Kotlin 扩展函数以 Intent extras 开始 activity

Question

我正在尝试为 Context 编写一个 kotlin 扩展函数，它将在 android 中启动一个新的 activity，并带有给定的 class 名称和意图附加列表。我能够在没有任何额外功能的情况下成功启动 activity，但我遇到了问题。

fun <T> Context.openActivity(it: Class<T>, pairs: List<Pair<String, Any>>) {
  var intent = Intent()
  pairs.forEach {
     intent.putExtra(it.first, it.second)
  }
  startActivity(intent)
}

Main issue here is -> intent.putExtra() doesn't except second param as Any

Answer 1

Intent 对象中没有方法 putExtra(String, Any)。您可以使用 Bundle 对象来保存您的数据：

fun <T> Context.openActivity(it: Class<T>, bundleKey: String, bundle: Bundle) {
    var intent = Intent(this, it)
    intent.putExtra(bundleKey, bundle)
    startActivity(intent)
}

要在 Context 对象中调用它：

val bundle = Bundle()
bundle.putString("Key", "Value") // you can put another object here
openActivity(SomeActivity::class.java, "Bundle Key", bundle)

Answer 2

考虑使用 Bundle，而不是使用成对列表。然后你可以用 putExtras(Bundle).

添加它

如果你想更进一步，你可以添加一个 lambda 扩展来配置附加功能：

fun <T> Context.openActivity(it: Class<T>, extras: Bundle.() -> Unit = {}) {
  val intent = Intent(this, it)
  intent.putExtras(Bundle().apply(extras))
  startActivity(intent)
}

那么你可以这样称呼它：

openActivity(MyActivity::class.java) {
  putString("string.key", "string.value")
  putInt("string.key", 43)
  ...
}

Answer 3

这是开始的扩展函数activity:

inline fun <reified T : Activity> Context.openActivity(noinline extra: Intent.() -> Unit) {
      val intent = Intent(this, T::class.java)
      intent.extra()
      startActivity(intent)
}

你可以这样调用这个函数：

openActivity<MyActivity> {
    addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
    putExtra(LaBoxConstants.DEFAULT_LANDING, Default_Landing)
    putExtra(HomeActivity.APP_RELAUNCH, AppReLaunched)
}

注意：这不是推荐的开始方式 ACTIVITY。使用 STARTACTIVITY 代替。

Answer 4

声明：

inline fun <reified T : Activity> Context.startActivity(block: Intent.() -> Unit = {}) {
    startActivity(Intent(this, T::class.java).apply(block))
}

使用简单：

startActivity<MainActivity>()

有额外的

startActivity<MainActivity>{
   putExtra("param 1", "Simple")
}

Answer 5

这是开始的扩展函数activity:

inline fun <reified T : Activity> Context.openActivity(vararg params: Pair<String, Any>) {
    val intent = Intent(this, T::class.java)
    intent.putExtras(*params)
    this.startActivity(intent)
}

fun Intent.putExtras(vararg params: Pair<String, Any>): Intent {
    if (params.isEmpty()) return this
    params.forEach { (key, value) ->
        when (value) {
            is Int -> putExtra(key, value)
            is Byte -> putExtra(key, value)
            is Char -> putExtra(key, value)
            is Long -> putExtra(key, value)
            is Float -> putExtra(key, value)
            is Short -> putExtra(key, value)
            is Double -> putExtra(key, value)
            is Boolean -> putExtra(key, value)
            is Bundle -> putExtra(key, value)
            is String -> putExtra(key, value)
            is IntArray -> putExtra(key, value)
            is ByteArray -> putExtra(key, value)
            is CharArray -> putExtra(key, value)
            is LongArray -> putExtra(key, value)
            is FloatArray -> putExtra(key, value)
            is Parcelable -> putExtra(key, value)
            is ShortArray -> putExtra(key, value)
            is DoubleArray -> putExtra(key, value)
            is BooleanArray -> putExtra(key, value)
            is CharSequence -> putExtra(key, value)
            is Array<*> -> {
                when {
                    value.isArrayOf<String>() ->
                        putExtra(key, value as Array<String?>)
                    value.isArrayOf<Parcelable>() ->
                        putExtra(key, value as Array<Parcelable?>)
                    value.isArrayOf<CharSequence>() ->
                        putExtra(key, value as Array<CharSequence?>)
                    else -> putExtra(key, value)
                }
            }
            is Serializable -> putExtra(key, value)
        }
    }
    return this
}

使用简单：

openActivity<TestActivity>("key0" to "value0", "key1" to "value1")

Kotlin 中提供了一种更简单的方法

Use the bundleOf()

inline fun <reified T : Activity> Context.openActivity1(vararg params: Pair<String, Any?>) {
    val intent = Intent(this, T::class.java)
    intent.putExtras(bundleOf(*params))
    this.startActivity(intent)
}

Answer 6

我个人更喜欢一种方法，我有一个方法为 activity 定义标志，以避免每次调用 startActivity 时都必须重新编写标志。

internal inline fun <reified T: Activity> Context.startActivity(activity: KClass<T>, noinline modifyIntent: Intent.() -> Unit) {
    val intent = Intent(this, activity.java)
        .addFlags(flagsForActivity(activity))
        .modifyIntent()

    startActivity(intent)
}

private fun <T: Activity> flagsForActivity(activity: KClass<T>): Int {
    return when (activity) {
        LoginActivity::class -> Intent.SPECIFIC_FLAGS
        else -> Intent.DEFAULT_FLAGS
    }
}

然后它的调用方式是

startActivity(LoginActivity::class) {
    putExtra("Username", "username")
}

Kotlin 扩展函数以 Intent extras 开始 activity

Kotlin extension function start activity with Intent extras

android

kotlin

kotlin-extension

kotlin-android-extensions