标签:val 记录 学习 override activity fun import android
实现广播强制下线功能
继承关系
LoginActivity
package com.example.broadcastbestpractice0
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_login.*
import kotlin.math.log
class LoginActivity : BaseActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_login)
login.setOnClickListener {
val account=accountEdit.text.toString()
val password=passwordEdit.text.toString()
if(account=="admin"&&password=="123456"){
val intent= Intent(this,MainActivity::class.java)
startActivity(intent)
finish()
}else{
Toast.makeText(this,"account or password is invalid",Toast.LENGTH_SHORT).show()
}
}
}
}
MainActivity
package com.example.broadcastbestpractice0
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : BaseActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
forceOffline.setOnClickListener {
val intent =Intent("com.example.broadcastbestpractice.FORCE_OFFLINE")
sendBroadcast(intent)//发送标准广播
}
}
}
由于每个Activity 都要接收广播,因此将接收广播的逻辑代码统一写在他们的相同父类BaseActivity当中,重写方法时首先会调用父类中的方法.
BaseActivity
package com.example.broadcastbestpractice0
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.Bundle
import android.os.ResultReceiver
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity
open class BaseActivity : AppCompatActivity() {
lateinit var receiver: ForeOfflineReceiver
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
ActivityCollector.addActivity(this)
}
override fun onDestroy() {
super.onDestroy()
ActivityCollector.removeActivity(this)
}
override fun onResume() {
super.onResume()
val intentFilter=IntentFilter()
intentFilter.addAction("com.example.broadcastbestpractice.FORCE_OFFLINE")
receiver=ForeOfflineReceiver()
registerReceiver(receiver,intentFilter)
}//获得栈顶的位置.
override fun onPause() {
super.onPause()
unregisterReceiver(receiver)
}//失去栈顶的位置.
inner class ForeOfflineReceiver : BroadcastReceiver(){
override fun onReceive(context: Context, intent: Intent) {
AlertDialog.Builder(context).apply {
setTitle("Warning")
setMessage("You are forced to be offline. Please try to login again.")
setCancelable(false)
setPositiveButton("OK"){
_, _ -> ActivityCollector.finishAll()
val i =Intent(context,LoginActivity:: class.java)
context.startActivity(i)
}
show()
}
}
}
}
将会用到的方法写在ActivityCollector中(用 object 关键字创建单例可直接调用其中的方法)
package com.example.broadcastbestpractice0
import android.app.Activity
object ActivityCollector {
private val activities=ArrayList<Activity>()
fun addActivity(activity: Activity){
activities.add(activity)
}
fun removeActivity(activity: Activity){
activities.remove(activity)
}
fun finishAll(){
for(activity in activities){
if(!activity.isFinishing){
activity.finish()
}
}
activities.clear()
}
}
文件存储
package com.example.filepersistencetest
import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
import java.io.BufferedWriter
import java.io.OutputStreamWriter
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
override fun onDestroy() {
super.onDestroy()
val inputText=editText.text.toString()
save(inputText)
}//在退出程序后 editText中的内容会被保存.
private fun save(inputText: String) {
val output=openFileOutput("data", Context.MODE_PRIVATE)
val writer=BufferedWriter(OutputStreamWriter(output))
writer.use {
it.write(inputText)
}
}
}
标签:val,记录,学习,override,activity,fun,import,android 来源: https://blog.csdn.net/weixin_44110537/article/details/113527233
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