优化读写逻辑

quickstart.md

@@ -21,6 +21,7 @@ DEMO代码地址：[https://github.com/alibaba/easyexcel/blob/master/src/test/ja
 * [自定义样式](#styleWrite)
 * [合并单元格](#mergeWrite)
 * [使用table去写入](#tableWrite)
+* [动态头，实时生成头写入](#dynamicHeadWrite)
 * [web中的写](#webWrite)
 
 ## 读excel样例
@@ -697,6 +698,47 @@ public class WidthAndHeightData {
     }
 ```
 
+### <span id="tableWrite" />动态头，实时生成头写入
+##### excel示例
+![img](img/readme/quickstart/write/dynamicHeadWrite.png)
+##### 对象
+参照：[对象](#simpleWriteObject)
+##### 代码
+```java
+    /**
+     * 动态头，实时生成头写入
+     * <p>
+     * 思路是这样子的，先创建List<String>头格式的sheet仅仅写入头,然后通过table 不写入头的方式 去写入数据
+     *
+     * <li>1. 创建excel对应的实体对象 参照{@link DemoData}
+     * <li>2. 然后写入table即可
+     */
+    @Test
+    public void dynamicHeadWrite() {
+        String fileName = TestFileUtil.getPath() + "dynamicHeadWrite" + System.currentTimeMillis() + ".xlsx";
+        // write的时候 不传入 class 在table的时候传入
+        EasyExcelFactory.write(fileName)
+            // 这里放入动态头
+            .head(head()).sheet("模板")
+            // table的时候 传入class 并且设置needHead =false
+            .table().head(DemoData.class).needHead(Boolean.FALSE).doWrite(data());
+    }
+
+    private List<List<String>> head() {
+        List<List<String>> list = new ArrayList<List<String>>();
+        List<String> head0 = new ArrayList<String>();
+        head0.add("字符串" + System.currentTimeMillis());
+        List<String> head1 = new ArrayList<String>();
+        head1.add("数字" + System.currentTimeMillis());
+        List<String> head2 = new ArrayList<String>();
+        head2.add("日期" + System.currentTimeMillis());
+        list.add(head0);
+        list.add(head1);
+        list.add(head2);
+        return list;
+    }
+```
+
 ### <span id="webWrite" />web中的写
 ##### 示例代码
 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)

src/main/java/com/alibaba/excel/annotation/write/style/ColumnWidth.java

@@ -15,10 +15,11 @@ import java.lang.annotation.Target;
 @Retention(RetentionPolicy.RUNTIME)
 @Inherited
 public @interface ColumnWidth {
+
     /**
      * Column width
      * <p>
-     * -1 mean the auto set width
+     * -1 means the default column width is used
      */
     int value() default -1;
 }

src/main/java/com/alibaba/excel/context/WriteContextImpl.java

@@ -275,7 +275,7 @@ public class WriteContextImpl implements WriteContext {
         }
         for (WriteHandler writeHandler : handlerList) {
             if (writeHandler instanceof CellWriteHandler) {
-                ((CellWriteHandler)writeHandler).afterCellCreate(writeSheetHolder, writeTableHolder, cell, head,
+                ((CellWriteHandler)writeHandler).afterCellCreate(writeSheetHolder, writeTableHolder, null, cell, head,
                     relativeRowIndex, true);
             }
         }

src/main/java/com/alibaba/excel/metadata/AbstractHolder.java

@@ -36,12 +36,12 @@ public abstract class AbstractHolder implements ConfigurationHolder {
 
     public AbstractHolder(BasicParameter basicParameter, AbstractHolder prentAbstractHolder) {
         this.newInitialization = Boolean.TRUE;
-        if (basicParameter.getHead() == null && prentAbstractHolder != null) {
+        if (basicParameter.getHead() == null && basicParameter.getClazz() == null && prentAbstractHolder != null) {
             this.head = prentAbstractHolder.getHead();
         } else {
             this.head = basicParameter.getHead();
         }
-        if (basicParameter.getClazz() == null && prentAbstractHolder != null) {
+        if (basicParameter.getHead() == null && basicParameter.getClazz() == null && prentAbstractHolder != null) {
             this.clazz = prentAbstractHolder.getClazz();
         } else {
             this.clazz = basicParameter.getClazz();

src/main/java/com/alibaba/excel/write/ExcelBuilderImpl.java

@@ -179,8 +179,8 @@ public class ExcelBuilderImpl implements ExcelBuilder {
         beforeCellCreate(row, head, relativeRowIndex);
         Cell cell = WorkBookUtil.createCell(row, cellIndex);
         Object value = oneRowData.get(dataIndex);
-        converterAndSet(context.currentWriteHolder(), value.getClass(), cell, value, null);
-        afterCellCreate(head, cell, relativeRowIndex);
+        CellData cellData = converterAndSet(context.currentWriteHolder(), value.getClass(), cell, value, null);
+        afterCellCreate(head, cellData, cell, relativeRowIndex);
     }
 
