查看“Android studio”的源代码

[[分类:编程]]

==项目中引用MPChartLib== 
1、 将MPChartLib文件夹拷贝到项目根目录 
 
2、在根目录里的settings.gradle里增加include ':app', ':MPChartLib' 
 
3、将文件MPChartLib.aar拷贝到libs文件夹里 
 
4、在build.grade(app)中增加 
 
dependencies { 
implementation project(':MPChartLib') 
} 
  
==设置app自动启动== 
  
增加权限 
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/> 
注册消息接收 
<receiver android:name=".BootBroadcastReceiver"> 
<intent-filter> 
<action android:name="android.intent.action.BOOT_COMPLETED" /> 
</intent-filter> 
</receiver> 
  
消息接收函数 
class BootBroadcastReceiver: BroadcastReceiver() { 
override public fun onReceive(context: Context, intent: Intent) { 
val mBootIntent = Intent(context, MainActivity::class.java) 
mBootIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK) 
context.startActivity(mBootIntent) 
} 
} 
  
==获取位置信息（kotlin）== 
val locationManager = getSystemService(Context.LOCATION_SERVICE) as LocationManager 
val location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER) 
if (location != null) { 
val sb = StringBuffer() 
sb.append('实时的位置信息：经度：') 
sb.append(location.longitude) 
sb.append('纬度：') 
sb.append(location.latitude) 
sb.append('高度：') 
sb.append(location.altitude) 
sb.append('速度：') 
sb.append(location.speed) 
sb.append('方向：') 
sb.append(location.bearing) 
sb.append('精度：') 
sb.append(location.accuracy) 
Toast.makeText(applicationContext, sb.toString(), Toast.LENGTH_LONG).show() 
} 
添加权限 
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> 
  
==发送Notification消息(kotlin)== 
fun sendNotification(channel_id:String ,channle_name:String,nTitle:String,nContentText:String,id:Int){ 
var notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager 
var notification: Notification? = null 
//val intent = Intent(Intent.ACTION_VIEW, Uri.parse('http://www.baidu.com/')) 
//val pendingIntent = PendingIntent.getActivity(this, 0, intent, 0) 
//如需链接到网站使用注释代码 
val intent = Intent() 
intent.setClass(this@MainActivity, MainActivity::class. 
val pendingIntent = PendingIntent.getActivity(this, 0, intent, 0) 
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) { 
val mChannel = NotificationChannel(channel_id, channle_name, NotificationManager.IMPORTANCE_LOW) 
notificationManager.createNotificationChannel(mChannel) 
notification = Notification.Builder(this) 
.setChannelId(channel_id) 
.setContentTitle(nTitle) 
.setContentText(nContentText) 
.setContentIntent(pendingIntent) 
.setSmallIcon(R.drawable.house).build() 
} else { 
val notificationBuilder = NotificationCompat.Builder(this) 
.setContentTitle(nTitle) 
.setContentText(nContentText) 
.setSmallIcon(R.drawable.house) 
.setOngoing(true) 
//.setChannel(id)//无效 
notification = notificationBuilder.build() 
} 
notificationManager.notify(id, notification) 
} 
  
==禁止使用http链接解决方法== 
访问网络时报异常  
Cleartext HTTP traffic to not permitted 
在<application标签里增加android:usesCleartextTraffic="true"即可 
  
==bitmap缩小显示== 
var matrix = Matrix() 
matrix.postScale(0.3f,0.3f)//长和宽放大缩小的比例 
val resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true) 
  
==textview 连续左移== 
设置一下参数，自动连续左移动 
android:ellipsize="marquee" 
android:focusable="auto" 
android:focusableInTouchMode="true" 
android:marqueeRepeatLimit="marquee_forever" 
android:scrollHorizontally="true" 
android:singleLine="true" 
  
==useAndroidx Error== 
编译报错 This project uses AndroidX dependencies, but the 'android.useAndroidX' property is not enabled. 
  
