Spring AOP创建代理对象源码解析

Dear 丶 2022-11-12 05:27 256阅读 0赞

# 引言 #

**概述：** AOP系列文章：  
[【1】Spring Aop初始化源码分析][1_Spring Aop]  
[【2】Spring AOP创建代理对象源码解析][2_Spring AOP]  
[【3】Spring AOP 链式调用过程源码解析][3_Spring AOP]  
[【4】Spring 事务执行过程源码解析][4_Spring]

# 1 工程简介 #

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## 1.1 pom ##

<properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <maven.compiler.source>1.8</maven.compiler.source>
            <maven.compiler.target>1.8</maven.compiler.target>
            <spring.version>5.2.8.RELEASE</spring.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.13</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${ spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.16.20</version>
            </dependency>
            
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-api</artifactId>
                <version>1.7.10</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-classic</artifactId>
                <version>1.1.2</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>1.1.2</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aspects</artifactId>
                <version>${ spring.version}</version>
            </dependency>
        </dependencies>

## 1.2 AOP配置文件 ##

@Configuration
    @EnableAspectJAutoProxy
    @Import({ ServiceAopConfig.class, DaoAopConfig.class})
    public class AopConfig { 
    
    
    }
    
    @Configuration
    @Aspect
    public class DaoAopConfig { 
    
        /** * 声明切点 */
        @Pointcut("execution(* com.rosh.dao.*.*(..))")
        public void pointCut() { 
    
        }
    
        @Around("pointCut()")
        public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable { 
            System.out.println("DaoAopConfig invoke around start");
            Object proceed = proceedingJoinPoint.proceed();
            System.out.println("DaoAopConfig invoke around end");
            return proceed;
        }
    }
    
    
    
    @Configuration
    @Aspect
    public class ServiceAopConfig { 
    
        /** * 声明切点 */
        @Pointcut("execution(* com.rosh.service.*.*(..))")
        public void pointCut() { 
    
        }
    
        @Around("pointCut()")
        public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable { 
            System.out.println("ServiceAopConfig invoke around start");
            Object proceed = proceedingJoinPoint.proceed();
            System.out.println("ServiceAopConfig invoke around end");
            return proceed;
        }
    
        @Before("pointCut()")
        public void before(){ 
            System.out.println("ServiceAopConfig invoke before");
        }
    
        @After("pointCut()")
        public void after() { 
            System.out.println("ServiceAopConfig invoke after");
        }
    }

## 1.3 StudentDao ##

@Repository
    public class StudentDao { 
    
        public void addStudent() { 
    
            System.out.println("StudentDao invoke addStudent");
    
        }
    
    }

## 1.4 Service ##

public interface StudentService { 
    
         void addStudent();
    
    }
    
    
    @Service
    public class StudentServiceImpl implements StudentService { 
    
        @Override
        public void addStudent() { 
            System.out.println("StudentServiceImpl invoke addStudent()");
        }
    }

## 1.5 RoshTest ##

public class RoshTest { 
    
        @Test
        public void mainTest(){ 
    
            AnnotationConfigApplicationContext applicationContext=new AnnotationConfigApplicationContext("com.rosh");
            StudentService studentService = (StudentService) applicationContext.getBean("studentServiceImpl");
            studentService.addStudent();
    
            System.out.println("===============分割线================");
    
            StudentDao studentDao=(StudentDao) applicationContext.getBean("studentDao");
            studentDao.addStudent();
    
    
        }
    
    }

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# 2 AbstractAutoProxyCreator概述 #

**描述：** 该类作用在，Spring Aop初始化源码分析中具体分析过，核心作用是，在bean初始化时，后置加强。  
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protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) { 
    		if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) { 
    			return bean;
    		}
    		if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) { 
    			return bean;
    		}
    		if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) { 
    			this.advisedBeans.put(cacheKey, Boolean.FALSE);
    			return bean;
    		}
    
    		// Create proxy if we have advice.
    		/** * 【1】获取当前bean有效的Advisor，Advisor = advice + pointCut */
    		Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
    
    		if (specificInterceptors != DO_NOT_PROXY) { 
    			this.advisedBeans.put(cacheKey, Boolean.TRUE);
    
