文件下载（download） 前后台备注自用

1、后台

      1.1 ResponseBean 返回封装的格式

@Data
@Accessors(chain = true)
public class ResponseBean {
    private String retCode;
    private String retMsg;
    private Map<Object, Object> retMap;

}

　　1.2请求封装的格式

@Data
@Accessors(chain = true)
public class RequestBean {
    private Map sysMap;
    private List<Object> parameterList;

}

　　1.3后台服务接口

package com.test.demo.controller;

import com.test.demo.common.RequestBean;
import com.test.demo.common.ResponseBean;
import com.test.demo.common.RetCode;
import com.test.demo.util.FileUtil;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * @description: 文件相关
 * @author: ZhuGaoPo
 * @version:1.0
 */
@Slf4j
@RequestMapping(value = "/file")
@RestController
public class FileController {
  
    @PostMapping(value = "/downloadFile")
    @ApiOperation("文件下载到本地")
    public ResponseBean downloadFile(@RequestBody RequestBean requestBean) {
        log.info("接收到的数据为：" + requestBean);
        ResponseBean response = new ResponseBean();
        String filePath = String.valueOf(requestBean.getParameterList().get(0));
        BufferedReader br = null;
        try {
            br = new BufferedReader(new InputStreamReader(new FileInputStream(filePath), "GBK"));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = br.readLine()) != null) {
                stringBuilder.append(line).append('\n');
            }
            response.setRetCode(RetCode.SUCCESS);
            Map<Object, Object> retMap = new HashMap<>(RetCode.MAP_SIZE);
            retMap.put("data", stringBuilder.toString());
            response.setRetMap(retMap);
        } catch (Exception e) {
            response.setRetCode(RetCode.FAIL);
            log.error("下载模板失败", e);
        } finally {
            try {
                Objects.requireNonNull(br).close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        log.info("返回的数据为：" + response);
        return response;
    }
}

　　2、前台

             <el-button type="warning" plain @click="downloadFile()">
               下载
              </el-button>

　　

 downloadFile() {
//filePath为文件服务的路径
      const data = {
        sysMap: {
          features: '下载模板'
        },
        parameterList: [this.filePath]
      }
      this.$request({
        url: '/file/downloadFile',
        method: 'post',
        data
      }).then(res => {
        if (res.retCode === 'IF0000') {
          // 成功、加上 ‘\ufeff’ 解决导出 csv 乱码问题
          const blob = new Blob(['\ufeff' + res.retMap.data], { type: 'application/json;charset=UTF-8' })
          const a = document.createElement('a')
          // 指定下载的文件名
          a.download = '黑名单模板.csv'
          // URL对象
          a.href = URL.createObjectURL(blob)
          // 模拟点击
          a.click()
        } else {
          return false
        }
      }).catch(e => {})
    },