在gradle.propeties文件里增加如下语句，允许AnsiroidX 
android.useAndroidX=true 
==post获取数据（kotlin）== 
Thread(Runnable { 
val toMain1 = mAppMesHandler.obtainMessage() 
toMain1.arg1 = 1 
  
var conn: HttpURLConnection? = null 
var urlString = "http://server/new.php" 
try { 
conn = URL(urlString).openConnection() as HttpURLConnection 
conn.requestMethod = "POST" // 指定POST请求 
conn.doOutput = true // 设置请求过程可以传递参数给服务器 
  
// post请求参数 
val param = String.format("name=%s&age=%s&action=%s", "fengxueyan", "23", "query") 
DataOutputStream(conn.outputStream).use { os -> 
os.writeBytes(param) 
} 
conn.connect() 
conn.inputStream.use { input -> 
val data = input.bufferedReader().readText() 
toMain1.obj = data.toString() 
} 
} catch (e: Exception) { 
toMain1.obj = e.toString() 
} finally { 
conn?.disconnect() 
} 
  
mAppMesHandler.sendMessage(toMain1) 
}).start() 
  
  
//访问网络必须使用线程，而且线程不允许更新UI 
val mAppMesHandler = object : Handler() { 
override fun handleMessage(msg: Message) { 
if(msg.arg1 == 1){ 
var hList0 = msg.obj as String 
textView.setText(hList0) 
// Toast.makeText(applicationContext,hList0,Toast.LENGTH_LONG).show() 
} 
  
  
} 
} 
==时间日期选择== 
<TimePicker 
android:id="@+id/ptime" 
android:layout_width="310dp" 
android:layout_height="347dp" 
app:layout_constraintEnd_toEndOf="parent" 
app:layout_constraintStart_toStartOf="parent" 
app:layout_constraintTop_toBottomOf="@+id/button2" /> 
  
textView.setText(ptime.hour.toString()+":"+ptime.minute.toString()) 
  
<DatePicker 
android:id="@+id/pdate" 
android:layout_width="358dp" 
android:layout_height="428dp" 
android:layout_marginTop="20dp" 
app:layout_constraintEnd_toEndOf="parent" 
app:layout_constraintHorizontal_bias="0.566" 
app:layout_constraintStart_toStartOf="parent" 
app:layout_constraintTop_toBottomOf="@+id/button2" /> 
  
textView.setText(pdate.year.toString()+"-"+(pdate.month+1).toString()+"-"+pdate.dayOfMonth.toString()) 
==多个Fragment和Activity的简易数据交换方法（kotlin）== 
动态创建多个Fragment后，和Activity数据交换有很多种方式，消息方式简单快捷，代码量少 
  
在Activity中定义消息处理 
val mMainHandler = object : Handler() { 
    override fun handleMessage(msg: Message) { 
        if (msg.arg1 == 1) { 
            val sVerRes = msg.obj as String 
            Toast.makeText(applicationContext, sVerRes, Toast.LENGTH_LONG).show() 
        } 
  
} 
  
  
在Fragment里定义消息handle 
private var aHandle:Handler? = null 
  
  
建立初始化函数，将Activity的消息handle传入 
fun setHandler(AHandler: Handler?) { 
    try {    
        aHandle = AHandler 
    } catch (e: Exception) { 
   throw ClassCastException(context.toString()  
    } 
  
} 
  
Activity向Fragment传递数据直接定义函数 
Fragment向Activity传递数据发送消息 
val toMain1 = aHandle!!.obtainMessage() 
toMain1.obj = “message or data” 
toMain1.arg1 = 1 
  
aHandle!!.sendMessage(toMain1) 
==实现扫码二维码（kotlin）== 
dependencies增加引用 
implementation 'com.hongyelinggu:scancode:1.0.0' 
  
申请相机权限 
<uses-permission android:name="android.permission.CAMERA"/> 
val REQUEST_EXTERNAL_STORAGE = 1234 
if (ActivityCompat.checkSelfPermission(this, 
"android.permission.CAMERA") != PackageManager.PERMISSION_GRANTED ) { 
ActivityCompat.requestPermissions(this, 
arrayOf(Manifest.permission.CAMERA), REQUEST_EXTERNAL_STORAGE) 
} 
else{ 
  
} 
  
执行扫描 
startActivityForResult(Intent(this@MainActivity, CommonScanActivity::class.java), 1) 
  
