【Android学习笔记】更新Gradle到4遇到的问题

To take advantage of all the latest features (such as Instant Run), improvements and security fixes, we strongly recommend that you update the Android Gradle plugin to version 3* and Gradle to version 4.

遇到的问题：

WARNING: Configuration ‘compile’ is obsolete and has been replaced with ‘implementation’ and ‘api’.

解决方法：把Gradle Scripts文件夹中的build.gradle文件中的compile全部换成implementation

WARNING: The specified Android SDK Build Tools version (25.0.2) is ignored, as it is below the minimum supported version (28.0.3) for Android Gradle Plugin 3.2.1.

解决方法：build.gradle中compileSdkVersion 版本号与buildToolsVersion不匹配。
改为匹配即可。
改为：buildToolsVersion ‘28.0.3’

编译时出现错误：

org.gradle.api.UncheckedIOException: Failed to capture snapshot of input files for task ‘:app:mergeDebugResources’ property ‘aapt2FromMaven’ during up-to-date check.

还不明白这个错误的原因是什么！
尝试修改： dependencies { classpath 'com.android.tools.build:gradle:3.2.1' (把3.2.1改为4.6，报错！入坑)
查看blog发现：

build.gradle里的版本和gradle-wrapper.properties里面的版本根本就不是一个玩意儿！build.gralde里的classpath 'com.android.tools.build:gradle:3.0.1’指的是Android Studio的gradle插件版本，而gradle-wrapper.properties里的distributionUrl=https://services.gradle.org/distributions/gradle-4.4-all.zip才是指定的gradle版本！

查看另一个成功的配置：

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// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    String osName = System.getProperty("os.name").toLowerCase();
    if (osName.contains("windows")) {
        buildDir = "C:/tmp/${rootProject.name}/${project.name}"
    }
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28

    defaultConfig {
        applicationId "com.example.android.sunshine"
        minSdkVersion 14
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.0.0'

    // TODO (10) Remove this dependency as we won't be needing it for the project until later


    // Instrumentation dependencies use androidTestImplementation
    // (as opposed to testImplementation for local unit tests run in the JVM)
    androidTestImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support:support-annotations:28.0.0'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test:rules:1.0.2'
}

最后得到的文件是

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    buildToolsVersion '28.0.3'

    defaultConfig {
        applicationId "com.android.example.favoritetoys"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'

    // TODO (7) Remove the ConstraintLayout dependency as we aren't using it for these simple projects
    implementation 'com.android.support.constraint:constraint-layout:1.0.0-beta4'
}

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    String osName = System.getProperty("os.name").toLowerCase();
    if (osName.contains("windows")) {
        buildDir = "C:/tmp/${rootProject.name}/${project.name}"
    }
    repositories {
        jcenter()
        google()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

可以成功运行