package com.person;import sun.awt.image.DataBufferNative;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;/**
* 增、删、改、查单个、查所有
* 只做数据库访问操作！不参与逻辑判断
* 数据库一张表的访问的操作复用！
*/public class PersonDaoImpl {//新增public int insert(Person person){Connection connection = null;PreparedStatement preparedStatement = null;String sql = "insert into person(name,age,borndate,email,address) values(?,?,?,?,?);";try {connection = DBUtils.getConnection();preparedStatement = connection.prepareStatement(sql);preparedStatement.setString(1,person.getName());preparedStatement.setInt(2,person.getAge());preparedStatement.setDate(3,null);preparedStatement.setString(4,person.getEmail());preparedStatement.setString(5,person.getAddress());int result = preparedStatement.executeUpdate();return result;} catch (SQLException e) {e.printStackTrace();}finally {DBUtils.closeAll(connection,preparedStatement,null);}return 0;}//修改public int update(Person person){Connection connection =null;PreparedStatement preparedStatement = null;String sql = "update person setname=?,age=?,borndate=?,email=?,address=? where id = ?";try {connection = DBUtils.getConnection();preparedStatement = connection.prepareStatement(sql);preparedStatement.setString(1,person.getName());preparedStatement.setInt(2,person.getAge());preparedStatement.setDate(3,null);preparedStatement.setString(4,person.getEmail());preparedStatement.setString(5,person.getAddress());preparedStatement.setInt(6,person.getId());int result = preparedStatement.executeUpdate();return result;} catch (SQLException e) {e.printStackTrace();}finally {DBUtils.closeAll(connection,preparedStatement,null);}return 0;}//删除public int delete(int id){Connection connection = null;PreparedStatement preparedStatement = null;String sql = "delete from person where id= ?;";connection = DBUtils.getConnection();try {preparedStatement = connection.prepareStatement(sql);preparedStatement.setInt(1,id);int result = preparedStatement.executeUpdate();return result;} catch (SQLException e) {e.printStackTrace();}finally {DBUtils.closeAll(connection,preparedStatement,null);}return 0;}//查单个public Person select(int id){Connection connection = null;PreparedStatement preparedStatement = null;ResultSet resultSet = null;String sql = "select * from person where id = ?;";Person person = null;try {connection = DBUtils.getConnection();preparedStatement = connection.prepareStatement(sql);preparedStatement.setInt(1,id);resultSet = preparedStatement.executeQuery();if(resultSet.next()){person = new Person();int pid= resultSet.getInt("id");String name = resultSet.getString("name");int age = resultSet.getInt("age");Date bornDate = resultSet.getDate("borndate");String email = resultSet.getString("email");String address = resultSet.getString("address");person.setId(pid);person.setName(name);person.setAge(age);person.setBornDate(bornDate);person.setEmail(email);person.setAddress(address);}return person;} catch (SQLException e) {e.printStackTrace();}finally {DBUtils.closeAll(connection,preparedStatement,resultSet);}return null;}//查所有public List<Person> selectAll(){Connection connection = null;PreparedStatement preparedStatement = null;ResultSet resultSet = null;Person person = null;List<Person> personList = new ArrayList<>();try {connection = DBUtils.getConnection();preparedStatement = connection.prepareStatement("select * from person;");resultSet = preparedStatement.executeQuery();while(resultSet.next()){int pid= resultSet.getInt("id");String name = resultSet.getString("name");int age = resultSet.getInt("age");Date bornDate = resultSet.getDate("borndate");String email = resultSet.getString("email");String address = resultSet.getString("address");person = new Person(pid,name,age,bornDate,email,address);personList.add(person);}return personList;} catch (Exception e) {e.printStackTrace();}return null;}
}