返回结果字符串 
override fun onActivityResult(requestCode:Int, resultCode:Int, data:Intent?){ 
super.onActivityResult(requestCode, resultCode, data) 
val rCode = data!!.extras!!.getString(Constant.REQUEST_SCAN_MODE) //得到新Activity关闭后返回的数据 
Toast.makeText(applicationContext, rCode, Toast.LENGTH_LONG).show() 
} 
==读取写入文本文件（kotlin）== 
写入文件 
  
val fn = filesDir.toString() + "文件名.txt" 
var fff = "文本内容" 
try { 
val tfw = FileWriter(fn) 
tfw.write(fff) 
tfw.close() 
  
Toast.makeText(applicationContext, "保存成功", Toast.LENGTH_LONG).show() 
} catch (e: Exception) { 
Toast.makeText(applicationContext, e.toString(), Toast.LENGTH_LONG).show() 
} 
  
读取文件 
val fn = filesDir.toString() + "文件名.txt" 
try { 
val fb = FileReader(fn) 
val tv2:TextView = findViewById(R.id.textView2) 
tv2.setText(fb.readText())    //显示到TextView 
fb.close() 
} 
catch(e:Exception){ 
Toast.makeText(applicationContext, e.toString(), Toast.LENGTH_LONG).show() 
} 
  
如果路径访问需要权限 
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission> 
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission> 
  
//获取sd卡读写权限 
//val REQUEST_EXTERNAL_STORAGE = 1234 
if (ActivityCompat.checkSelfPermission(this, 
"android.permission.WRITE_EXTERNAL_STORAGE") != PackageManager.PERMISSION_GRANTED ) { 
ActivityCompat.requestPermissions(this, 
arrayOf(WRITE_EXTERNAL_STORAGE, READ_EXTERNAL_STORAGE), REQUEST_EXTERNAL_STORAGE) 
} 
else{ 
  
} 
==多项选择对话框 kotlin== 
val builder = AlertDialog.Builder(this) 
builder.setTitle("请选择") 
builder.setIcon(R.drawable.ic_launcher_foreground) 
builder.setCancelable(true) 
  
val items = arrayOf("第一项", "第二项", "第三项") 
var selected = booleanArrayOf(true, false, true) 
  
  
builder.setMultiChoiceItems(items, selected) { dialog, which, isChecked -> // dialog.dismiss(); 
// Toast.makeText(this@MainActivity, items[which] + isChecked, Toast.LENGTH_SHORT).show() 
  
} 
  
//此代码实现输入文本对话框 
//val filename :EditText = EditText(this) 
//builder.setView(filename) 
  
builder.setPositiveButton(" 确定发送 ") { dialogInterface, i -> 
val tw: TextView = findViewById(R.id.textView1) 
var sd = "" 
for (i in 0 until items.count()) { 
if (selected[i]) 
sd += items[i] 
} 
tw.setText(sd) 
Toast.makeText(this@MainActivity, sd, Toast.LENGTH_SHORT).show() 
  
//tw.setText(filename.text.toString()) 
} 
builder.setNegativeButton("取消发送") { dialogInterface, i -> 
// finish() 
  
  
} 
builder.show() 
==OptionsMenu kotlin== 
app 右键 new=》android resouce file 
resouce type 选择Menu 
创建菜单项目，编辑ID和title 
//显示菜单 
override fun onCreateOptionsMenu(menu: Menu?): Boolean { 
menuInflater.inflate(R.menu.mainmanu,menu) 
return true 
// return super.onCreateOptionsMenu(menu) 
} 
//处理菜单点击响应 
override fun onOptionsItemSelected(item: MenuItem): Boolean { 
  
if(item?.itemId == R.id.menu_exit){ 
finish() 
} 
if(item?.itemId == R.id.menu_upate){ 
Toast.makeText(this,"system update",Toast.LENGTH_LONG).show() 
} 
  
return super.onOptionsItemSelected(item) 
  
