuthService {
    // ...
}

@Service
public class ProductService {
    @AdminOnly
    public void insert(Product product) {
        // ...
    }
    @AdminOnly
    public void delete(Long id) {
        // ...
    }
}

1.3. 单元测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class ProductServiceTest {
    @Autowired
    ProductService productService;
    @Test(expected = RuntimeException.class)
    public void testDelete() {
        CurrentUserHolder.set("tom");
        productService.delete(1L);
    }
    @Test
    public void testInsert() {
        CurrentUserHolder.set("admin");
        productService.insert(new Product());
    }
}

2. 使用详解

@Aspect
@Pointcut(expression)
Advice

2.1. 切面表达式

designators（描述符）
- 匹配方法
  - execution()
- 匹配注解
  - @target()
  - @args()
  - @within()
  - @annotation()
- 匹配包、类型
  - within()
- 匹配对象
  - @this()
  - @bean()
  - @target()
- 匹配参数
  - @args()
wildcard（通配符）
- *：匹配任意数量的字符
- +：匹配指定类及其子类
- ..：一般用于匹配任意数的子包或参数
operator（运算符）
- &&：与操作符
- ||：或操作符
- !：非操作符

2.1.1. 匹配方法

execution（
    modifier-pattern?
    ret-type-pattern
    declaring-type-pattern?
    name-pattern(param-pattern)
    throws-pattern?
)

// 匹配service包下所有以Service结尾的类的所有方法
@Pointcut("execution(public * org.example.spring_aop.aspect.service.*Service.*(..))")
// 匹配service包及子包下所有以Service结尾的类的所有方法
@Pointcut("execution(public * org.example.spring_aop.aspect.service..*Service.*(..))")
// 匹配service包下所有以Service结尾的类中返回类型为String的方法
@Pointcut("execution(public String org.example.spring_aop.aspect.service.*Service.*(..))")
// 匹配service包下所有以Service结尾的类中无返回的方法
@Pointcut("execution(public void org.example.spring_aop.aspect.service.*Service.*(..))")
// 匹配service包下所有以Service结尾的类中无参的方法
@Pointcut("execution(public * org.example.spring_aop.aspect.service.*Service.*())")
// 匹配service包下所有以Service结尾的类中只有一个参数且为Long类型的方法
@Pointcut("execution(public * org.example.spring_aop.aspect.service.*Service.*(Long))")
// 匹配service包下所有以Service结尾的类中抛出IllegalAccessException异常的方法
@Pointcut("execution(public * org.example.spring_aop.aspect.service.*Service.*(..) throws java.lang.IllegalAccessException)")

2.1.2. 匹配包/类型

// 匹配ProductService类里头的所有方法
@Pointcut("within(org.example.spring_aop.aspect.service.ProductService)")
// 匹配sub包下所有类的方法
@Pointcut("within(org.example.spring_aop.aspect.service.sub.*)")
// 匹配service包及子包下所有以Service结尾的类的所有方法
@Pointcut("within(org.example.spring_aop.aspect.service..*Service)")

2.1.3. 匹配对象

// 匹配AOP对象的目标对象为指定类型的方法，即Loggable的aop代理对象的方法
@Pointcut("this(org.example.spring_aop.aspect.log.Loggable)")
// 匹配实现Loggable接口的目标对象的方法，即Loggable实现类的方法
@Pointcut("target(org.example.spring_aop.aspect.log.Loggable)")
// 匹配所有以Service结尾的bean里面的方法
@Pointcut("bean(*Service)")

2.1.4. 匹配参数

// 匹配只有一个参数且为Long类型的方法
@Pointcut("args(Long)")
@Pointcut("execution(* *..*(Long))")
// 匹配第一个参数为Long类型的方法
@Pointcut("args(Long,..)")
// 匹配只有两个参数且分别为Long、String类型的方法
@Pointcut("args(Long,String)")

2.1.5. 匹配注解

// 匹配有AdminOnly注解的方法
@Pointcut("@annotation(org.example.spring_aop.aspect.annotation.AdminOnly)")
// 匹配有NeedSecured注解的类中的所有方法
@Pointcut("@within(org.example.spring_aop.aspect.annotation.NeedSecured)")
// 匹配有NeedSecured注解的类中的所有方法，要求注解的RetentionPolicy必须为RUNTIME
@Pointcut("@target(org.example.spring_aop.aspect.annotation.NeedSecured)")
// 匹配传入参数类型有NeedSecured注解的方法
@Pointcut("@args(org.example.spring_aop.aspect.annotation.NeedSecured)")

