JDBC事务

什么事务？

一件事情有N个单元组成，要么这N个单元同行执行成功，要么同时失败，就是值将这N个单元都放在一个事务里。

Mysql事务：

例如：zhangsan——lisi转帐，对应于两条sql语句

update account set money=money-100 where aname=‘zhangsan’;

update account set money=money+100 where aname=‘lisi’;

MySql默认自动提交。及执行一条sql语句提交一次事务。

数据库默认事务是自动提交的，一条Sql语句就是一个事务，如果想多条sql放在一个事务中执行，则需要使用如下语句。
开启事务：Start transaction

提交事务：commit 这句代码所指示的是从数据库开启事务到提交事务中间的所有sql都认为是真真正正的更新到数据库！！

事务回滚：rollback；回滚功能，从开启事务到事务回滚，中间所有的sql语句都认为是无效数据，不更新数据库，回滚到开启事务！如果进行了回滚功能，则必须要重新开启，重新提交（commit）方可有效

JDBC事务：

Connection.setAutoCommit(false); // 相当于start transaction 默认是true，false是不用自动提交（手动提交的意思）

Connection.rollback(); rollback

Connection.commit(); commit

注意：控制事务的connection必须是同一个

执行sql的connection与开启事务的connnection必须是同一个才能对事务进行控制

DBUtils事务

QueryRunner

有参构造：QueryRunner runner = new QueryRunner(DataSource dataSource);

有参构造将数据源(连接池)作为参数传入QueryRunner，QueryRunner会从连接池中获得一个数据库连接资源操作数据库，所以直接使用无Connection参数的update方法即可操作数据库

无参构造：QueryRunner runner = new QueryRunner();

无参的构造没有将数据源（连接池）作为参数传入QueryRunner，那么我们在使用QueryRunner对象操作数据库时要使用有Connection参数的方法

package com.oracle.domain;

public class Users {
	private String uid;
	private String username;
	private String password;
	private String name;
	private String email;
	private String telephone;
	private String birthday;
	private String sex;
	private int state;
	private String code;

	public String getUid() {
		return uid;
	}

	public void setUid(String uid) {
		this.uid = uid;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public String getTelephone() {
		return telephone;
	}

	public void setTelephone(String telephone) {
		this.telephone = telephone;
	}

	public String getBirthday() {
		return birthday;
	}

	public void setBirthday(String birthday) {
		this.birthday = birthday;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public int getState() {
		return state;
	}

	public void setState(int state) {
		this.state = state;
	}

	public String getCode() {
		return code;
	}

	public void setCode(String code) {
		this.code = code;
	}

	public String toString() {
		return "Users [uid=" + uid + ", username=" + username + ", password=" + password + ", name=" + name + ", email="
				+ email + ", telephone=" + telephone + ", birthday=" + birthday + ", sex=" + sex + ", state=" + state
				+ ", code=" + code + "]";
	}

}

package com.oracle.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import com.oracle.domain.Users;
import com.oracle.tools.JDBCUtils;
import com.oracle.tools.MyDBUtils;

public class UserDao {
    //注册
	public void register(Users users) throws SQLException{
		//创建QueryRunner对象
		QueryRunner qr=new QueryRunner(MyDBUtils.getDataSource());
		String sql="insert into users(uid,username,password,email,name,sex,birthday) values(?,?,?,?,?,?,?)";
		qr.update(
		sql, new Object[] {users. getUid(), users. getUsername(), users. getPassword(),users. getEmail(),users. getName(),users. getSex(),users. getBirthday()});

	}
	//登录
	public int login(String username,String password) throws SQLException{
		QueryRunner qr = new QueryRunner(MyDBUtils.getDataSource());
		String sql = "select count(*) from users where username=? and password=?";
		Long count = qr.query(sql, new ScalarHandler<Long>(),username,password);
		return count.intValue();

	}
}

package com.oracle.service;

import java.sql.SQLException;

import com.oracle.dao.UserDao;
import com.oracle.domain.Users;

public class UsersService {
  private UserDao usersDao=new UserDao();
  //注册
  public void register(Users users){
	  try {
		usersDao.register(users);
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
  }
  //登录
  public int login(String username,String password){
	  int count=0;
	  try {
		count=usersDao.login(username, password);
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	  return count;
   }
}