用户在导出统计数据时需要导出大量图片.目前用的比较多的poi导出能支持批量导出大量数据(不包括自媒体).但是当需要导出大量图片时,即使设置了flushSize ,但是对于图片对象却没有效果,图片在内存中无法释放,写的图片越多,占用内存越大,导致频繁GC,甚至OOM
excel文件由声明,表数据,单元格数据,媒体文件等等组件组成, 这些组件分别对应了不同的数据单元.只要把数据分别写入对应的组件,最后构建成一个需要的excel文件.
采用流式方法写入文件,不会导致内存堆积而占用太多系统资源,有效避免频繁GC问题
- 支持自动合并单元格
- 使用流式处理,支持大量图片导出
- 支持注解导出,在实体上添加注解,自动生成标题
经测试,可以生成几个G的文件。(保证生成的文件没问题,文件是否能打开由使用者计算机决定)
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在项目的pom.xml的dependencies中加入以下内容: 点击查看最新版本 ${excel-x.version}
<dependency>
<groupId>top.minwk</groupId>
<artifactId>excel-x</artifactId>
<version>${excel-x.version}</version>
</dependency>
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@GetMapping("/export/lastversion/{row}") public void exportLastVersion(HttpServletResponse response, @PathVariable int row) throws IOException { /* 操作窗口 当写入excel数据行数大于flushSize时{@link Sheet.SheetHandler#createRow(int)}, 会刷新数据到流,调用该方法 {@link com.ibiz.excel.picture.support.flush.DrawingXmlRelsHandler#copyPictureAppendDrawingRelsXML(Sheet, Picture)} 将图片刷新在磁盘中 不会占用内存空间 flushSize = -1 时不刷新流 */ Workbook workBook = Workbook.getInstance(1); Sheet sheet = workBook.createSheet("测试"); // 给标题行加上背景色,加颜色时,会对字体加粗 sheet.addCellStyle(new CellStyle(0, "66cc66")); List<UserPicture> list = new ArrayList<>(); UserPicture userPicture; for (int r = 0; r < row; r++) { userPicture = new UserPicture(); userPicture.setAge(15); userPicture.setName("测试-" + r); // 导出本地单张图片 userPicture.setPicture("E:\\test\\img\\1.jpg"); // 导出url单张图片 userPicture.setHeaderPicture("https://portrait.gitee.com/uploads/avatars/user/552/1657608_mwk719_1641537497.png"); // 导出本地图片集合 userPicture.setPictures(Arrays.asList("E:\\test\\img\\1.jpg","E:\\test\\img\\2.jpg")); // 导出url图片集合 userPicture.setUrlPictures(Arrays.asList("https://portrait.gitee.com/uploads/avatars/user/552/1657608_mwk719_1641537497.png", "https://img2.baidu.com/it/u=2602880481,728201544&fm=26&fmt=auto")); list.add(userPicture); } sheet.write(UserPicture.class).createRow(list); WebUtil.writeExcel(workBook, "最新使用示例代码导出".concat(String.valueOf(System.currentTimeMillis())).concat(".xlsx"), response); }
/** * @auther 喻场 * @date 2020/7/813:41 */ public class UserPicture { public UserPicture() { } @ExportModel( sort = 0, title = "姓名") private String name; @ExportModel(sort = 1, title = "年龄") private Integer age; @ExportModel(sort = 3, title = "部门") private String department; @ExportModel(sort = 2, isPicture = true, title = "图片1") private String picture; @ExportModel(sort = 4, isPicture = true, title = "图片2") private String headerPicture; @ExportModel(sort = 5, isPicture = true, title = "多图片") private List<String> pictures; @ExportModel(sort = 6, isPicture = true, title = "url多图片") private List<String> urlPictures; public UserPicture(String name, Integer age, String department, String picture) { this.name = name; this.age = age; this.department = department; this.picture = picture; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getDepartment() { return department; } public void setDepartment(String department) { this.department = department; } public String getPicture() { return picture; } public void setPicture(String picture) { this.picture = picture; } public String getHeaderPicture() { return headerPicture; } public void setHeaderPicture(String headerPicture) { this.headerPicture = headerPicture; } public List<String> getPictures() { return pictures; } public void setPictures(List<String> pictures) { this.pictures = pictures; } public List<String> getUrlPictures() { return urlPictures; } public void setUrlPictures(List<String> urlPictures) { this.urlPictures = urlPictures; } }
