SpringMvc实现导出Excel视图

   SpringMvc提供了AbstractXlsView提供Excel视图，它是一个抽象类，提供了一个抽象方法-buildExcelDocument要去实现，其它方法，AbstractXlsView其它方法已经实现了

    buildExcelDocuent主要任务是去创建一个workbook,它要用到POI的API

        
            org.apache.poi
            poi
            3.15
        

然后我们开始实现这个视图，这个视图不是一个逻辑视图，所以无需视图解析器也可以实现它，代码如下

package com.example.eurekaclient.excel;

import org.apache.commons.lang.StringUtils;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.web.servlet.view.document.AbstractXlsView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Map;

/**
 * @ClassName ExcelView
 * @Description TODO
 * @Author Mr.G
 * @Date 2018/9/20 18:19
 * @Version 1.0
 */
public class ExcelView extends AbstractXlsView {
    private String fileName=null;
    private ExcelExportService excelExportService=null;
    public ExcelView(ExcelExportService excelExportService){
        this.excelExportService=excelExportService;
    }
    public ExcelView(String fileName,ExcelExportService excelExportService){
        this.fileName=fileName;
        this.excelExportService=excelExportService;
    }

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public ExcelExportService getExcelExportService() {
        return excelExportService;
    }

    public void setExcelExportService(ExcelExportService excelExportService) {
        this.excelExportService = excelExportService;
    }

    /**
     * Application-provided subclasses must implement this method to populate
     * the Excel workbook document, given the model.
     *
     * @param model    the model Map
     * @param workbook the Excel workbook to populate
     * @param request  in case we need locale etc. Shouldn't look at attributes.
     * @param response in case we need to set cookies. Shouldn't write to it.
     */
    @Override
    protected void buildExcelDocument(Map model, Workbook workbook, HttpServletRequest request, HttpServletResponse response) throws Exception {
       if(excelExportService==null){
           throw new RuntimeException("导出接口不能为空");
       }
       if(!StringUtils.isEmpty(fileName)){
           String reqCharset=request.getCharacterEncoding();
           reqCharset=reqCharset==null?"UTF-8":reqCharset;
           fileName=new String(fileName.getBytes(reqCharset),"ISO8859-1");
           response.setHeader("Content-disposition","attachment;fileName="+fileName);
       }
       excelExportService.makeWorkBook(model,workbook);

    }
}

fileName是下载文件的名字，excelExportService是创建Workbook的规则，因为我们会根据不同需求创建不同形式的excel表格，所以我们把这个接口抽象出来当作公用接口，有不同需求的话，就用不同的方式去实现

写出这个接口

package com.example.eurekaclient.excel;

import org.apache.poi.ss.usermodel.Workbook;

import java.util.Map;

/**
 * @ClassName ExcelExportService
 * @Description TODO
 * @Author Mr.G
 * @Date 2018/9/11 22:23
 * @Version 1.0
 */
public interface ExcelExportService {

    public void makeWorkBook(Map model, Workbook workbook);
}

然后去写这个接口的实现

package com.example.eurekaclient.excel;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import com.example.eurekaclient.swagger2.entity.User;
import com.example.eurekaclient.swagger2.server.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.ModelAndView;

import java.util.List;
import java.util.Map;

/**
 * @ClassName ExcelController
 * @Description TODO
 * @Author Mr.G
 * @Date 2018/9/21 10:16
 * @Version 1.0
 */
@RestController
@RequestMapping("excel")
public class ExcelController {
    @Autowired
    private UserService userService;
    @RequestMapping(value="export",method=RequestMethod.GET)
    public ModelAndView export(){
        ModelAndView mv=new ModelAndView();
        ExcelView ev=new ExcelView(exportService());
        ev.setFileName("所有角色.xlsx");
        List userList =userService.selectAll();
        mv.addObject("userList",userList);
        mv.setView(ev);
        return mv;
    }
    @SuppressWarnings({ "unchecked"})
    private ExcelExportService exportService(){
        return (Map model,Workbook workbook)->{
            List userList=(List)model.get("userList");
            Sheet sheet=workbook.createSheet("所有角色");
            Row title= sheet.createRow(0);
            title.createCell(0).setCellValue("姓名");
            title.createCell(1).setCellValue("年纪");
            for(int i=0;i

我们这里用了lambda表达式，去实现Workbook格式的接口，文件名是所有角色，表格有两列，用的是springCloud系列的数据库

user表

这里讲解一个我当时困惑后来想明白的点，我们的Excel视图是继承AbstactXlsView，而AbstactXlsView继承ModelAndView,所以当我们返回mv时，它会通过调用渲染的方法，而AbstactXlsView是实现了自己的渲染方法，我们规则都给了它，它会根据这些规则渲染我们需要的表格

代码结束了，上效果图