android studio 遇到的问题

 dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.+'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    //androidTestImplementation 'com.android.support.test:runner:1.0.2'
    //androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

}

这三个依赖 注释掉 就没有问题不注释就会出现
Could not get resource 'https://dl.google.com/dl/android/maven2/junit/junit/4.12/junit-4.12.pom'.
> Could not HEAD 'https://dl.google.com/dl/android/maven2/junit/junit/4.12/junit-4.12.pom'. Received status code 400 from server: Bad Reques 这种问题 怎么解决呢 很急

翻墙 或者 换个镜像地址 如果没用到单元测试 就删掉吧

你有依赖包吗，你最好检查一下，具体我不知道怎么去看依赖包存在吗？