事務管理入門-JDBC/Hibernate事務管理器/Spring註解 3種方式

http://coderdream.iteye.com/blog/434561

在軟件開發過程中，經常會遇到事務問題，下面我們來看看最簡單的JDBC和Spring分別如何處理事務。

 

關於事務控制的場景當然是轉賬，我們使用的數據庫是MySQL。

打開test數據庫後，運行下面的數據庫腳本：

DROP TABLE IF EXISTS account;
CREATE TABLE account (
accountId int primary key auto_increment,
accountname varchar(20),
money int not null
);

INSERT INTO ACCOUNT(ACCOUNTNAME,MONEY) VALUES('zhangsan',100);
INSERT INTO ACCOUNT(ACCOUNTNAME,MONEY) VALUES('lisi',100);

 

1、JDBC中的事務控制

 

代碼1：AccountDAO.java

package com.coderdream;

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

public class AccountDAO {

    public void transfer(Integer fromAccountId, Integer toAccountId, int money) {
        try {
            // 1. 註冊驅動
            Class.forName("com.mysql.jdbc.Driver");

            // 2. 獲取數據庫的連接
            Connection conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost/test", "root", "1234");

            // 3. 獲取表達式
            Statement stmt1 = conn.createStatement();
            Statement stmt2 = conn.createStatement();
            Statement stmt3 = conn.createStatement();
            Statement stmt4 = conn.createStatement();

            // 執行插入數據的 SQL
            ResultSet rs1 = stmt1
                    .executeQuery("SELECT MONEY FROM ACCOUNT WHERE ACCOUNTID="
                            + fromAccountId);
            // 5. 顯示結果集裏面的數據
            int money1 = 0;
            while (rs1.next()) {
                System.out.println(rs1.getInt(1));
                money1 = rs1.getInt(1);
            }

            // 修改
            money1 -= money;
            System.out.println("money1: " + money1);
            stmt2.executeUpdate("UPDATE ACCOUNT SET MONEY=" + money1
                    + " WHERE ACCOUNTID=" + fromAccountId);

            // 執行插入數據的 SQL
            ResultSet rs2 = stmt3
                    .executeQuery("SELECT MONEY FROM ACCOUNT WHERE ACCOUNTID="
                            + toAccountId);
            // 5. 顯示結果集裏面的數據
            int money2 = 0;
            while (rs2.next()) {
                System.out.println(rs2.getInt(1));
                money2 = rs2.getInt(1);
            }

            // 修改
            money2 += money;
            System.out.println("money2: " + money2);
            stmt2.executeUpdate("UPDATE ACCOUNT SET MONEY=" + money2
                    + " WHERE ACCOUNTID=" + toAccountId);

            // 6. 釋放資源
            rs1.close();
            rs2.close();
            stmt1.close();
            stmt2.close();
            stmt3.close();
            stmt4.close();
            conn.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

 

代碼2：AccountService.java

package com.coderdream;

public class AccountService {

    private AccountDAO accountDAO;

    /**
     * 通過 Spring 向 Service ͨszh注入 Dao
     *
     * @param accountDAO
     */
    public void setAccountDAO(AccountDAO accountDAO) {
        this.accountDAO = accountDAO;
    }

    /**
     * 轉賬
     *
     * @param fromAccountId
     *            轉出帳號
     * @param toAccountId
     *            轉入帳號
     * @param money
     *            轉賬金額
     */
    public void transfer(Integer fromAccountId, Integer toAccountId, int money) {
        accountDAO.transfer(fromAccountId, toAccountId, money);
    }
}

 

代碼3：Main.java

package com.coderdream;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class Main {

    /**
     * @param args
     */
    public static void main(String[] args) {

        ApplicationContext act = new FileSystemXmlApplicationContext(
                "src/applicationContext.xml");
        AccountService accountService = (AccountService) act
                .getBean("accountService");
        try {
            // 帳號1轉賬1元至帳號2
            accountService.transfer(1, 2, 1);//A
               } catch (Exception e) {
            System.out.println("轉賬失敗!");
        }
    }
}

 

代碼4：applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

    <bean id="accountDAO" class="com.coderdream.AccountDAO" />

    <bean id="accountService" class="com.coderdream.AccountService">
        <property name="accountDAO" ref="accountDAO"></property>
    </bean>
</beans>

 

上面的代碼是沒有加事務控制的，如果把‘A’處的代碼換成：

// 帳號1轉賬1元至帳號3
accountService.transfer(1, 3, 1);//A

 

則由於帳號3不存在，所以會出現問題，帳號1的金額會減1，而帳號2的金額不會變，轉賬的1元就“不翼而飛”了，所以必須在Dao層加入事務控制。

 

