【发布时间】：2015-12-03 23:54:36
【问题描述】：
我的 servlet 遇到了关于从数据库中删除记录的问题。 请查看我的 servlet 代码并纠正我。先感谢您 当手动提供单个 ID 时，DeleteRow servlet 可以正常工作。 场景是：
ManageSinger.java servlet 显示数据库中的记录以及每行中的“删除”超链接。但问题是每当我尝试按下删除按钮时..它会在 deleterow.java servlet 中接收到 ID 的空值.. 请从这里指导我如何只能将相应的 ID 传递给另一个 servlet。
ManageSinger.java
package com.ea.servlet;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class ManageSinger extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {
PrintWriter out = res.getWriter();
res.setContentType("text/html");
out.println("<html><body>");
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/EATWO","root","");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from singerdetails");
out.println("<form method = \"post\">");
out.println("<table border=1 width=50% height=50%>");
out.println("<tr><th align=\"center\">Singer Name</th><th align=\"center\">StageName</th><th align=\"center\">Language</th><th></th><tr>");
while (rs.next()) {
String singername = rs.getString("singername");
String stagename = rs.getString("stagename");
String language = rs.getString("language");
String id = rs.getString("userID");
HttpSession session = req.getSession(true);
session.setAttribute("userID",id);
out.println("<tr><td align=\"center\">" + singername + "</td><td align=\"center\">" + stagename + "</td><td align=\"center\">" + language + "</td><td align=\"center\"><a href = \"./deleterow\">Delete</a></td></tr>");
}
out.println("</table>");
out.println("</form");
out.println("</body></html>");
con.close();
}
catch (Exception e) {
e.printStackTrace();
}finally{
}
}
}
DeleteRow.java
package com.ea.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.jws.Oneway;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class DeleteRow extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException
{
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
Connection con;
PreparedStatement st;
ResultSet rs;
try
{
HttpSession session = req.getSession(true);
Class.forName("com.mysql.jdbc.Driver");
String id = (String) session.getAttribute("id");
System.out.println(id);
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/EATWO","root","");
st= con.prepareStatement("delete from singerdetails where userID = ?");
st.setString(1, id);
st.executeUpdate();
int i = st.executeUpdate();
if(i!=0)
pw.println("Deleting row...");
else if (i==0)
{
pw.println("<br>Row has been deleted successfully.");
}
}
catch(SQLException sx)
{
pw.println(sx);
}
catch(ClassNotFoundException cx)
{
pw.println(cx);
}
}
}
【问题讨论】：
-
这里应该说 String id = (String) session.getAttribute("userID");而不是 DeleteRow.java 中的 (String) session.getAttribute("id")
-
谢谢！！！有效。行正在删除。但不正确。当我单击第 5 行的删除时。最后一行被删除.. @AvinashReddy 你能再看看吗
-
这意味着最后一个用户 ID 正在传递，而不是所需的用户 ID。请从这里帮助我
-
在 ManageSinger.java 中，而你正在这样做 out.println("
" + 歌手名 + " " + 舞台名 + " " + 语言 + " 删除 -
@AvinashReddy 也许您可以发表评论作为答案。