     private void addJavaObjectToExcel(Object oneRowData, Row row, int relativeRowIndex, List<Field> fieldList) {
@@ -202,9 +202,9 @@ public class ExcelBuilderImpl implements ExcelBuilder {
             beforeCellCreate(row, head, relativeRowIndex);
             Cell cell = WorkBookUtil.createCell(row, cellIndex);
             Object value = beanMap.get(name);
-            converterAndSet(currentWriteHolder, excelContentProperty.getField().getType(), cell, value,
-                excelContentProperty);
-            afterCellCreate(head, cell, relativeRowIndex);
+            CellData cellData = converterAndSet(currentWriteHolder, excelContentProperty.getField().getType(), cell,
+                value, excelContentProperty);
+            afterCellCreate(head, cellData, cell, relativeRowIndex);
             beanMapHandledSet.add(name);
         }
         // Finish
@@ -229,8 +229,8 @@ public class ExcelBuilderImpl implements ExcelBuilder {
             }
             beforeCellCreate(row, null, relativeRowIndex);
             Cell cell = WorkBookUtil.createCell(row, cellIndex++);
-            converterAndSet(currentWriteHolder, value.getClass(), cell, value, null);
-            afterCellCreate(null, cell, relativeRowIndex);
+            CellData cellData = converterAndSet(currentWriteHolder, value.getClass(), cell, value, null);
+            afterCellCreate(null, cellData, cell, relativeRowIndex);
         }
     }
 
@@ -261,7 +261,7 @@ public class ExcelBuilderImpl implements ExcelBuilder {
 
     }
 
-    private void afterCellCreate(Head head, Cell cell, int relativeRowIndex) {
+    private void afterCellCreate(Head head, CellData cellData, Cell cell, int relativeRowIndex) {
         List<WriteHandler> handlerList = context.currentWriteHolder().writeHandlerMap().get(CellWriteHandler.class);
         if (handlerList == null || handlerList.isEmpty()) {
             return;
@@ -269,7 +269,7 @@ public class ExcelBuilderImpl implements ExcelBuilder {
         for (WriteHandler writeHandler : handlerList) {
             if (writeHandler instanceof CellWriteHandler) {
                 ((CellWriteHandler)writeHandler).afterCellCreate(context.writeSheetHolder(), context.writeTableHolder(),
-                    cell, head, relativeRowIndex, false);
+                    cellData, cell, head, relativeRowIndex, false);
             }
         }
         if (null != context.writeWorkbookHolder().getWriteWorkbook().getWriteHandler()) {
@@ -277,10 +277,10 @@ public class ExcelBuilderImpl implements ExcelBuilder {
         }
     }
 
-    private void converterAndSet(WriteHolder currentWriteHolder, Class clazz, Cell cell, Object value,
+    private CellData converterAndSet(WriteHolder currentWriteHolder, Class clazz, Cell cell, Object value,
         ExcelContentProperty excelContentProperty) {
         if (value == null) {
-            return;
+            return null;
         }
         if (value instanceof String && currentWriteHolder.globalConfiguration().getAutoTrim()) {
             value = ((String)value).trim();
@@ -296,13 +296,13 @@ public class ExcelBuilderImpl implements ExcelBuilder {
         switch (cellData.getType()) {
             case STRING:
                 cell.setCellValue(cellData.getStringValue());
-                return;
+                return cellData;
             case BOOLEAN:
                 cell.setCellValue(cellData.getBooleanValue());
-                return;
+                return cellData;
             case NUMBER:
                 cell.setCellValue(cellData.getDoubleValue());
-                return;
+                return cellData;
             default:
                 throw new ExcelDataConvertException("Not supported data:" + value + " return type:" + cell.getCellType()
                     + "at row:" + cell.getRow().getRowNum());

src/main/java/com/alibaba/excel/write/handler/CellWriteHandler.java

@@ -3,6 +3,7 @@ package com.alibaba.excel.write.handler;
 import org.apache.poi.ss.usermodel.Cell;
 import org.apache.poi.ss.usermodel.Row;
 
+import com.alibaba.excel.metadata.CellData;
 import com.alibaba.excel.metadata.Head;
 import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
 import com.alibaba.excel.write.metadata.holder.WriteTableHolder;
@@ -36,9 +37,11 @@ public interface CellWriteHandler extends WriteHandler {
      *            Nullable
      * @param cell
      * @param head
+     * @param cellData
+     *            Nullable.
