How to use offline bundle on android for react native project?

How to use offline bundle on android?
I didn`t see the document about use offline bundle on android.
I tried to uncomment the code in build.gradle.

project.ext.react = [
        // the name of the generated asset file containing your JS bundle
    bundleAssetName: "index.android.bundle",

    // the entry file for bundle generation
    entryFile: "index.android.js",

    // whether to bundle JS and assets in debug mode
    bundleInDebug: false,

    // whether to bundle JS and assets in release mode
    bundleInRelease: true,

    // the root of your project, i.e. where "package.json" lives
    root: "../../",

    // where to put the JS bundle asset in debug mode
    jsBundleDirDebug: "$buildDir/intermediates/assets/debug",

    // where to put the JS bundle asset in release mode
    jsBundleDirRelease: "$buildDir/intermediates/assets/release",

    // where to put drawable resources / React Native assets, e.g. the ones you use via
    // require('./image.png')), in debug mode
    resourcesDirDebug: "$buildDir/intermediates/res/merged/debug",

    // where to put drawable resources / React Native assets, e.g. the ones you use via
    // require('./image.png')), in release mode
    resourcesDirRelease: "$buildDir/intermediates/res/merged/release",

    // by default the gradle tasks are skipped if none of the JS files or assets change; this means
    // that we don't look at files in android/ or ios/ to determine whether the tasks are up to
    // date; if you have any other folders that you want to ignore for performance reasons (gradle
    // indexes the entire tree), add them here. Alternatively, if you have JS files in android/
    // for example, you might want to remove it from here.
    inputExcludes: ["android/**", "ios/**"]
]

but it didn`t work.It still fetch the JS bundle from the server.
Is there something I missed?