} 
==ContextMenu kotlin == 
app 右键 new=》android resouce file 
resouce type 选择Menu 
创建菜单项目，编辑ID和title 
  
 override fun onCreateContextMenu(menu: ContextMenu?, v: View?, menuInfo: ContextMenu.ContextMenuInfo?) { 
 super.onCreateContextMenu(menu, v, menuInfo) 
 menuInflater.inflate(R.menu.menupop,menu) 
 menu!!.setHeaderTitle("请选择")  
 } 
重载函数  
 override fun onContextItemSelected(item: MenuItem): Boolean { 
    if(item.itemId == R.id.media_route_menu_item1){ 
    Toast.makeText(this,"11111111",Toast.LENGTH_LONG).show() 
  } 
  return super.onContextItemSelected(item) 
 } 
  
onCreate 
  
 val bt_menu: Button = findViewById(R.id.button_menu) 
 registerForContextMenu(bt_menu) 
 bt_menu.setOnClickListener { 
 openContextMenu(it) 
 }
如果在list view item弹出菜单，直接
 val tv_houseList = findViewById(R.id.listview_house_list) as ListView
 registerForContextMenu(tv_houseList) 
这样长按item自动会弹出菜单

==androidstudio使用WebView显示网页（kotlin）==
 val wset = wview1.settings
   wset.javaScriptEnabled = true
      wview1.setWebViewClient(object : WebViewClient() {
            override fun shouldOverrideUrlLoading(view: WebView, url: String): Boolean {
                view.loadUrl(url)
                return true
            }
        })
 wview1.loadUrl(“http://www.baidu.com”)

在AndroidManifest.xml增加
 android:usesCleartextTraffic="true"
需要添加网络权限

如果需要支持网页弹出alert：
 wview1.setWebChromeClient (object : WebChromeClient() 
    override fun onJsAlert(view: WebView,url: String,message: String,result: JsResult):Boolean{
          return super.onJsAlert(view, url, message, result)
     }
  })

==androidstudio使用viewPager显示多张图片并关联tabLayout（kotlin）==
val mImgId = intArrayOf(R.drawable.h1, R.drawable.h2, R.drawable.h3)
     val mList = ArrayList()
    var tabName : Array = Array(3,{""})

       tabName[0] = "TAB1"
       tabName[1] = "TAB2"
       tabName[2] = "TAB3"

        vpage.setAdapter(object : PagerAdapter() {
           override fun destroyItem(container: ViewGroup, position: Int, `object`: Any) {
             container.removeView(mList.get(position))
           }
           override fun instantiateItem(container: ViewGroup, position: Int): Any {
              val imageView = ImageView(this@MainActivity)
             imageView.setImageResource(mImgId[position])
             imageView.setScaleType(ImageView.ScaleType.CENTER_CROP)
             container.addView(imageView)
              mList.add(imageView)
              return imageView
           }
           override fun getCount(): Int {
              return mImgId.size
           }
           override fun isViewFromObject(view: View, `object`: Any): Boolean {
              return view === `object`
           }
           override fun getPageTitle(position:Int):CharSequence{
               return tabName[position]
           }

       })
       tabcus.setupWithViewPager(vpage)
==使用ViewPager2和TabLayout实现多frgment切换==
 private fun initTab(){
        val viewpage = findViewById(R.id.viewpage2) as ViewPager2
        viewpage.adapter = object : FragmentStateAdapter(this){
            override fun getItemCount(): Int {
                return  3
            }
            override fun createFragment(position: Int): Fragment {
                return when(position){
                    0 -> myFragment()
                    1 -> hlistFragment()
                    else -> hlistFragment()
                }
            }
        }
        val tabmain = findViewById(R.id.tabLayout) as TabLayout

        TabLayoutMediator(
            tabmain,
            viewpage,
            object : TabLayoutMediator.TabConfigurationStrategy{
                override fun onConfigureTab(tab: TabLayout.Tab, position: Int) {
                    when(position){
                        0 -> tab.text = "资源汇总"
                        1 -> tab.text = "我的房源"
                        else -> tab.text = "房源资源库"
                    }
                }
            }).attach()
xml文件
 <com.google.android.material.tabs.TabLayout
 <androidx.viewpager2.widget.ViewPager2

