Failed to resolve: com.android.support:appcompat-v7:27.+ 解决方法

failed to resolve: com.android.support:appcompat-v7:27.+ 解决方法。新创建一个android studio project.出现了failed to resolve: com.android.support:appcompat-v7:27.+问题。

我的工作环境是 android studio 2.3.3。

app 下的 build.gradle文件内容如下：

apply plugin: 'com.android.application'

android {
    compilesdkversion 27
    buildtoolsversion "27.0.3"
    defaultconfig {
        applicationid "com.bestgo.facebookdownload"
        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'
        }
    }
}

dependencies {
    compile filetree(dir: 'libs', include: ['*.jar'])
    androidtestcompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:27.0.0'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testcompile 'junit:junit:4.12'
}

project下的build.gradle文件内容如下：

????

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

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'

        // note: do not place your application dependencies here; they belong
        // in the inpidual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: delete) {
    delete rootproject.builddir
}

解决方法：

?在project 下的build.gradle 文件里的 allprojects加入以下代码：

????????maven {
? ? ? ? ? ? url "https://maven.google.com"

? ? ? ? }

加入后的build.gradle文件如下：

 

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

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'

        // note: do not place your application dependencies here; they belong
        // in the inpidual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
}

task clean(type: delete) {
    delete rootproject.builddir
}