求助：JSP的删除修改语句写在SERVLET里怎么实现

这是主页面代码，增加功能已经用servlet实现。不需要jsp页面了
<%@ page language="java" pageEncoding="utf-8" contentType="text/html;charset=utf-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="test.DBBean"%>
<jsp:useBean id = "myDBbean" class = "test.DBBean">
</jsp:useBean>
<html>
  <head>
    <title>欢迎进入新闻查询系统</title>
    <script type="text/javascript"">
    function validate()
    {
    var num=document.forms['biaoge'].num.value;
    if(num<=0){
     alert("编号不能为空，请输入编号！");
     return false;
    }
    else{
     return true;
    }
     //document.getElementById("form").submit();
    }
    </script>
  </head>
<body><h2>新闻查询系统</h2>
<%      ResultSet rs=myDBbean.query("select * from news");
     out.println("<table border=1 width=400>");
     out.println("<tr>");
     out.println("<td align=center>编号</td>");
     out.println("<td align=center>主题</td>");
     out.println("<td align=center>作者</td>");
     out.println("<td align=center>日期</td>");
     out.println("<td align=center colspan=2>操作</td>");
     out.println("</tr>");
     while (rs.next()){
     out.println("<tr>");
     out.println("<td align=center>"+rs.getString("num").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("theme").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("author").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("date").trim()+"</td>");
     out.println("<td align=center><a href='update.jsp?num="+ rs.getString("num").trim()+"'>修改</a>"+"</td>");
     out.println("<td align=center><a href='delete.jsp?num="+ rs.getString("num").trim()+"'>删除</a>"+"</td>");
     }
     out.println("</table>");
        myDBbean.close();
     %>

<br><br><br><h3>增加</h3><hr><form onSubmit="return validate()"  method="post" name="biaoge" action="servlet/MyServlet" ><br><br>
编号：<input type="text" name="num" ><br>
<br>
主题：<input type="text" name="theme" ><br>
<br>
作者：<input type="text" name="author" ><br>
<br>
日期：<input type="text" name="date"  ><br>
<br>
<input type="submit" value=提交></form>
<form action=mainpage.jsp method=post>
查询新闻编号：<input type="text" name="num">
<input type=submit value=提交><br><br>
</form>
</body>
</html>

你说你写了一个DBBean的类，那么就可以把它用单独的类文件来放啊，然后在servlet里面进行调用。其实servlet跟JSP实际上是一个东西，JSP会在后台编译成servlet。了解这个就没问题了。

这是SERVLETpackage servlet;import java.io.*;import javax.servlet.*;
import javax.servlet.http.*;import test.DBBean;public class MyServlet extends HttpServlet {
public void init(ServletConfig config) throws ServletException {
super.init(config);
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException { try {
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=gb2312");
DBBean dbbean = new DBBean();
request.setCharacterEncoding("utf-8");
String insert = "insert into news(num,theme,author,date) values('"
+ request.getParameter("num") + "','"
+ request.getParameter("theme") + "','"
+ request.getParameter("author") + "','"
+ request.getParameter("date") + "')";
dbbean.update(insert);
dbbean.close();
response.sendRedirect("/task/mainpage.jsp"); } catch (Exception ex) {
ex.printStackTrace();
} } public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
}

你直接在servlet里面直接DBBean myDbBean = new DBBean();
ResultSet rs=myDbbean.query("select * from news");看到这样应该理解了吧，接下来就还是一样的遍历rs啦。

