Kotlin 扩展函数使用 Intent extras 启动 Activity

Question

我正在尝试为 Context 编写一个 kotlin 扩展函数，它将使用给定的类名和意图附加列表在 android 中启动一个新活动。我能够在没有任何额外内容的情况下成功开始活动，但我面临着问题。

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)
}

这里的主要问题是 ->intent.putExtra() 不排除第二个参数 任意

Answer 1

不要使用成对列表，而是考虑使用

Bundle

。然后您可以使用

putExtras(Bundle)

添加它。

如果您想更进一步，您可以添加 lambda 扩展来配置额外功能：

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

那么你可以将其称为：

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

Answer 2

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>()

额外

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

Answer 3

这是启动活动的扩展函数：

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 中提供了更简单的方法

使用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 4

这是启动活动的扩展函数：

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：这不是推荐的开始活动方式。使用 STARTACTIVITY 代替。

Answer 5

我个人更喜欢一种方法，其中我有一个定义活动标志的方法，以避免必须为每个 startActivity 调用重写标志。

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")
}

Answer 6

putExtra(String, Any)

对象中没有方法

Intent

。您可以使用

Bundle

对象来保存数据：

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

在

Context

对象内调用它：

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

Answer 7

 private inline fun <reified T : Any> Context.startActivity() {
    val intent = Intent(this, T::class.java)
    startActivity(intent)
    finish()
}

使用

通过活动

startActivity<MainActivity2>()