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interface-buoy

Kotlin and groovy provide very convenient operators, the operator ?. is only invoked when the reference object is not empty, but unfortunately, this utility operator is not provided in java.

I wrote a blog to analyze the principles of the ?. operators in kotlin and groovy. The kotlinc and groovyc compilers compile the ?. to the same effect as if (callback != null) {} bytecode.

Interface-buoy is an Android gradle plugin that uses ASM to dynamically modify java bytecode during the build process. Combine dynamic proxies and reflections to achieve the same effect as the '?.' effect.

Note that we only modify the method defined in the java interface, that is which will trigger the invokeinterface instruction at runtime.

Blog link : 在Java 中安全使用接口引用

Usage

Command Line

$ git clone git@github.com:SmartDengg/interface-buoy.git
$ cd interface-buoy/
$ ./gradlew build

AGP

Add Android gradle plugin dependency to your any application or library module's build.gradle.

buildscript {
    repositories {
        maven { url 'https://jitpack.io' }
    }
    dependencies {
        classpath 'com.github.SmartDengg.interface-buoy:interface-buoy-gradle:1.3.0'
    }
}

apply plugin: 'com.android.application' // or apply plugin: 'com.android.library'
apply plugin: 'com.smartdengg.interfacebuoy' // or apply plugin: 'interfacebuoy'

dependencies {
  implementation fileTree(include: ['*.jar'], dir: 'libs')
  implementation 'com.github.SmartDengg.interface-buoy:interface-buoy-runtime:1.3.0'
}

Optional

In the java code you can use BuoySettings.loggable = true to control whether to print the log, the default is not to print the log.

Support

If the invoked interface method has a return type but not a void type, its bytecode will not be modified. Currently only the void return type is supported.

  • void return type
  • other return type

Principle

Before:


invokeinterface #3,  2            // InterfaceMethod Callback.onProgress:(I)V

After:


invokestatic  #23                 // Method buoy$onProgress:(LCallback;I)V


static void buoy$onProgress(JavaSample$Callback, int);
Code:
   0: aload_0
   1: ldc           #25                 // String Callback
   3: ldc           #27                 // String Callback.onProgress:(int)void
   5: invokestatic  #33                 // Method com/smartdengg/interfacebuoy/compiler/InterfaceBuoy.proxy:(Ljava/lang/Object;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
   8: iload_1
   9: invokeinterface #37,  2           // InterfaceMethod Callback.onProgress:(I)V
  14: return

  1. Replaces invokeinterface with invokestatic at compile time.

  2. Generated Buoy$onProgress method at compile time to prevent calling interface methods on an null object.

About me

email : hi4joker@gmail.com

blog : 小鄧子

weibo : -小鄧子-

License

See the LICENSE file for license rights and limitations (MIT).