AspectJ: a facet oriented framework

1.1 download: http://www.eclipse.org/downloads/download.php?file=/tools/aspectj/aspectj-1.8.13.jar
1.2 direct installation
1.3 create a new application and add configuration in build.gradle: copy the complete code here

apply plugin: 'com.android.application'
import org.aspectj.bridge.IMessage
import org.aspectj.bridge.MessageHandler
import org.aspectj.tools.ajc.Main
buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.aspectj:aspectjtools:1.8.13'
        classpath 'org.aspectj:aspectjweaver:1.8.13'
    }
}

repositories {
    mavenCentral()
}
android {
    compileSdkVersion 27
    buildToolsVersion "27.0.3"

    defaultConfig {
        applicationId "com.example.a02_aop"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

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

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 {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:27.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
    compile files('libs/aspectjrt.jar')
}

1.4 copy a development package under the installation directory: aspectjrt.jar

After the completion of the appeal configuration, start to write the code. First, analyze the main functions. If there is a net, click the button to jump. If there is no net, it will not jump

First add comments: checkNet

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

Then use AOP facet. First, find the Pointcut("execution (full path of annotation * (..))"), then find the facet @ Around("the method to find the pointcut above") public Object checkNet(ProceedingJoinPoint joinPoint) throws Throwable {}, complete code

@Aspect
public class SectionAspect {
    /**
     * Find the tangent point of processing
     * * *(..)  Can handle all methods
     */
    @Pointcut("execution(@com.example.a02_aop.CheckNet * *(..))")
    public void checkNetBehavior() {

    }

    /**
     * Processing section
     */
    @Around("checkNetBehavior()")
    public Object checkNet(ProceedingJoinPoint joinPoint) throws Throwable {
        Log.e("TAG", "checkNet");
        //Get CheckNet comments
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        CheckNet checkNet = signature.getMethod().getAnnotation(CheckNet.class);
        if (checkNet != null) {
            Object object = joinPoint.getThis();
            Context context = getContext(object);
            if (context != null) {
                //Judge whether there is network
                if (!isNetworkAvailable(context)) {
                    //No net returns null
                    Toast.makeText(context, "Please check the Internet", Toast.LENGTH_SHORT).show();
                    return null;
                }
            }
        }

        return joinPoint.proceed();//Continue execution
    }

    /**
     * Judge whether there is a network at present
     */
    public boolean isNetworkAvailable(Context context) {
        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivityManager != null) {
            NetworkInfo[] infos = connectivityManager.getAllNetworkInfo();
            if (infos != null && infos.length > 0) {
                for (NetworkInfo info : infos) {
                    if (info.getState() == NetworkInfo.State.CONNECTED) {
                        return true;
                    }
                }
            }
        }
        return false;
    }

    public Context getContext(Object object) {
        if (object instanceof Activity) {
            return (Context) object;
        } else if (object instanceof Fragment) {
            return ((Fragment) object).getActivity();
        } else if (object instanceof View) {
            return ((View) object).getContext();
        }
        return null;
    }
}

Just add the CheckNet method where you need to use it