基于XML的AOP实现事务控制

前面讲过使用动态代理来实现事务控制，现在使用AOP实现事务控制

Spring的AOP就是通过配置的方式实现动态代理从而创建代理对象，而不是用动态代理去编码的方式，以下将用动态代理去编码的方式修改为配置的方式来实现事务控制。

1、 创建maven的jar工程，添加依赖jar包

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>commons-dbutils</groupId>
            <artifactId>commons-dbutils</artifactId>
            <version>1.4</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.7</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
    </dependencies>

和事务相关的jar包spring-tx-5.0.2.RELEASE.jar，spring框架为我们提供了一组事务控制的接口。这组接口是在spring-tx-5.0.2.RELEASE.jar 中。

2、创建数据库eesy下的account1表

3、创建Account实体类

public class Account implements Serializable {
    private Integer id;
    private String name;
    private Float money;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Float getMoney() {
        return money;
    }
    public void setMoney(Float money) {
        this.money = money;
    }
    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", money=" + money +
                '}';
    }
}

4、写业务层接口IAccountService

public interface IAccountService {
    /**
     * 更新
     * @param account
     */
    void updateAccount(Account account);
    /**
     * 转账
     * @param sourceName        转出账户名称
     * @param targetName        转入账户名称
     * @param money             转账金额
     */
    void transfer(String sourceName,String targetName,Float money);
}

5、 写业务层接口的实现类，在类中添加set方法以XML的方式注入依赖

public class AccountServiceImpl implements IAccountService{
    private IAccountDao accountDao;
    public void setAccountDao(IAccountDao accountDao) {
        this.accountDao = accountDao;
    }
    @Override
    public void updateAccount(Account account) {
        accountDao.updateAccount(account);
    }
    @Override
    public void transfer(String sourceName, String targetName, Float money) {
        System.out.println("transfer....");
            //2.1根据名称查询转出账户
            Account source = accountDao.findAccountByName(sourceName);
            //2.2根据名称查询转入账户
            Account target = accountDao.findAccountByName(targetName);
            //2.3转出账户减钱
            source.setMoney(source.getMoney()-money);
            //2.4转入账户加钱
            target.setMoney(target.getMoney()+money);
            //2.5更新转出账户
            accountDao.updateAccount(source);
//            int i=1/0;
            //2.6更新转入账户
            accountDao.updateAccount(target);
    }
}

6、创建持久层接口IAccountDao

public interface IAccountDao {
    /**
     * 更新
     * @param account
     */
    void updateAccount(Account account);

    /**
     * 根据名称查询账户
     * @param accountName
     * @return  如果有唯一的一个结果就返回，如果没有结果就返回null
     *          如果结果集超过一个就抛异常
     */
    Account findAccountByName(String accountName);
}

7、创建持久层实现类AccountDaoImpl

public class AccountDaoImpl implements IAccountDao {
    private QueryRunner runner;
    private ConnectionUtils connectionUtils;
    public void setRunner(QueryRunner runner) {
        this.runner = runner;
    }
    public void setConnectionUtils(ConnectionUtils connectionUtils) {
        this.connectionUtils = connectionUtils;
    }
    @Override
    public void updateAccount(Account account) {
        try{
            runner.update(connectionUtils.getThreadConnection(),"update account1 set name=?,money=? where id=?",account.getName(),account.getMoney(),
　　　　　　　　　　　　　　　　account.getId());
        }catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
    @Override
    public Account findAccountByName(String accountName) {
        try{
            List<Account> accounts = runner.query(connectionUtils.getThreadConnection(),"select * from account1 where name = ? ",
　　　　　　　　　　new BeanListHandler<Account>(Account.class),accountName);
            if(accounts == null || accounts.size() == 0){
                return null;
            }
            if(accounts.size() > 1){
                throw new RuntimeException("结果集不唯一，数据有问题");
            }
            return accounts.get(0);
        }catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