    			/** * 【2】创建代理对象 */
    			Object proxy = createProxy(
    					bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
    			this.proxyTypes.put(cacheKey, proxy.getClass());
    			return proxy;
    		}
    
    		this.advisedBeans.put(cacheKey, Boolean.FALSE);
    		return bean;
    	}

# 3 创建代理对象源码解析 #

## 3.1 createProxy ##

**描述：** 主流程调用方法AbstractAutoProxyCreator类createProxy 方法。

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
    			@Nullable Object[] specificInterceptors, TargetSource targetSource) { 
    
    		if (this.beanFactory instanceof ConfigurableListableBeanFactory) { 
    			AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
    		}
    
    		/** * 【1】创建代理工厂，赋值。 */
    		ProxyFactory proxyFactory = new ProxyFactory();
    		proxyFactory.copyFrom(this);
    
    		/** * 【2】 proxyTargetClass为true时代表使用cglib，为false使用jdk，默认值是false。 * 判断当前被代理对象是使用jdk增强还是使用cglib增强 * */
    		if (!proxyFactory.isProxyTargetClass()) { 
    			//根据最开始@EnableAspectJAutoProxy注解中的proxyTargetClass参数判断是否应该使用cglib代理
    			if (shouldProxyTargetClass(beanClass, beanName)) { 
    				proxyFactory.setProxyTargetClass(true);
    			}
    			else { 
    				//如果是接口增强那么使用jdk，否则使用cglib
    				evaluateProxyInterfaces(beanClass, proxyFactory);
    			}
    		}
    		//构建advisor
    		Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
    		//把advisor加入到代理工厂中
    		proxyFactory.addAdvisors(advisors);
    		//把targetSource对象加入代理工厂(实际对象、被代理对象)
    		proxyFactory.setTargetSource(targetSource);
    		customizeProxyFactory(proxyFactory);
    
    		proxyFactory.setFrozen(this.freezeProxy);
    		if (advisorsPreFiltered()) { 
    			proxyFactory.setPreFiltered(true);
    		}
    
    		/** * 【3】 获取代理对象 */
    		return proxyFactory.getProxy(getProxyClassLoader());
    	}

## 3.2 ProxyFactory 获取代理对象 ##

**描述：** 先获取AOP代理

public Object getProxy(@Nullable ClassLoader classLoader) { 
    		/** * 创建AOP代理（JDK、CGLIB）并且获得代理对象 */
    		return createAopProxy().getProxy(classLoader);
    	}

protected final synchronized AopProxy createAopProxy() { 
    		if (!this.active) { 
    			activate();
    		}
    		return getAopProxyFactory().createAopProxy(this);
    	}

@Override
    	public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException { 
    		if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) { 
    
    			// 如果targetClass是接口类，使用JDK来生成Proxy
    			Class<?> targetClass = config.getTargetClass();
    			if (targetClass == null) { 
    				throw new AopConfigException("TargetSource cannot determine target class: " +
    						"Either an interface or a target is required for proxy creation.");
    			}
    			if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) { 
    				return new JdkDynamicAopProxy(config);
    			}
    
    			// 如果不是接口类，使用CGLIB生成Proxy
    			return new ObjenesisCglibAopProxy(config);
    		}
    		else { 
    			return new JdkDynamicAopProxy(config);
    		}
    	}

## 3.3 根据AOP不同的代理获取代理对象 ##

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# 4 StudentDao 代理Debug #

**描述：** 每个代理对象都对应一个代理工厂，工厂是new 创建的。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 6]  
**描述：** 选择cglib、jdk代理生成代理对象。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 7]  
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**描述：** 创建AOP代理。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 10]  
**描述：** CglibAopProxy获取代理对象。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 11]  
**描述：** 获取到cglib增强代理对象。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 12]

# 5 StudentServiceImpl 代理Debug #

**描述：** StudentServiceImpl 实现StudentService接口使用jdk代理。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 13]  
**描述：** AOP获取JDK代理。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 14]  
**描述：** 获取代理对象。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 15]  
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[1_Spring Aop]: https://blog.csdn.net/qq_34125999/article/details/115057552
[2_Spring AOP]: https://blog.csdn.net/qq_34125999/article/details/115107521
[3_Spring AOP]: https://blog.csdn.net/qq_34125999/article/details/115155125
[4_Spring]: https://blog.csdn.net/qq_34125999/article/details/115220975
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