十二. 三层架构

12.1 什么是三层

12.2 三层搭建

/**
* 将所有数据表的操作,抽离成一个公用的方法;
* @Param sql 语句
* @Param sql语句对应的参数
* @return
*/
public static boolean executeDML(String sql,Object... params){try {//获取连接Connection connection = getConnection();//获取预处理的对象PreparedStatement ps = connection.prepareStatement(sql);//设置参数if(null != params){for(int i = 0 ; i < params.length ; i++){//1:给占位符设置参数;2:获取参数ps.setObject(i+1,params[i]);}}int i = ps.executeUpdate();close(null,ps,connection);return i > 0;} catch (SQLException sqlException) {sqlException.printStackTrace();}return false;
}

/**
* 通用的查询;需要将我们的数据表信息,封装到List里面进行返回
* @param sql 查询语句
* @param cls 实体类的字节码对象
* @param params 查询语句里面的占位符
* @param <T> 实体类类型泛型
* @return 就是我们查询到的数据集合
*/public static <T> List<T> executeDQL(String sql, Class<T> cls , Object...params) {try {Connection connection = getConnection(); //获取连接//获取预处理sqlPreparedStatement preparedStatement = connection.prepareStatement(sql);//设置参数if(null != params){for(int i = 0 ; i < params.length ; i++){preparedStatement.setObject(i+1,params[i]);}}//执行查询 得到结果集ResultSet resultSet = preparedStatement.executeQuery();//获取元数据(我们的列名)ResultSetMetaData metaData = resultSet.getMetaData();//列的总数int columnCount = metaData.getColumnCount();//用来保存我们所有的表数据List<T> list = new ArrayList<T>();T t;//用来保存我们一条数据//遍历结果集while(resultSet.next()){ //每一行记录的遍历过程中t = cls.newInstance();//根据字节码文件,构建一个实体类的对象//获取所有列的数据for(int i = 1 ; i <= columnCount ; i++){//你的查询语句有时候有别名String columnLabel = metaData.getColumnLabel(i);//根据列名获取我们的记录Object object = resultSet.getObject(columnLabel);//需要将拿到的这一列的记录,放到t对象指定的属性里面;//需要拿到这个t对象的属性,然后赋值;//解决方案2: 如果Object是NULL没有必要设置了if(null != object){try {Field field = cls.getDeclaredField(columnLabel);//根据属性的名称通过反射获取他的属性对象field.setAccessible(true);field.set(t,object);} catch (NoSuchFieldException e) {//代表我们当前这个实体类里面,没有这个属性}}}//需要将t对象保存到listlist.add(t);}close(resultSet,preparedStatement,connection);return list;} catch (SQLException sqlException) {sqlException.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (InstantiationException e) {e.printStackTrace();}return null;
}

package com.project.utils;import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;/**
* 连接池工具类
*/public class DBUtils {private static DruidDataSource dataSource;static {Properties properties = new Properties();InputStream is = DBUtils.class.getResourceAsStream("/database.properties");try {properties.load(is);dataSource = (DruidDataSource)DruidDataSourceFactory.createDataSource(properties);} catch (IOException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}}// 返回一个数据源public static DataSource getDataSource(){return dataSource;}
}

package com.project.dao.impl;import com.project.dao.UserDao;
import com.project.entity.User;
import com.project.utils.DBUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import java.sql.SQLException;
import java.util.List;public class UserDaoImpl implements UserDao {//1.创建QueryRunner对象，并传递一个数据源对象private QueryRunner queryRunner = new QueryRunner(DBUtils.getDataSource());@Overridepublic int insert(User user) {Object[] params={user.getId(),user.getUsername(),user.getPassword(),user.getSex(),user.getEmail(),user.getAddress()};try {return queryRunner.update("insert into user(id,username,password,sex,email,address) values(?,?,?,?,?,?)",params);} catch (SQLException e) {e.printStackTrace();}return 0;}@Overridepublic int update(User user) {Object[] params={user.getUsername(),user.getPassword(),user.getSex(),user.getEmail(),user.getAdd ress(),user.getId()};try {return queryRunner.update("update user setusername=?,password=?,sex=?,email=?,address=? where id = ?",params);} catch (SQLException e) {e.printStackTrace();}return 0;}@Overridepublic int delete(int id) {try {return queryRunner.update("delete from user where id = ?",id);} catch (SQLException e) {e.printStackTrace();}return 0;}@Overridepublic User select(int id) {try {//把查询到的记录封装成 指定对象return queryRunner.query("select * from user where id = ?", newBeanHandler<User>(User.class), id);} catch (SQLException e) {e.printStackTrace();}return null;}/*** 查询所有* @return*/@Overridepublic List<User> selectAll() {try {return queryRunner.query("select * from user;",newBeanListHandler<User>(User.class));} catch (SQLException e) {e.printStackTrace();}return null;}
}