8、创建ConnectionUtils工具类（先从数据源中获取一个连接，并且把连接存入ThreadLocal中从而实现连接与线程的绑定）

public class ConnectionUtils {
    private ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
    private DataSource dataSource;
    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }
    /**
     * 获取当前线程上的连接
     * @return
     */
    public Connection getThreadConnection() {
        try{
            //1.先从ThreadLocal上获取
            Connection conn = tl.get();
            //2.判断当前线程上是否有连接
            if (conn == null) {
                //3.从数据源中获取一个连接，并且存入ThreadLocal中
                conn = dataSource.getConnection();
                tl.set(conn);
            }
            //4.返回当前线程上的连接
            return conn;
        }catch (Exception e){
            throw new RuntimeException(e);
        }
    }
    /**
     * 把连接和线程解绑
     */
    public void removeConnection(){
        tl.remove();
    }
}

9、创建事务管理相关的工具类TransactionManager

public class TransactionManager {
    private ConnectionUtils connectionUtils;
    public void setConnectionUtils(ConnectionUtils connectionUtils) {
        this.connectionUtils = connectionUtils;
    }
    /**
     * 开启事务
     */
    public  void beginTransaction(){
        try {
            connectionUtils.getThreadConnection().setAutoCommit(false);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    /**
     * 提交事务
     */
    public  void commit(){
        try {
            connectionUtils.getThreadConnection().commit();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    /**
     * 回滚事务
     */
    public  void rollback(){
        try {
            connectionUtils.getThreadConnection().rollback();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    /**
     * 释放连接
     */
    public  void release(){
        try {
            connectionUtils.getThreadConnection().close();//还回连接池中
            connectionUtils.removeConnection();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

10、创建bean.xml文件，导入带有aop的约束，配置bean对象。

使用XML的方式配置四种通知类型。

<?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:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">

     <!-- 配置Service -->
    <bean id="accountService" class="com.itheima.service.impl.AccountServiceImpl">
        <!-- 注入dao -->
        <property name="accountDao" ref="accountDao"></property>
    </bean>

    <!--配置Dao对象-->
    <bean id="accountDao" class="com.itheima.dao.impl.AccountDaoImpl">
        <!-- 注入QueryRunner -->
        <property name="runner" ref="runner"></property>
        <!-- 注入ConnectionUtils -->
        <property name="connectionUtils" ref="connectionUtils"></property>
    </bean>

    <!--配置QueryRunner-->
    <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype"></bean>

    <!-- 配置数据源 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <!--连接数据库的必备信息-->
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/eesy"></property>
        <property name="user" value="root"></property>
        <property name="password" value="123456"></property>
    </bean>

    <!-- 配置Connection的工具类 ConnectionUtils -->
    <bean id="connectionUtils" class="com.itheima.utils.ConnectionUtils">
        <!-- 注入数据源-->
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <!-- 配置事务管理器-->
    <bean id="txManager" class="com.itheima.utils.TransactionManager">
        <!-- 注入ConnectionUtils -->
        <property name="connectionUtils" ref="connectionUtils"></property>
    </bean>

    <!--配置aop-->
    <aop:config>
        <!--配置通用切入点表达式-->
        <aop:pointcut id="pt1" expression="execution(* com.itheima.service.impl.*.*(..))"></aop:pointcut>
        <aop:aspect id="txAdvice" ref="txManager">
            <!--配置前置通知：开启事务-->
            <aop:before method="beginTransaction" pointcut-ref="pt1"></aop:before>
            <!--配置后置通知：提交事务-->
            <aop:after-returning method="commit" pointcut-ref="pt1"></aop:after-returning>
            <!--配置异常通知：回滚事务-->
            <aop:after-throwing method="rollback" pointcut-ref="pt1"></aop:after-throwing>
            <!--配置最终通知：释放连接-->
            <aop:after method="release" pointcut-ref="pt1"></aop:after>
        </aop:aspect>
    </aop:config>
</beans>

11、使用Junit单元测试，测试我们的配置

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:bean.xml")
public class AccountServiceTest {
    @Autowired
    private  IAccountService as;
    @Test
    public  void testTransfer(){
        as.transfer("aaa","bbb",100f);
    }
}

结果：

当没有添加int i=1/0时，正常转账。 如果在更新转出账户之后出现了异常，则转出账户的钱没少100，而转入账户的钱未增加100.保证了事务的一致性，