面向切面編程可以實現在不修改原來代碼的情況下，增加我們所需的業務處理邏輯，比如：添加日志。本文AOP實例是基於Aspect Around注解實現的，我們需要在調用API函數的時候，統計函數調用的具體信息，包括：函數簽名，傳入參數，函數處理時間，異常信息攔截等, @Around是可以同時在所攔截方法的前后執行一段邏輯，可以滿足我們的需求。
目標對象
目標對象是一個客戶管理服務，下面分別是其服務接口定義和具體業務邏輯實現。
API
public interface CustomerManagerService {
void addCustomer(String customer) throws CustomeExistException;
}
Implementation
public class customerManager implements CustomerManagerService {
private List<String> list = Lists.newArrayList();
public void addCustomer(String customer) throws CustomeExistException {
if (list.contains(customer)) {
throw new CustomeExistException("Customer exists, repeat operation");
}
list.add(customer);
}
@Override
public String toString() {
return "customerManager{" +
"list=" + list +
'}';
}
}
切面類代理
切面代理可以實現對客戶管理服務的控制，在切面類中定義Advice函數，設定切面要增加的業務邏輯。APIProxy定義了一個簡單的切面類around advice，作用范圍為com.mj.spring.aop.api包下面所有的函數, 當作用域內的函數被調用時會執行aroundAdvice中的業務邏輯。
@Aspect
public class APIProxy {
private final static Log LOGGER = LogFactory.getLog(APIProxy.class);
//切面應用范圍是在com.mj.spring.aop.api下面所有的接口函數
@Around("execution(* com.mj.spring.aop.api..*.*(..))")
public void aroundAdvice(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
Signature signature = proceedingJoinPoint.getSignature();
String args = Arrays.toString(proceedingJoinPoint.getArgs());
long start = System.currentTimeMillis();
try {
proceedingJoinPoint.proceed();
} catch (Exception e) {
if (e instanceof CustomeExistException) {
LOGGER.warn(e.getMessage());
}
LOGGER.error(String.format("Method:%s call failed parameter input:%s",
signature,
args), e);
} finally {
LOGGER.info(String.format("method:%s parameter input:%s carry_out_time:%s ms",
signature, args, System.currentTimeMillis() - start));
}
}
}
ProceedingJoinPoint接口
ProceedingJoinPoint接口提供了很多實用的函數，便於用戶獲取應用切面點函數具體的信息。下面四個接口是我們用的比較多的：
- Object proceed() throws Throwable; 調用要攔截的方法
- Object proceed(Object[] var1) throws Throwable;調用要攔截的方法，可以自定義傳入參數
- Object[] getArgs();獲取攔截方法的傳入參數
- Signature getSignature();獲取攔截方法的方法簽名
XML配置
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.1.xsd">
<!-- 使能AOP-->
<aop:aspectj-autoproxy/>
<!--聲明切面類 -->
<bean id="apiProxy" class="com.mj.spring.aop.aspect.APIProxy"></bean>
<!-- 聲明customerManager bean-->
<bean id="customerManagerService" class="com.mj.spring.aop.impl.customerManager"></bean>
</beans>
測試類
public class customerManagerTest {
private ApplicationContext applicationContext = null;
@Before
public void setUp() throws Exception {
applicationContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");
}
@Test
public void should_print_normal_log_info_when_add_a_customer() throws Exception {
CustomerManagerService customerManagerService = (CustomerManagerService) applicationContext.getBean("customerManagerService");
customerManagerService.addCustomer("Mengya");
}
@Test
public void should_print_warn_log_info_when_add_a_same_customer_twice() throws Exception {
CustomerManagerService customerManagerService = (CustomerManagerService) applicationContext.getBean("customerManagerService");
customerManagerService.addCustomer("Mengya");
customerManagerService.addCustomer("Mengya");
}
}
運行第一個Test，接口調用信息：
2015-09-24 18:25:42,000 INFO [com.mj.spring.aop.aspect.APIProxy] - method:void com.mj.spring.aop.api.CustomerManagerService.addCustomer(String) parameter input:[Mengya] carry_out_time:0 ms
運行第二個Test，異常報錯信息會被攔截下來：
2015-09-24 18:26:58,885 INFO [com.mj.spring.aop.aspect.APIProxy] - method:void com.mj.spring.aop.api.CustomerManagerService.addCustomer(String) parameter input:[Mengya] carry_out_time:0 ms
2015-09-24 18:26:58,886 WARN [com.mj.spring.aop.aspect.APIProxy] - Customer exists, repeat operation
2015-09-24 18:26:58,888 ERROR [com.mj.spring.aop.aspect.APIProxy] - Method:void com.mj.spring.aop.api.CustomerManagerService.addCustomer(String) call failed parameter input:[Mengya]
com.mj.spring.aop.impl.CustomeExistException: Customer exists, repeat operation
at com.mj.spring.aop.impl.customerManager.addCustomer(customerManager.java:16)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85)
at com.mj.spring.aop.aspect.APIProxy.aroundAdvice(APIProxy.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:68)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
at com.sun.proxy.$Proxy12.addCustomer(Unknown Source)
at com.mj.spring.aop.impl.customerManagerTest.should_print_normal_log_info_when_add_a_same_customer_twice(customerManagerTest.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:78)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:212)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
2015-09-24 18:26:58,905 INFO [com.mj.spring.aop.aspect.APIProxy] - method:void com.mj.spring.aop.api.CustomerManagerService.addCustomer(String) parameter input:[Mengya] carry_out_time:20 ms
Console窗口日志無法打印問題
使用log4j有時候我們會遇到日志無法在concole窗口打印的問題，console窗口提示日志配置異常。
log4j:WARN No appenders could be found for logger (org.springframework.core.env.StandardEnvironment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
解決這個問題很簡單，和src平級目錄創建log4j.properties文件，輸入下面內容，就可以解決這個問題了
log4j.rootLogger=INFO,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
Conslusion
本文講解了Spring AOP在函數接口調用性能分析及其日志處理方面的應用，希望能夠給大家帶來一些幫助和啟發。