代碼5：加入事務控制後的AccountDAO

public class AccountDAO {

    public void transfer(Integer fromAccountId, Integer toAccountId, int money) {
        Connection conn = null;
        ResultSet rs1 = null;
        Integer rs2 = null;
        ResultSet rs3 = null;
        Integer rs4 = null;
        Statement stmt1 = null;
        Statement stmt2 = null;
        Statement stmt3 = null;
        Statement stmt4 = null;
        // 1. 註冊驅動
        try {
            Class.forName("com.mysql.jdbc.Driver");

            // 2. 獲取數據庫的連接
            conn = DriverManager.getConnection("jdbc:mysql://localhost/test",
                    "root", "1234");

            conn.setAutoCommit(false);

            // 3. 獲取表達式
            stmt1 = conn.createStatement();
            stmt2 = conn.createStatement();
            stmt3 = conn.createStatement();
            stmt4 = conn.createStatement();

            // 執行插入數據的 SQL
            rs1 = stmt1
                    .executeQuery("SELECT MONEY FROM ACCOUNT WHERE ACCOUNTID="
                            + fromAccountId);
            // 5. 顯示結果集裏面的數據
            int money1 = 0;
            while (rs1.next()) {
                System.out.println(rs1.getInt(1));
                money1 = rs1.getInt(1);
            }

            // 修改
            money1 -= money;
            System.out.println("money1: " + money1);
            rs2 = stmt2.executeUpdate("UPDATE ACCOUNT SET MONEY=" + money1
                    + " WHERE ACCOUNTID=" + fromAccountId);
            if (1 != rs2) {
                throw new Exception(" 轉出失敗，帳號： " + fromAccountId);
            }

            // 執行插入數據的 SQL
            rs3 = stmt3
                    .executeQuery("SELECT MONEY FROM ACCOUNT WHERE ACCOUNTID="
                            + toAccountId);
            // 5. 顯示結果集裏面的數據
            int money2 = 0;
            while (rs3.next()) {
                System.out.println(rs3.getInt(1));
                money2 = rs3.getInt(1);
            }

            // 修改
            money2 += money;
            System.out.println("money2: " + money2);
            rs4 = stmt2.executeUpdate("UPDATE ACCOUNT SET MONEY=" + money2
                    + " WHERE ACCOUNTID=" + toAccountId);
            if (1 != rs4) {
                throw new Exception(" 轉入失敗，帳號： " + toAccountId);
            }

            conn.commit();
            System.out.println("轉帳成功！");
        } catch (Exception e) {
            try {
                conn.rollback();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
            e.printStackTrace();
        }
        // 6. 釋放資源
        finally {
            try {
                if (rs1 != null) {
                    rs1.close();
                }
                if (rs3 != null) {
                    rs3.close();
                }
                if (stmt1 != null) {
                    stmt1.close();
                }
                if (stmt2 != null) {
                    stmt2.close();
                }
                if (stmt3 != null) {
                    stmt3.close();
                }
                if (stmt4 != null) {
                    stmt4.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

 

2、Spring中的事務控制方式一：Hibernate的事務管理器託管

我們先來看看通過Spring+Hibernate來操作數據庫的簡單示例。

先通過 MyEclipse 生成Hibernate 需要的 Bean 及 hbm.xml文件：

 

代碼6：Account.java

package com.coderdream;

/**
 * Account entity.
 *
 * @author MyEclipse Persistence Tools
 */
public class Account implements java.io.Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 909891879728703117L;

    private Integer accountId;
    private String accountname;
    private Integer money;

    // Property accessors

    public Integer getAccountId() {
        return this.accountId;
    }

    public void setAccountId(Integer accountId) {
        this.accountId = accountId;
    }

    public String getAccountname() {
        return this.accountname;
    }

    public void setAccountname(String accountname) {
        this.accountname = accountname;
    }

    public Integer getMoney() {
        return this.money;
    }

    public void setMoney(Integer money) {
        this.money = money;
    }

    // Constructors

    /** default constructor */
    public Account() {
    }

    /** full constructor */
    public Account(String accountname, Integer money) {
        this.accountname = accountname;
        this.money = money;
    }

}

 

代碼7：Account.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.coderdream.Account" table="account" catalog="test">
        <id name="accountId" type="java.lang.Integer">
            <column name="accountId" />
            <generator class="native" />
        </id>
        <property name="accountname" type="java.lang.String">
            <column name="accountname" length="20" />
        </property>
        <property name="money" type="java.lang.Integer">
            <column name="money" length="20" />
        </property>
    </class>
</hibernate-mapping>

 

代碼8：

package com.coderdream;

import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

public class AccountDAO extends HibernateDaoSupport {

    public void addMoney(Integer accountId, int money) {
        Account account = (Account) getHibernateTemplate().get(Account.class,
                accountId);
        account.setMoney(account.getMoney() + money);
        getHibernateTemplate().saveOrUpdate(account);
    }

    public void subMoney(Integer accountId, int money) {
        Account account = (Account) getHibernateTemplate().get(Account.class,
                accountId);
        account.setMoney(account.getMoney() - money);
        getHibernateTemplate().saveOrUpdate(account);
    }
}