package com.web;import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.entity.User;
import com.util.Util;public class UserServlet extends HttpServlet{
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// String s=request.getHeader("referer");
// System.out.println(s);
String url=request.getRequestURI();
String path=url.substring(url.lastIndexOf("/"),url.lastIndexOf("."));
Util.setEncoding(request, response);
if("/query".equals(path)){
Connection conn=null;
PreparedStatement stmt=null;
ResultSet rs=null;
String sql="select * from T_USER";
List<Object> lists=new ArrayList<Object>();
try{
conn=Util.getConnection();
stmt=conn.prepareStatement(sql);
rs=stmt.executeQuery();
while(rs.next()){
User user=new User();
user.setId(rs.getInt(1));
user.setName(rs.getString(2));
user.setPassword(rs.getString(3));
lists.add(user);
}
}catch(Exception e){
e.printStackTrace();
}finally{
Util.close(conn);
}
PrintWriter out=response.getWriter();
out.print(Util.toJson(lists.toArray()));
out.close();
}else if("/add".equals(path)){
int id=Integer.parseInt(request.getParameter("id"));
String name=request.getParameter("name");
String password=request.getParameter("password");
Connection conn=null;
PreparedStatement stmt=null;
ResultSet rs=null;
String sql1="select * from t_user where id=?";
String sql="insert into t_user values(?,?,?)";
String sql2="update t_user set name=?,password=? where id=?";
try{
conn=Util.getConnection();
stmt=conn.prepareStatement(sql1);
stmt.setInt(1, id);
rs=stmt.executeQuery();
if(!rs.next()){
stmt=conn.prepareStatement(sql);
stmt.setInt(1, id);
stmt.setString(2, name);
stmt.setString(3, password);
stmt.executeUpdate();
}else{
stmt=conn.prepareStatement(sql2);
stmt.setString(1, name);
stmt.setString(2, password);
stmt.setInt(3, id);
stmt.executeUpdate();
}
}catch(Exception e){
e.printStackTrace();
}finally{
Util.close(conn);
}
}else if("/delete".equals(path)){
int id=Integer.parseInt(request.getParameter("id"));
Connection conn=null;
PreparedStatement stmt=null;
String sql="delete t_user where id=?";
try{
conn=Util.getConnection();
stmt=conn.prepareStatement(sql);
stmt.setInt(1,id);
stmt.executeUpdate();
}catch(Exception e){
e.printStackTrace();
}finally{
Util.close(conn);
}
}else if("/modify".equals(path)){
int id=Integer.parseInt(request.getParameter("id"));
String name=request.getParameter("name");
String password=request.getParameter("password");
Connection conn=null;
PreparedStatement stmt=null;
String sql="update t_user set id=?,name=?,password? where id=?";
User user=null;
try{
conn=Util.getConnection();
stmt=conn.prepareStatement(sql);
stmt.setInt(1, id);
stmt.setString(2, name);
stmt.setString(3, password);
stmt.setInt(4, id);
stmt.executeUpdate();
}catch(Exception e){
e.printStackTrace();
}
}else if("/queryOne".equals(path)){
int id=Integer.parseInt(request.getParameter("id"));
Connection conn=null;
PreparedStatement stmt=null;
ResultSet rs=null;
User user=null;
String sql="select * from t_user where id=?";
try{
conn=Util.getConnection();
stmt=conn.prepareStatement(sql);
stmt.setInt(1, id);
rs=stmt.executeQuery();
if(rs.next()){
user=new User();
user.setId(rs.getInt(1));
user.setName(rs.getString(2));
user.setPassword(rs.getString(3));
}
}catch(Exception e){
e.printStackTrace();
}finally{
Util.close(conn);
}
PrintWriter out=response.getWriter();
out.println(Util.toJson(user));
out.close();
}
}
}

这是我写的一个跟extjs结合的增删改查希望对你有帮助

我没有在jsp中写代码的经历，怎么给你注释啊，而且我这写的只是纯粹为了简单也没给代码分层，你还是慢慢看吧

//信息删除方法
    public void delete(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException{
     Connection conn=null;
     Statement stat=null;
     conn=connect();
stat=conn.createStatement();
String id2=request.getParameter("id");
stat.execute("delete from student where id="+id2+"");
request.getRequestDispatcher("delete.jsp").forward(request, response);
    }
    //信息修改方法
    public void update1(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException{
     String id4=request.getParameter("id");
    request.setAttribute("result", select(id4,""));
        request.getRequestDispatcher("update1.jsp").forward(request, response);
    }
    public void update(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException{
     Connection conn=null;
     Statement stat=null;
        String id3=request.getParameter("id");
        String name3=request.getParameter("name");
        String age3=request.getParameter("age");
        String gender3=request.getParameter("gender");
        String major3=request.getParameter("major");
     conn=connect();
stat=conn.createStatement();
stat.execute("update student set id="+id3+",name='"+name3+"',age="+age3+",gender='"+gender3+"',major='"+major3+"' where id="+id3+"");
request.setAttribute("result", select(id3,""));
    request.getRequestDispatcher("update.jsp").forward(request, response);
    }

