1.EasyExcel 导出

1.1. Response流导出单sheet页

1.1.1 response流处理（防止中文乱码）：

		response.setContentType("application/vnd.ms-excel");response.setCharacterEncoding("utf-8");String fileName = URLEncoder.encode(getTitle(), "UTF-8").replaceAll("\\+", "%20");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");

1.1.2 根据excel映射对象导出（适合结构化数据：列表台账）

excel导出实体：

@Data
@NoArgsConstructor
//@ContentRowHeight(50)//内容单元格高度
//@HeadRowHeight(50)//表头单元格高度
//@ColumnWidth(50)//单元格宽度
public class DemoExcelBO {@ExcelProperty(value = {"导出台账","序号"})private Integer no;@ExcelProperty(value = {"导出台账","编号"})private  String  code;
}

执行实际的导出动作：

        //要导出的excel 数据List<DemoExcelBO> dataList = new ArrayList<>();//指定outputStream和 excel映射实体EasyExcel.write(response.getOutputStream(), DemoExcelBO.class)//注册 WriteHandler ，getDefaultWriteHandler() 见下.registerWriteHandler(getDefaultWriteHandler())//注入原生 或 自定义转换器.registerConverter(new DateStringConverter()).registerConverter(new BigDecimalStringConverter()).sheet("这是指定要写入的sheet页").doWrite(dataList );

1.1.3. 根据单元格集合导出（适合非结构化数据：详情页）

		//执行excel写入对象ExcelWriter excelWriter = EasyExcel.write(url).build();//当前sheet页 写入对象创建者ExcelWriterSheetBuilder sheetBuilder = EasyExcel.writerSheet("测试sheet");//todo sheetBuilder  可以注入 writeHandlerWriteSheet writeSheet = sheetBuilder.build();//实际要写入的数据 ，List<Object> 为每一行的合并前的数据，放入List中为整个要写入的数据List<List<Object>> dataList = new ArrayList<>();//可以多次调用  excelWriter.write() 方法 。 写入同一sheet 的话 ，WriteSheet 对象不变excelWriter.write(list, writeSheet);//关流excelWriter.finish();

1.2. 单元格样式（背景色、加粗、字体、边框）

HorizontalCellStyleStrategy 分别设置 表头 和 表体 的样式：

	//默认设置的样式 （表头样式 和 表体样式 不同）default WriteHandler getDefaultWriteHandler() {WriteCellStyle headWriteCellStyle = new WriteCellStyle();headWriteCellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());WriteFont headWriteFont = new WriteFont();
//        headWriteFont.setBold(true);// 加粗headWriteFont.setFontHeightInPoints((short) 11);//字体大小headWriteCellStyle.setWriteFont(headWriteFont);headWriteCellStyle.setWrapped(false);//自动换行
//        headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.LEFT);//CENTERWriteCellStyle contentWriteCellStyle = new WriteCellStyle();contentWriteCellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());contentWriteCellStyle.setVerticalAlignment(VerticalAlignment.CENTER);contentWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);contentWriteCellStyle.setBorderBottom(BorderStyle.NONE);//THINcontentWriteCellStyle.setBorderLeft(BorderStyle.NONE);contentWriteCellStyle.setBorderRight(BorderStyle.NONE);contentWriteCellStyle.setBorderTop(BorderStyle.NONE);contentWriteCellStyle.setWrapped(false);//自动换行HorizontalCellStyleStrategy horizontalCellStyleStrategy = new HorizontalCellStyleStrategy(headWriteCellStyle, contentWriteCellStyle);return horizontalCellStyleStrategy;}

1.3. 单元格合并策略

easyExcel 抽象父类类 ：AbstractMergeStrategy

public abstract class AbstractMergeStrategy implements CellWriteHandler {@Overridepublic void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {//在创建单元格之前调用}@Overridepublic void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,Head head, Integer relativeRowIndex, Boolean isHead) {//创建单元格后调用}@Overridepublic void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {//在单元格上的所有操作完成后调用if (isHead) {return;}merge(writeSheetHolder.getSheet(), cell, head, relativeRowIndex);}//合并策略protected abstract void merge(Sheet sheet, Cell cell, Head head, Integer relativeRowIndex);
}

1.3.1 只合并一次

easyExcel 预制子类：OnceAbsoluteMergeStrategy

//创建单元格时只合并一次
public class OnceAbsoluteMergeStrategy extends AbstractMergeStrategy {private int firstRowIndex;private int lastRowIndex;private int firstColumnIndex;private int lastColumnIndex;
}

1.3.2. 循环合并

easyExcel 预制子类：LoopMergeStrategy

//循环区域合并
public class LoopMergeStrategy extends AbstractMergeStrategy {private int eachRow;private int columnCount;private int columnIndex;
}

