Android Gradle 多环境URL请求设置

public class Constant { 
　　public static final String URL= “http://XXXXX“; 
}

apply plugin: ‘com.android.application‘

android {
    compileSdkVersion 21
    buildToolsVersion "19.1.0"

    lintOptions {
        abortOnError false
    }

    defaultConfig {
        applicationId "com.example.teamlab.myapplication"
        minSdkVersion 9
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    }
    signingConfigs {
        debug {
            storeFile file("src/main/keystore/debug.keystore")
            storePassword "android"
            keyPassword "android"
        }
        release {
            storeFile file("src/main/keystore/debug.keystore")
            storePassword "android"
            keyPassword "android"
        }
        staging {
            storeFile file("src/main/keystore/debug.keystore")
            storePassword "android"
            keyPassword "android"
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile(‘proguard-android.txt‘), ‘proguard-rules.pro‘
        }
        debug {
            minifyEnabled false
            proguardFiles getDefaultProguardFile(‘proguard-android.txt‘), ‘proguard-rules.pro‘
        }
    }
    productFlavors {
        dev {
            applicationId ‘com.example.teamlab.myapplication.dev‘
            signingConfig signingConfigs.debug
        }
        staging {
            signingConfig signingConfigs.debug
            applicationId ‘com.example.teamlab.myapplication.staging‘
        }
        product {
            applicationId ‘com.example.teamlab.myapplication‘
            signingConfig signingConfigs.debug
        }
    }
    packagingOptions {
        exclude ‘META-INF/notice.txt‘
        exclude ‘META-INF/license.txt‘
    }
}

dependencies {
    compile fileTree(dir: ‘libs‘, include: [‘*.jar‘])
    compile ‘com.android.support:appcompat-v7:21.+‘
    compile ‘com.android.support:support-v4:21.+‘
    compile ‘cn.pedant.sweetalert:library:1.3‘
    compile ‘com.mcxiaoke.volley:library:1.0.+‘
    androidTestCompile ‘junit:junit:4.10‘
    androidTestCompile ‘org.robolectric:robolectric:2.3+‘
    androidTestCompile ‘com.squareup:fest-android:1.0.+‘
    compile project(‘:slidingmenu‘)
}