建立Fragement list 用于访问每个动态创建的Fragment
 var list_frm:ArrayList<Fragment> = ArrayList()

             override fun createFragment(position: Int): Fragment {
                 when(position){
                    0 -> {
                        val fg =  myFragment()
                        list_frm.add(fg )
                        return fg
                    }
                    1 -> {
                        val fg =  hlistFragment()
                        list_frm.add(fg)
                        return fg
                    }
                    else -> {
                        val fg =  hlistFragment()
                        list_frm.add(fg)
                        return fg
                    }
                }
            }
==使用BaseAdapter为listview装入数据==

  class myAdapter (context: Activity,listValue:String): BaseAdapter(){
      private var ct:Activity
      private var lv:String
      init {
          ct = context
          lv = listValue

      }
      override fun getCount():Int{
          val hma_list = lv.split("^")
          return hma_list.count()
      }
      override fun getItem(position: Int):String{
          val hma_list = lv.split("^")
          return hma_list[position].toString()
      }
      override fun getItemId(position: Int):Long{
          return position.toLong()
      }

      override fun getView(position: Int, view: View?, parent: ViewGroup): View {
          val rowView = ct.layoutInflater.inflate(R.layout.layout_house_info_item, null, true)
          val hm_name = rowView.findViewById(R.id.tv_item_name) as TextView
          val hm_price = rowView.findViewById(R.id.tv_item_price) as TextView
          val hm_size = rowView.findViewById(R.id.tv_item_size) as TextView
          val hm_room = rowView.findViewById(R.id.tv_item_room) as TextView
          val hm_time = rowView.findViewById(R.id.tv_item_time) as TextView
          val hm_status = rowView.findViewById(R.id.tv_item_status) as TextView
          val hma_list = lv.split("^")
          var hma_value = hma_list[position].split("~")
          hm_name.text = hma_value[0]
          if(hma_value[12] == "2" )
              hm_price.text = hma_value[4]+"/月"
          else
              hm_price.text = hma_value[2]+"万"
          hm_size.text = hma_value[9] +"  "+ hma_value[1]+"平米"
          hm_room.text = hma_value[6]+"室"+hma_value[7]+"厅"+hma_value[8]+"卫    "+hma_value[5]+"层"
          hm_time.text = "最后跟进"+hma_value[11]
          return rowView
      }
  }
listview 操作
   val adapter = myAdapter(this,listStr)
   tv_houseList.setAdapter(adapter)
==让EditText不能编辑，只读==
  et_tel.keyListener = null
==让WebView支持手机定位==
静态申请权限
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_GPS" />
    <uses-permission android:name="android.permission.ACCESS_ASSISTED_GPS" />
    <uses-permission android:name="android.permission.ACCESS_LOCATION" />
动态申请权限
    if (ActivityCompat.checkSelfPermission(this,
            "android.permission.WRITE_EXTERNAL_STORAGE") != PackageManager.PERMISSION_GRANTED ) {
            ActivityCompat.requestPermissions(this,
                arrayOf(ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION), 1234)
        }
设置WebView参数
        val wview1 = findViewById(R.id.vview1) as WebView
        val wset = wview1.settings
        wset.javaScriptEnabled = true
        wset.setGeolocationEnabled(true)  //允许定位
        wview1.setWebViewClient(object : WebViewClient() {
            override fun shouldOverrideUrlLoading(view: WebView, url: String): Boolean {
                view.loadUrl(url)
                return true
            }
        })

        wview1.setWebChromeClient (object : WebChromeClient() {
            override fun onJsAlert(view: WebView, url: String, message: String, result: JsResult):Boolean{
                return super.onJsAlert(view, url, message, result)
            }
            override fun onGeolocationPermissionsShowPrompt(
                origin: String?,
                callback: GeolocationPermissions.Callback?
            ) {
                val remember = true
                val builder: AlertDialog.Builder = AlertDialog.Builder(this@MainActivity)
                builder.setTitle("位置信息")
                builder.setMessage(origin + "允许获取您的地理位置信息吗？").setCancelable(true)
                            .setPositiveButton("允许",
                                DialogInterface.OnClickListener { dialog, id ->
                                    callback?.invoke(
                                        origin,
                                        true,
                                        remember
                                    )
                                })
                            .setNegativeButton("不允许",
                                DialogInterface.OnClickListener { dialog, id ->
                                    callback?.invoke(
                                        origin,
                                        false,
                                        remember
                                    )
                                })
                        val alert: AlertDialog = builder.create()
                        alert.show()
                }
            })