2.2. Advice 注解

@SpringBootConfiguration
@ComponentScan("org.example.spring_aop.advice")
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class AdviceApplication {
}

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface AdminOnly {
}

业务逻辑

@Service
public class ProductService {
    public String findProductNameById(Long id) {
        System.out.println("execute getProductNameById(id=" + id + ")");
        return "product name";
    }
    public void exceptionMethod(String arg) throws IllegalAccessException {
        System.out.println("execute exceptionMethod(arg=" + arg + ")");
        throw new IllegalAccessException("one exception");
    }
    @AdminOnly
    public void addProduct(Long id, String name) {
        System.out.println("execute addProduct(id=" + id + ", name=" + name + ")");
    }
    @AdminOnly
    public void deleteProduct(Long id) {
        System.out.println("execute deleteProduct(id=" + id + ")");
    }
    public void loopUpProduct(Long id) {
        System.out.println("execute loopUpProduct(id=" + id + ")");
    }
}

单元测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class ProductServiceTest {
    @Autowired
    ProductService productService;
    @Test
    public void testExecution() {
        productService.findProductNameById(1L);
        System.out.println("==========");
        try {
            productService.exceptionMethod("arg");
        } catch (IllegalAccessException ignored) {
        }
        System.out.println("==========");
        productService.addProduct(2L, "name2");
        System.out.println("==========");
        productService.deleteProduct(1L);
        System.out.println("==========");
        productService.loopUpProduct(2L);
    }
}

2.2.1. After

@Pointcut("@annotation(org.example.spring_aop.advice.annotation.AdminOnly)")
public void matchAnnotation() {
}

@After("matchAnnotation()")
public void advice1() {
    System.out.println("###after matchAnnotation");
}

execute getProductNameById(id=1)
==========
execute exceptionMethod(arg=arg)
==========
execute addProduct(id=2, name=name2)
###after matchAnnotation
==========
execute deleteProduct(id=1)
###after matchAnnotation
==========
execute loopUpProduct(id=2)

@Pointcut("execution(* *..*(Long))")
public void matchLongArg() {
}

@After("matchLongArg()")
public void advice2() {
    System.out.println("###after matchLongArg");
}

execute getProductNameById(id=1)
###after matchLongArg
==========
execute exceptionMethod(arg=arg)
==========
execute addProduct(id=2, name=name2)
==========
execute deleteProduct(id=1)
###after matchLongArg
==========
execute loopUpProduct(id=2)
###after matchLongArg

2.2.2. AfterThrowing

@Pointcut("execution(* *..*(*) throws java.lang.IllegalAccessException)")
public void matchException() {
}

@AfterThrowing("matchException()")
public void advice3() {
    System.out.println("###afterThrowing matchException");
}

execute getProductNameById(id=1)
==========
execute exceptionMethod(arg=arg)
###afterThrowing matchException
==========
execute addProduct(id=2, name=name2)
==========
execute deleteProduct(id=1)
==========
execute loopUpProduct(id=2)

2.2.3. AfterReturning

@Pointcut("execution(String *..*.*(..))")
public void matchReturn() {
}

@AfterReturning(value = "matchReturn()", returning = "result")
public void advice4(Object result) {
    System.out.println("###afterReturning matchReturn, result = " + result);
}

execute getProductNameById(id=1)
###afterReturning matchReturn, result = product name
==========
execute exceptionMethod(arg=arg)
==========
execute addProduct(id=2, name=name2)
==========
execute deleteProduct(id=1)
==========
execute loopUpProduct(id=2)

2.2.4. Around

@Pointcut("execution(* *..*(Long))")
public void matchLongArg() {
}

@Around("matchLongArg()")
public Object advice5(ProceedingJoinPoint joinPoint) {
    System.out.println("###around before");
    Object result = null;
    try {
        result = joinPoint.proceed(joinPoint.getArgs());
        System.out.println("###around after returning, result = " + result);
    } catch (Throwable throwable) {
        System.out.println("###around after throwing");
    } finally {
        System.out.println("###around finally");
    }
    return result;
}

###around before
execute getProductNameById(id=1)
###around after returning, result = product name
###around finally
==========
execute exceptionMethod(arg=arg)
==========
execute addProduct(id=2, name=name2)
==========
###around before
execute deleteProduct(id=1)
###around after returning, result = null
###around finally
==========
###around before
execute loopUpProduct(id=2)
###around after returning, result = null
###around finally