继承 AbstractMergeStrategy 重写 merge（）方法 ，可自定义合并策略

1.4. 列宽样式策略

easyExcel 抽象父类：

public abstract class AbstractColumnWidthStyleStrategy implements CellWriteHandler, NotRepeatExecutor {@Overridepublic String uniqueValue() {return "ColumnWidthStyleStrategy";}@Overridepublic void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {//在创建单元格之前调用
}@Overridepublic void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,Head head, Integer relativeRowIndex, Boolean isHead) {//在创建单元格之后调用
}@Overridepublic void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {//在单元格上的所有操作完成后调用setColumnWidth(writeSheetHolder, cellDataList, cell, head, relativeRowIndex, isHead);}//列宽样式策略protected abstract void setColumnWidth(WriteSheetHolder writeSheetHolder, List<CellData> cellDataList, Cell cell, Head head,Integer relativeRowIndex, Boolean isHead);}

1.4.1. 根据每个列标题返回列宽

easyExcel 预制子类：AbstractHeadColumnWidthStyleStrategy

//根据每个列标题返回列宽
public abstract class AbstractHeadColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy {
}

1.4.2. 以最长列的宽度作为所有列的宽度

easyExcel 预制子类：LongestMatchColumnWidthStyleStrategy

//以最长列的宽度作为宽度
public class LongestMatchColumnWidthStyleStrategy extends AbstractColumnWidthStyleStrategy {
}

1.4.3. 定长列宽

easyExcel 预制子类：SimpleColumnWidthStyleStrategy

//所有列的宽度相同
public class SimpleColumnWidthStyleStrategy extends AbstractHeadColumnWidthStyleStrategy {
}

继承 AbstractColumnWidthStyleStrategy 重写 setColumnWidth（）方法 ，可自定义列宽策略

1.4.4. 自动调整列宽（推荐）

在这里插入代码片

1.5. 转换器

easyExcel 转换器 父接口：

public interface Converter<T> {// 写入excel时 ，指定一个class ，该class 会在写入时 被拦截执行转换Class supportJavaTypeKey();// 读取excel时 ，指定一个excel字段类型，该类型 会在读取时 被拦截执行转换CellDataTypeEnum supportExcelTypeKey();//写入时 ， java 类型 转换 excel数据类型 动作T convertToJavaData(CellData cellData, ExcelContentProperty contentProperty,GlobalConfiguration globalConfiguration) throws Exception;//读取时 ， excel数据类型 转换  java 类型动作CellData convertToExcelData(T value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration)throws Exception;
}

有预制转换器，均实现改接口，如需自定义转换器，可实现 Converter 接口。

1.5.1. 转换器注入方式

方式一： 在excel实体上指定 某些特定字段生效

public class ContractAccountExcelBO {@ExcelProperty(value = {"合同导出台账","","序号"} ,converter = IntegerStringConverter.class)private Integer no;
}

方式二： .registerConverter() 方法注入 ，本次读取或写入时，均生效

 //要导出的excel 数据
List<DemoExcelBO> dataList = new ArrayList<>();
EasyExcel.write(response.getOutputStream(),DemoExcelBO.class ).registerConverter(new BigDecimalStringConverter()).doWrite(dataList);//

1.5.2. 转换器 注解

指定日期格式注解：@DateTimeFormat(“yyyy-MM-dd”)
指定数字格式注解：@NumberFormat("#.00")
NumberFormat 中 format格式 遵循 Bigdecimal.format() 策略（#不补位，没有数字则空。0自动补位，没有数字自动补零）。

1.6. RowWriteHandler 行处理器

// 行创建 动作 拦截器
public interface RowWriteHandler extends WriteHandler {//行 创建前执行void beforeRowCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Integer rowIndex,Integer relativeRowIndex, Boolean isHead);//行 创建后执行void afterRowCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,Integer relativeRowIndex, Boolean isHead);//在该行的所有操作完成后调用。填充数据时不调用此方法。void afterRowDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,Integer relativeRowIndex, Boolean isHead);
}

1.7. CellWriteHandler 单元格处理器

// 单元格创建 动作 拦截器
public interface CellWriteHandler extends WriteHandler {//单元格创建 前动作void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row, Head head,Integer columnIndex, Integer relativeRowIndex, Boolean isHead);//单元格创建 后动作void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head,Integer relativeRowIndex, Boolean isHead);//在单元格上的所有操作完成后调用void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead);
}

1.8. 图片导出

EasyExcel支持5种图片类型导出，根据1.1.3.把图片形式放入单元格中，写会即可

@Data
@ContentRowHeight(200)
@ColumnWidth(200 / 8)
public class ImageData {// 图片导出方式有5种private File file;private InputStream inputStream;/*** 如果string类型 必须指定转换器，string默认转换成string，该转换器是官方支持的*/@ExcelProperty(converter = StringImageConverter.class)private String string;private byte[] byteArray;/*** 根据url导出 版本2.1.1才支持该种模式*/private URL url;
}

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