 

代碼9：

package com.coderdream;

public class AccountService {

    private AccountDAO accountDAO;

    /**
     * 通過 Spring 將 DAO 注入到 Service
     *
     * @param accountDAO
     */
    public void setAccountDAO(AccountDAO accountDAO) {
        this.accountDAO = accountDAO;
    }

    /**
     * 轉賬方法包括兩個原子方法：轉出方法和轉入方法
     *
     * @param fromAccountId
     * @param toAccountId
     * @param money
     */
    public void transfer(Integer fromAccountId, Integer toAccountId, int money) {
        accountDAO.subMoney(fromAccountId, money);
        accountDAO.addMoney(toAccountId, money);
    }
}

 

代碼10：

package com.coderdream;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class Main {

    /**
     * @param args
     */
    public static void main(String[] args) {

        ApplicationContext act = new FileSystemXmlApplicationContext(
                "src/applicationContext.xml");
        AccountService accountService = (AccountService) act
                .getBean("accountService");
        try {
            // 帳號1轉賬1元至帳號2
            accountService.transfer(1, 2, 1);// B
        } catch (Exception e) {
            System.out.println("轉賬失敗");
        }
    }
}

 

上面的代碼同樣沒有加入事務控制，如果在‘B’處將轉入的帳號設置爲不存在的帳號3，同樣會有問題，下面我們來加入事務控制，我們需要修改 applicationContext.xml 文件：

 

代碼11：增加事務後的 applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

    <bean id="dataSource"
        class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName"
            value="com.mysql.jdbc.Driver">
        </property>
        <property name="url" value="jdbc:mysql://localhost:3306/test"></property>
        <property name="username" value="root"></property>
        <property name="password" value="1234"></property>
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource">
            <ref bean="dataSource" />
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">
                    org.hibernate.dialect.MySQLDialect
                </prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
        <property name="mappingResources">
            <list>
                <value>com/coderdream/Account.hbm.xml</value>
            </list>
        </property>
    </bean>

    <!-- 引用Hibernate的事務管理器 -->
    <bean id="transactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>

    <bean id="accountDAO" class="com.coderdream.AccountDAO">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>

    <!-- 通過事務管理器來管理Service -->
    <bean id="accountService"
        class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
        <property name="transactionManager" ref="transactionManager"></property>
        <property name="target">
            <bean class="com.coderdream.AccountService">
                <property name="accountDAO" ref="accountDAO"></property>
            </bean>
        </property>
        <property name="transactionAttributes">
            <props>
                <prop key="transfer">PROPAGATION_REQUIRED</prop>
            </props>
        </property>
    </bean>
</beans>

 

3、Spring中的事務控制方式二：註解方式

當然，我們還可以通過註解的方式加入事務的控制。

我們需要先在 applicationContext.xml 聲明事務控制器和註解：

 

代碼12：applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <bean id="dataSource"
        class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName"
            value="com.mysql.jdbc.Driver">
        </property>
        <property name="url" value="jdbc:mysql://localhost:3306/test"></property>
        <property name="username" value="root"></property>
        <property name="password" value="1234"></property>
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource">
            <ref bean="dataSource" />
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">
                    org.hibernate.dialect.MySQLDialect
                </prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
        <property name="mappingResources">
            <list>
                <value>com/coderdream/Account.hbm.xml</value>
            </list>
        </property>
    </bean>

    <!-- 引用Hibernate的事務管理器 -->
    <bean id="transactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>

    <!-- 使用annotation定義事務 -->
    <tx:annotation-driven transaction-manager="transactionManager" />

    <bean id="accountDAO" class="com.coderdream.AccountDAO">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>

    <bean id="accountService" class="com.coderdream.AccountService">
        <property name="accountDAO" ref="accountDAO"></property>
    </bean>
</beans>

 

同時需要在Service層的要使用的方法上聲明事務，如：

@Transactional(readOnly = false)

 如果只是對數據庫進行查詢操作，這裏的“readOnly = true“，如果是”增/刪/改“操作，則爲 false。

 

代碼13：在方法上加入“註解式”事務控制後的 AccountService.java

package com.coderdream;

public class AccountService {

    private AccountDAO accountDAO;

    /**
     * 通過 Spring 將 DAO 注入到 Service
     *
     * @param accountDAO
     */
    public void setAccountDAO(AccountDAO accountDAO) {
        this.accountDAO = accountDAO;
    }

    /**
     * 轉賬方法包括兩個原子方法：轉出方法和轉入方法
     *
     * @param fromAccountId
     * @param toAccountId
     * @param money
     */
    @Transactional(readOnly = false)
    public void transfer(Integer fromAccountId, Integer toAccountId, int money) {
        accountDAO.subMoney(fromAccountId, money);
        accountDAO.addMoney(toAccountId, money);
    }
}

 

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