      * @param relativeRowIndex
      * @param isHead
      */
-    void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head,
-        int relativeRowIndex, boolean isHead);
+    void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, CellData cellData,
+        Cell cell, Head head, int relativeRowIndex, boolean isHead);
 }

src/main/java/com/alibaba/excel/write/merge/AbstractMergeStrategy.java

@@ -4,6 +4,7 @@ import org.apache.poi.ss.usermodel.Cell;
 import org.apache.poi.ss.usermodel.Row;
 import org.apache.poi.ss.usermodel.Sheet;
 
+import com.alibaba.excel.metadata.CellData;
 import com.alibaba.excel.metadata.Head;
 import com.alibaba.excel.write.handler.CellWriteHandler;
 import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
@@ -22,7 +23,7 @@ public abstract class AbstractMergeStrategy implements CellWriteHandler {
     }
 
     @Override
-    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
+    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, CellData cellData, Cell cell,
                                 Head head, int relativeRowIndex, boolean isHead) {
         if (isHead) {
             return;

src/main/java/com/alibaba/excel/write/style/AbstractCellStyleStrategy.java

@@ -5,6 +5,7 @@ import org.apache.poi.ss.usermodel.Row;
 import org.apache.poi.ss.usermodel.Workbook;
 
 import com.alibaba.excel.event.NotRepeatExecutor;
+import com.alibaba.excel.metadata.CellData;
 import com.alibaba.excel.metadata.Head;
 import com.alibaba.excel.write.handler.CellWriteHandler;
 import com.alibaba.excel.write.handler.SheetWriteHandler;
@@ -46,8 +47,8 @@ public abstract class AbstractCellStyleStrategy implements CellWriteHandler, She
     }
 
     @Override
-    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
-        Head head, int relativeRowIndex, boolean isHead) {
+    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, CellData cellData,
+        Cell cell, Head head, int relativeRowIndex, boolean isHead) {
         if (isHead) {
             setHeadCellStyle(cell, head, relativeRowIndex);
         } else {

src/main/java/com/alibaba/excel/write/style/column/AbstractColumnWidthStyleStrategy.java

@@ -2,9 +2,9 @@ package com.alibaba.excel.write.style.column;
 
 import org.apache.poi.ss.usermodel.Cell;
 import org.apache.poi.ss.usermodel.Row;
-import org.apache.poi.ss.usermodel.Sheet;
 
 import com.alibaba.excel.event.NotRepeatExecutor;
+import com.alibaba.excel.metadata.CellData;
 import com.alibaba.excel.metadata.Head;
 import com.alibaba.excel.write.handler.CellWriteHandler;
 import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
@@ -29,20 +29,22 @@ public abstract class AbstractColumnWidthStyleStrategy implements CellWriteHandl
     }
 
     @Override
-    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
-        Head head, int relativeRowIndex, boolean isHead) {
-        setColumnWidth(writeSheetHolder.getSheet(), cell, head, relativeRowIndex, isHead);
+    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, CellData cellData,
+        Cell cell, Head head, int relativeRowIndex, boolean isHead) {
+        setColumnWidth(writeSheetHolder, cellData, cell, head, relativeRowIndex, isHead);
     }
 
     /**
      * Sets the column width when head create
      *
-     * @param sheet
+     * @param writeSheetHolder
+     * @param cellData
      * @param cell
      * @param head
      * @param relativeRowIndex
      * @param isHead
      */
-    protected abstract void setColumnWidth(Sheet sheet, Cell cell, Head head, int relativeRowIndex, boolean isHead);