}

高手们都不在吗？帮帮忙我在servlet又写了个删除，请问mainpage中怎么把num传过来。貌似原来的语句不行。public void delete(HttpServletRequest request, HttpServletResponse response)
throws ClassNotFoundException, SQLException, ServletException,
IOException {
try {
DBBean dbbean_delete = new DBBean();
String ch = request.getParameter("num");
String sql = "delete from news where num='"+ch+"'";
dbbean_delete.update(sql);
dbbean_delete.close();
response.sendRedirect("/task/mainpage.jsp");
} catch (Exception ex) {
ex.printStackTrace();
}
}
mainpage里的语句，看是不是链接那里的语句有问题。
     out.println("<tr>");
     out.println("<td align=center>"+rs.getString("num").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("theme").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("author").trim()+"</td>");
     out.println("<td align=center>"+rs.getString("date").trim()+"</td>");
     out.println("<td align=center><a href='servlet/MyServlet?num="+ rs.getString("num").trim()+"'>修改</a>"+"</td>");
     out.println("<td align=center><a href='servlet/MyServlet?num="+ rs.getString("num").trim()+"'>删除</a>"+"</td>");
     }
     out.println("</table>");
        myDBbean.close();

仔细看看你的代码，你用的是sendRedirect，这上客户端跳转，如果你在这种情况下还需要传参数，只能用session或者cookie。
而一般情况下，我们就没必要用sendRedirect了，除非是那种未登录时跳转到登录页面的，那些一般是用这个。你可以直接。request.setAttribute("num","num");
request.getRequestDispatcher("跳转到的页面").forward(request,response);这里只会进行结果的转发，也就是服务器端的跳转，请求还在的。而上面的sendRedirect是二次请求，上次请求已经不在了。
而在JSP页面中，可以根据你自己喜欢，用EL表达式，可以像下面的
num:${num}这种情况默认在request中取参数，{}里面的是参数名称，如果不清楚可以看看EL教程。
如果这个不懂，可以用
num:<%=request.getAttribute("num")%>这样就可以取出了。

JSP直接传参数过去。点击不同按钮时候传递一个不同的参数，servlet直接在request中获取你要执行的动作。是要增加还是删除。
然后就是IF ELSE的事情了。

+1.
初学servlet时，就这么用。

谢谢各位了，我现在把增加删除修改分别写了3个servlet，还不会写到一个里面。
就是想知道，如何传递参数，增加比较好说，我加一个<input type="hidden" name="methodName" value="3"/> 这个3传递过去让函数判断，执行3的增加方法但是我的删除和修改是用的out print输出的表格，现在是加了个链接out.println("<td align=center><a href='servlet/deleteServlet?num="+ rs.getString("num").trim()+"'>删除</a>"+"</td>"); 这个语句里面怎么加一个参数让servlet判断呢？不知道我说的高手们能理解不，嘿嘿。初学好辛苦。

<a href='servlet/deleteServlet?num="+ rs.getString("num").trim()+"&type=?'>
这里type 可以自己设置
你可以设定type=1 为增加，2为修改 3为删除 ......
然后在servlet里面判断type的值就可以了

感谢回复，我去试试！还能帮我再看个问题吗？SERVLET里面的JAVASCRIPT语句提示框不能显示中文，是问号。代码如下
else{
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=utf-8");
response.setCharacterEncoding("utf-8");
out.println("<script language = javascript>alert('编号为空，请重新输入！')");
out.println("window.history.go(-1)</script>");
}

不是吧。我所有编码都设置的utf-8呀。

调试易

求助：JSP的删除修改语句写在SERVLET里怎么实现

解决方案 »