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实体对象需要实现BizExcelPojoInterface接口
@GetMapping("/export/dynamic-config-header") public void exportDynamicConfigHeader(HttpServletResponse response) throws IOException { // 模拟需要导出的数据集合 List<Student> students = new ArrayList<>(); students.add(new Student("李四", 16, null, null, 0)); students.add(new Student("张三", 17, null, Arrays.asList("https://portrait.gitee.com/uploads/avatars/user/552/1657608_mwk719_1641537497.png", "https://img2.baidu.com/it/u=2602880481,728201544&fm=26&fmt=auto"), 1)); students.add(new Student("王五", 15, IMG_PATH_1, null, 2)); // 配置导出excel的表头、顺序、对应导出的数据集合的字段、是否是图片、单元格宽度等 List<BizExcelRel> excels = new ArrayList<>(); excels.add(new BizExcelRel("姓名", "name", 2)); excels.add(new BizExcelRel("年龄", "age", 3)); excels.add(new BizExcelRel("表现", "performance", 4)); excels.add(new BizExcelRel("头像", "headPicture", 5, true, 20)); excels.add(new BizExcelRel("相册", "album", 6, true)); // 创建excel Workbook workBook = Workbook.getInstance(100); Sheet sheet = workBook.createSheet("测试"); // 创建样式 CellStyle cellStyle = new CellStyle(0, "F0F0F0"); // 创建数据字典 Map<String, String> performanceMap = new HashMap<>(3); performanceMap.put("0", "一般"); performanceMap.put("1", "良好"); performanceMap.put("2", "优秀"); // 构建sheet ExcelTableProcessor.sheet(sheet) // 添加样式 .addCellStyle(cellStyle) // 添加对应属性字段的数据字典 .registryEnumMap("performance", performanceMap) // 构建excel .buildExcel(excels, students); WebUtil.writeExcel(workBook, "ExportExampleDynamicConfigHeader".concat(String.valueOf(System.currentTimeMillis())).concat(".xlsx"), response); }
public class Student implements BizExcelPojoInterface { public Student(String name, Integer age) { this.name = name; this.age = age; } public Student(String name, Integer age, String headPicture) { this.name = name; this.age = age; this.headPicture = headPicture; } public Student(String name, Integer age, String headPicture, List<String> album, Integer performance) { this.name = name; this.age = age; this.headPicture = headPicture; this.album = album; this.performance = performance; } private String name; private Integer age; private String headPicture; /** * 相册 */ private List<String> album; /** * 表现 0一般;1良好;2优秀 */ private Integer performance; public Integer getPerformance() { return performance; } public void setPerformance(Integer performance) { this.performance = performance; } public List<String> getAlbum() { return album; } public void setAlbum(List<String> album) { this.album = album; } public String getHeadPicture() { return headPicture; } public void setHeadPicture(String headPicture) { this.headPicture = headPicture; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } }
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excel含图片导出demo地址,具体使用以后缀最新日期为准,其他示例仅供测试
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设置项目jvm堆栈大小都是20m
-Xms20m -Xmx20m -Dfile.encoding=UTF-8 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=D:\log\springlearn.hprof
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复制上方 【最新使用示例代码】到项目中
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找一堆图片随机添加到UserPicture中
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导出一个5000条的记录,在最大堆栈占用为20m的情况下,导出excel大小为700m,未发生内存溢出情况
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- 修复合并后的单元格没有边框线
- 添加导出网络链接图片到excel中
- 添加createRow集合列表生成excel方法
- 修改CellStyle样式的使用
