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AOP 面向切面的编程思想。 Spring的主要特性之一,今天我整理了一下,小牛试刀,写了一个Demo分享给大家。
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切面最主要的功能是在不影响主业务方法逻辑的情况下,在执行业务方法之前或之后加入执行代码。
在JavaEE中最常见的莫过于事务控制, 使得程序员只需关注核心业务逻辑,而无需关注事务相反非业务而又必须要的代码。
切面的主要组件有:
1、切面(@Aspect)。
2、切点(@Pointcut)、
3、通知方法(@Advise),主要有3个
1、执行前通知- @Before
2、执行后通知- @After
3、环绕通知- @Around
关系图如下:
AOP项目展开截图:
InstanceFactory 源码:
package com.hianzuo.aop; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.ArrayList; import java.util.HashMap; import java.util.List; /** * Created by Ryan * On 2017/10/5. */ public class InstanceFactory { private static final HashMap, Object> classBeanMap = new HashMap<>(); private static final HashMap beanNameMap = new HashMap<>(); private static final HashMap , List > mAspectPointcutMethodListMap = new HashMap<>(); public static T getInstance(Class clazz) { return (T) classBeanMap.get(clazz); } public static T getInstance(String beanName) { return (T) classBeanMap.get(beanName); } public static void init(String pnScan) { List > classes = ClassUtil.getClasses(pnScan); for (Class> clazz : classes) { if (isAspectClazz(clazz)) { initAspect(clazz); } } for (Class> clazz : classes) { if (isBeanClazz(clazz)) { initBean(clazz); } } } private static void initAspect(Class> aspectClazz) { Method[] methods = aspectClazz.getMethods(); Object obj; try { obj = aspectClazz.newInstance(); } catch (Exception e) { throw new RuntimeException(e); } for (Method method : methods) { if (method.isAnnotationPresent(Before.class)) { Before adviceBefore = method.getAnnotation(Before.class); List adviceList = getAspectAdviceList(Before.class); adviceList.add(new AspectAdviceMethod(adviceBefore.value(), adviceBefore.order(), obj, method)); } if (method.isAnnotationPresent(After.class)) { After adviceAfter = method.getAnnotation(After.class); List adviceList = getAspectAdviceList(After.class); adviceList.add(new AspectAdviceMethod(adviceAfter.value(), adviceAfter.order(), obj, method)); } if (method.isAnnotationPresent(Around.class)) { Around adviceAround = method.getAnnotation(Around.class); List adviceList = getAspectAdviceList(Around.class); adviceList.add(new AspectAdviceAroundMethod(adviceAround.value(), adviceAround.order(), obj, method)); } } } private static List getAspectAdviceList(Class extends Annotation> adviceClazz) { List methodList = mAspectPointcutMethodListMap.get(adviceClazz); if (null == methodList) { methodList = new ArrayList<>(); mAspectPointcutMethodListMap.put(adviceClazz, methodList); } return methodList; } private static boolean isAspectClazz(Class> aClass) { if (aClass.isAnnotationPresent(Aspect.class)) { return true; } return false; } private static void initBean(Class> beanClazz) { Class>[] interfaces = beanClazz.getInterfaces(); if (null == interfaces) return; for (Class> anInterface : interfaces) { String beanName = getBeanName(anInterface); Object obj = newInstanceProxyClass(anInterface, beanClazz); beanNameMap.put(beanName, obj); classBeanMap.put(anInterface, obj); } } private static Object newInstanceProxyClass(Class> anInterface, Class> beanClazz) { try { Object targetObj = beanClazz.newInstance(); return Proxy.newProxyInstance(targetObj.getClass().getClassLoader(), new Class>[]{anInterface}, new AspectHandler(targetObj, mAspectPointcutMethodListMap)); } catch (Exception e) { throw new RuntimeException(e); } } private static String getBeanName(Class> anInterface) { return anInterface.getSimpleName(); } private static boolean isBeanClazz(Class> aClass) { if (aClass.isAnnotationPresent(Component.class)) { return true; } return false; } }
AspectHandler 源码:
package com.hianzuo.aop; import java.lang.annotation.Annotation; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.util.*; /** * Created by Ryan * On 2017/10/5. */ class AspectHandler implements InvocationHandler { private Object targetObj; private HashMap, List> mAspectPointcutMethodListMap; private HashMap> mBeforeMethodMap = new HashMap<>(); private HashMap> mAfterMethodMap = new HashMap<>(); private HashMap mAroundMethodMap = new HashMap<>(); public AspectHandler(Object targetObj, HashMap, List> map) { this.targetObj = targetObj; this.mAspectPointcutMethodListMap = map; } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { List beforeMethods = getBeforeMethodList(method); JointPoint beforePoint = new JointPoint().setTargetObj(targetObj).setProxy(proxy).setMethod(method).setArgs(args); for (AspectAdviceMethod adviceMethod : beforeMethods) { adviceMethod.invoke(beforePoint); } AspectAdviceAroundMethod aroundMethod = getAroundMethodList(method); Object obj; if (null != aroundMethod) { obj = aroundMethod.invoke(beforePoint); } else { obj = method.invoke(targetObj, args); } List afterMethods = getAfterMethodList(method); JointPoint afterPoint = new JointPoint().setTargetObj(targetObj).setProxy(proxy).setMethod(method).setArgs(args).setResult(obj); for (AspectAdviceMethod adviceMethod : afterMethods) { adviceMethod.invoke(afterPoint); } return obj; } private AspectAdviceAroundMethod getAroundMethodList(Method method) { if (mAroundMethodMap.containsKey(method)) return mAroundMethodMap.get(method); List adviceMethods = mAspectPointcutMethodListMap.get(Around.class); if (null == adviceMethods) return null; List list = new ArrayList<>(); for (AspectAdviceMethod adviceMethod : adviceMethods) { AspectAdviceAroundMethod adviceAroundMethod = (AspectAdviceAroundMethod) adviceMethod; if (adviceAroundMethod.match(method)) { list.add(adviceAroundMethod); } } AspectAdviceAroundMethod aroundMethod = null; if (!list.isEmpty()) { sortAdviceList(list); AspectAdviceAroundMethod upMethod = null; for (AspectAdviceAroundMethod adviceAroundMethod : list) { if (null == aroundMethod) aroundMethod = adviceAroundMethod; if (null != upMethod) { upMethod.setNextMethod(adviceAroundMethod); } upMethod = adviceAroundMethod; } } mAroundMethodMap.put(method, aroundMethod); return aroundMethod; } private static void sortAdviceList(List extends AspectAdviceMethod> list) { Collections.sort(list, (Comparator) (o1, o2) -> { Integer order1 = o1.getPointMethodOrder(); Integer order2 = o2.getPointMethodOrder(); return order1.compareTo(order2); }); } private List getAfterMethodList(Method method) { return getAspectAdviceMethods(After.class, mAspectPointcutMethodListMap, mAfterMethodMap, method); } private List getBeforeMethodList(Method method) { return getAspectAdviceMethods(Before.class, mAspectPointcutMethodListMap, mBeforeMethodMap, method); } private static List getAspectAdviceMethods(Class extends Annotation> adviceClass, HashMap, List> dataMap, HashMap> methodMap, Method method) { List aspectAdviceMethods = methodMap.get(method); if (null != aspectAdviceMethods) return aspectAdviceMethods; aspectAdviceMethods = new ArrayList<>(); methodMap.put(method, aspectAdviceMethods); List methods = dataMap.get(adviceClass); if (null == method) return aspectAdviceMethods; for (AspectAdviceMethod adviceMethod : methods) { if (adviceMethod.match(method)) { aspectAdviceMethods.add(adviceMethod); } } sortAdviceList(aspectAdviceMethods); return aspectAdviceMethods; } }