如何從java彈簧控制器GUI上下載CSV文件？

Question

我是軟件開發領域的新人，剛上大學。做我的第一個大項目。

我想下載CSV文件，當用戶選擇項目的開始日期和結束日期，所以該文件應該返回project.csv與項目名稱，日期從..到..

最重要的是，我試圖在點擊「導出」鏈接後從GUI下載文件。我所知道的是我必須製造一個彈簧控制器。我不得不錯過一些部分，因爲它不工作。 我的java類正在將csv文件寫入我的C盤，但它不會執行下載部分。另外，CSV文件應該從數據庫寫入用戶計算機，而不是寫入我的磁盤。

希望你能理解我。讓我知道如果這是明確的。

我的代碼：

ExportController.java

@RestController 
    @RequestMapping("/config") 
    public class ExportController { 
     private String filePath = "C:\\test\\project.csv"; 
     private static final int BUFFER_SIZE = 4096; 

     @Autowired 
     private ExportService exportService; 
     ServletContext context; 

     @RequestMapping(value = "export/all", method = RequestMethod.POST) 
     public String list(@RequestParam("startDate")String date, @RequestParam("endDate")String date2, HttpServletResponse response, HttpServletRequest request) throws ServletException, ParseException, IOException { 
      DateFormat format = new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH); 
      Date date_obj = format.parse(date); 
      Date date2_obj = format.parse(date2); 

      // get absolute path of the application 
      ServletContext context = request.getServletContext(); 
      String appPath = context.getRealPath(""); 
      System.out.println("appPath = " + appPath); 

      // construct the complete absolute path of the file 
      String fullPath = filePath;  
      File downloadFile = new File(fullPath); 
      FileInputStream inputStream = new FileInputStream(downloadFile); 

      // get MIME type of the file 
      String mimeType = context.getMimeType(fullPath); 
      if (mimeType == null) { 
       // set to binary type if MIME mapping not found 
       mimeType = "application/octet-stream"; 
      } 

      System.out.println("MIME type: " + mimeType); 

      CsvWriterProject.savetofile(); 

      String csv = "Employee FN/LN: Eatrick Hughes Contract type: External, Activity: WAR, Effort date: 2016-02-17, Name: udfuhfd, Entity: BA, Start date: 2016-02-17, End_date: 2016-02-18"; 

      response.setContentType("application/csv"); 
      response.setHeader("Content-Disposition", "attachment; filename=project.csv"); 
      response.setHeader("Pragma", "public"); 
      response.setHeader("Expires", "0"); 
      response.setHeader("Content-Length", String.valueOf(csv.length())); 
      response.setHeader("Content-type","application/csv"); 
     // response.setContentType(mimeType); 
     // response.setContentLength((int) downloadFile.length()); 
      // get output stream of the response 
      OutputStream outStream = response.getOutputStream(); 
      PrintWriter pw = new PrintWriter(outStream); 
      pw.print(pw); 


      byte[] buffer = new byte[BUFFER_SIZE]; 
      int bytesRead = -1; 

      // write bytes read from the input stream into the output stream 
      while ((bytesRead = inputStream.read(buffer)) != -1) { 
       outStream.write(buffer, 0, bytesRead); 
      } 
      inputStream.close(); 
      outStream.flush(); 
      outStream.close(); 
      return csv; 


     } 
    } 

這裏是angularJS

$scope.export_all = function(item){ 
     $http.post('config/export/all?startDate='+item.startDate+"&endDate="+item.endDate) 
     .success(function(response) { 
      $scope.export = response; 

       }); 
    }; 

讓我知道如果你需要更多的信息。

Answer 1

您可以使用HttpServletResponse的（javax.servlet.http.HttpServletResponse）

下面是示例代碼：

package com.export.test; 

import javax.servlet.http.HttpServletResponse; 

import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.RequestMethod; 
import org.springframework.web.bind.annotation.RestController; 


@RestController 
@RequestMapping(value = "/exportTest") 
public class ExportControllerTest { 
    @RequestMapping(value = "/export", method = RequestMethod.GET) 
    public void exportStream(HttpServletResponse response) { 
     try { 
      String responseTosend = "Testing export for rest cliet"; 
      response.getOutputStream() 
        .write((responseTosend).getBytes("UTF-8")); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 
} 

修改按您的要求。 查閱文件以獲取更多信息https://docs.oracle.com/javaee/6/api/javax/servlet/http/HttpServletResponse.html