2.2.5. Before

@Pointcut("execution(* *..*(Long))")
public void matchLongArg() {
}

@Before("matchLongArg() && args(productId)")
public void advice6(Long productId) {
    System.out.println("###before, arg = " + productId);
}

###before, arg = 1
execute getProductNameById(id=1)
==========
execute exceptionMethod(arg=arg)
==========
execute addProduct(id=2, name=name2)
==========
###before, arg = 1
execute deleteProduct(id=1)
==========
###before, arg = 2
execute loopUpProduct(id=2)

2.3. Advice 注解的顺序关系

业务逻辑

@Component
public class LogService {
    public String log(Long id) throws IllegalAccessException {
        Long exceptionId = 2L;
        System.out.println("log from LogService.log");
        if (id.equals(exceptionId)) {
            return "log content: " + id;
        } else {
            throw new IllegalAccessException("exception in LogService.log");
        }
    }
}

定义切面

@Pointcut("execution(* *..log(..))")
public void matchLogMethod() {
}

单元测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class LogServiceTest {
    @Autowired
    LogService logService;
    @Test
    public void testExecution() {
        String result = null;
        try {
            result = logService.log(1L);
            System.out.println("result = " + result);
        } catch (IllegalAccessException ignored) {
        }
        System.out.println("==========");
        try {
            result = logService.log(2L);
            System.out.println("result = " + result);
        } catch (IllegalAccessException ignored) {
        }
    }
}

2.3.1. 没有 Around 注解

###before, arg = 1
log from LogService.log
###afterThrowing matchException
###after matchLongArg
==========
###before, arg = 2
log from LogService.log
###afterReturning matchReturn, result = log content: 2
###after matchLongArg
result = log content: 2

2.3.2. 有 Around 注解

###around before
###before, arg = 1
log from LogService.log
###around after throwing
###around finally
###afterReturning matchReturn, result = null
###after matchLongArg
result = null
==========
###around before
###before, arg = 2
log from LogService.log
###around after returning, result = log content: 2
###around finally
###afterReturning matchReturn, result = log content: 2
###after matchLongArg
result = log content: 2

2.4. 小结

Pointcut 表达式组成：

切面表达式
- designators（描述符）
  - @execution
  - @within
  - @target
  - @args
  - @annotation
- wildcards（通配符）
- operator（操作符）
Advice 注解
- @Before
- @After
- @AfterThrowing
- @AfterReturning
- @Around

3. 实现原理

概述
设计
- 代理模式
- 责任链模式
实现
- JDK 实现
- Cglib 实现

3.1. 原理概述

织入的时机

编译期(AspectJ)
类加载时(AspectJ 5+)
运行时(Spring AOP) √

运行时织入

运行时织入是怎么实现的？
从静态代理到动态代理
基于接口代理和基于继承代理

3.2. 代理模式

public interface Subject {
    void request();
}

public class RealSubject implements Subject {
    @Override
    public void request() {
        System.out.println("real subject execute request");
    }
}

public class ProxySubject implements Subject {
    private final Subject realSubject;
    public ProxySubject(Subject realSubject) {
        this.realSubject = realSubject;
    }
    @Override
    public void request() {
        System.out.println("before");
        try {
            this.realSubject.request();
        } catch (Exception e) {
            System.out.println("ex: " + e.getMessage());
            throw e;
        } finally {
            System.out.println("finally");
        }
    }
}

Subject subject = new ProxySubject(new RealSubject());
subject.request();

before
real subject execute request
finally

3.3. jdk 代理

静态代理和动态代理

静态代理的缺点
动态代理的两类实现：基于接口的代理和基于继承的代理
两类实现的代理：jdk 代理和 cglib 代理

jdk 实现要点

类：java.lang.reflect.Proxy
接口：InvocationHandler
只能基于接口进行动态代理

public interface Subject {
    void request();
    void hello();
}

public class RealSubject implements Subject {
    @Override
    public void request() {
        System.out.println("real subject execute request");
    }
    @Override
    public void hello() {
        System.out.println("real subject execute hello");
    }
}

public class JdkProxySubject implements InvocationHandler {
    private final Subject realSubject;
    public JdkProxySubject(Subject realSubject) {
        this.realSubject = realSubject;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        Object result;
        System.out.println("before");
        try {
            result = method.invoke(realSubject, args);
        } catch (Exception e) {
            System.out.println("ex: " + e.getMessage());
            throw e;
        } finally {
            System.out.println("finally");
        }
        return result;
    }
}

