How to Specify Character Encoding for Gradle

We, programmers living in the multi-bytes world, need knowledge of specifying character encoding.

For Gradle, it is the following:

usePlugin 'groovy'

repositories {
    mavenCentral()
}
dependencies {
    groovy group:'org.codehaus.groovy', name:'groovy', version:'1.7-beta-2'
}

def defaultEncoding = 'UTF-8'
compileJava {
    options.encoding = defaultEncoding  // affects *.java under src/main/java
                                        // alternative: "file.encoding" property
compileTestJava {
    options.encoding = defaultEncoding  // affects *.java under src/test/java
                                        // alternative: "file.encoding" property
}
compileGroovy {
    groovyOptions.encoding = defaultEncoding  // affects *.groovy under src/main/groovy
    options.encoding = defaultEncoding        // affects *.java under src/main/groovy
}
compileTestGroovy {
    groovyOptions.encoding = defaultEncoding  // affects *.groovy under src/test/groovy
    options.encoding = defaultEncoding        // affects *.java under src/test/groovy
}