Userdao:数据访问接口(Data Access Object 数据访问对象)
UserDaoImpl:新建类实现接口定义规则
Jdbcutil:工具类构建
Properties:配置文件
TestUserDaoImpl:负责单元测试
与CRUD区别:
设定了接口,并且新建类实现接口定义规则
代码
Userdao:
package com.itheima.dao;
/**
* 定义操作数据库的方法
*/
public interface UserDao {
//update t_user set name=? where id = ?
/**
* 根据id去更新具体的用户名
* @param id
* @param name
*/
void update(int id , String name);
void delete(int id);
/**
* 执行添加
* @param userName
* @param password
*/
void insert(String userName , String password);
/**
* 查询所有
*/
void findAll();
/**
* 登录方法
* @param username
* @param password
*/
void login(String username , String password);
}
UserDaoImpl:
package com.itheima.dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import com.itheima.dao.UserDao;
import com.itheima.uitl.JDBCUtil;
public class UserDaoImpl implements UserDao{
@Override
public void findAll() {
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();
String sql = "select * from t_user";
rs = st.executeQuery(sql);
while(rs.next()){
String userName = rs.getString("username");
String password = rs.getString("password");
System.out.println(userName+"="+password);
}
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.release(conn, st, rs);
}
}
/*@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='10086'
String sql = "select * from t_user where username='"+ username +"' and password='"+ or +"'";
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.release(conn, st, rs);
}
}*/
@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
String sql = "select * from t_user where username=? and password=?";
//预先对sql语句执行语法的校验, ? 对应的内容,后面不管传递什么进来,都把它看成是字符串。 or select
PreparedStatement ps = conn.prepareStatement(sql);
//? 对应的索引从 1 开始。
ps.setString(1, username);
ps.setString(2, password);
rs = ps.executeQuery();
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.release(conn, st, rs);
}
}
@Override
public void insert(String userName, String password) {
Connection conn = null;
PreparedStatement ps = null;
try {
conn = JDBCUtil.getConn();
String sql = "insert into t_user values(null , ? , ?)";
ps = conn.prepareStatement(sql);
//给占位符赋值 从左到右数过来,1 代表第一个问号, 永远你是1开始。
ps.setString(1, userName);
ps.setString(2, password);
int result = ps.executeUpdate();
if(result>0){
System.out.println("添加成功");
}else{
System.out.println("添加失败");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtil.release(conn, ps);
}
}
@Override
public void delete(int id) {
Connection conn = null;
PreparedStatement ps = null;
try {
conn = JDBCUtil.getConn();
String sql = "delete from t_user where id = ?";
ps = conn.prepareStatement(sql);
//给占位符赋值 从左到右数过来,1 代表第一个问号, 永远你是1开始。
ps.setInt(1, id);
int result = ps.executeUpdate();
if(result>0){
System.out.println("删除成功");
}else{
System.out.println("删除失败");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtil.release(conn, ps);
}
}
@Override
public void update(int id, String name) {
Connection conn = null;
PreparedStatement ps = null;
try {
conn = JDBCUtil.getConn();
String sql = "update t_user set username=? where id =?";
ps = conn.prepareStatement(sql);
//给占位符赋值 从左到右数过来,1 代表第一个问号, 永远你是1开始。
ps.setString(1, name);
ps.setInt(2, id);
int result = ps.executeUpdate();
if(result>0){
System.out.println("更新成功");
}else{
System.out.println("更新失败");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
JDBCUtil.release(conn, ps);
}
}
}
Jdbcutil:
package com.itheima.uitl;
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;
static{
try {
//1. 创建一个属性配置对象
Properties properties = new Properties();
InputStream is = new FileInputStream("jdbc.properties");
//使用类加载器,去读取src底下的资源文件。 后面在servlet
// InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
//导入输入流。
properties.load(is);
//读取属性
driverClass = properties.getProperty("driverClass");
url = properties.getProperty("url");
name = properties.getProperty("name");
password = properties.getProperty("password");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取连接对象
* @return
*/
public static Connection getConn(){
Connection conn = null;
try {
Class.forName(driverClass);
//静态代码块 ---> 类加载了,就执行。 java.sql.DriverManager.registerDriver(new Driver());
//DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//DriverManager.getConnection("jdbc:mysql://localhost/test?user=monty&password=greatsqldb");
//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。
conn = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 释放资源
* @param conn
* @param st
* @param rs
*/
public static void release(Connection conn , Statement st , ResultSet rs){
closeRs(rs);
closeSt(st);
closeConn(conn);
}
public static void release(Connection conn , Statement st){
closeSt(st);
closeConn(conn);
}
private static void closeRs(ResultSet rs){
try {
if(rs != null){
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
rs = null;
}
}
private static void closeSt(Statement st){
try {
if(st != null){
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
st = null;
}
}
private static void closeConn(Connection conn){
try {
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
conn = null;
}
}
}
Properties:
driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/user
name=root
password=XXXXXX
TestUserDaoImpl:
package com.itheima.test;
import org.junit.Test;
import com.itheima.dao.UserDao;
import com.itheima.dao.impl.UserDaoImpl;
public class TestUserDaoImpl {
@Test
public void testInsert(){
UserDao dao = new UserDaoImpl();
dao.insert("aobama", "911");
}
@Test
public void testUpdate(){
UserDao dao = new UserDaoImpl();
dao.update(2, "itheima");
}
@Test
public void testDelete(){
UserDao dao = new UserDaoImpl();
dao.delete(30);
}
@Test
public void testFindAll(){
//面向父类编程 接口编程
UserDao dao = new UserDaoImpl(); //体现多态的特征
// UserDaoImpl dao = new UserDaoImpl();
dao.findAll();
}
// "10087 "+" or 1=1" === “10087 or 1=1”
@Test
public void testLogin(){
UserDao dao = new UserDaoImpl();
dao.login("admin", "100234khsdf88' or '1=1");
// dao.login("admin", "10087 "+" or 1=1");
// select * from t_user where username='admin' and password='100234khsdf88'or '1=1'
// SELECT * FROM t_user WHERE username='admin' AND PASSWORD='10087' or '1=1'
}
}