首先,你的方面类应该有一个@Aspect
注释。其次,如果你想使用Spring AOP而不是完整的AspectJ,你的方面和所有的目标类都应该是Spring @Component
s。
话虽如此,这里是一个小样本。我用普通的AspectJ创建了它,但Spring AOP中的方面代码应该是相同的。
Helper类使代码编译并运行:
package de.scrum_master.app;
import java.util.Random;
public class Host {
private static final Random RANDOM = new Random();
private String name;
public Host(String name) {
this.name = name;
}
public void doSomething() {
if (RANDOM.nextBoolean())
throw new RuntimeException("oops!");
}
@Override
public String toString() {
return "Host(name=" + name + ")";
}
}
package de.scrum_master.app;
import java.util.HashMap;
import java.util.Map;
public class ConfigReader {
private Map<Integer, Host> hostMap = new HashMap<>();
public ConfigReader() {
hostMap.put(1, new Host("mercury"));
hostMap.put(2, new Host("venus"));
hostMap.put(3, new Host("earth"));
hostMap.put(4, new Host("mars"));
}
public Map<Integer, Host> getHostMap() {
return hostMap;
}
}
驱动程序:
我不喜欢Iterator
这是从老版本的JDK的遗物,所以我用更现代的Java风格for
循环取而代之。
package de.scrum_master.app;
class MyClass {
private ConfigReader configReader = new ConfigReader();
void check() throws Exception {
for (Host host : configReader.getHostMap().values()) {
System.out.println(host);
host.doSomething();
}
}
public static void main(String[] args) throws Exception {
new MyClass().check();
}
}
看点与切入点/建议做记录和异常在同一时间处理:
另外请注意,我的意见在代码的最后一刻。
package de.scrum_master.aspect;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
@Aspect
public class AopLogger {
private static final InheritableThreadLocal<String> indent = new InheritableThreadLocal<String>() {
@Override
protected String initialValue() {
return "";
}
};
@Around("execution(* de.scrum_master.app..*(..)) && !execution(* toString())")
public Object logAround(ProceedingJoinPoint thisJoinPoint) throws Throwable {
Object result = null;
System.out.println(indent.get() + ">> " + thisJoinPoint);
try {
indent.set(indent.get() + " ");
result = thisJoinPoint.proceed();
indent.set(indent.get().substring(2));
} catch (Exception e) {
System.out.println(indent.get() + "Caught exception: " + e);
indent.set(indent.get().substring(2));
}
System.out.println(indent.get() + "<< " + thisJoinPoint);
// Attention: If a method with a caught exception does not have 'void'
// return type, we return a (probably unexpected) result of 'null' here.
// So maybe we should not catch all execptions but rather pick more
// specific joinpoints where we are sure we can cleanly handle the
// corresponding exceptions.
return result;
}
}
控制台日志:
>> execution(void de.scrum_master.app.MyClass.main(String[]))
>> execution(void de.scrum_master.app.MyClass.check())
>> execution(Map de.scrum_master.app.ConfigReader.getHostMap())
<< execution(Map de.scrum_master.app.ConfigReader.getHostMap())
Host(name=mercury)
>> execution(void de.scrum_master.app.Host.doSomething())
Caught exception: java.lang.RuntimeException: oops!
<< execution(void de.scrum_master.app.Host.doSomething())
Host(name=venus)
>> execution(void de.scrum_master.app.Host.doSomething())
<< execution(void de.scrum_master.app.Host.doSomething())
Host(name=earth)
>> execution(void de.scrum_master.app.Host.doSomething())
Caught exception: java.lang.RuntimeException: oops!
<< execution(void de.scrum_master.app.Host.doSomething())
Host(name=mars)
>> execution(void de.scrum_master.app.Host.doSomething())
Caught exception: java.lang.RuntimeException: oops!
<< execution(void de.scrum_master.app.Host.doSomething())
<< execution(void de.scrum_master.app.MyClass.check())
<< execution(void de.scrum_master.app.MyClass.main(String[]))
第二个方面的变体分离异常处理记录:
package de.scrum_master.aspect;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
@Aspect
public class AopLogger {
private static final InheritableThreadLocal<String> indent = new InheritableThreadLocal<String>() {
@Override
protected String initialValue() {
return "";
}
};
@Around("execution(* de.scrum_master.app..*(..)) && !execution(* toString())")
public Object logAround(ProceedingJoinPoint thisJoinPoint) throws Throwable {
System.out.println(indent.get() + ">> " + thisJoinPoint);
try {
indent.set(indent.get() + " ");
Object result = thisJoinPoint.proceed();
indent.set(indent.get().substring(2));
System.out.println(indent.get() + "<< " + thisJoinPoint);
return result;
} catch (Exception e) {
indent.set(indent.get().substring(2));
System.out.println(indent.get() + "<< " + thisJoinPoint);
throw e;
}
}
@Around("execution(void de.scrum_master.app.Host.doSomething())")
public void handleException(ProceedingJoinPoint thisJoinPoint) throws Throwable {
try {
thisJoinPoint.proceed();
} catch (Exception e) {
System.out.println(indent.get() + "Caught exception: " + e);
}
}
}
日志输出保持不变,但这次的异常处理是在一个更精确的切入点单独建议。日志建议只关注日志记录(如果不是正确的缩进,甚至不需要尝试捕获)。异常处理建议只做自己的工作。
随意问后续问题。
你没有提供足够的信息;如果连接点在doSomething方法中(假设它是公共的),那么它应该足够让try catch块返回proceedingJoinPoint.proceed()。 “什么对你有好处......”当你进入doSomething时,以及方法何时返回,你可能会记录下来;其实很奇怪,在代码中缺少这个。 –
当我把try catch块返回proceedingJoinPoint.proceed()迭代结束,应用程序退出。当我把try catch块放在host.doSomething()周围时,迭代继续,但是我不能在logAround – user2683906
中记录任何东西,首先找出连接点是什么:在你的IDE中放置一个断点,返回proceedingJoinPoint.proceed()和检查ProceedingJoinPoint的各个领域 - 你应该看到哪个方法被拦截。尝试从那里推理。 –