#连接设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mytest
username=root
password=123456
#<!-- 初始化连接 -->
initialSize=10
#最大连接数量
maxActive=50
#<!-- 最小空闲连接 -->
minIdle=5
#<!-- 超时等待时间以毫秒为单位 60000毫秒/1000等于60秒 -->
maxWait=5000

public class DbUtils {//声明连接池对象private static DruidDataSource ds;static{//实例化配置对象Properties properties=new Properties();try {//加载配置文件内容properties.load(DbUtils.class.getResourceAsStream("druid.properties"));ds = (DruidDataSource)DruidDataSourceFactory.createDataSource(properties);} catch (IOException e) {e.printStackTrace();}}//获取连接对象public static Connection getConnection() {try {return ds.getConnection();} catch (SQLException e) {e.printStackTrace();}return null;}//释放资源。。
}

/*
一、主要配置
1、dataSourceClassName
这是DataSourceJDBC驱动程序提供的类的名称。请注意，如果您正在使用jdbcUrl“旧式”基于DriverManager的JDBC驱动程序配置，则不需要此属性 。 默认值：无
2、jdbcUrl
请注意，如果使用此属性，您仍然可以使用DataSource属性来配置您的驱动程序，实际上建议您使用URL本身中指定的驱动程序参数。 默认值：无
3、username
此属性设置从基础驱动程序获取连接时使用的默认身份验证用户名。
4、password
此属性设置从基础驱动程序获取连接时使用的默认身份验证密码。
*/

public static void main(String[] args) throws SQLException {HikariConfig hikariConfig = new HikariConfig();//设置urlhikariConfig.setJdbcUrl("jdbc:mysql://localhost:3306/mytest?characterEncoding=UTF-8");//数据库帐号hikariConfig.setUsername("root");//数据库密码hikariConfig.setPassword("123456");HikariDataSource ds = new HikariDataSource(hikariConfig);
}

//如果保存1w条记录
String sql = "insert into userinfo(uname,upass) values(?,?)";
Connection connection = DBUtilPool.getConnectionByDruid();
long start = System.currentTimeMillis();
PreparedStatement preparedStatement = connection.prepareStatement(sql);
for(int i = 0 ; i < 10000 ; i++){preparedStatement.setObject(1,"jack"+i);preparedStatement.setObject(2,"aaaa"+i);preparedStatement.addBatch(); //将当前的sql预编译好以后,加到批处理; 不会直接执行到数据库里面if(i % 500 == 0){preparedStatement.executeBatch(); //执行我们批处理preparedStatement.clearBatch(); //把上面的执行了,需要清空}
}
preparedStatement.executeBatch(); //最后一次进行批处理
long end = System.currentTimeMillis();
System.out.println("");
System.out.println(end-start);

BEGIN ;-- 代表我们开启了一个事务
UPDATE user_acount SET umoney = umoney-200 WHERE uname = 'jack';-- 断网了 断电了
UPDATE user_acount SET umoney = umoney+200 WHERE uname = 'rose';ROLLBACK -- 回滚事务(代表整个事务执行失败)
COMMIT; -- 提交事务

-- 默认提交事务
begin;
commit; -- 提交事务
rollback; -- 事务回滚//代码里面默认回滚事务
connection.setAutoCommit(false); //不自动提交事务
connection.commit();//提交事务
connection.rollback();//回滚事务