解决Android studio 3.5.3出现Cause: unable to find valid certification path to requested target 报错的问题

修改根目录（注意是根目录！！！不是app工程下面）下的build.gradle，整个文件替换成如下内容：

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

buildscript {

    repositories {

        maven { url 'http://maven.aliyun.com/nexus/content/repositories/google' }

        maven { url 'http://maven.aliyun.com/nexus/content/repositories/jcenter'}

    }

    dependencies {

        classpath 'com.android.tools.build:gradle:3.5.3'

        // NOTE: Do not place your application dependencies here; they belong

        // in the individual module build.gradle files

    }

}

allprojects {

    repositories {

//    google()

//    jcenter()

        maven { url 'http://maven.aliyun.com/nexus/content/repositories/google' }

        maven { url 'http://maven.aliyun.com/nexus/content/repositories/jcenter'}

    }

}

然后就同步成功了。

参考资料：https://www.jb51.net/article/182527.htm

classpath 'com.android.tools.build:gradle:3.6.1'

这个classpath必须要根据android studio版本来设置。