JDBC连接基本步骤

package cn.itheima.test;

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

import org.junit.Test;

/**
 * 测试sql注入问题
 * 
 * @author Never Say Never
 * @date 2016年7月28日
 * @version V1.0
 */
public class TestLogin {

	@Test
	public void testLogin() {
		try {
			login1("zs' or 'zs", "zs");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * 用户登录方法
	 * 
	 * @param username
	 * @param password
	 * @throws ClassNotFoundException
	 * @throws SQLException
	 */
	public void login(String username, String password) throws ClassNotFoundException, SQLException {
		// 1.注册驱动
		Class.forName("com.mysql.jdbc.Driver");
		// 2.获取连接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web08", "root", "root");
		// 3.创建执行sql语句的对象
		Statement stmt = conn.createStatement();
		// 4.书写一个sql语句
		String sql = "select * from tbl_user where " + "uname='" + username + "' and upassword='" + password + "'";
		// 5.执行sql语句
		ResultSet rs = stmt.executeQuery(sql);
		// 6.对结果集进行处理
		if (rs.next()) {
			System.out.println("恭喜您，" + username + ",登录成功!");
			System.out.println(sql);
		} else {
			System.out.println("账号或密码错误!");
		}
		if (rs != null)
			rs.close();
		if (stmt != null)
			stmt.close();
		if (conn != null)
			conn.close();
	}

	public void login1(String username, String password) throws ClassNotFoundException, SQLException {
		// 1.注册驱动
		Class.forName("com.mysql.jdbc.Driver");
		// 2.获取连接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/web08", "root", "root");
		// 3.编写sql语句
		String sql = "select * from tbl_user where uname=? and upassword=?";
		// 4.创建预处理对象
		PreparedStatement pstmt = conn.prepareStatement(sql);
		// 5.设置参数(给占位符)
		pstmt.setString(1, username);
		pstmt.setString(2, password);
		// 6.执行查询操作
		ResultSet rs = pstmt.executeQuery();
		// 7.对结果集进行处理
		if (rs.next()) {
			System.out.println("恭喜您，" + username + ",登录成功!");
			System.out.println(sql);
		} else {
			System.out.println("账号或密码错误!");
		}
		if (rs != null)
			rs.close();
		if (pstmt != null)
			pstmt.close();
		if (conn != null)
			conn.close();
	}
}

package cn.itheima.test;

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

import org.junit.Test;

/**
 * 测试查询所有用户的类
 * @author Administrator
 *
 */
public class QueryAll {
	
	@Test
	public void testQueryAll(){
		Connection conn= null;
		Statement stmt = null;
		ResultSet rs = null;
		try {
			//1.注册驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接
			String url ="jdbc:mysql://127.0.0.1:3306/web08?useUnicode=true&characterEncoding=utf8";
			String username="root";
			String password="root";
			conn = DriverManager.getConnection(url,username,password);
			//3.获取执行sql语句对象
			stmt = conn.createStatement();
			//4.编写sql语句
			String sql = "select * from tbl_user";
			//5.执行sql语句
			rs = stmt.executeQuery(sql);
			//6.处理结果集
			while(rs.next()){
				System.out.println("用户名："+rs.getString(2)+" 密码："+rs.getString("upassword"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(rs!=null)
				try {
					rs.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			if(stmt!=null)
				try {
					stmt.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			if(conn!=null)
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
		}
	}
}