优雅地管理 gradle 版本依赖

通常Android studio生成的gradle 项目都会有一个项目级别的build.gradle文件、以及若干个module级别的 build.gradle文件。

在app module的build.gradle文件中我们可以使用如下的语句引入依赖

apply plugin: 'com.android.application'
    android {
        …
    } ...
    dependencies {
        // support libraries
        compile 'com.android.support:appcompat-v7:23.4.0'
        compile 'com.android.support:design:23.4.0'
        compile 'com.android.support:percent:23.4.0'
        compile 'com.android.support:cardview-v7:23.4.0'
        compile 'com.android.support:gridlayout-v7:23.4.0'
    
        //play services
        compile 'com.google.android.gms:play-services-location:9.2.1'
        compile 'com.google.android.gms:play-services-gcm:9.2.1'
    
        // other dependencies
        ...
}

痛点在于多次重复出现的版本号23.4.0，9.2.1，如果有多个module同时依赖了这些lib，
这个buidl version还将出现多次。

解决方案

通过如下的方法可以稍微改进一下

apply plugin: 'com.android.application'
    android {
    ...
    }
    ...

    ext {
        supportLibraryVersion = '23.4.0'
        playServicesVersion = '9.2.1'
    }
    
    dependencies {
        // support libraries
        compile "com.android.support:appcompat-v7:$supportLibraryVersion"
        compile "com.android.support:design:$supportLibraryVersion"
        compile "com.android.support:percent:$supportLibraryVersion"
        compile "com.android.support:cardview-v7:$supportLibraryVersion"
        compile "com.android.support:gridlayout-v7:$supportLibraryVersion"
    
        //play services
        compile "com.google.android.gms:play-services-location:$playServicesVersion"
        compile "com.google.android.gms:play-services-gcm:$playServicesVersion"
    
        // other dependencies
        ...
    }

值得注意的地方有两点：

单引号''变成了""
通过$来引用属性值

groovy String参考链接 string interpolation

如果project中有多个module怎么办？

把ext代码块移动到项目的build.gradle 中即可

buildscript {
    ...
}

allprojects {
    ...
}
...

ext {
    // sdk and tools
    minSdkVersion = 14
    targetSdkVersion = 23
    compileSdkVersion = 23
    buildToolsVersion = '23.0.2'

    // dependencies versions
    supportLibraryVersion = '23.4.0'
    playServicesVersion = '9.2.1'
}

module中的build.gradle如下

apply plugin: 'com.android.application'
android {
    ...
}
...

dependencies {
    // support libraries
    compile "com.android.support:appcompat-v7:$rootProject.supportLibraryVersion"
    compile "com.android.support:design:$rootProject.supportLibraryVersion"
    compile "com.android.support:percent:$rootProject.supportLibraryVersion"
    compile "com.android.support:cardview-v7:$rootProject.supportLibraryVersion"
    compile "com.android.support:gridlayout-v7:$rootProject.supportLibraryVersion"

    //play services
    compile "com.google.android.gms:play-services-location:$rootProject.playServicesVersion"
    compile "com.google.android.gms:play-services-gcm:$rootProject.playServicesVersion"

    // other dependencies
    ...
}

注意一点就好：用$rootProject.propority来引用

Contents

如果project中有多个module怎么办？