无法使用Gradle构建Android应用程序,但使用sudo除外

我正在尝试使用gradle构建一个简单的’Hello world’安卓应用程序.如果我发出命令它会建立好

但没有sudo,

FAILURE: Build Failed with an exception.

* what went wrong:
A problem occurred configuring project ':MystudioApplication'.
> Failed to notify project evaluation listener.
   > Could not resolve all dependencies for configuration ':MystudioApplication:_DebugCompile'.
      > Could not find any version that matches com.android.support:appcompat-v7:+.
        required by:
            workspace:MystudioApplication:unspecified

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD Failed

@R_242_10586@l time: 12.621 secs

以下是我的build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.6.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.0"

    defaultConfig {
        minSdkVersion 7
        targetSdkVersion 19
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:+'
}

请帮忙