+    protected abstract void setColumnWidth(WriteSheetHolder writeSheetHolder, CellData cellData, Cell cell, Head head,
+        int relativeRowIndex, boolean isHead);
 
 }

src/main/java/com/alibaba/excel/write/style/column/AbstractHeadColumnWidthStyleStrategy.java

@@ -1,9 +1,10 @@
 package com.alibaba.excel.write.style.column;
 
 import org.apache.poi.ss.usermodel.Cell;
-import org.apache.poi.ss.usermodel.Sheet;
 
+import com.alibaba.excel.metadata.CellData;
 import com.alibaba.excel.metadata.Head;
+import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
 
 /**
  * Returns the column width according to each column header
@@ -12,14 +13,15 @@ import com.alibaba.excel.metadata.Head;
  */
 public abstract class AbstractHeadColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy {
     @Override
-    protected void setColumnWidth(Sheet sheet, Cell cell, Head head, int relativeRowIndex, boolean isHead) {
+    protected void setColumnWidth(WriteSheetHolder writeSheetHolder, CellData cellData, Cell cell, Head head,
+        int relativeRowIndex, boolean isHead) {
         if (!isHead && relativeRowIndex != 0) {
             return;
         }
         Integer width = columnWidth(head);
         if (width != null) {
             width = width * 256;
-            sheet.setColumnWidth(cell.getColumnIndex(), width);
+            writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), width);
         }
     }
 

src/main/java/com/alibaba/excel/write/style/column/LongestMatchColumnWidthStyleStrategy.java

@@ -0,0 +1,66 @@
+package com.alibaba.excel.write.style.column;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.poi.ss.usermodel.Cell;
+
+import com.alibaba.excel.metadata.CellData;
+import com.alibaba.excel.metadata.Head;
+import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
+
+/**
+ * Take the width of the longest column as the width.
+ * <p>
+ * This is not very useful at the moment, for example if you have Numbers it will cause a newline.And the length is not
+ * exactly the same as the actual length.
+ *
+ * @author Jiaju Zhuang
+ */
+public class LongestMatchColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy {
+
+    private static final int MAX_COLUMN_WIDTH = 256;
+
+    Map<Integer, Map<Integer, Integer>> cache = new HashMap<Integer, Map<Integer, Integer>>(8);
+
+    @Override
+    protected void setColumnWidth(WriteSheetHolder writeSheetHolder, CellData cellData, Cell cell, Head head,
+        int relativeRowIndex, boolean isHead) {
+        if (!isHead && cellData == null) {
+            return;
+        }
+        Map<Integer, Integer> maxColumnWidthMap = cache.get(writeSheetHolder.getSheetNo());
+        if (maxColumnWidthMap == null) {
+            maxColumnWidthMap = new HashMap<Integer, Integer>(16);
+            cache.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap);
+        }
+        Integer columnWidth = dataLength(cellData, cell, isHead);
+        if (columnWidth < 0) {
+            return;
+        }
+        if (columnWidth > MAX_COLUMN_WIDTH) {
+            columnWidth = MAX_COLUMN_WIDTH;
+        }
+        Integer maxColumnWidth = maxColumnWidthMap.get(head.getColumnIndex());
+        if (maxColumnWidth == null || columnWidth > maxColumnWidth) {
+            maxColumnWidthMap.put(head.getColumnIndex(), columnWidth);
+            writeSheetHolder.getSheet().setColumnWidth(head.getColumnIndex(), columnWidth * 256);
+        }
+    }
+
+    private Integer dataLength(CellData cellData, Cell cell, boolean isHead) {
+        if (isHead) {
+            return cell.getStringCellValue().getBytes().length;
+        }
+        switch (cellData.getType()) {
