RoboAspectJ

RoboAspectJ is a Gradle plugin to introduce AspectJ (Aspect-Orient Programming) to Android project. It compiles aspects(if needed) and weave them all together in FULL-PROJECT scope. This means project (or subproject) sources, external libraries and local dependencies will all be dealt with by default.

Note: This plugin may change due to the modification of transform-api. So you may keep track of RoboAspectJ to make sure you're using the most recent version.

latest version: v0.9.1

Prerequisite

Android Plugin (application) 2.1.0

Apply

Add plugin dependency in buildscript classpath:

buildscript {
    dependencies {
        classpath 'com.meituan.gradle:roboaspectj:0.9.+'
    }
}

Apply plugin:

apply plugin: 'com.meituan.roboaspectj'

Coding

There are basically 2 ways to write your aspects and weave them into production code:

As Source

write aspects in @AspectJ syntax under your project's java source directory. e.g. {$projectDir}/src/main/java/

As Library

compile and bundle your aspects independently using ajc, then make it dependency in build script. For example:

compile 'com.example.myaspects:library:1.0'

This way may be a little bit complicated. But it's suitable for those who want to maintain their aspects as an independent project.

Variant-Specific Concern

While RoboAspectJ is registered globally, we still can do our crosscutting concern under specific variant. Actually, this is already done by Android plugin.

As Source

put variant-specific aspects under corresponding folder.

For example, I want to do some performance monitoring in myflavor, so I will write aspects under ${projectDir}/src/myflavor/java/.

As Library

add variant-specific aspects dependency to corresponding configuration scope.

myflavorCompile 'com.example.myaspects:library:1.0'

Configuration

There is an extension aspectj for you to do some tweaking.

Exclude

If you want to leave some artifact untouched from AspectJ, using:

aspectj {
	exclude group: 'com.google.android', module: 'support-v4'
}

Java runtime

When applying rxjava or retrolambda, you may need jrt.jar as classpath. Configure it by:

aspectj {
	javartNeeded true
}

Disable

For debug or performance use, you can disable weaving:

aspectj {
    enable false    //by default, it's true and you don't have to add this statement.
}

alternatively, set roboaspectj.enable property false when run gradle.

$ gradle clean assembleDebug -Droboaspectj.enable=false

Maybe you want it to be smarter to disable it when it's a debug flavor, then add this to your build script:

aspectj {
    disableWhenDebug true // default is false
}

or, specify roboaspectj.disableWhenDebug property.

$ gradle clean assembleDebug -Droboaspectj.disableWhenDebug=true

Though weaving is disabled, Aspects and AspectJ compile dependencies are all still there. It's only the weaving step doesn't happen.

Note: Corresponding property has precedence over config in build script in both of these 2 cases. For instance, weaving will not take effect when your roboaspectj.enable property is false, no matter what you config in build script.

License

Code is under the Apache Licence v2.

Feedback

This plugin is currently a prototype, and it still has much to improve. Feel free to contact: xuxizhi@meituan.com