优化读写逻辑

README.md

@@ -67,27 +67,36 @@ DEMO代码地址：[https://github.com/alibaba/easyexcel/blob/master/src/test/ja
     }
 ```
 
-### web下载实例写法
-```
-public class Down {
-    @GetMapping("/a.htm")
-    public void cooperation(HttpServletRequest request, HttpServletResponse response) {
-        ServletOutputStream out = response.getOutputStream();
-         response.setContentType("multipart/form-data");
+### web上传、下载
+DEMO代码地址：[https://github.com/alibaba/easyexcel/blob/master/src/test/java/com/alibaba/easyexcel/test/demo/web/WebTest.java](/src/test/java/com/alibaba/easyexcel/test/demo/web/WebTest.java)
+```java
+ /**
+     * 文件下载
+     * <li>1. 创建excel对应的实体对象 参照{@link DownloadData}
+     * <li>2. 设置返回的 参数
+     * <li>3. 直接写，这里注意，finish的时候会自动关闭OutputStream,当然你外面再关闭异常问题不大
+     */
+    @GetMapping("download")
+    public void download(HttpServletResponse response) throws IOException {
+        response.setContentType("application/vnd.ms-excel");
         response.setCharacterEncoding("utf-8");
-        response.setHeader("Content-disposition", "attachment;filename="+fileName+".xlsx");
-        ExcelWriter writer = new ExcelWriter(out, ExcelTypeEnum.XLSX, true);
-        String fileName = new String(("UserInfo " + new SimpleDateFormat("yyyy-MM-dd").format(new Date()))
-                .getBytes(), "UTF-8");
-        Sheet sheet1 = new Sheet(1, 0);
-        sheet1.setSheetName("第一个sheet");
-        writer.write0(getListString(), sheet1);
-        writer.finish();
-      
-        out.flush();
-        }
+        response.setHeader("Content-disposition", "attachment;filename=demo.xlsx");
+        EasyExcelFactory.write(response.getOutputStream(), DownloadData.class).sheet("模板").doWrite(data()).finish();
+    }
+
+    /**
+     * 文件上传
+     * <li>1. 创建excel对应的实体对象 参照{@link UploadData}
+     * <li>2. 由于默认异步读取excel，所以需要创建excel一行一行的回调监听器，参照{@link UploadDataListener}
+     * <li>3. 直接读即可
+     */
+    @PostMapping("upload")
+    @ResponseBody
+    public String upload(MultipartFile file) throws IOException {
+        EasyExcelFactory.read(file.getInputStream(), UploadData.class, new UploadDataListener()).sheet().doRead()
+            .finish();
+        return "success";
     }
-}
 ```
 ### 联系我们
 有问题阿里同事可以通过钉钉找到我，阿里外同学可以通过git留言。其他技术非技术相关的也欢迎一起探讨。

src/main/java/com/alibaba/excel/write/builder/ExcelWriterBuilder.java

@@ -192,7 +192,7 @@ public class ExcelWriterBuilder {
         if (sheetName != null) {
             excelWriterSheetBuilder.sheetName(sheetName);
         }
-        return new ExcelWriterSheetBuilder(excelWriter);
+        return excelWriterSheetBuilder;
     }
 
 }

src/test/java/com/alibaba/easyexcel/test/demo/web/DownloadData.java

@@ -0,0 +1,22 @@
+package com.alibaba.easyexcel.test.demo.web;
+
+import java.util.Date;
+
+import com.alibaba.excel.annotation.ExcelProperty;
+
+import lombok.Data;
+
+/**
+ * 基础数据类
+ *
+ * @author zhuangjiaju
+ **/
+@Data
+public class DownloadData {
+    @ExcelProperty("字符串标题")
+    private String string;
+    @ExcelProperty("日期标题")
+    private Date date;
+    @ExcelProperty("数字标题")
+    private Double doubleData;
+}

src/test/java/com/alibaba/easyexcel/test/demo/web/UploadData.java

@@ -0,0 +1,17 @@
+package com.alibaba.easyexcel.test.demo.web;
+
+import java.util.Date;
+
+import lombok.Data;
+
+/**
+ * 基础数据类
+ *
+ * @author zhuangjiaju
+ **/
+@Data
+public class UploadData {
+    private String string;
+    private Date date;
+    private Double doubleData;
+}

