Servlet实现数据库查询（MyEclipse10,Tomcat7.0,JDK1.7,）——Java Web练习（三）

1.MyEclipse | New Web Project :TestServlet01，修改index.jsp的代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%

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 'index.jsp' starting page</title>

    <style>

        body, div, td, input {font-size:18px; margin:0px; }

        .line {margin:2px; }

    </style>

  </head>

  <body>

  <form action="/TestServlet01/servlet/PostServlet" method="POST">

  <div align="center">

    <br/>

    <fieldset style='width:60%'>

        <legend>填写用户信息</legend>

        <br/>

        <div class='line'>

            <div align="left">出发地:

                <input type="text" id="start" name="start" style='font-size:18px' width=200/>

            </div>

        </div>

        <div class='line'>

            <div align="left">

                <br/><input type="submit" name="Select" value="提交信息" style='font-size:18px'/><br/>

            </div>

        </div>

    </fieldset>

</div>

</form>

</body>

</html>

2.src文件夹右键Add | Package ：servlet

3.servlet的Package右键：New | Servlet （此时Web.xml中自然会增加对应的配置）：PostServlet.java：

package servlet;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class PostServlet extends HttpServlet {

    //自定义变量

    private Connection connection = null; //定义数据库连接对象

    private String driverName = "com.mysql.jdbc.Driver"; //数据库驱动器

    private String userName = "root"; //数据库用户名

    private String userPasswd = "123456"; //密码

    private String dbName = "test01"; //数据库名称

    private String tableName = "Train"; //表明

    //连接字符串 数据库地址URL MySQL数据库端口3306

    private String url = "jdbc:mysql://localhost:3306/" + dbName + "?user="

            + userName + "&password=" + userPasswd;

    //初始化方法

    public void init(ServletConfig config) throws ServletException

    {

        super.init(config);

    }

    public PostServlet() {

        super();

    }

    //处理GET请求方法

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException

    {

        response.setCharacterEncoding("UTF-8"); //设置输出编码

        request.setCharacterEncoding("UTF-8");

        response.setContentType("text/html");  //设置输出类型

        PrintWriter out = response.getWriter(); //获取out对象

        try {

            //数据库操作

            Class.forName(driverName).newInstance();

            connection = DriverManager.getConnection(url);

            Statement statement = connection.createStatement();

            String startName = request.getParameter("start"); //获取出发地

            //注意:startName需要加单引号 否则报错 ——错误：Unknown column 'BeiJing' in 'where clause'

            String sql = "SELECT * FROM " + tableName +" WHERE startname='" + startName+"';";

            if(startName=="") {

                sql = "SELECT * FROM " + tableName;

            }

            ResultSet rs = statement.executeQuery(sql); 

            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>");

            out.println("  <fieldset style='width:60%' ><legend>搜索结果</legend><br />");

            out.println("    <TABLE align='center'border='1' cellspacing='1' cellpadding='1'>");

            out.println("        <TR><TH>车号</TH><TH>出发地</TH><TH>到达地</TH></TR>");

            //循环输出查询结果

            while(rs.next()) {

                out.println("        <TR><TD>" + rs.getString(1) + "</TD>");

                out.println("        <TD>" + rs.getString(2) + "</TD>");

                out.println("        <TD>" + rs.getString(3) + "</TD></TR>");

            }

            out.println("  </TABLE>");

            out.println("  </fieldset>");

            out.println("  </BODY>");

            out.println("</HTML>");

            out.flush();

            out.close();

            rs.close(); // 关闭记录集

            statement.close(); // 关闭声明

        } catch(Exception e) {

            System.out.println("错误："+e.getMessage());

            response.sendRedirect("index.jsp");

        }

    }

    //处理POST请求方法

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException

    {

        doGet(request,response);

    }

    //销毁方法

    public void destroy() {

        super.destroy(); // Just puts "destroy" string in log

        try {

            connection.close(); // 关闭连接对象

        }catch(Exception e) {

            System.out.println("关闭数据库错误："+e.getMessage());

        }

    }

}

4.MySQL中新建表、增加记录：

use test01;

create table Train(id varchar(20) primary key,startname varchar(20),endname varchar(20));

insert train(id,startname,endname) values('T61','KunMing','BeiJing');

insert train(id,startname,endname) values('T62','BeiJing','KunMing');

insert train(id,startname,endname) values('T74','ChangSha','BeiJing');

insert train(id,startname,endname) values('T75','BeiJing','ChangSha');

insert train(id,startname,endname) values('T87','GuiYang','BeiJing');

insert train(id,startname,endname) values('T88','BeiJing','GuiYang');

5.效果：

Servlet实现数据库查询（MyEclipse10,Tomcat7.0,JDK1.7,）——Java Web练习（三）

注意：修改数据库的连接字符串（在PostServlet.java文件中）

本文引用自：http://blog.****.net/eastmount/article/details/45725077