安卓集成AOP：AspectJ

AOP是什么？

AOP （Aspect Oriented Programming，面向切面编程），可以在运行时动态地将代码切入到类中指定方法、指定位置上的一种技术。说白了，就是把横切逻辑从业务逻辑 中抽离出来。哪些属于横切逻辑呢？比如，性能监控、日志、权限控制等等。

AOP相关概念：

JointPoint(连接点)
Pointcut(切入点)
Advice(增强)
Adivisor(切面)
Before Advice(前置增强)
After Advice(后置增强)
Around Advice(环绕增强)
Throws Advice(抛出增强)
Introduction Advice(引入增强)

接入方法

1.拷贝如下文件到工程根目录下（是根目录，不是app目录下），命名为aspectj.gradle

import org.aspectj.bridge.IMessage
import org.aspectj.bridge.MessageHandler
import org.aspectj.tools.ajc.Main

final def log = project.logger
final def variants = project.android.applicationVariants

buildscript {

    repositories {
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        maven{ url 'http://maven.aliyun.com/nexus/content/repositories/jcenter'}
        jcenter()
    }
    dependencies {
        classpath 'org.aspectj:aspectjtools:1.9.1'
    }
}

variants.all { variant ->
    if (!variant.buildType.isDebuggable()) {
        log.debug("Skipping non-debuggable build type '${variant.buildType.name}'.")
        return;
    }

    JavaCompile javaCompile = variant.javaCompile
    javaCompile.doLast {
        String[] args = ["-showWeaveInfo",
                         "-1.8",
                         "-inpath", javaCompile.destinationDir.toString(),
                         "-aspectpath", javaCompile.classpath.asPath,
                         "-d", javaCompile.destinationDir.toString(),
                         "-classpath", javaCompile.classpath.asPath,
                         "-bootclasspath", project.android.bootClasspath.join(File.pathSeparator)]
        log.debug "ajc args: " + Arrays.toString(args)

        MessageHandler handler = new MessageHandler(true);
        new Main().run(args, handler);
        for (IMessage message : handler.getMessages(null, true)) {
            switch (message.getKind()) {
                case IMessage.ABORT:
                case IMessage.ERROR:
                case IMessage.FAIL:
                    log.error message.message, message.thrown
                    break;
                case IMessage.WARNING:
                    log.warn message.message, message.thrown
                    break;
                case IMessage.INFO:
                    log.info message.message, message.thrown
                    break;
                case IMessage.DEBUG:
                    log.debug message.message, message.thrown
                    break;
            }
        }
    }
}
dependencies {
    implementation 'org.aspectj:aspectjrt:1.9.1'
}

2.app下的build.gradle文件中增加：

apply from: '../aspectj.gradle'

实际使用样例

(以“限制按钮只允许单击”为例)

1. 定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface SingleClick {
}

2. 添加按钮控制实现类

/**
 * 避免连续点击
 */
@Aspect
public class SingleClickAspect {
    private long lastClickTime = 0;
    private String TAG = SingleClickAspect.class.getSimpleName();
    private final long MIN_CLICK_DELAY_TIME = 600;

    @Pointcut("execution(@com..SingleClick * *(..))")
    public void methodAnnotated() {
    }

    @Around("methodAnnotated()")
    public void aroundJoinPoint(ProceedingJoinPoint joinPoint) throws Throwable {
        long currentTime = Calendar.getInstance().getTimeInMillis();
        if (currentTime - lastClickTime > MIN_CLICK_DELAY_TIME) {//过滤掉600毫秒内的连续点击
            if (BuildConfig.DEBUG) {
                Log.d(TAG, "点击发生时间:" + currentTime);
            }
            lastClickTime = currentTime;
            //执行原方法
            joinPoint.proceed();
        }
        else
        {
            Log.d(TAG, "点击事件被过滤");
        }
    }

}

3. 使用

@Override
    protected void onCreate(Bundle savedInstanceState) {
        findViewById(R.id.button).setOnClickListener(this);
    }

    @SingleClick
    @Override
    public void onClick(View v) {
        Toast.makeText(MainActivity.this, "我被点击了", Toast.LENGTH_SHORT).show();
    }

4. 按钮点击后,后台打印日志

D/SingleClickAspect: 点击发生时间:1554689576613
D/SingleClickAspect: 点击事件被过滤
D/SingleClickAspect: 点击事件被过滤

Demo源代码

https://gitee.com/cxyzy1/aop_demo.git

参考资料

https://www.jianshu.com/p/c66f4e3113b3

https://www.jianshu.com/p/f577aec99e17

利用aop监控方法耗时（hugo）： https://yq.aliyun.com/articles/7104

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