- 添加用户可自定义背景色样式
- 添加使用注解可对图片集合进行导出
- 添加自定义图片的高度;图片高度和单元格高度自适应
- 修复导出图片集合变多时单元格宽度不够
- 修复导出数据行数大于100 excel打开异常
- 修复导出多组图片excel中缺失部分图片问题
- 添加使用注解导出含图片或文本的使用示例
- 修复图片遮挡所在单元格边框线
- 修复f使用注解导出图片所在下边框不是加粗实线
- 简化使用示例
- 修复flushSize = -1 时不刷新流
- 修复其他未知问题
- 修复MD5时未关闭流
- 添加合并单元列值
- 添加设置单元格背景色
- 添加可自定义单元格宽度
- 添加设置字体,目前有默认字体
- 修复office打开提示需修复的问题
EXCEL由几大组件构建而成
- workbook代表一个excel工作文件
- Sheet对应文件中多个sheet页
- Row 为sheet页中的行数据,包含多个Cell单元格
- Cell 具体单元格数据
- MergeCell 合并单元格信息,指定了合并起始行和结束行,起始列和结束列
- Picture 为图片信息,一个Sheet有n个Picture
需要导出的字段使用ExportModel注解,程序会自动识别标题,合并单元格,插入图片
/**
* 导出模型
* 使用该注解程序会根据相应属性对单元格做设置
*/
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface ExportModel {
/**排序*/
int sort() default 0;
/**是否是图片*/
boolean isPicture() default false;
/**表头*/
String title() default "";
/**已这列为准进行合并列*/
boolean mergeMaster() default false;
/**这一列是否要合并*/
boolean merge() default false;
}
创建一个工作文件,需要经过一个工作周期,分别对应init(初始化) , write(写数据), close(关闭)
init 初始化各个组件,构建流并写入组件头部信息 write 写入内容 close 写入剩余内存中的数据到流, 写入组件尾部信息,关闭工作文件
init, write, close分别对应了三种事件,程序使用事件驱动机制,当监听器监听到组件在执行对应注册事件时分别进行相应操作
事件
监听器
部分代码
public interface WorkbookEvent<E extends ContentListener> {
WorkbookEvent registry(E listener);
void onEvent(Sheet sheet);
}
public class InitListener extends AbstractContentListener {
@Override
public void invoke(Sheet sheet) {
repositories.forEach(r -> r.write(sheet));
}
}
触发init事件,最后一行
void init() {
sheetContext = SheetContext.getInstance(Sheet.this);
ContentListener init = ListenerFactory.getInstance(InitListener.class);
ContentListener flush = ListenerFactory.getInstance(FlushListener.class);
ContentListener close = ListenerFactory.getInstance(CloseListener.class);
sheetContext.getRepositoryHolder().forEach((alias, rep) -> {
if (!closeAlias.contains(alias)) {
//app.xml workbook.xml最后写,考虑getSheetName
init.addRepository(rep);
flush.addRepository(rep);
}
close.addRepository(rep);
});
sheetContext.getEvents().add(EventFactory.getInstance(InitEvent.class).registry(init));
sheetContext.getEvents().add(EventFactory.getInstance(FlushEvent.class).registry(flush));
sheetContext.getEvents().add(EventFactory.getInstance(CloseEvent.class).registry(close));
//创建组件文件
sheetContext.getEvents().stream().filter(e -> e instanceof InitEvent).forEach(e -> e.onEvent(Sheet.this));
}
Write方法很简单,只是把内存中的缓存写入流。
public void write(Sheet sheet) {
try {
if (null == write) {
return;
}
writeToStream();
} catch (Exception e) {
throw new RuntimeException("写文件异常 :" + file.getAbsolutePath(), e);
}
}
private void writeToStream() {
try {
if (!hasWriteXmlHead && writeXmlHead) {
write.write(AutoXmlHeadEndContent.XML_HEAD);
hasWriteXmlHead = true;
}
write.write(content.toString());
clearContent();
} catch (IOException e) {
throw new RuntimeException("写文件异常 :" + file.getAbsolutePath(), e);
}
}
在写入流之前,需要把写入的数据先写入缓存中,这里使用代理。部分代码:
public class Sheet1Handler implements InvocationHandler {
private IRepository target;
public Sheet1Handler(IRepository proxy) {
this.target = proxy;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Sheet sheet = (Sheet)args[0];
if (method.getName().equals("write")) {
List<Row> rows = sheet.getRows();
if (!rows.isEmpty()) {
//未刷新过说明没有写入过流,这里主要为了写表头
//如果写过了,则从脚标1开始,原因是为了对比合并单元格在row1中保存上一次刷新的最后一条数据
int subIndex = !sheet.hasFlush() ? 0 : 1;
setMergeCell(sheet, rows);
rows.subList(subIndex, rows.size()).stream().forEach(r -> writeSheetXML(r));
}
} else if (method.getName().equals("close")) {
setEndSheetData();
setMergeContent(sheet);
}
return method.invoke(target, args);
}
}