Subject subject = (Subject) Proxy.newProxyInstance(
        SubjectTest.class.getClassLoader(),
        new Class[]{Subject.class},
        new JdkProxySubject(new RealSubject())
);
subject.request();
subject.hello();

before
real subject execute request
finally
before
real subject execute hello
finally

3.4. jdk 代理源码解析

Proxy.newProxyInstance
getProxyClass0、ProxyClassFactory、ProxyGenerator
newInstance

3.4.1. 设置保存生成的动态代理类

// jdk1.8 及之前版本
System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", "true");

// jdk11
System.setProperty("jdk.proxy.ProxyGenerator.saveGeneratedFiles", "true");
// System.getProperties().put("jdk.proxy.ProxyGenerator.saveGeneratedFiles", "true");
// -Djdk.proxy.ProxyGenerator.saveGeneratedFiles=true

3.4.2. 动态代理类源码解析

public final class $Proxy7 extends Proxy implements Subject {
    // ...
    private static Method m3;
    private static Method m4;
    public $Proxy7(InvocationHandler var1) throws  {
        super(var1);
    }
    // ...
}

static {
    try {
        // ...
        m3 = Class.forName("org.example.spring_aop.proxy.jdk.Subject").getMethod("request");
        m4 = Class.forName("org.example.spring_aop.proxy.jdk.Subject").getMethod("hello");
    } catch (NoSuchMethodException var2) {
        throw new NoSuchMethodError(var2.getMessage());
    } catch (ClassNotFoundException var3) {
        throw new NoClassDefFoundError(var3.getMessage());
    }
}

public final void request() throws  {
    try {
        super.h.invoke(this, m3, (Object[])null);
    } catch (RuntimeException | Error var2) {
        throw var2;
    } catch (Throwable var3) {
        throw new UndeclaredThrowableException(var3);
    }
}
public final void hello() throws  {
    try {
        super.h.invoke(this, m4, (Object[])null);
    } catch (RuntimeException | Error var2) {
        throw var2;
    } catch (Throwable var3) {
        throw new UndeclaredThrowableException(var3);
    }
}

3.5. cglib 动态代理

public class DemoMethodInterceptor implements MethodInterceptor {
    @Override
    public Object intercept(Object o, Method method, Object[] objects,
                            MethodProxy methodProxy)
            throws Throwable {
        Object result;
        System.out.println("before in cglib");
        try {
            result = methodProxy.invokeSuper(o, objects);
        } catch (Exception e) {
            System.out.println("ex: " + e.getMessage());
            throw e;
        } finally {
            System.out.println("finally in cglib");
        }
        return result;
    }
}

Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(RealSubject.class);
enhancer.setCallback(new DemoMethodInterceptor());
Subject subject = (Subject) enhancer.create();
subject.request();
subject.hello();

before in cglib
real subject execute request
finally in cglib
before in cglib
real subject execute hello
finally in cglib

jdk 与 cglib 代理对比

jdk 只能针对有接口的类的接口方法进行动态代理
cglib 基于继承来实现代理，无法对 static、final 类进行代理
cglib 基于继承来实现代理，无法对 private、static 方法进行代理

3.6. Spring 对两种实现的选择

Spring 如何选择使用 jdk 代理还是 cglib 代理？

如果目标对象实现了接口，默认使用 jdk 代理
如果目标对象没有实现接口，默认使用 cglib 代理
如果目标对象实现了接口，且强制使用 cglib 代理，则使用 cglib 代理

@SpringBootApplication
// 强制试用 cglib 代理
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class AppDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(AppDemoApplication.class, args);
    }
}

3.7. 责任链模式

3.7.1. 链式调用

public abstract class Handler {
    private Handler successorHandler;
    public Handler getSuccessorHandler() {
        return successorHandler;
    }
    public void setSuccessorHandler(Handler successorHandler) {
        this.successorHandler = successorHandler;
    }
    public void execute() {
        this.handleProcess();
        if (successorHandler != null) {
            this.successorHandler.execute();
        }
    }
    protected abstract void handleProcess();
}

public class HandlerA extends Handler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by A");
    }
}

public class HandlerB extends Handler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by B");
    }
}

public class HandlerC extends Handler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by C");
    }
}