src/test/java/com/alibaba/easyexcel/test/demo/web/UploadDataListener.java

@@ -0,0 +1,49 @@
+package com.alibaba.easyexcel.test.demo.web;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.alibaba.excel.context.AnalysisContext;
+import com.alibaba.excel.event.AnalysisEventListener;
+import com.alibaba.fastjson.JSON;
+
+/**
+ * 模板的读取类
+ *
+ * @author zhuangjiaju
+ */
+public class UploadDataListener extends AnalysisEventListener<UploadData> {
+    private static final Logger LOGGER = LoggerFactory.getLogger(UploadDataListener.class);
+    /**
+     * 每隔5条存储数据库，实际使用中可以3000条，然后清理list ，方便内存回收
+     */
+    private static final int BATCH_COUNT = 5;
+    List<UploadData> list = new ArrayList<UploadData>();
+
+    @Override
+    public void invoke(UploadData data, AnalysisContext context) {
+        LOGGER.info("解析到一条数据:{}", JSON.toJSONString(data));
+        list.add(data);
+        if (list.size() >= BATCH_COUNT) {
+            saveData();
+            list.clear();
+        }
+    }
+
+    @Override
+    public void doAfterAllAnalysed(AnalysisContext context) {
+        saveData();
+        LOGGER.info("所有数据解析完成！");
+    }
+
+    /**
+     * 加上存储数据库
+     */
+    private void saveData() {
+        LOGGER.info("{}条数据，开始存储数据库！", list.size());
+        LOGGER.info("存储数据库成功！");
+    }
+}

src/test/java/com/alibaba/easyexcel/test/demo/web/WebTest.java

@@ -0,0 +1,64 @@
+package com.alibaba.easyexcel.test.demo.web;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
+import javax.servlet.http.HttpServletResponse;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.multipart.MultipartFile;
+
+import com.alibaba.excel.EasyExcelFactory;
+
+/**
+ * web读写案例
+ *
+ * @author zhuangjiaju
+ **/
+@Controller
+public class WebTest {
+    /**
+     * 文件下载
+     * <li>1. 创建excel对应的实体对象 参照{@link DownloadData}
+     * <li>2. 设置返回的 参数
+     * <li>3. 直接写，这里注意，finish的时候会自动关闭OutputStream,当然你外面再关闭异常问题不大
+     */
+    @GetMapping("download")
+    public void download(HttpServletResponse response) throws IOException {
+        response.setContentType("application/vnd.ms-excel");
+        response.setCharacterEncoding("utf-8");
+        response.setHeader("Content-disposition", "attachment;filename=demo.xlsx");
+        EasyExcelFactory.write(response.getOutputStream(), DownloadData.class).sheet("模板").doWrite(data()).finish();
+    }
+
+    /**
+     * 文件上传
+     * <li>1. 创建excel对应的实体对象 参照{@link UploadData}
+     * <li>2. 由于默认异步读取excel，所以需要创建excel一行一行的回调监听器，参照{@link UploadDataListener}
+     * <li>3. 直接读即可
+     */
+    @PostMapping("upload")
+    @ResponseBody
+    public String upload(MultipartFile file) throws IOException {
+        EasyExcelFactory.read(file.getInputStream(), UploadData.class, new UploadDataListener()).sheet().doRead()
+            .finish();
+        return "success";
+    }
+
+    private List<DownloadData> data() {
+        List<DownloadData> list = new ArrayList<DownloadData>();
+        for (int i = 0; i < 10; i++) {
+            DownloadData data = new DownloadData();
+            data.setString("字符串" + 0);
+            data.setDate(new Date());
+            data.setDoubleData(0.56);
+            list.add(data);
+        }
+        return list;
+    }
+}

src/test/java/com/alibaba/easyexcel/test/demo/write/DemoData.java

@@ -7,23 +7,16 @@ import com.alibaba.excel.annotation.ExcelProperty;
 import lombok.Data;
 
 /**
- * 基础数据类.行高 列宽可以忽略
+ * 基础数据类
  *
  * @author zhuangjiaju
  **/
 @Data
 public class DemoData {
-
     @ExcelProperty("字符串标题")
     private String string;
-    /**
-     * 指定写到excel的格式
-     */
     @ExcelProperty("日期标题")
     private Date date;
-    /**
-     * 数字转成百分比，默认数字存到excel是数字，不存在格式，现在要变成百分比就变成文本了，所以要指定转换器
-     */
     @ExcelProperty("数字标题")
     private Double doubleData;
 }