+            case STRING:
+                return cellData.getStringValue().getBytes().length;
+            case BOOLEAN:
+                return cellData.getBooleanValue().toString().getBytes().length;
+            case NUMBER:
+                return cellData.getDoubleValue().toString().getBytes().length;
+            default:
+                return -1;
+        }
+    }
+}

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

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

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

@@ -25,6 +25,7 @@ import com.alibaba.excel.write.metadata.WriteTable;
 import com.alibaba.excel.write.metadata.style.WriteCellStyle;
 import com.alibaba.excel.write.metadata.style.WriteFont;
 import com.alibaba.excel.write.style.HorizontalCellStyleStrategy;
+import com.alibaba.excel.write.style.column.LongestMatchColumnWidthStyleStrategy;
 
 /**
  * 写的常见写法
@@ -218,6 +219,70 @@ public class WriteTest {
         excelWriter.finish();
     }
 
+    /**
+     * 动态头，实时生成头写入
+     * <p>
+     * 思路是这样子的，先创建List<String>头格式的sheet仅仅写入头,然后通过table 不写入头的方式 去写入数据
+     *
+     * <li>1. 创建excel对应的实体对象 参照{@link DemoData}
+     * <li>2. 然后写入table即可
+     */
+    @Test
+    public void dynamicHeadWrite() {
+        String fileName = TestFileUtil.getPath() + "dynamicHeadWrite" + System.currentTimeMillis() + ".xlsx";
+        // write的时候 不传入 class 在table的时候传入
+        EasyExcelFactory.write(fileName)
+            // 这里放入动态头
+            .head(head()).sheet("模板")
+            // table的时候 传入class 并且设置needHead =false
+            .table().head(DemoData.class).needHead(Boolean.FALSE).doWrite(data());
+    }
+
+    /**
+     * 自动列宽(不太精确)
+     * <p>
+     * 这个目前不是很好用，比如有数字就会导致换行。而且长度也不是刚好和实际长度一致。 所以需要精确到刚好列宽的慎用。 当然也可以自己参照
+     * {@link LongestMatchColumnWidthStyleStrategy}重新实现.
+     *
+     * <li>1. 创建excel对应的实体对象 参照{@link DemoData}
+     * <li>3. 注册策略{@link LongestMatchColumnWidthStyleStrategy}
+     * <li>2. 直接写即可
+     */
+    @Test
+    public void longestMatchColumnWidthWrite() {
+        String fileName =
+            TestFileUtil.getPath() + "longestMatchColumnWidthWrite" + System.currentTimeMillis() + ".xlsx";
+        // 这里 需要指定写用哪个class去读，然后写到第一个sheet，名字为模板 然后文件流会自动关闭
+        EasyExcelFactory.write(fileName, LongestMatchColumnWidthData.class)
+            .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).sheet("模板").doWrite(dataLong());
+    }
+
+    private List<LongestMatchColumnWidthData> dataLong() {
+        List<LongestMatchColumnWidthData> list = new ArrayList<LongestMatchColumnWidthData>();
+        for (int i = 0; i < 10; i++) {
+            LongestMatchColumnWidthData data = new LongestMatchColumnWidthData();
+            data.setString("测试很长的字符串测试很长的字符串测试很长的字符串" + i);
+            data.setDate(new Date());
+            data.setDoubleData(1000000000000.0);
+            list.add(data);
+        }
+        return list;
+    }
+
+    private List<List<String>> head() {
+        List<List<String>> list = new ArrayList<List<String>>();
+        List<String> head0 = new ArrayList<String>();
+        head0.add("字符串" + System.currentTimeMillis());
+        List<String> head1 = new ArrayList<String>();
+        head1.add("数字" + System.currentTimeMillis());
+        List<String> head2 = new ArrayList<String>();
+        head2.add("日期" + System.currentTimeMillis());
+        list.add(head0);
+        list.add(head1);
+        list.add(head2);
+        return list;
+    }
+
     private List<DemoData> data() {
         List<DemoData> list = new ArrayList<DemoData>();
         for (int i = 0; i < 10; i++) {