Handler handlerA = new HandlerA();
Handler handlerB = new HandlerB();
Handler handlerC = new HandlerC();
handlerA.setSuccessorHandler(handlerB);
handlerB.setSuccessorHandler(handlerC);
handlerA.execute();

handle by A
handle by B
handle by C

3.7.2. 使用 Chain

public class Chain {
    private final List<ChainHandler> chainHandlers;
    private int index = 0;
    public Chain(List<ChainHandler> chainHandlers) {
        this.chainHandlers = chainHandlers;
    }
    public void proceed() {
        if (index >= this.chainHandlers.size()) {
            return;
        }
        chainHandlers.get(index++).execute(this);
    }
}

public abstract class ChainHandler {
    public void execute(Chain chain) {
        this.handleProcess();
        chain.proceed();
    }
    protected abstract void handleProcess();
}

public class ChainHandlerA extends ChainHandler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by A");
    }
}

public class ChainHandlerB extends ChainHandler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by B");
    }
}

public class ChainHandlerC extends ChainHandler {
    @Override
    protected void handleProcess() {
        System.out.println("handle by C");
    }
}

List<ChainHandler> chainHandlers = Arrays.asList(
        new ChainHandlerA(),
        new ChainHandlerB(),
        new ChainHandlerC()
);
Chain chain = new Chain(chainHandlers);
chain.proceed();

handle by A
handle by B
handle by C

3.8. 小结

静态代理与动态代理
代理模式与责任链模式
jdk 代理与 cglib 代理的区别及局限

4. 经典代码

Spring-AOP 在开源项目中应用

Transactional 注解：事务
PreAuthorize 注解：安全
Cacheable 注解：缓存

4.1. Transactional 注解

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.4.3.RELEASE</version>
  <relativePath/>
</parent>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>${mysql.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <version>${spring.boot.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.3.1</version>
  </dependency>
</dependencies>

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://192.168.9.16:44060/spring_aop_transaction?useUnicode=true&characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=MySQL@root123456
spring.jpa.hibernate.ddl-auto=update
spring.jpa.database-platform=org.hibernate.dialect.MySQL5Dialect

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @Column(unique = true)
    private String name;
    // ...
}

@Entity
public class OperationLog {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String content;
    private Date createdAt;
    // ...
}

public interface UserDao extends JpaRepository<User, Long> {
}

public interface OperationLogDao extends JpaRepository<OperationLog, Long> {
}

@Component
public class DemoService {
    @Autowired
    UserDao userDao;
    @Autowired
    OperationLogDao operationLogDao;
    @Transactional
    public void addUser(String name) {
        OperationLog log = new OperationLog();
        log.setContent("create user:" + name);
        operationLogDao.save(log);
        User user = new User();
        user.setName(name);
        userDao.save(user);
    }
}

@SpringBootApplication
public class TransactionDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(TransactionDemoApplication.class, args);
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class TransactionDemoApplicationTest {
    @Autowired
    DemoService demoService;
    @Test
    public void testWithoutTransaction() {
        demoService.addUser("tom");
    }
}

第一次执行测试，插入日志，插入用户
第二次执行测试，由于无法插入用户，也没有插入日志

4.2. PreAuthorize 注解

安全校验 @PreAuthorize

MethodSecurityInterceptor
PreInvocationAuthorizationAdviceVoter
ExpressionBasedPreInvocationAdvice

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.4.3.RELEASE</version>
  <relativePath/>
</parent>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <version>${spring.boot.version}</version>
    <scope>test</scope>
  </dependency>
</dependencies>

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests()
                .antMatchers("/", "/index").permitAll()
                .anyRequest().authenticated()
                .and()
                .httpBasic()
                .and()
                .logout()
                .permitAll();
    }
    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth)
            throws Exception {
        auth
                .inMemoryAuthentication()
                .withUser("demo").password("demo").roles("USER")
                .and()
                .withUser("admin").password("admin").roles("ADMIN");
    }
}

@RestController
public class DemoController {
    @RequestMapping("/index")
    public String index() {
        return "index";
    }
    @RequestMapping("/common")
    public String commonAccess() {
        return "only login can view";
    }
    @RequestMapping("/admin")
    @PreAuthorize("hasRole('ROLE_ADMIN')")
    public String admin() {
        return "only admin can access";
    }
}

@SpringBootApplication
public class SecurityDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(SecurityDemoApplication.class, args);
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class SecurityDemoApplicationTest {
    @Test
    public void contextLoads() {
    }
}

4.3. Cacheable 注解

缓存 @Cacheable

AnnotationCacheAspect
CacheInterceptor
CacheAspectSupport

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.4.3.RELEASE</version>
  <relativePath/>
</parent>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <version>${spring.boot.version}</version>
    <scope>test</scope>
  </dependency>
</dependencies>

