如何編寫CSV文件並在瀏覽器中打開

Question

我想在新瀏覽器中打開文件，而不是將其保存爲本地文件。

下面是我的servlet，它保存到我的本地驅動器，但我想在瀏覽器中打開它。我認爲，而不是FileWriter我應該使用OutPutStream，但一些我如何理解如何使用它。

protected void doGet(HttpServletRequest request, 
     HttpServletResponse response) throws ServletException, IOException { 
    Connection conn = null; 
    ResultSet result = null; 
    PreparedStatement selectStmt = null; 
    try { 
     conn = DBUtil.getConnection(); 
     if(request.getParameter("param1").equals("RED9")){ 
      selectStmt = conn.prepareStatement("select * from TableName"); 
     }else if(request.getParameter("param1").equals("RED921")){ 
      selectStmt = conn.prepareStatement("select * from TableName"); 
    result = selectStmt.executeQuery(); 
     FileWriter f = new FileWriter("c://myFile.cvs); 
     while(result.next()){ 

     writer.append(result.getString("PARTC_SSN")); 
     writer.append(','); 

     writer.append("\n"); 
      } 
      writer.flush(); 
    writer.close(); 
      }catch(Exception e){ 
     e.printStackTrace(); 
    }finally { 
     try { 
      if (result != null) { 
       result.close(); 
       result = null; 
      } 
      if (selectStmt != null) { 
       selectStmt.close(); 
       selectStmt = null; 
      } 
      if (conn != null) { 
       conn.close(); 
       conn = null; 
      } 

     } catch (SQLException e) { 
      DBUtil 
        .log("Exception from ExcelReportServlet class, Method -createNoEcmatsRegDoc " 
          + e); 
     } 
    } 

} 

Answer 1

兩件事。首先，用響應寫入器替換文件寫入器，並確保告訴響應期望正確的輸出格式。此外，如果發生異常，請務必關閉寫入器。無論如何，這裏是我的猜測你的代碼可能應該看起來像：

/* 
* To change this license header, choose License Headers in Project Properties. 
* To change this template file, choose Tools | Templates 
* and open the template in the editor. 
*/ 
package gov.ca.water.preciptemp; 

import java.io.IOException; 
import java.io.PrintWriter; 
import java.sql.Connection; 
import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.util.logging.Level; 
import java.util.logging.Logger; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

/** 
* 
* @author hdunsford 
*/ 
public class DailyHydroServlet1 extends HttpServlet { 

    private static final Logger logger = Logger.getLogger(DailyHydroServlet1.class.getName()); 

    /** 
    * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods. 
    * 
    * @param request servlet request 
    * @param response servlet response 
    * @throws ServletException if a servlet-specific error occurs 
    * @throws IOException if an I/O error occurs 
    */ 
    protected void processRequest(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 


     response.setContentType("text/html;charset=UTF-8"); 
     Connection conn = null; 
     ResultSet result = null; 
     PreparedStatement selectStmt = null; 
     PrintWriter out; 
     try { 
      out = response.getWriter(); 
      conn = DBUtil.getConnection(); 
      if (request.getParameter("param1").equals("RED9")) { 
       selectStmt = conn.prepareStatement("select * from TableName"); 
      } else if (request.getParameter("param1").equals("RED921")) { 
       selectStmt = conn.prepareStatement("select * from TableName"); 
       result = selectStmt.executeQuery(); 

       while (result.next()) { 

        out.append(result.getString("PARTC_SSN")); 
        out.append(','); 

        out.append("\n"); 
       } 
       out.flush(); 
       out.close(); 
      } 
     } catch (Exception ex) { 
      try{ 
       out.close(); 
      }catch(Exception e){ 
       //ignore 
      } 
      logger.log(Level.SEVERE, ex.getMessage(), ex); 
     } finally { 
      try { 
       if (result != null) { 
        result.close(); 
        result = null; 
       } 
       if (selectStmt != null) { 
        selectStmt.close(); 
        selectStmt = null; 
       } 
       if (conn != null) { 
        conn.close(); 
        conn = null; 
       } 

      } catch (SQLException e) { 
       DBUtil.log("Exception from ExcelReportServlet class, Method -createNoEcmatsRegDoc " 
           + e); 
      } 
     } 

    } 


    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> 
    /** 
    * Handles the HTTP <code>GET</code> method. 
    * 
    * @param request servlet request 
    * @param response servlet response 
    * @throws ServletException if a servlet-specific error occurs 
    * @throws IOException if an I/O error occurs 
    */ 
    @Override 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
     processRequest(request, response); 
    } 

    /** 
    * Handles the HTTP <code>POST</code> method. 
    * 
    * @param request servlet request 
    * @param response servlet response 
    * @throws ServletException if a servlet-specific error occurs 
    * @throws IOException if an I/O error occurs 
    */ 
    @Override 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
     processRequest(request, response); 
    } 

    /** 
    * Returns a short description of the servlet. 
    * 
    * @return a String containing servlet description 
    */ 
    @Override 
    public String getServletInfo() { 
     return "Short description"; 
    }// </editor-fold> 

}