从数据库中读取数据（AJAX版本）

现在是用ajax 做从数据库读取数据的例子

1个jsp
Reg。jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>









  用户名：
  
  
  
  
电话：
    
    
    
  
  
城市：
    
    

    
    
  
  

    
    
    
  

1个servlet

package sl;

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

import javabean.yonghu;

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

import db.DB;

public class zf extends HttpServlet {

	/**
	 * The doGet method of the servlet. 

	 *
	 * 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 {

		response.setContentType("text/xml");//设置返回的信息的类型
		PrintWriter out = response.getWriter();//为了显示输出。

		ArrayList a =new DB().yonghu();

		/**
		 * 做循环输出
		 */

		out.println("");
		for(int i=0;i			yonghu b=(yonghu)a.get(i);
			out.println(""+b.getCity()+"");
		}
		out.println("");
		out.flush();//把流中的东西刷出去
		out.close();//关闭
	}

	/**
	 * The doPost method of the servlet. 

	 *
	 * 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 {


	}

}

DB包

package db;

import java.sql.*;
import java.text.SimpleDateFormat;
import java.util.*;

import javabean.yonghu;


public class DB {
	private Connection conn;//用来连接数据库的“数据库连接对象”

	private PreparedStatement stmt;//数据库操作对象

	private ResultSet rs;

	public DB() {
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(
					"jdbc:mysql://localhost:3306/test728", "root", "1234");
					} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public boolean adduser(String username,String tel,String city) {
		try {

			stmt = conn
					.prepareStatement("insert into test728.user(username,tel,city) values(?,?,?)");
			//stmt.setInt(1, name);
			stmt.setString(1, username);
			stmt.setString(2, tel);
			stmt.setString(3, city);

			stmt.execute();

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return false;

	}

		 public ArrayList yonghu(){
			ArrayList a=new ArrayList();
			try {

				stmt=conn.prepareStatement("select distinct city from test728.user");


				rs=stmt.executeQuery();
				while(rs.next()){

					yonghu c=new yonghu();
					//c.setId(Integer.parseInt(rs.getString("id")));
					//c.setUsername(rs.getString("username"));
					//c.setTel("tel");
					c.setCity(rs.getString("city"));
					a.add(c);

				}

			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

			return a;
		}
}

1 个javabean

package javabean;

public class yonghu {
	private int id;
	private String username;
	private String tel;
	private String city;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getTel() {
		return tel;
	}
	public void setTel(String tel) {
		this.tel = tel;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}

}

Web.xml

  
    action
    org.apache.struts.action.ActionServlet
    
      config
      /WEB-INF/struts-config.xml
    
    
      debug
      3
    
    
      detail
      3
    
    0
  
  
    This is the description of my J2EE component
    This is the display name of my J2EE component
    zf
    sl.zf
  

  
    action
    *.do
  
  
    zf
    /servlet/zf