AspectJ在android上的开发

Android上运用AOP的思想开发，可以快速的帮助我们简化在横向开发中的重复性工作，简单的说就是把涉及到众多模块的某一类问题进行统一管理比如：性能检测、日志打印手机等。
AspectJ实际上是对AOP编程思想的一个实践，当然，除了AspectJ以外，还有很多其它的AOP实现，例如ASMDex、javassist等，但目前最好、最方便的，依然是AspectJ。

直接贴例子

• 引入插件，这边是添加在app.gradle, 不是添加在项目的gradle中

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

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'org.aspectj:aspectjtools:1.8.1'   //引入aspectj的classpath
  }
}

apply plugin: 'com.android.application'

android {
  compileSdkVersion 26
  buildToolsVersion "26.0.2"
  defaultConfig {
    applicationId "m4399.aspectjdemo"
    minSdkVersion 19
    targetSdkVersion 26
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
    release {
      minifyEnabled false
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
  }
}

dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  compile 'com.android.support:appcompat-v7:26.+'
  compile 'com.android.support.constraint:constraint-layout:1.0.2'
  testCompile 'junit:junit:4.12'
  compile 'org.aspectj:aspectjrt:1.8.1'   //添加对应的依赖
}


final def log = project.logger
final def variants = project.android.applicationVariants
//在全局变量中配置编译项以及，对应的log输出
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;
      }
    }
  }
}

• 编写注解

@Retention(RetentionPolicy.CLASS)
@Target({ ElementType.CONSTRUCTOR, ElementType.METHOD })
public @interface DebugTrace {
}

• 日志打印类

public class DebugLog {
  private DebugLog() {}

  /**
   * Send a debug log message
   *
   * @param tag Source of a log message.
   * @param message The message you would like logged.
   */
  public static void log(String tag, String message) {
    Log.d(tag, message);
  }
}

• 方法耗时检测类

public class StopWatch {

  private long startTime;
  private long endTime;
  private long elapsedTime;

  public StopWatch() {
    //empty
  }

  private void reset() {
    startTime = 0;
    endTime = 0;
    elapsedTime = 0;
  }

  public void start() {
    reset();
    startTime = System.nanoTime();
  }

  public void stop() {
    if (startTime != 0) {
      endTime = System.nanoTime();
      elapsedTime = endTime - startTime;
    } else {
      reset();
    }
  }

  public long getTotalTimeMillis() {
    return (elapsedTime != 0) ? TimeUnit.NANOSECONDS.toMillis(endTime - startTime) : 0;
  }
}

• Aspect 类的开发

@Aspect
public class TraceAspect {

  private static final String POINTCUT_METHOD =
      "execution(@com.bao.aspectjdemo.DebugTrace * *(..))";  //对应着注解类的包名+类名

  private static final String POINTCUT_CONSTRUCTOR =
      "execution(@com.bao.aspectjdemo.DebugTrace *.new(..))";

  @Pointcut(POINTCUT_METHOD)
  public void methodAnnotatedWithDebugTrace() {}

  @Pointcut(POINTCUT_CONSTRUCTOR)
  public void constructorAnnotatedDebugTrace() {}

  @Around("methodAnnotatedWithDebugTrace() || constructorAnnotatedDebugTrace()")
  public Object weaveJoinPoint(ProceedingJoinPoint joinPoint) throws Throwable {
    MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
    String className = methodSignature.getDeclaringType().getSimpleName();
    String methodName = methodSignature.getName();

    final StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    Object result = joinPoint.proceed();
    stopWatch.stop();

    DebugLog.log(className, buildLogMessage(methodName, stopWatch.getTotalTimeMillis()));

    return result;
  }

  /**
   * Create a log message.
   *
   * @param methodName A string with the method name.
   * @param methodDuration Duration of the method in milliseconds.
   * @return A string representing message.
   */
  private static String buildLogMessage(String methodName, long methodDuration) {
    StringBuilder message = new StringBuilder();
    message.append("AspectJDemo --> ");
    message.append(methodName);
    message.append(" --> ");
    message.append("[");
    message.append(methodDuration);
    message.append("ms");
    message.append("]");

    return message.toString();
  }
}

• 调用

  @DebugTrace
  @Override
  public void onClick(View v) {
    try {
      Thread.sleep(10);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

以上是个人参考例子https://github.com/android10/Android-AOPExample 熟悉了一遍
补充：Android-AOPExample的例子下载下来，在gradle版本再2.3.0及其以上的版本编译会出现问题
报错误：No such property: project for class: com.android.build.gradle.LibraryPlugin

• 解决方法一：注释掉LibraryPlugin plugin = project.plugins.getPlugin(LibraryPlugin)
  和 "-bootclasspath", plugin.project.android.bootClasspath.join(File.pathSeparator)
• 解决方法二：将plugin.project.android.bootClasspath.join(File.pathSeparator) 替换为 android.bootClasspath.join(File.pathSeparator)

参考文章：

• https://www.jianshu.com/p/f90e04bcb326
• https://www.jianshu.com/p/b96a68ba50db
• https://blog.csdn.net/woshimalingyi/article/details/51476559
• https://blog.csdn.net/eclipsexys/article/details/54425414
• Aspect-oriented programming.
• Aspect-oriented software development.