新增jdk8 案例

src/main/java/com/alibaba/excel/read/listener/PageReadListener.java

@@ -0,0 +1,47 @@
+package com.alibaba.excel.read.listener;
+
+import java.util.List;
+import java.util.function.Consumer;
+
+import com.alibaba.excel.context.AnalysisContext;
+import com.alibaba.excel.util.ListUtils;
+
+/**
+ * page read listener
+ *
+ * @author Jiaju Zhuang
+ */
+public class PageReadListener<T> implements ReadListener<T> {
+    /**
+     * Single handle the amount of data
+     */
+    public static final int BATCH_COUNT = 3000;
+    /**
+     * Temporary storage of data
+     */
+    private List<T> cachedData = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
+    /**
+     * consumer
+     */
+    private final Consumer<List<T>> consumer;
+
+    public PageReadListener(Consumer<List<T>> consumer) {
+        this.consumer = consumer;
+    }
+
+    @Override
+    public void invoke(T data, AnalysisContext context) {
+        cachedData.add(data);
+        if (cachedData.size() >= BATCH_COUNT) {
+            consumer.accept(cachedData);
+            // 存储完成清理 list
+            cachedData = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
+        }
+    }
+
+    @Override
+    public void doAfterAllAnalysed(AnalysisContext context) {
+        consumer.accept(cachedData);
+    }
+
+}

src/test/java/com/alibaba/easyexcel/test/demo/read/DemoDataListener.java

@@ -3,13 +3,13 @@ package com.alibaba.easyexcel.test.demo.read;
 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;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * 模板的读取类
  *
@@ -21,8 +21,11 @@ public class DemoDataListener extends AnalysisEventListener<DemoData> {
     /**
      * 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;
+    private static final int BATCH_COUNT = 3000;
-    List<DemoData> list = new ArrayList<DemoData>();
+    /**
+     * 缓存的数据
+     */
+    private List<DemoData> list = new ArrayList<>(BATCH_COUNT);
     /**
      * 假设这个是一个DAO，当然有业务逻辑这个也可以是一个service。当然如果不用存储这个对象没用。
      */
@@ -45,8 +48,7 @@ public class DemoDataListener extends AnalysisEventListener<DemoData> {
     /**
      * 这个每一条数据解析都会来调用
      *
-     * @param data
+     * @param data    one row value. Is is same as {@link AnalysisContext#readRowHolder()}
-     *            one row value. Is is same as {@link AnalysisContext#readRowHolder()}
      * @param context
      */
     @Override
@@ -57,7 +59,7 @@ public class DemoDataListener extends AnalysisEventListener<DemoData> {
         if (list.size() >= BATCH_COUNT) {
             saveData();
             // 存储完成清理 list
-            list.clear();
+            list = new ArrayList<>(BATCH_COUNT);
         }
     }
 

src/test/java/com/alibaba/easyexcel/test/demo/read/ReadTest.java

@@ -1,25 +1,29 @@
 package com.alibaba.easyexcel.test.demo.read;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
-import org.junit.Ignore;
-import org.junit.Test;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import com.alibaba.easyexcel.test.util.TestFileUtil;
 import com.alibaba.excel.EasyExcel;
 import com.alibaba.excel.ExcelReader;
 import com.alibaba.excel.annotation.ExcelProperty;
 import com.alibaba.excel.annotation.format.DateTimeFormat;
 import com.alibaba.excel.annotation.format.NumberFormat;
+import com.alibaba.excel.context.AnalysisContext;
 import com.alibaba.excel.converters.DefaultConverterLoader;
 import com.alibaba.excel.enums.CellExtraTypeEnum;
+import com.alibaba.excel.read.listener.PageReadListener;
+import com.alibaba.excel.read.listener.ReadListener;
 import com.alibaba.excel.read.metadata.ReadSheet;
 import com.alibaba.fastjson.JSON;
 
+import org.junit.Ignore;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * 读的常见写法
  *
@@ -41,18 +45,69 @@ public class ReadTest {
      */
     @Test
     public void simpleRead() {
-        // 有个很重要的点 DemoDataListener 不能被spring管理，要每次读取excel都要new,然后里面用到spring可以构造方法传进去
+        // 写法1：JDK8+ ,不用额外写一个ReadListener
-        // 写法1：
         String fileName = TestFileUtil.getPath() + "demo" + File.separator + "demo.xlsx";
         // 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
-        EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).sheet().doRead();
+        // 这里每次会读取3000条数据 然后返回过来 直接调用使用数据就行
+        EasyExcel.read(fileName, DemoData.class, new PageReadListener<DemoData>(dataList -> {
+            for (DemoData demoData : dataList) {
+                LOGGER.info("读取到一条数据{}", JSON.toJSONString(demoData));
+            }
+        })).sheet().doRead();
 
         // 写法2：
+        // 匿名内部类 不用额外写一个ReadListener
+        fileName = TestFileUtil.getPath() + "demo" + File.separator + "demo.xlsx";
+        // 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
+        EasyExcel.read(fileName, DemoData.class, new ReadListener<DemoData>() {
+            /**
+             * 单次缓存的数据量
+             */
+            public static final int BATCH_COUNT = 3000;
+            /**
+             *临时存储
+             */
+            private List<DemoData> cachedData = new ArrayList<>(BATCH_COUNT);
+
+            @Override
+            public void invoke(DemoData data, AnalysisContext context) {
+                cachedData.add(data);
+                if (cachedData.size() >= BATCH_COUNT) {
+                    saveData();
+                    // 存储完成清理 list
+                    cachedData = new ArrayList<>(BATCH_COUNT);
+                }
+            }
+
+            @Override
+            public void doAfterAllAnalysed(AnalysisContext context) {
+                saveData();
+            }
+
+            /**
+             * 加上存储数据库
+             */
+            private void saveData() {
+                LOGGER.info("{}条数据，开始存储数据库！", cachedData.size());
+                LOGGER.info("存储数据库成功！");
+            }
+        }).sheet().doRead();
+
+        // 有个很重要的点 DemoDataListener 不能被spring管理，要每次读取excel都要new,然后里面用到spring可以构造方法传进去
+        // 写法3：
+        fileName = TestFileUtil.getPath() + "demo" + File.separator + "demo.xlsx";
+        // 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
+        EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).sheet().doRead();
+
+        // 写法4：
         fileName = TestFileUtil.getPath() + "demo" + File.separator + "demo.xlsx";
+        // 一个文件一个reader
         ExcelReader excelReader = null;
         try {
             excelReader = EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).build();
+            // 构建一个sheet 这里可以指定名字或者no
             ReadSheet readSheet = EasyExcel.readSheet(0).build();
+            // 读取一个sheet
             excelReader.read(readSheet);
         } finally {
             if (excelReader != null) {