@Component
public class MenuService {
    @Cacheable(cacheNames = {"menu"})
    public List<String> getMenuList() {
        System.out.println("mock:get from db");
        return Arrays.asList("article", "comment", "admin");
    }
}

@SpringBootApplication
@EnableCaching
public class CacheDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(CacheDemoApplication.class, args);
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class CacheDemoApplicationTests {
    @Autowired
    MenuService menuService;
    @Test
    public void testCache() {
        System.out.println("call:" + menuService.getMenuList());
        System.out.println("call:" + menuService.getMenuList());
    }
}

mock:get from db
call:[article, comment, admin]
call:[article, comment, admin]

5. 案例实战

5.1. 实战案例背景和目标

商家产品管理系统
记录产品修改的操作记录
什么人在什么时间修改了哪些产品的哪些字段为什么值

5.2. 实现思路

利用 aspect 去拦截增删改方法
利用反射获取对象的新旧值
利用 @Around 的 advice 去记录操作记录

5.3. pom 依赖

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.4.3.RELEASE</version>
  <relativePath/>
</parent>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>${mysql.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
    <version>${spring.boot.version}</version>
  </dependency>
  <dependency>
    <groupId>commons-beanutils</groupId>
    <artifactId>commons-beanutils</artifactId>
    <version>${beanutils.version}</version>
  </dependency>
  <dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>${fastjson.version}</version>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <version>${spring.boot.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.3.0</version>
  </dependency>
  <dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-impl</artifactId>
    <version>2.3.0</version>
  </dependency>
  <dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-core</artifactId>
    <version>2.3.0</version>
  </dependency>
  <dependency>
    <groupId>javax.activation</groupId>
    <artifactId>activation</artifactId>
    <version>1.1.1</version>
  </dependency>
</dependencies>

5.4. 数据库配置

spring:
  jpa:
    hibernate:
      ddl-auto: update
    properties:
      hibernate:
        enable_lazy_load_no_trans: false
  datasource:
    username: root
    password: MySQL@root123456
    url: jdbc:mysql://192.168.9.16:44060/spring_aop_datalog
    driver-class-name: com.mysql.cj.jdbc.Driver
  data:
    mongodb:
      host: 192.168.9.16
      port: 44061
      database: spring_aop_datalog
      repositories:
        enabled: true

5.5. 领域模型

public class Action {
    private String id;
    private Long objectId;
    private String objectClass;
    private String operator;
    private Date operateTime;
    private ActionType actionType;
    private List<ChangeItem> changes = new ArrayList<>();
    // ...
}

public enum ActionType {
    INSERT("添加", 1),
    UPDATE("更新", 2),
    DELETE("删除", 3);
    // ...
}

public class ChangeItem {
    private String field;
    private String fieldShowName;
    private String oldValue;
    private String newValue;
    // ...
}

public interface ActionDao extends MongoRepository<Action, String> {
}

5.6. 产品模型

@Entity
public class Product {
    @Id
    @GeneratedValue
    private Long id;
    @Datalog(name = "产品名称")
    private String name;
    private String category;
    private String detail;
    private BigDecimal buyPrice;
    private BigDecimal sellPrice;
    private String provider;
    private Date onlineTime;
    private Date updateTime;
    public Product() {
    }
    public Product(String name) {
        this.name = name;
    }
    // ...
}

@Target({ElementType.FIELD, ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Datalog {
    // 中文字段名
    String name();
}

public interface ProductDao extends JpaRepository<Product, Long> {
    Product findById(Long id);
}

5.7. 切面设计

@Aspect
@Component
public class DatalogAspect {
    private static final Logger logger = LoggerFactory.getLogger(DatalogAspect.class);
    @Autowired
    ActionDao actionDao;
    @Pointcut("execution(public * org.example.spring_aop.datalog.dao.*.save*(..))")
    public void save() {
    }
    @Pointcut("execution(public * org.example.spring_aop.datalog.dao.*.delete*(..))")
    public void delete() {
    }
    // ...
}

