servlet中Java连接数据库后的基本操作

servlet中Java连接数据库后的基本操作

在eclipse中新建一个工程:login
在Server中新建一个服务器,基本的操作不用说了,在前两天的笔记中可以找到;
需要知道数据库的用户名和密码:用户名:user.密码:yufei
需要改变的地方:

地方一:web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

<display-name>login</display-name>

<welcome-file-list>

<welcome-file>login.html</welcome-file>

</welcome-file-list>

<servlet-name>LoginServlet</servlet-name>

<servlet-class>login.com.LoginServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>LoginServlet</servlet-name>

<url-pattern>/LoginServlet</url-pattern>

</servlet-mapping>

</web-app>

地方二:在Java Resources 里面新建包和html文件比如:login.com(包),LoginServlet.java文件

下面是:LoginServlet.java里面的内容:

package login.com;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

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;

public class LoginServlet extends HttpServlet{

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

// TODO Auto-generated method stub

//处理中文的乱码

resp.setContentType("text/html;charset=utf-8");//响应

req.setCharacterEncoding("utf-8"); //请求

String name = req.getParameter("username"); //username是输入框对应的name String pwd = req.getParameter("pwd"); try {

try {

//表单填写的都是字符串

Class.forName("com.mysql.jdbc.Driver");

Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/login", "root", "yufei");

// System.out.println(connection);

String sql = "select * from conn where name=? and pwd=? ;";

PreparedStatement preparedStatement = connection.prepareStatement(sql);

System.out.println("name:"+name+"============" +"pwd" + pwd);

preparedStatement.setString(1, name);

preparedStatement.setString(2, pwd);

ResultSet re = preparedStatement.executeQuery();

PrintWriter out = resp.getWriter();

out.print("<h1>==========</h1>");

String sql1 = "select * from student";

PreparedStatement sprint = connection.prepareStatement(sql1);

ResultSet studinf = sprint.executeQuery();

while(re.next()){

out.print("<h1>登录成功</h1>");

out.print("<h5>学生的信息是:</h5>");

while(studinf.next()){

out.print("<p>学生的姓名是:"+ studinf.getString("name")+"===id号:"+studinf.getString("id")+"===性别是:"+studinf.getString("gender")+"===年龄是:"+studinf.getString("age")+"</p>");

}

return;//终止程序

}

out.print("<h1>登录失败</h1>");

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

//form默认的提交方式是get

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

// TODO Auto-generated method stub

doPost(req,resp);

}

地方三:在文件WebContent里面新建一个html文件,比如:login.html

下面是:login.html内容:

<!DOCTYPE html>

<html>

<head>

<title>login</title>

</head>

<body>

<h1> welcome to login</h1>

<button>login</button>

</form>

</div>

</body>

</html>

地方四:添加夹包-在文件夹WEB-INF的lib里面加上夹包Server和mysql