jdbc.properties:
driverClass=com.mysql.jdbc.Driver
url = jdbc:mysql://localhost/jdbc
name = root
password = root
JDBCUtil:
package com.test.util;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
static String driverClass = null;
static String url = null;
static String name = null;
static String password = null;
//读取jdbc.properties
static{
try {
//1.创建一个属性配置对象
Properties properties = new Properties();
//1.对应文件位于工程根目录
//InputStream is = new FileInputStream("jdbc.properties");
//2.使用类加载器,读取drc下的资源文件 对应文件位于src目录底下 建议使用
InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
//2.导入输入流,抓取异常
properties.load(is);
//3.读取属性
driverClass = properties.getProperty("driverClass");
url = properties.getProperty("url");
name = properties.getProperty("name");
password = properties.getProperty("password");
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
/**
* 注册驱动 建立参数
* <p>Title: close</p>
* <p>Description: </p>
* @param connection
* @param resultSet
* @param statement
*/
public static Connection getConn(){
Connection connection = null;
//2. 建立连接 参数一: 协议 + 访问的数据库 , 参数二: 用户名 , 参数三: 密码。
try {
//Class.forName(driverClass);可写可不写
//Class.forName(driverClass);
connection = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return connection;
}
/**
* 释放资源
* <p>Title: close</p>
* <p>Description: </p>
* @param connection
* @param resultSet
* @param statement
*/
public static void close(Connection connection,ResultSet resultSet,Statement statement){
closeRS(resultSet);
closeSt(statement);
closeConn(connection);
}
public static void close(Connection connection,Statement statement){
closeSt(statement);
closeConn(connection);
}
private static void closeRS(ResultSet resultSet){
try {
if(resultSet !=null){
resultSet.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
resultSet = null;
}
}
private static void closeSt(Statement statement){
try {
if(statement !=null){
statement.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
statement = null;
}
}
private static void closeConn(Connection connection){
try {
if(connection !=null){
connection.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
connection = null;
}
}
}
UserDao:
package com.test.dao;
/**
* 定义操作数据库的方法
* <p>Title: UserDao</p>
* <p>Description: </p>
* <p>Company: www.itcast.cn</p>
* @version 1.0
*/
public interface UserDao {
//查询
//void findAll();
//登录方法
void login(String username , String password);
}
UserDaoImpl:
package com.test.dao.impl;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import com.test.dao.UserDao;
import com.test.util.JDBCUtil;
public class UserDaoImpl implements UserDao {
/**
* 查询
* <p>Title: findAll</p>
* <p>Description: </p>
* @see com.test.dao.UserDao#findAll()
*/
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
// public void findAll() {
// try {
// connection = JDBCUtil.getConn();
// statement = connection.createStatement();
// String sql ="select * from user";
// resultSet = statement.executeQuery(sql);
// while(resultSet.next()){
// String username = resultSet.getString("username");
// String password = resultSet.getString("password");
//
// System.out.println("username="+username+",password="+password);
// }
// } catch (Exception e) {
// // TODO: handle exception
// }finally{
// JDBCUtil.close(connection, resultSet, statement);
// }
//
// }
//
/**
* 登录
* <p>Title: login</p>
* <p>Description: </p>
* @param username
* @param password
* @see com.test.dao.UserDao#login(java.lang.String, java.lang.String)
*/
@Override
public void login(String username, String password) {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
//1. 获取连接对象
conn = JDBCUtil.getConn();
//2. 创建statement对象
st = conn.createStatement();
// SELECT * FROM t_user WHERE username='admin' AND PASSWORD='123456'
String sql = "select * from user where username='"+ username +"' and password='"+ password +"'";
rs = st.executeQuery(sql);
if(rs.next()){
System.out.println("登录成功");
}else{
System.out.println("登录失败");
}
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.close(connection, resultSet, statement);
}
}
}
JunitTest:
package com.test.example;
import org.junit.Test;
import com.test.dao.UserDao;
import com.test.dao.impl.UserDaoImpl;
public class JunitTest {
//查询
// @Test
// public void testFindAll(){
// UserDao dao = new UserDaoImpl();
// dao.findAll();
// }
// //登录
@Test
public void testLogin(){
UserDao dao = new UserDaoImpl();
//dao.login("admin", "123456");//可行
dao.login("admin", "123456 'or'1=1");//可行
}
}
数据库:
运行结果: