事務處理的三種方式(簡單小Demo)

概述：事務指的是邏輯上的一組操作,組成這組操作的各個邏輯單元要麼一起成功,要麼一起失敗.

mysql.sql

create table account(
	id int primary key auto_increment,
	name varchar(20),
	money double
);

insert into account values (null,'張三',10000);

insert into account values (null,'鳳姐',10000);

JDBC中事務的管理：

Dbutils實現事務管理：

界面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>轉賬頁面</h1>
<form action="${ pageContext.request.contextPath }/這裏寫Servlet" method="post">
	付款人:<input type="text" name="from"><br/>
	收款人:<input type="text" name="to"><br/>
	轉賬金額:<input type="text" name="money"><br/>
	<input type="submit" value="轉賬">
</form>
</body>
</html>

jar包：

方式一：

把多個對於數據庫的操作所有的Connection綁定到當前線程中。該業務的操作所用到的Connection全部由當前線程管理。

JDBCUtilsShiwu.java（jdbc工具類）

package com.it.utils;

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

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

/**
 * JDBC的工具類：把多個對於數據庫的操作所有的Connection綁定到當前線程中。
			     該業務的操作所用到的Connection全部由當前線程管理
 * @author admin
 */
public class JDBCUtilsShiwu {
	private static final ComboPooledDataSource DATA_SOURCE =new ComboPooledDataSource();
	private static final ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
	/**
	 * 獲得連接的方法
	 */
	public static Connection getConnection(){
		Connection conn = null;
		try {
			conn = tl.get();
			if(conn == null){
				conn = DATA_SOURCE.getConnection();
				tl.set(conn);
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}
	
	public static void beginTransaction() throws SQLException{
		Connection conn = null;
		conn = tl.get();
		if(conn == null){
			conn = DATA_SOURCE.getConnection();
			tl.set(conn);
		}
		conn.setAutoCommit(false);
	}
	
	public static void commitTransaction() throws SQLException{
		Connection conn = tl.get();
		conn.commit();
	}
	
	public static void rollBackTransaction() throws SQLException{
		Connection conn = tl.get();
		conn.rollback();
	}
	
	public static DataSource getDataSource(){
		return DATA_SOURCE;
	}
	
}

c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
 <!-- 默認配置 -->
  <default-config>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
	<property name="jdbcUrl">jdbc:mysql:///day315</property>
	<property name="user">root</property>
	<property name="password">root</property>
	<property name="initialPoolSize">5</property>
	<property name="maxPoolSize">20</property>
  </default-config>
</c3p0-config>

Servlet02.java

package com.it.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.it.services.Services02;

/**
 * @author 侯青華
 * @version 創建時間：2018年3月15日  下午8:59:03
 */
public class Servlet02 extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//解決中文亂碼
		request.setCharacterEncoding("utf-8");
		//接收表單提交數據
		String from = request.getParameter("from");
		String to = request.getParameter("to");
		double money = Double.parseDouble(request.getParameter("money"));
		//調用service層處理
		Services02 services02 = new Services02();
		try {
			services02.trans(from,to,money);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

Services02.java

package com.it.services;

import java.sql.SQLException;

import com.it.dao.Dao02;
import com.it.utils.JDBCUtilsShiwu;

public class Services02 {
	/**
	 * 處理方案二： 思想： 把多個對於數據庫的操作所有的Connection綁定到當前線程中。 該業務的操作所用到的Connection全部由當前線程管理
	 * 
	 * @param from
	 * @param to
	 * @param money
	 * @throws Exception 
	 */
	public void trans(String from, String to, double money) throws Exception {
		
			Dao02 dao02 = new Dao02();
		try {
			//開啓事務
			JDBCUtilsShiwu.beginTransaction();
			//處理業務
			//扣錢
			dao02.outmoney(from,money);
			//加錢
			dao02.inmoney(to,money);
			//提交事務
			JDBCUtilsShiwu.commitTransaction();
		} catch (SQLException e) {
			//異常回滾事務
			try {
				JDBCUtilsShiwu.rollBackTransaction();
			} catch (SQLException e1) {
				e1.printStackTrace();
			}
			e.printStackTrace();
		}

	}

}

Dao02.java

package com.it.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import com.it.utils.JDBCUtilsShiwu;

public class Dao02 {

	public void outmoney(String from, double money) throws Exception {
		// 從工具類中獲得連接，工具類會自動從線程中拿
		Connection conn = JDBCUtilsShiwu.getConnection();
		String sql = "update account set money = money - ? where name = ?";
		PreparedStatement pst = conn.prepareStatement(sql);
		pst.setDouble(1, money);
		pst.setString(2, from);
		pst.executeUpdate();
		pst.close();
	}

	public void inmoney(String to, double money) throws Exception {
		// 從工具類中獲得連接，工具類會自動從線程中拿
		Connection conn = JDBCUtilsShiwu.getConnection();
		String sql = "update account set money = money + ? where name = ?";
		PreparedStatement pst = conn.prepareStatement(sql);
		pst.setDouble(1, money);
		pst.setString(2, to);
		pst.executeUpdate();
		pst.close();

	}

}

方式二：

把多個對於數據庫的操作所有的Connection提取到Service層。也就是說，由Service層來給dao層傳遞Connection。

c3p0jdbcUtils.java(工具類)

package com.it.utils;

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

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;



/**
 * jdbc c3p0工具類
 * 
 * @author 侯青華
 *
 */
public class c3p0jdbcUtils {
	// 私有構造
	private c3p0jdbcUtils() {
	}

	// c3p0數據源
	private static final ComboPooledDataSource DATA_SOURCE = new ComboPooledDataSource();

	/**
	 * 獲得連接
	 */
	public static Connection getConnection() {
		Connection conn = null;
		try {
			conn = DATA_SOURCE.getConnection();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
	}

	public static DataSource getDataSource() {
		return DATA_SOURCE;
	}

	/**
	 * 釋放資源
	 */
	/**
	 * 釋放資源的方法
	 */
	public static void release(ResultSet rs, Statement pst, Connection conn) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			// 垃圾回收儘快回收對象.
			rs = null;
		}
		if (pst != null) {
			try {
				pst.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			// 垃圾回收儘快回收對象.
			pst = null;
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			// 垃圾回收儘快回收對象.
			conn = null;
		}
	}

	public static void release(Statement pst, Connection conn) {
		if (pst != null) {
			try {
				pst.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			// 垃圾回收儘快回收對象.
			pst = null;
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			// 垃圾回收儘快回收對象.
			conn = null;
		}
	}

}

Servlet01.java

package com.it.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.it.services.Services01;

/**
 * @author 侯青華
 * @version 創建時間：2018年3月15日  下午8:43:31
 */
public class Servlet01 extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//解決中文亂碼post
		request.setCharacterEncoding("UTF-8");
		String from = request.getParameter("from");
		String to = request.getParameter("to");
		double money = Double.parseDouble(request.getParameter("money"));
		//service層處理業務
		Services01 services01 = new Services01();
		services01.trans(from,to,money);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

Services01.java

package com.it.services;

import java.sql.Connection;
import java.sql.SQLException;

import com.it.dao.Dao01;
import com.it.utils.c3p0jdbcUtils;

public class Services01 {
	/**
	 * 處理方案一： 思想： 把多個對於數據庫的操作所有的Connection提取到Service層.
	 * 也就是說，由Service層來給dao層傳遞Connection
	 * 
	 * @param from
	 * @param to
	 * @param money
	 */
	public void trans(String from, String to, double money) {
		Dao01 dao01 = new Dao01();
		// 初始化鏈接
		Connection conn = null;
		try {
			conn = c3p0jdbcUtils.getConnection();
			// 禁止事務自動提交
			conn.setAutoCommit(false);
			// 扣錢
			dao01.kouqian(from, money, conn);
			/*
			 * 測試事務 int x = 2 / 0;
			 */
			// 增加錢
			dao01.jiaqian(to, money, conn);
			// 提交事務
			conn.commit();
		} catch (Exception e) {
			// 出現異常回滾事務
			try {
				conn.rollback();
			} catch (SQLException e1) {
				e1.printStackTrace();
			}
		}
	}

