Java55spring：AOP

Posted 2021-06-29 码农编程录

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文章目录

1.转账业务
2.jdk动态代理原理
3.cglib动态代理
4.动态代理实现service层事物的管理
5.aop入门

1.转账业务

在这里插入图片描述

1.1 配置文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.itheima</groupId>
    <artifactId>spring_day03_01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <!-- java编译插件 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.9</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.0.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>3.1</version>
        </dependency>
    </dependencies>
</project>

//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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
       
    <context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder>

    <bean id="accountService" class="com.itheima.service.impl.AccountServiceImpl">
        <property name="accountDao" ref="accountDao"></property>
    </bean>

    <bean id="accountDao" class="com.itheima.dao.impl.AccountDaoImpl">
        <property name="jdbcTemplate" ref="jdbcTemplate"></property>
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <constructor-arg name="dataSource" ref="dataSource"></constructor-arg>
    </bean>

    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
        <property name="driverClassName" value="${jdbc.driverClass}"></property>
    </bean>

    <bean id="factoryBean" class="com.itheima.utils.ProxyBeanFactory">
        <property name="accountService" ref="accountService"></property>
    </bean>
    <bean id="proxyAccountService" factory-bean="factoryBean" factory-method="getAccountServiceProxyObject"></bean>
</beans>

//jdbc.properties
jdbc.url=jdbc:mysql://localhost:3306/spring_day02
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.username=root
jdbc.password=root

1.2 service

package com.itheima.service;

public interface AccountService {
    public void transfer(String outName,String inName,double money);
    public void update();
    public void delete();
}

package com.itheima.service.impl;
import com.itheima.dao.AccountDao;
import com.itheima.domain.Account;
import com.itheima.service.AccountService;

public class AccountServiceImpl implements AccountService {
    private AccountDao accountDao;
    public void setAccountDao(AccountDao accountDao) {
        this.accountDao = accountDao;
    }
    @Override
    public void update() {
        System.out.println("更新");
    }
    @Override
    public void delete() {
        System.out.println("删除");
    }
    @Override
    public void transfer(String outName, String inName, double money) {
    	//对update，delete，transfer三个方法都加上事务，用动态代理对AccountServiceImpl进行增强
       //创建AccountServiceImpl对象的代理对象, 我们调用这些update方法执行代理对象的方法。
      //动态代理方式没有impl实现类，怎么装到spring容器中？以前不管是注解还是bean标签都要求有实现类
      //装配对象即创建对象的三种方式
//        try {
//            System.out.println("开启事务");
            //1.查询付款人的账户信息
            Account outAccount = accountDao.findAccountByName(outName);
            //2.查询收款人的账户信息
            Account inAccount = accountDao.findAccountByName(inName);
            //对2人的账户进行添加和减少的操作
            outAccount.setMoney(outAccount.getMoney()-money);
            inAccount.setMoney(inAccount.getMoney()+money);

            //3.将更新后的账户信息更新到数据库
            accountDao.update(outAccount);
            int i = 1/0;
            accountDao.update(inAccount);
//            System.out.println("提交事务");
//        } catch (Exception e) {
//            System.out.println("回滚事务");
//            e.printStackTrace();
//        }
    }
}

1.3 dao

package com.itheima.dao;
import com.itheima.domain.Account;

public interface AccountDao {
    public Account findAccountByName(String name);
    public void update(Account account);
}

package com.itheima.dao.impl;
import com.itheima.dao.AccountDao;
import com.itheima.domain.Account;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

public class AccountDaoImpl implements AccountDao {
    private JdbcTemplate jdbcTemplate ;
    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }
    @Override
    public Account findAccountByName(String name) {
        String sql = "select * from account where name = ?";
        Account account = null;
        try {
            account = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(Account.class), name);
        } catch (DataAccessException e) {
            e.printStackTrace();
        }
        return account;
    }
    @Override
    public void update(Account account) {
        String sql = "update account set money = ? where name = ?";
        jdbcTemplate.update(sql,account.getMoney(),account.getName());
    }
}

1.4 test

package com.itheima.service;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import javax.annotation.Resource;
import static org.junit.Assert.*;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class AccountServiceTest {
    @Resource(name = "proxyAccountService")
    private AccountService accountService;
    @Test
    public void transfer() {
        String outName = "aaa";
        String inName ="bbb";
        double money = 500;
        accountService.transfer(outName,inName,money);
    }
    @Test
    public void update(){
        accountService.update();
    }
    @Test
    public void delete(){
        accountService.delete();
    }
}

transfer执行结果如下：
在这里插入图片描述

2.jdk动态代理原理

package com.itheima.proxy;

public interface IActor {
    public void sing();
    public void active();
}

package com.itheima.proxy;

public class ActorImpl implements IActor {
    @Override
    public void sing() {
        System.out.println("唱歌");
    }
    @Override
    public void active() {
        System.out.println("表演");
    }
}

动态代理：不修改源码情况下，对现有方法进行增强，要增强的功能只要写一遍就可以了。

package com.itheima.proxy;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class JdkProxyTest {
    public static void main(String[] args) {
        IActor actor = new ActorImpl();  //需要创建一个对象来代理需要增强的actor对象
        /**
         *  参数1：类加载器，一般写被代理对象的类加载器
         *  参数2：接口，被代理对象实现的接口。
         *  参数3：处理器
         */
        IActor iActor = (IActor) Proxy.newProxyInstance(actor.getClass().getClassLoader(), actor.getClass().getInterfaces(),
                new InvocationHandler() {   //选中方法名，按ctrl+q查看方法注释
                    /**
                     * @param proxy  被代理对象本身。没用。
                     * @param method 被调用的方法。
                     * @param args   调用方法时传递的参数
                     */
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        System.out.println("增强的功能");
                        /**
                         *  参数1：方法调用时依赖的对象
                         *  参数2：调用方法时需要传递的参数
                         */                       
                        return method.invoke(actor,args);  //调用原有方法的功能
                    }
                });

        iActor.sing();
        iActor.active();
        
//        IActor actor2 = new $Proxy0();
//        actor2.sing();
//        actor2.active();
    }
}

在这里插入图片描述

3.cglib动态代理

jdk动态代理产生iActor对象必须要有接口IActor，但很多时候我们要增强的对象ActorImpl没有接口IActor ，用cglib动态代理。
在这里插入图片描述

<dependency>
  <groupId>cglib</groupId>
  <artifactId>cglib</artifactId>
  <version>3.1</version>
</dependency>

package com.itheima.proxy;

public class Actor2 {
    public void dance(){
        System.out.println("跳舞");
    }
}

package com.itheima.proxy;
import net.sf.cglib.proxy.Enhancer;
import net.sf阿里四面：你知道Spring AOP创建Proxy的过程吗？
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