5.8. Around 注解

/**
 * 1、判断是什么类型的操作,增加 / 删除 / 还是更新
 * 增加 / 更新 save(Product), 通过 id 区分是增加还是更新
 * 删除 delete(id)
 * 2、获取 changeItem
 * (1)新增操作, before 直接获取, after 记录下新增之后的 id
 * (2)更新操作, before 获取操作之前的记录, after 获取操作之后的记录,然后 diff
 * (3)删除操作, before 根据 id 取记录
 * 3、保存操作记录
 *
 * @param pjp pjp
 * @return Object
 * @throws Throwable Throwable
 */
@Around("save() || delete()")
public Object addOperateLog(ProceedingJoinPoint pjp) throws Throwable {
    Object returnObj = null;
    // TODO BEFORE OPERATION init action
    String method = pjp.getSignature().getName();
    ActionType actionType = null;
    Action action = new Action();
    Long id = null;
    Object oldObj = null;
    try {
        if ("save".equals(method)) {
            // insert or update
        } else if ("delete".equals(method)) {
            // delete
        }
        returnObj = pjp.proceed(pjp.getArgs());
        // TODO AFTER OPERATION save action
        action.setActionType(actionType);
        if (ActionType.INSERT == actionType) {
            // new id
        } else if (ActionType.UPDATE == actionType) {
            // old value and new value
        }
        // dynamic get from threadLocal / session
        action.setOperator("admin");
        action.setOperateTime(new Date());
        actionDao.save(action);
    } catch (Exception e) {
        logger.error(e.getMessage(), e);
    }
    return returnObj;
}

// insert or update
Object obj = pjp.getArgs()[0];
try {
    id = Long.valueOf(PropertyUtils.getProperty(obj, "id").toString());
} catch (Exception e) {
    // ignore
}
if (id == null) {
    actionType = ActionType.INSERT;
    List<ChangeItem> changeItems = DiffUtil.getInsertChangeItems(obj);
    action.getChanges().addAll(changeItems);
    action.setObjectClass(obj.getClass().getName());
} else {
    actionType = ActionType.UPDATE;
    action.setObjectId(id);
    oldObj = DiffUtil.getObjectById(pjp.getTarget(), id);
    action.setObjectClass(oldObj.getClass().getName());
}

// delete
id = Long.valueOf(pjp.getArgs()[0].toString());
actionType = ActionType.DELETE;
oldObj = DiffUtil.getObjectById(pjp.getTarget(), id);
ChangeItem changeItem = DiffUtil.getDeleteChangeItem(oldObj);
action.getChanges().add(changeItem);
action.setObjectId(Long.valueOf(pjp.getArgs()[0].toString()));
action.setObjectClass(oldObj.getClass().getName());

// new id
Object newId = PropertyUtils.getProperty(returnObj, "id");
action.setObjectId(Long.valueOf(newId.toString()));

// old value and new value
Object newObj = DiffUtil.getObjectById(pjp.getTarget(), id);
List<ChangeItem> changeItems = DiffUtil.getChangeItems(oldObj, newObj);
action.getChanges().addAll(changeItems);

5.9. 获取新旧值

public static List<ChangeItem> getChangeItems(Object oldObj, Object newObj) {
    Class cl = oldObj.getClass();
    List<ChangeItem> changeItems = new ArrayList<ChangeItem>();
    // 获取字段中文名称
    Map<String, String> fieldCnNameMap = getFieldNameMap(cl);
    try {
        BeanInfo beanInfo = Introspector.getBeanInfo(cl, Object.class);
        for (PropertyDescriptor propertyDescriptor : beanInfo.getPropertyDescriptors()) {
            String field = propertyDescriptor.getName();
            // 获取字段旧值
            String oldProp = getValue(PropertyUtils.getProperty(oldObj, field));
            // 获取字段新值
            String newProp = getValue(PropertyUtils.getProperty(newObj, field));
            // 对比新旧值
            if (!oldProp.equals(newProp)) {
                ChangeItem changeItem = new ChangeItem();
                changeItem.setField(field);
                String cnName = fieldCnNameMap.get(field);
                changeItem.setFieldShowName(StringUtils.isEmpty(cnName) ? field : cnName);
                changeItem.setNewValue(newProp);
                changeItem.setOldValue(oldProp);
                changeItems.add(changeItem);
            }
        }
    } catch (Exception e) {
        logger.error("There is error when convert changeItem", e);
    }
    return changeItems;
}

5.10. 程序入口

@SpringBootApplication
public class DatalogApplication {
    public static void main(String[] args) {
        SpringApplication.run(DatalogApplication.class, args);
    }
}

5.11. 单元测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class DatalogApplicationTests {
    @Autowired
    ProductDao productDao;
    // ...
}

@Test
public void testInsert() {
    Product product = new Product();
    product.setName("dell computer");
    product.setOnlineTime(new Date());
    product.setBuyPrice(new BigDecimal("29.5"));
    product.setCategory("computer");
    product.setDetail("this is a dell notebook");
    product.setUpdateTime(new Date());
    productDao.save(product);
    System.out.println("new product id:" + product.getId());
}

