Question

我试图从oracle sql数据库中获取所有图像，但每次都会显示一个图像。我正在使用会话变量来传输行的uuid。

简化示例：

JSP代码：

HttpSession ses2=request.getSession();
Connection cn3;
PreparedStatement ps3;
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
cn3=DriverManager.getConnection("jdbc:odbc:sm","system","gecbsp");
ps3=cn3.prepareStatement("select * from sm_post order by time DESC");
ResultSet rs5=ps3.executeQuery();
while(rs5.next())
{
String puid = rs5.getString("post_uuid");
ses2.setAttribute("ses_puid",puid);
out.println("<img src = './post_pic' width = '400px' height = '300px' border = '2' align = 'middle' name = '"+puid+"'/>");
}
}
catch(Exception ee)
{
ee.printStackTrace();
}

图片Servlet：

import java.io.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.swing.JOptionPane;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class post_pic extends HttpServlet{

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {




        HttpSession ses2=request.getSession();
        String puid = (String)ses2.getAttribute("ses_puid");
        String imgLen="";
        Connection cn;
        PreparedStatement ps;
        try
        {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            cn=DriverManager.getConnection("jdbc:odbc:sm","system","gecbsp");
            ps=cn.prepareStatement("select post_image from sm_post where post_uuid = ?");
            ps.setString(1,puid);
            ResultSet rs = ps.executeQuery();
            if(rs.next()){
                  imgLen = rs.getString(1);
                  System.out.println(imgLen.length());
                  }  
            ps=cn.prepareStatement("select post_image from sm_post where post_uuid = ?");
            ps.setString(1,puid);
            ResultSet rs2 = ps.executeQuery();
            if(rs2.next()){
                  int len = imgLen.length();
                  byte [] rb = new byte[len];
                  InputStream readImg = rs2.getBinaryStream(1);
                  int index=readImg.read(rb, 0, len);
                  System.out.println("index"+index);
                  ps.close();
                  cn.close();
                  response.reset();
                  response.setContentType("image/jpg");
                  response.getOutputStream().write(rb,0,len);
                  response.getOutputStream().flush();
                  }
                  }
                  catch (Exception e){
                  e.printStackTrace();
                  }
                  ses2.setAttribute("ses_puid", puid);

            }

    }

我的数据库中有5个图片，但在每个img src标记中，它显示了最新插入的图片。

Answer 1

您在循环中覆盖会话属性：

ses2.setAttribute("ses_puid",puid);

尝试使用请求参数而不是会话属性：

<强> JSP：

out.println("<img src = './post_pic?puid="+puid+"' width = '400px' height = '300px' border = '2' align = 'middle' name = '"+puid+"'/>");

<强>的Servlet

String puid = request.getParameter("puid");

Answer 2

List<String> images = new ArrayList<String>();
    while (rs5.next()) {
        String puid = rs5.getString("post_uuid");
        images.add(puid);
    }
ses2.setAttribute("ses_puid", images);

并使用JSP中的图像列表

如何通过调用while（rs.next（））中的单个servlet从数据库中获取不同的图像

2 个答案: