一、简介
依赖：
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>4.1.9.RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.1.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>4.1.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>4.1.9.RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
拦截器：
@Aspect
@Component
public class SomeInterceptor {
将拦截器注册到工厂：
<context:component-scan base-package="yourpackage"></context:component-scan>
开启代理（false 对应 jdk 动态代理，true 对应 cglib 动态代理）：
<aop:aspectj-autoproxy proxy-target-class="false"></aop:aspectj-autoproxy>
二、pointcut
execution - for matching method execution join points, this is the primary pointcut designator you will use when working with Spring AOP ①
within - limits matching to join points within certain types (simply the execution of a method declared within a matching type when using Spring AOP) ①
this - limits matching to join points (the execution of methods when using Spring AOP) where the bean reference (Spring AOP proxy) is an instance of the given type ②
target - limits matching to join points (the execution of methods when using Spring AOP) where the target object (application object being proxied) is an instance of the given type ②
args - limits matching to join points (the execution of methods when using Spring AOP) where the arguments are instances of the given types ②
@target - limits matching to join points (the execution of methods when using Spring AOP) where the class of the executing object has an annotation of the given type ②
@args - limits matching to join points (the execution of methods when using Spring AOP) where the runtime type of the actual arguments passed have annotations of the given type(s) ②
@within - limits matching to join points within types that have the given annotation (the execution of methods declared in types with the given annotation when using Spring AOP) ②
@annotation - limits matching to join points where the subject of the join point (method being executed in Spring AOP) has the given annotation ②
- ① 是最主要切面工具，excution 针对方法签名，within 针对类名
- ②是在①的前提下辅助获取特定信息，比如代理对象(this)、被代理对象(target)、入参(args)、类注解(@within)、方法注解(@annotation)、入参注解(@args)
- 当然只有②时相当于①是所有方法
- 见最后对各个概念的理解
1. execution
syntax：
execution(modifiers-pattern? ret-type-pattern declaring-type-pattern?name-pattern(param-pattern) throws-pattern?)
如下图，execution 匹配的是方法签名，是最基础的匹配方式
示意：
modifiers-pattern: 方法修饰符
ret-type-pattern: 返回值类型
declaring-type-pattern: 方法所在类
name-pattern: 方法名
param-pattern: 参数类型列表
throws-pattern: 异常
简版：
execution(ret-type-pattern name-pattern(param-pattern))
详细：
All parts except the returning type pattern (ret-type-pattern in the snippet above), name pattern, and parameters pattern are optional. The returning type pattern determines what the return type of the method must be in order for a join point to be matched. Most frequently you will use * as the returning type pattern, which matches any return type. A fully-qualified type name will match only when the method returns the given type. The name pattern matches the method name. You can use the * wildcard as all or part of a name pattern. If specifying a declaring type pattern then include a trailing . to join it to the name pattern component. The parameters pattern is slightly more complex: () matches a method that takes no parameters, whereas (..) matches any number of parameters (zero or more). The pattern (*) matches a method taking one parameter of any type, (*,String) matches a method taking two parameters, the first can be of any type, the second must be a String.
示例：
@Aspect
@Component
public class SomeInterceptor {
@Pointcut("execution(* doTask*(..))")
public void methodsToBeProfiled() {
}
@Around("methodsToBeProfiled()")
public void profile(ProceedingJoinPoint pjp) throws Throwable {
System.out.println(pjp.getSignature().getName());
}
}
2. within
syntax:
with(declaring-type-pattern)
如下图，with 是匹配类的全限定名，不是匹配方法
示例：
@Aspect
@Component
public class SomeInterceptor {
@Pointcut("within(cn.zno..*)")
public void methodsToBeProfiled() {
}
@Around("methodsToBeProfiled()")
public void profile(ProceedingJoinPoint pjp) throws Throwable {
System.out.println(pjp.getSignature().getName());
}
}
3. this
syntax:
this(advice-method's-arg-ref-of-target's-proxy-type)
这个是匹配目标类的代理对象
示例：
@Aspect
@Component
public class SomeInterceptor {
@Before("execution(* doTaskA(..)) && this(s)")
public void validateAccount(SomeClass s) {
System.out.println(s.getClass());
}
// class cn.zno.testaspect.SomeClass$$EnhancerBySpringCGLIB$$5c6bdbdc
}
4. target
syntax:
target(advice-method's-arg-ref-of-target-type)
这个是匹配目标类的实例，即被代理对象
示例：
@Aspect
@Component
public class SomeInterceptor {
@Before("execution(* doTaskA(..)) && target(s)")
public void validateAccount(SomeClass s) {
System.out.println(s.getClass());
}
// class cn.zno.testaspect.SomeClass
}
5. args
syntax:
args(advise-method's-arg-ref-list-of-target-current-method's-arg-type-list)
获取目标对象的正在执行方法的入参列表
示例：
@Aspect
@Component
public class SomeInterceptor {
@Before("execution(* doTaskA(..)) && args(s,i)")
public void validateAccount(String s,Integer i) {
System.out.println(s);
System.out.println(i);
}
// abc
// 123
}
6. @target
syntax:
@target(advise-method's-arg-ref-of-annotation-type-on-target-class)
获取目标类的注解
示例：
@Aspect
@Component
public class SomeInterceptor {
@Before("execution(* doTaskA(..)) && @target(s)")
public void validateAccount(SomeAnnotation s) {
System.out.println(s.value());
}
// 123
}
@Component
@SomeAnnotation("123")
public class SomeClass {
public void doTaskA(String s1,Integer i1) {
}
}
7. @args
syntax:
@args(advise-method's-arg-ref-list-of-target's-current-method's-arg's-type's-annotation-type-list)
one-one (第一个入参类有第一个注解类，第二个入参类有第二个注解类，以此类推）
示例：
@SomeAnnotation("111")
public class Other {
}
@Component
public class SomeClass {
public void doTaskA(Other s1) {
}
}
@Aspect
@Component
public class SomeInterceptor {
@Around("execution(* doTaskA(..)) && @args(s)")
public void validateAccount(SomeAnnotation s) {
System.out.println(s.value());// 111
}
}
8. @within
syntax:
@within(advise-method's-arg-ref-of-annotation-type-on-target-class)
和@target 有区别（未做详细调查）
示例：
@Component
@SomeAnnotation("1212")
public class SomeClass {
public void doTaskA(String s1) {
}
}
@Aspect
@Component
public class SomeInterceptor {
@Around("execution(* doTask*(..)) && @within(s)")
public void validateAccount(SomeAnnotation s) {
System.out.println(s.value());// 1212
}
}
9. @annotation
syntax:
@annotation(advise-method's-arg-ref-of-annotation-type-on-target-class-method)
示例：
@Component
public class SomeClass {
@SomeAnnotation("333")
public void doTaskA(String s1) {
}
}
@Aspect
@Component
public class SomeInterceptor {
@Around("@annotation(s)")
public void validateAccount(SomeAnnotation s) {
System.out.println(s.value());// 333
}
}
10. combine ( and or not) : && || !
@Pointcut("execution()")
private void a() {}
@Pointcut("within()")
private void b() {}
@Pointcut("a() && b()")
private void ab() {}
或者
@Pointcut("execution() && within()")
private void ab() {}
三、advise(对切面的处理链路)
1. 切面是获取方法集合，advise 是对每一个方法的处理链路，即可以多个advise针对同一个方法。任何一个advise 方法都可以获取 JoinPoint
@Around("@annotation(s)")
public void validateAccount(JoinPoint jp) {
System.out.println(jp.getSignature());
}
2. @Before
@Before(value="execution(* doTask*(..))")
public void validateAccount(JoinPoint jp) {
System.out.println(jp.getSignature());
}
@AfterReturning
public Integer doTaskA(String s1,String s2) {
return new Integer("111");
}
@AfterReturning(value="execution(* doTask*(..))",returning="ret")
public void validateAccount(JoinPoint jp,Object ret) {
System.out.println(jp.getSignature());
System.out.println(ret.getClass());
}
输出：
Integer cn.zno.testaspect.SomeClass.doTaskA(String,String) class java.lang.Integer
@AfterThrowing
public Integer doTaskA(String s1,String s2) {
if(1<2)
throw new RuntimeException("eee");
return new Integer("111");
}
@AfterThrowing(value="execution(* doTask*(..))",throwing="e")
public void validateAccount(JoinPoint jp,Exception e) {
System.out.println(jp.getSignature());
System.out.println(e.getMessage());
}
输出：
Integer cn.zno.testaspect.SomeClass.doTaskA(String,String) eee
问题：如何将异常处理，使其不再往外抛？需参考spring mvc
@After(finally)
public Integer doTaskA(String s1,String s2) {
Integer integer;
try {
integer = new Integer("111");
}finally {
System.out.println(123);
}
return integer;
}
@After(value="execution(* doTask*(..))")
public void validateAccount(JoinPoint jp) {
System.out.println(jp.getSignature());
}
结果：
123 Integer cn.zno.testaspect.SomeClass.doTaskA(String,String)
确实在finally 块执行完毕之后才会拦截
@Around
public Integer doTaskA(String s1,String s2) {
Integer integer;
try {
integer = new Integer("111");
}finally {
System.out.println(123);
}
return integer;
}
@Around(value="execution(* doTask*(..))")
public void validateAccount(ProceedingJoinPoint pjp) {
System.out.println("before");
try {
pjp.proceed();
} catch (Throwable e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("after");
}
结果：
before 123 after
四、辅助工具
STS4 -> Window -> show view -> AspectJ-> Cross References
注意：需要运行一次单元测试，对应的advise 才会更新
1. 拦截器中有提示
2. 目标类中有提示
3. Cross References 有全部的！！（IMPORTANT!!)
五、补充知识点
1. 如何修改入参or返回结果
@Around("someAdvice()")
public Object someAdvice(ProceedingJoinPoint pjp) throws Throwable {
// a. 获取目标方法入参列表
Object[] args = pjp.getArgs();
// b. 修改目标入参
...
// c. 传入修改后入参列表并 d.返回目标方法结果 （如果调用无参方法 proceed(); 则使用原有参数列表）
Object proceed = pjp.proceed(args);
// e. 修改目标方法返回结果
...
// f. 返回修改后的结果
return proceed;
}
六、理解
标签：pattern,void,class,Aspect,execution,type,public From： https://www.cnblogs.com/zno2/p/10342135.html