@Test
public void testUpdate() {
    Product product = productDao.findOne(1L);
    product.setName("test-update");
    product.setBuyPrice(new BigDecimal("23.5"));
    product.setOnlineTime(new Date());
    productDao.save(product);
}

@Test
public void testDelete() {
    productDao.delete(1L);
}

5.12. 小结

利用反射获取新旧值
利用 Around 的 advice 去记录修改记录
利用注解去增加中文字段名

6. 课程总结

6.1. 课程要点

AOP 的适用范围及优劣势
AOP 的概念及 Spring 的切面表达式
AOP 的实现原理及运用

6.2. 使用 Spring AOP 的注意事项/坑

不要把重要的业务逻辑放到 AOP 中处理
无法拦截 static、final 方法，private 方法
无法拦截内部方法调用

6.2.1. 第二次调用无法走缓存

@Component
public class MenuService {
    @Cacheable(cacheNames = {"menu"})
    public List<String> getMenuList() {
        System.out.println("mock:get from db");
        return Arrays.asList("article", "comment", "admin");
    }
    public List<String> getRecommends() {
        System.out.println("inner call");
        return getMenuList();
    }
}

@Test
public void testInnerCall() {
    System.out.println("call:" + menuService.getRecommends());
    System.out.println("call:" + menuService.getRecommends());
}

inner call
mock:get from db
call:[article, comment, admin]
inner call
mock:get from db
call:[article, comment, admin]

6.2.2. 第二次调用走缓存

@Component
public class MenuService {
    @Cacheable(cacheNames = {"menu"})
    public List<String> getMenuList() {
        System.out.println("mock:get from db");
        return Arrays.asList("article", "comment", "admin");
    }
    public List<String> getRecommends() {
        System.out.println("inner call");
        MenuService proxy = ApplicationContextHolder.getContext().getBean(MenuService.class);
        return proxy.getMenuList();
    }
}

@Component
public class ApplicationContextHolder implements ApplicationContextAware {
    private static ApplicationContext ctx;
    public static ApplicationContext getContext() {
        return ctx;
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
            throws BeansException {
        ctx = applicationContext;
    }
}

@Test
public void testInnerCall() {
    System.out.println("call:" + menuService.getRecommends());
    System.out.println("call:" + menuService.getRecommends());
}

inner call
mock:get from db
call:[article, comment, admin]
inner call
call:[article, comment, admin]

6.3. 小结

合理利用面向切面编程提升代码质量
掌握 Spring AOP 概念及实现原理
了解 AOP 的优缺点及 Spring AOP 的使用局限

Spring-AOP

1. 实现一个权限控制

1.1. 传统方式

1.2. AOP 方式

1.3. 单元测试

2. 使用详解

2.1. 切面表达式

2.1.1. 匹配方法

2.1.2. 匹配包/类型

2.1.3. 匹配对象

2.1.4. 匹配参数

2.1.5. 匹配注解

2.2. Advice 注解

2.2.1. After

2.2.2. AfterThrowing

2.2.3. AfterReturning

2.2.4. Around

2.2.5. Before

2.3. Advice 注解的顺序关系

2.3.1. 没有 Around 注解

2.3.2. 有 Around 注解

2.4. 小结

3. 实现原理

3.1. 原理概述

3.2. 代理模式

3.3. jdk 代理

3.4. jdk 代理源码解析

3.4.1. 设置保存生成的动态代理类

3.4.2. 动态代理类源码解析

3.5. cglib 动态代理

3.6. Spring 对两种实现的选择

3.7. 责任链模式

3.7.1. 链式调用

3.7.2. 使用 Chain

3.8. 小结

4. 经典代码

4.1. Transactional 注解

4.2. PreAuthorize 注解

4.3. Cacheable 注解

5. 案例实战

5.1. 实战案例背景和目标

5.2. 实现思路

5.3. pom 依赖

5.4. 数据库配置

5.5. 领域模型

5.6. 产品模型

5.7. 切面设计

5.8. Around 注解

5.9. 获取新旧值

5.10. 程序入口

5.11. 单元测试

5.12. 小结

6. 课程总结

6.1. 课程要点

6.2. 使用 Spring AOP 的注意事项/坑

6.2.1. 第二次调用无法走缓存

6.2.2. 第二次调用走缓存

6.3. 小结

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