jsp 实现查询功能

要求：

实现查询功能

1.数据库代码

create database mvce;
use mvce;
create table test2(
id int not null identity,   
tname char(10) not null,
tttype char(20) not null,
tatt char(20) not null,
tkfsname char(10) not null,
tcity char(20) not null,
taddress char(50) not null,
tbeizhu char(50) not null,
)
---------------------------------------------------------
insert into test2 values('wanke bai','big','black','vanke','changchun','beihu','king')

2.数据

po/User.jsp

package po;

public class User {
    int id;
    String tname;
      String ttype;
      String tatt;
      String tkfsname;
      String tcity;
      String taddress;
      String tbeizhu;
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    public User(int id, String tname, String ttype, String tatt,
            String tkfsname, String tcity, String taddress, String tbeizhu) {
        super();
        this.id = id;
        this.tname = tname;
        this.ttype = ttype;
        this.tatt = tatt;
        this.tkfsname = tkfsname;
        this.tcity = tcity;
        this.taddress = taddress;
        this.tbeizhu = tbeizhu;
    }
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTname() {
        return tname;
    }

    public void setTname(String tname) {
        this.tname = tname;
    }

    public String getTtype() {
        return ttype;
    }

    public void setTtype(String ttype) {
        this.ttype = ttype;
    }

    public String getTatt() {
        return tatt;
    }

    public void setTatt(String tatt) {
        this.tatt = tatt;
    }

    public String getTkfsname() {
        return tkfsname;
    }

    public void setTkfsname(String tkfsname) {
        this.tkfsname = tkfsname;
    }

    public String getTcity() {
        return tcity;
    }

    public void setTcity(String tcity) {
        this.tcity = tcity;
    }

    public String getTaddress() {
        return taddress;
    }

    public void setTaddress(String taddress) {
        this.taddress = taddress;
    }

    public String getTbeizhu() {
        return tbeizhu;
    }

    public void setTbeizhu(String tbeizhu) {
        this.tbeizhu = tbeizhu;
    }
}

3.数据连接  db/Dbconn.jsp  

package db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DbConn {

    public  static Connection  getConn()
    {
        Connection con =null;
        try {
            //    Class.forName("com.mysql.jdbc.Driver"); // 加载驱动程序
                Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

            } catch (ClassNotFoundException e) {
                System.out.println("加载驱动程序错误" + e.getMessage());
            }
            try {
                // 创建连接 testdb是数据库名称
                 con = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;DatabaseName=mvce", "sa", "123456");

            } catch (SQLException e) {

                System.out.println("数据库连接操作出错" + e.getMessage());
            }
        
        return con;
    }
}

4.数据库处理  dao/UserDAO.java

package dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import db.DbConn;
import po.User;

public class UserDAO {

    public  List<User> getUserList()
    {
        List<User> ls=new ArrayList<User>();
        try {
            // 创建连接 testdb是数据库名称
            Connection con =DbConn.getConn();
                // 创建声明SQL对象
            Statement stm = con.createStatement();
            // 执行SQL语句，得到结果集，结果集放到ResultSet对象中
            ResultSet rs = stm.executeQuery("select * from test2");
            // 通过循环，从结果集对象中取得数据
            while (rs.next()) {

                               //从数据库中获取字段 内容 放到main.jsp 界面
                int id = rs.getInt("id"); // 取得int类型的字段id的值，
                String tname = rs.getString("tname"); // 取得字符类型的字段username的值，
                String ttype = rs.getString("ttype");
                String tatt=rs.getString("tatt");
                String tkfsname=rs.getString("tkfsname");
                String tcity=rs.getString("tcity");
                String taddress=rs.getString("taddress");
                String tbeizhu=rs.getString("tbeizhu");
                User u=new User();

                  u.setId(id);
                  u.setTname(tname);
                  u.setTtype(ttype);
                  u.setTatt(tatt);
                  u.setTkfsname(tkfsname);
                  u.setTcity(tcity);
                  u.setTaddress(taddress);
                  u.setTbeizhu(tbeizhu);
                  ls.add(u);


            }
        } catch (SQLException e) {

            System.out.println("数据库操作出错" + e.getMessage());
        }
        return ls;
    }
}

5.中间媒介  servlet/GetUsersServlet.java

用LoginServlet 需要跳转到 Get    要不然的没有数据没有传递过去  会报错的

package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.UserDAO;
import db.DbConn;

public class LoginServlet extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public LoginServlet() {
        super();
    }

    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }

    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
          doPost(request,response);
    }

    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out
                .println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
        out.println("<HTML>");
        out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
        out.println("  <BODY>");
        

        
        
            response.sendRedirect("../servlet/GetUsersServlet");
            

   
        
        out.println("  </BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }

    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }

}

package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import po.User;

import dao.UserDAO;

public class GetUsersServlet extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public GetUsersServlet() {
        super();
    }

    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }

    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request,response);
    }

    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //
        response.sendRedirect("../servlet/GetUsersServlet");
        
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out
                .println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
        out.println("<HTML>");
        out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
        out.println("  <BODY>");
          HttpSession  session=request.getSession(true);
         
         UserDAO udao=new UserDAO();
          List<User> ls= udao.getUserList();
             session.setAttribute("userlist", ls);
            response.sendRedirect("../main.jsp");
            
        out.println("  </BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }

    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }

}

6.jsp 页面

main.jsp 数据显示  

<%@ page language="java" import="java.util.*" pageEncoding="GB2312"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'Login.jsp' starting page</title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>
  
  <body>
    <div align="center" >
       <form method="get" action="servlet/LoginServlet">
       
               用户名:<input type="text" name="username"><br>
            密码：<input type="password" name="password"><br>
            <input type="submit" name="button1" value="登录">
        </form>
    </div>
</body>
</html>

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page import="po.*" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'main.jsp' starting page</title>
  </head>
  
  <body>
 <table width="502" border="1">
  <tr>
    <td width="37">房屋编号</td>
    <td width="63">房屋名称</td>
    <td width="52">房屋类型</td>
    <td width="52">房屋属性</td>
    <td width="61">开发商名称</td>
    <td width="197">所在城市</td>
    <td width="80">具体地址</td>
    <td width="80">备注</td>
  </tr>
  <%
        List<User> ls=(List<User>)session.getAttribute("userlist");
        for(int i=0;i<ls.size();i++)
        {
            User u=ls.get(i);
            %>
         <tr>
            <td><%=u.getId()%></td>
            <td><%=u.getTname()%></td>
            <td><%=u.getTtype()%></td>
            <td><%=u.getTatt()%></td>
            <td><%=u.getTkfsname()%></td>
            <td><%=u.getTcity()%></td>
            <td><%=u.getTaddress()%></td>
            <td><%=u.getTbeizhu()%></td>

        </tr>
       <% 
     }
   %>
   </table>
  </body>
</html>

遇到的问题：

servlet的转发问题   。  可不可以不用Login.jsp  直接显示