}

Dao01.java

package com.it.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;

public class Dao01 {

	public void kouqian(String from, double money, Connection conn) throws Exception {
		String sql ="update account set money = money - ? where name = ?";
		PreparedStatement pst = conn.prepareStatement(sql);
		pst.setDouble(1, money);
		pst.setString(2, from);
		pst.executeUpdate();
	}

	public void jiaqian(String to, double money, Connection conn) throws Exception {
		String sql ="update account set money = money + ? where name = ?";
		PreparedStatement pst = conn.prepareStatement(sql);
		pst.setDouble(1, money);
		pst.setString(2, to);
		pst.executeUpdate();
	}

}

方式三：（使用Dbutils）

底層使用的是“方式二”。區別在於，當使用DBUtils做事務管理的時候，使用DbUtils來提交或者回滾事務，

把多個對於數據庫的操作所有的Connection提取到Service層，也就是說，由Service層來給dao層傳遞Connection。（使用方式二中的工具類）

Servlet03.java

package com.it.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.it.services.Services02;
import com.it.services.Services03;

/**
 * @author 侯青華
 * @version 創建時間：2018年3月15日  下午8:59:03
 */
public class Servlet03 extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//解決中文亂碼
		request.setCharacterEncoding("utf-8");
		//接收表單提交數據
		String from = request.getParameter("from");
		String to = request.getParameter("to");
		double money = Double.parseDouble(request.getParameter("money"));
		//調用service層處理
		Services03 services02 = new Services03();
		try {
			services02.trans(from,to,money);
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		
		
		
		
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

Services03.java

package com.it.services;

import java.sql.Connection;

import org.apache.commons.dbutils.DbUtils;

import com.it.dao.Dao03;
import com.it.utils.c3p0jdbcUtils;

public class Services03 {
/**
 * 	底層原理：
		底層使用的是“事務管理處理方案一”。
		區別在於，當使用DBUtils做事務管理的時候，使用DbUtils來提交或者回滾事務
	思想：
		把多個對於數據庫的操作所有的Connection提取到Service層.
		也就是說，由Service層來給dao層傳遞Connection
 * @param from
 * @param to
 * @param money
 */
	public void trans(String from, String to, double money) {
		
		Dao03 dao03 = new Dao03();
		//禁止事務自動提交
		Connection conn = null;
		try {
			//獲得鏈接
			conn = c3p0jdbcUtils.getConnection();
			//處理業務
			dao03.outMoney(conn,from,money);
			dao03.inMoney(conn,to,money);
			//利用Dbutils提交事務
			DbUtils.commitAndCloseQuietly(conn);
		} catch (Exception e) {
			//利用Dbutils回滾事務
			DbUtils.rollbackAndCloseQuietly(conn);
			// TODO: handle exception
		}
		
		
	}
	

}

Dao03.java

package com.it.dao;

import java.sql.Connection;

import org.apache.commons.dbutils.QueryRunner;

public class Dao03 {

	public void outMoney(Connection conn, String from, double money) throws Exception {
		QueryRunner qry = new QueryRunner();
		String sql = "update account set money = money - ? where name = ?";
		qry.update(conn, sql, money ,from);
	}

	public void inMoney(Connection conn, String to, double money) throws Exception {
		QueryRunner qry = new QueryRunner();
		String sql = "update account set money = money + ? where name = ?";
		qry.update(conn, sql, money ,to);
	}

}

最後附錄上web.xml吧，這裏只做事務demo演示簡單的事務處理方式。

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>shiwu01</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>Servlet01</display-name>
    <servlet-name>Servlet01</servlet-name>
    <servlet-class>com.it.servlet.Servlet01</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Servlet01</servlet-name>
    <url-pattern>/Servlet01</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>Servlet02</display-name>
    <servlet-name>Servlet02</servlet-name>
    <servlet-class>com.it.servlet.Servlet02</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Servlet02</servlet-name>
    <url-pattern>/Servlet02</url-pattern>
  </servlet-mapping>
    <servlet>
    <description></description>
    <display-name>Servlet03</display-name>
    <servlet-name>Servlet03</servlet-name>
    <servlet-class>com.it.servlet.Servlet03</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Servlet03</servlet-name>
    <url-pattern>/Servlet03</url-pattern>
  </servlet-mapping>
</web-app>

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