java POI 如何实现Excel单元格内容换行

< dependency >

       < groupId >org.apache.poi</ groupId >

       < artifactId >poi</ artifactId >

       < version >3.15</ version >

   </ dependency >

   < dependency >

       < groupId >org.apache.poi</ groupId >

       < artifactId >poi-ooxml</ artifactId >

       < version >3.15</ version >

   </ dependency >

   < dependency >

       < groupId >commons-io</ groupId >

       < artifactId >commons-io</ artifactId >

       < version >2.5</ version >

   </ dependency >

@RestController

public class MyController {

     @RequestMapping ( "/ip/v5" )

     public void getExcel(HttpServletResponse response) throws IOException {

         ArrayList<String> arrayList = new ArrayList<String>();

         arrayList.add( "this is 单元格第1行" );

         arrayList.add( "this is 单元格第2行" );

         arrayList.add( "this is 单元格第3行" );

         arrayList.add( "this is 单元格第4行" );

         XSSFWorkbook workBook = new XSSFWorkbook();

         XSSFSheet sheet = workBook.createSheet();

         workBook.setSheetName( 0 , "ip-v4表" );

         XSSFCellStyle cs = workBook.createCellStyle(); // 换行的关键，自定义单元格内容换行规则

         cs.setWrapText( true );

         String fileName = "china-ip-v4" + ".xls" ; // 设置要导出的文件的名字

         String[] headers = { "掩码" };

         XSSFRow titleRow = sheet.createRow( 0 );

         // 在excel表中添加表头

         for ( int i = 0 ; i < headers.length; i++) {

             titleRow.createCell(i).setCellValue(headers[i]);

         }

         String content = String.join( "\n" , arrayList);

         int rowNum = 1 ;

         XSSFRow row1 = sheet.createRow(rowNum); // 创建一行

         XSSFCell cell = row1.createCell( 0 ); // 创建一个单元格

         // 如下也是可以的

         //cell.setCellValue("this is 单元格第1行 \n this is单元格第2行 \n this is 单元格第3行 \n this is 单元格第4行");

         cell.setCellValue(content);

         cell.setCellStyle(cs);

         response.setContentType( "application/octet-stream" );

         response.setHeader( "Content-disposition" , "attachment;filename=" + fileName);

         response.flushBuffer();

         workBook.write(response.getOutputStream());

     }

}

String str= "强制\r\n换行"