19.手写Spring AOP

本文主要是介绍19.手写Spring AOP，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.Spring AOP顶层设计

2.Spring AOP执行流程

下面是代码实现

3.在 application.properties中增加如下自定义配置:

#托管的类扫描包路径#
scanPackage=com.gupaoedu.vip.demotemplateRoot=layouts#切面表达式expression#
pointCut=public .* com.gupaoedu.vip.demo.service..*Service..*(.*)
#切面类
aspectClass=com.gupaoedu.vip.demo.aspect.LogAspect
#前置通知回调方法
aspectBefore=before
#后置通知回调方法
aspectAfter=after
#异常通知回调方法
aspectAfterThrow=afterThrowing
#异常类型捕获
aspectAfterThrowingName=java.lang.Exception

4.GPJdkDynamicAopProxy

public class GPJdkDynamicAopProxy implements InvocationHandler {private GPAdvisedSupport config;public GPJdkDynamicAopProxy(GPAdvisedSupport config) {this.config = config;}@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {Map<String,GPAdvice> advices = config.getAdvices(method,null);Object returnValue;try {invokeAdivce(advices.get("before"));returnValue = method.invoke(this.config.getTarget(),args);invokeAdivce(advices.get("after"));}catch (Exception e){invokeAdivce(advices.get("afterThrow"));throw e;}return returnValue;}private void invokeAdivce(GPAdvice advice) {try {advice.getAdviceMethod().invoke(advice.getAspect());} catch (IllegalAccessException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}}public Object getProxy() {return Proxy.newProxyInstance(this.getClass().getClassLoader(),this.config.getTargetClass().getInterfaces(),this);}
}

5.GPAdvisedSupport 配置解析

/*** 解析AOP配置的工具类*/
public class GPAdvisedSupport {private GPAopConfig config;private Object target;private Class targetClass;private Pattern pointCutClassPattern;private Map<Method,Map<String,GPAdvice>> methodCache;public GPAdvisedSupport(GPAopConfig config) {this.config = config;}//解析配置文件的方法private void parse() {//把Spring的Excpress变成Java能够识别的正则表达式String pointCut = config.getPointCut().replaceAll("\\.", "\\\\.").replaceAll("\\\\.\\*", ".*").replaceAll("\\(", "\\\\(").replaceAll("\\)", "\\\\)");//保存专门匹配Class的正则String pointCutForClassRegex = pointCut.substring(0, pointCut.lastIndexOf("\\(") - 4);pointCutClassPattern = Pattern.compile("class " + pointCutForClassRegex.substring(pointCutForClassRegex.lastIndexOf(" ") + 1));//享元的共享池methodCache = new HashMap<Method, Map<String, GPAdvice>>();//保存专门匹配方法的正则Pattern pointCutPattern = Pattern.compile(pointCut);try{Class aspectClass = Class.forName(this.config.getAspectClass());Map<String,Method> aspectMethods = new HashMap<String, Method>();for (Method method : aspectClass.getMethods()) {aspectMethods.put(method.getName(),method);}for (Method method : this.targetClass.getMethods()) {String methodString = method.toString();if(methodString.contains("throws")){methodString = methodString.substring(0,methodString.lastIndexOf("throws")).trim();}Matcher matcher = pointCutPattern.matcher(methodString);if(matcher.matches()){Map<String,GPAdvice> advices = new HashMap<String, GPAdvice>();if(!(null == config.getAspectBefore() || "".equals(config.getAspectBefore()))){advices.put("before",new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectBefore())));}if(!(null == config.getAspectAfter() || "".equals(config.getAspectAfter()))){advices.put("after",new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectAfter())));}if(!(null == config.getAspectAfterThrow() || "".equals(config.getAspectAfterThrow()))){GPAdvice advice = new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectAfterThrow()));advice.setThrowName(config.getAspectAfterThrowingName());advices.put("afterThrow",advice);}//跟目标代理类的业务方法和Advices建立一对多个关联关系，以便在Porxy类中获得methodCache.put(method,advices);}}}catch(Exception e){e.printStackTrace();}}//根据一个目标代理类的方法，获得其对应的通知public Map<String,GPAdvice> getAdvices(Method method, Object o) throws Exception {//享元设计模式的应用Map<String,GPAdvice> cache = methodCache.get(method);if(null == cache){Method m = targetClass.getMethod(method.getName(),method.getParameterTypes());cache = methodCache.get(m);this.methodCache.put(m,cache);}return cache;}//给ApplicationContext首先IoC中的对象初始化时调用，决定要不要生成代理类的逻辑public boolean pointCutMath() {return pointCutClassPattern.matcher(this.targetClass.toString()).matches();}public void setTargetClass(Class<?> targetClass) {this.targetClass = targetClass;parse();}public void setTarget(Object target) {this.target = target;}public Class getTargetClass() {return targetClass;}public Object getTarget() {return target;}
}

6.GPAdvice通知接口定义

@Data
public class GPAdvice {private Object aspect;private Method adviceMethod;private String throwName;public GPAdvice(Object aspect, Method adviceMethod) {this.aspect = aspect;this.adviceMethod = adviceMethod;}}

7.接入getBean()方法与IOC容器衔接

找到GPApplicationContext的 getBean()方法，我们知道getBean()中负责Bean初始化的方法其实就是instantiateBean() ,我们在初始化时就可以确定是否返回原生Bean还是Proxy Bean。代码实现
如下：

    //创建真正的实例对象private Object instantiateBean(String beanName, GPBeanDefinition beanDefinition) {String className = beanDefinition.getBeanClassName();Object instance = null;try {if(this.factoryBeanObjectCache.containsKey(beanName)){instance = this.factoryBeanObjectCache.get(beanName);}else {Class<?> clazz = Class.forName(className);//2、默认的类名首字母小写instance = clazz.newInstance();//==================AOP开始=========================//如果满足条件，就直接返回Proxy对象//1、加载AOP的配置文件GPAdvisedSupport config = instantionAopConfig(beanDefinition);config.setTargetClass(clazz);config.setTarget(instance);//判断规则，要不要生成代理类，如果要就覆盖原生对象//如果不要就不做任何处理，返回原生对象if(config.pointCutMath()){instance = new GPJdkDynamicAopProxy(config).getProxy();}//===================AOP结束========================this.factoryBeanObjectCache.put(beanName, instance);}}catch (Exception e){e.printStackTrace();}return instance;}private GPAdvisedSupport instantionAopConfig(GPBeanDefinition beanDefinition) {GPAopConfig config = new GPAopConfig();config.setPointCut(this.reader.getConfig().getProperty("pointCut"));config.setAspectClass(this.reader.getConfig().getProperty("aspectClass"));config.setAspectBefore(this.reader.getConfig().getProperty("aspectBefore"));config.setAspectAfter(this.reader.getConfig().getProperty("aspectAfter"));config.setAspectAfterThrow(this.reader.getConfig().getProperty("aspectAfterThrow"));config.setAspectAfterThrowingName(this.reader.getConfig().getProperty("aspectAfterThrowingName"));return new GPAdvisedSupport(config);}

8.LogAspect自定义切面配置

@Slf4j
public class LogAspect {//在调用一个方法之前，执行before方法public void before(){//这个方法中的逻辑，是由我们自己写的log.info("Invoker Before Method!!!");}//在调用一个方法之后，执行after方法public void after(){log.info("Invoker After Method!!!");}public void afterThrowing(){log.info("出现异常");}
}

9.IModifyService业务接口定义

/*** 增删改业务*/
public interface IModifyService {/*** 增加*/public String add(String name, String addr) throws Exception;/*** 修改*/public String edit(Integer id, String name);/*** 删除*/public String remove(Integer id);}

10.ModifyService切面业务逻辑实现

/*** 增删改业务*/
@GPService
public class ModifyService implements IModifyService {/*** 增加*/public String add(String name,String addr) throws Exception{throw new Exception("这是Tom故意抛出来的异常");//		return "modifyService add,name=" + name + ",addr=" + addr;}/*** 修改*/public String edit(Integer id,String name) {return "modifyService edit,id=" + id + ",name=" + name;}/*** 删除*/public String remove(Integer id) {return "modifyService id=" + id;}}