网站 流量 不够用二级网站免费建

相关文章链接

1. Easyexcel（1-注解使用）
2. Easyexcel（2-文件读取）
3. Easyexcel（3-文件导出）

响应头设置

通过设置文件导出的响应头，可以自定义文件导出的名字信息等

//编码格式为UTF-8
response.setCharacterEncoding("UTF-8");//让服务器告诉浏览器它发送的数据属于excel文件类型
response.setContentType("application/vnd.ms-excel;charset=UTF-8");//描述内容在传输过程中的编码格式，BINARY可能不止包含非ASCII字符，还可能不是一个短行（超过1000字符）。
response.setHeader("Content-Transfer-Encoding", "binary");//must-revalidate：强制页面不缓存，post-check=0, pre-check=0：0秒后，在显示给用户之前，该对象被选中进行更新过
response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");//表示响应可能是任何缓存的，即使它只是通常是非缓存或可缓存的仅在非共享缓存中
response.setHeader("Pragma", "public");//告诉浏览器这个文件的名字和类型，attachment：作为附件下载；inline：直接打开
response.setHeader("Content-Disposition", "attachment;filename=" + fileName + ".xls");

写入单个Sheet

一次性写入数据

指定导出内容所对应的对象信息，通过doWrite写入数据

注意：doWrite方法必须传入的是集合

@Data
public class User {@ExcelProperty(value = "用户Id")private Integer userId;@ExcelProperty(value = "姓名")private String name;@ExcelProperty(value = "手机")private String phone;@ExcelProperty(value = "邮箱")private String email;@ExcelProperty(value = "创建时间")private Date createTime;
}

@GetMapping("/download1")
public void download1(HttpServletResponse response) {try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");User user = new User();user.setUserId(123);user.setName("as");user.setPhone("15213");user.setEmail("5456");user.setCreateTime(new Date());EasyExcel.write(response.getOutputStream(), User.class).sheet("模板").doWrite(Arrays.asList(user));} catch (Exception e) {e.printStackTrace();}
}

分批写入数据

@GetMapping("/download2")
public void download2(HttpServletResponse response) {ExcelWriter excelWriter = null;try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");User user = new User();user.setUserId(123);user.setName("as");user.setPhone("15213");user.setEmail("5456");user.setCreateTime(new Date());excelWriter = EasyExcel.write(response.getOutputStream(), User.class).build();WriteSheet writeSheet = EasyExcel.writerSheet("测试").build();// 业务逻辑处理，分页查询excelWriter.write(Arrays.asList(user), writeSheet);excelWriter.write(Arrays.asList(user), writeSheet);} catch (Exception e) {e.printStackTrace();} finally {if (excelWriter != null) {excelWriter.finish();}}
}

通过WriteSheet对象可以指定要写入的Sheet，通过上面方式我们可以手工控制流的关闭，这样我们就可以实现多次写。可以实现分页查询获取数据，然后将数据写入Excel中，避免一次性加载的数据过多，导致内存溢出

在使用excelWriter.write方式时务必保证至少执行一次write，这样是为了将sheet和表头写入excel，否则打开excel时会报错。write的第一个参数可以为null

导出表头自定义

使用注解的方式定义表头时不能动态控制，每次修改表头内容时只能重新修改代码，这时可以通过head方法动态传参自定义表头

注意：内容结构必须是List<List<T>>，如果使用List<T>会出现问题

@GetMapping("/download3")
public void download3(HttpServletResponse response) {ExcelWriter excelWriter = null;try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");User user = new User();user.setUserId(123);user.setName("as");user.setPhone("15213");user.setEmail("5456");user.setCreateTime(new Date());List<List<String>> heads = new ArrayList<>();heads.add(Arrays.asList("姓名"));heads.add(Arrays.asList("年龄"));heads.add(Arrays.asList("地址"));excelWriter = EasyExcel.write(response.getOutputStream()).head(heads).build();WriteSheet writeSheet = EasyExcel.writerSheet("测试").build();excelWriter.write(Arrays.asList(user), writeSheet);} catch (Exception e) {e.printStackTrace();} finally {if (excelWriter != null) {excelWriter.finish();}}
}

导出内容自定义

当导出的内容不是某个固定的实体类时，希望导出不同的内容时可以通过List<List<String>>自定义要写入的内容

@GetMapping("/download5")
public void download5(HttpServletResponse response) {ExcelWriter excelWriter = null;try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");List<List<String>> heads = new ArrayList<>();heads.add(Arrays.asList("姓名"));heads.add(Arrays.asList("年龄"));heads.add(Arrays.asList("地址"));excelWriter = EasyExcel.write(response.getOutputStream()).head(heads).build();WriteSheet writeSheet = EasyExcel.writerSheet("测试").build();List<List<String>> dataList = new ArrayList<>();dataList.add(Arrays.asList("张三", "18", "上海"));dataList.add(Arrays.asList("李四", "28"));excelWriter.write(dataList, writeSheet);} catch (Exception e) {e.printStackTrace();} finally {if (excelWriter != null) {excelWriter.finish();}}
}

写入多个表头

若业务需求要求在同一个Sheet中写多个表，就需要用到WriteTable了。只定义一个WriteSheet，有几个表就定义几个WriteTable即可

@GetMapping("/download4")
public void download4(HttpServletResponse response) {ExcelWriter excelWriter = null;try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");User user = new User();user.setUserId(123);user.setName("as");user.setPhone("15213");user.setEmail("5456");user.setCreateTime(new Date());excelWriter = EasyExcel.write(response.getOutputStream()).build();WriteSheet writeSheet = EasyExcel.writerSheet("测试").build();List<List<String>> heads1 = new ArrayList<>();heads1.add(Arrays.asList("姓名"));heads1.add(Arrays.asList("年龄"));heads1.add(Arrays.asList("地址"));WriteTable writeTable1 = EasyExcel.writerTable(1).head(heads1).needHead(true).build();List<List<String>> heads2 = new ArrayList<>();heads2.add(Arrays.asList("姓名"));heads2.add(Arrays.asList("年龄"));heads2.add(Arrays.asList("地址"));heads2.add(Arrays.asList("出生日期"));WriteTable writeTable2 = EasyExcel.writerTable(2).head(heads2).needHead(true).build();excelWriter.write(Arrays.asList(user), writeSheet, writeTable1);excelWriter.write(Arrays.asList(user), writeSheet, writeTable2);} catch (Exception e) {e.printStackTrace();} finally {if (excelWriter != null) {excelWriter.finish();}}
}

写入多个Sheet

通过EasyExcel.writerSheet创建对应的sheet，然后在写入sheet时指定对应的WriteSheet即可，同时可指定每个Sheet对应的对象

@GetMapping("/download6")
public void download6(HttpServletResponse response) {ExcelWriter excelWriter = null;try {response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xls");List<List<String>> heads = new ArrayList<>();heads.add(Arrays.asList("姓名"));heads.add(Arrays.asList("年龄"));heads.add(Arrays.asList("地址"));excelWriter = EasyExcel.write(response.getOutputStream()).head(heads).build();WriteSheet writeSheet1 = EasyExcel.writerSheet(0, "测试1").build();WriteSheet writeSheet2 = EasyExcel.writerSheet(1, "测试2").build();User user = new User();user.setUserId(123);user.setName("as");user.setPhone("15213");user.setEmail("5456");user.setCreateTime(new Date());excelWriter.write(Arrays.asList(user), writeSheet1);excelWriter.write(Arrays.asList(user), writeSheet2);} catch (Exception e) {e.printStackTrace();} finally {if (excelWriter != null) {excelWriter.finish();}}
}