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:


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.csdn.net/eastmount/article/details/45725077
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