如何在Android中制作浮动窗口应用程序？

好吧，在我们的台式计算机上，我们可以轻松地还原窗口，在后台执行某些操作，并在需要时最大化窗口。但是我们在Android应用程序中看不到此功能。如今，我们可以看到android提供了Split Screen，但这是OS提供的功能，而不是应用程序的单独功能。让我们制作一个仅需单击按钮即可最小化和最大化自身的应用程序。此功能可以在很多方面为用户提供帮助。假设您正在阅读一些带有一些数学计算的pdf文档，然后在pdf查看器应用程序中使用最小化计算器将非常有帮助。有很多使用此功能的应用程序，例如剪贴板，MI计算器等。这是本文最终应用程序的演示。注意，我们将使用Java语言实现该项目。

分步实施

步骤1：创建一个新项目

要在Android Studio中创建新项目，请参阅如何在Android Studio中创建/启动新项目。请注意，选择Java作为编程语言。

步骤2：建立工作平台

• 为应用程序添加新的颜色：转到values-> colors.xml 。可以在此处添加任何自定义颜色。我们添加了这两种颜色。

XML

#FF2F8D46
#FF098043

• 删除ActionBar ：在Android Studio 4.1中，转到值->主题。有两个主题XML文件，一个用于亮模式，一个用于暗模式。在这两种XML中，在样式块中将父属性更改为Theme.MaterialComponents.DayNight.NoActionBar 。
• 更改应用程序的主色：在同一文件中，第一个项目块必须与应用程序的主色有关。在这里添加新添加的颜色。在项目块中，添加@ color / gfgTheme或@ color / gfgThemeTwo 。

步骤3：首先制作所有版式

3.a：开始处理activity_main.xml文件

该XML文件构成了应用程序主活动的布局。布局并不那么复杂。在ConstraintLayout中只有一个Button，TextView，EditText和一个接一个的Button。这是XML代码。

3.b：开始处理floating_layout.xml文件

转到res-> layout 。右键单击布局->新建->布局资源文件。添加布局的名称(floating_layout这里)。该XML文件构成了浮动窗口的布局。它具有与主布局相同的组件，但大小限制略有不同。这是XML代码。

步骤4：开始处理Java程序

我们在这里做了3节课。显然，第一个是MainActivity 。第二个是用于浮动窗口服务的FloatingWindowGFG ，最后一个是用于两个公共变量的Common类。

4.a：让我们为通用变量创建类

• 首先，让我们制作一个名为Common的包。右键单击项目包路径(此处为com.wheic.floatingedittext ) ->新建->包。
• 将会弹出一个窗口。预期的软件包名称已写出(对我来说是通用的)。将创建一个新的程序包。
• 右键单击新创建的包-> New-> Java Class 。预期的类名称已被写入(此处通用)。
• 创建了两个公共String变量，一个是currentDesc ，另一个是saveDesc 。两者均以空字符串启动。
• 这是通用代码。 Java类。

Java

package com.wheic.floatingedittext.Common;
  
public class Common {
    // The EditText String will be 
    // stored in this variable
    // when MINIMIZE or MAXIMIZE 
    // button is pressed
    public static String currentDesc = "";
      
    // The EditText String will be 
    // stored in this variable
    // when SAVE button is pressed
    public static String savedDesc = "";
}

4.b：开始使用MainActivity。 Java文件

• 首先，创建组件类的引用。创建了两个Button ，一个AlertDialog和一个EditText引用。
• 在转到onCreate()之前，将创建一些其他方法。
• isMyServiceRunning() ：此方法有助于查找此应用程序的浮动窗口服务是否正在运行。当已经可见浮动窗口时，如果打开同一应用程序，则需要此函数，因为这时需要停止浮动窗口服务。这是带有逐行说明的代码：

Java

private boolean isMyServiceRunning() {
       // The ACTIVITY_SERVICE is needed to retrieve a 
          // ActivityManager for interacting with the global system
       // It has a constant String value "activity".
       ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
         
          // A loop is needed to get Service information that are currently running in the System.
       // So ActivityManager.RunningServiceInfo is used. It helps to retrieve a
       // particular service information, here its this service.
       // getRunningServices() method returns a list of the services that are currently running
       // and MAX_VALUE is 2147483647. So at most this many services can be returned by this method.
       for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
             
             // If this service is found as a running, it will return true or else false.
           if (FloatingWindowGFG.class.getName().equals(service.service.getClassName())) {
               return true;
           }
       }
       return false;
   }

• requestOverlayDisplayPermission() ：该方法有助于将应用程序重定向到“设置”以启用“在其他应用程序上显示”。尽管为此，需要在AndroidManifest.xml文件中添加额外的一行。为此，转到app-> manifests-> AndroidManifest.xml 。在应用程序块之前添加以下行：

Java

private void requestOverlayDisplayPermission() {
        // An AlertDialog is created
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
          
          // This dialog can be closed, just by 
          // taping outside the dialog-box
        builder.setCancelable(true);
    
        // The title of the Dialog-box is set
        builder.setTitle("Screen Overlay Permission Needed");
    
        // The message of the Dialog-box is set
        builder.setMessage("Enable 'Display over other apps' from System Settings.");
    
        // The event of the Positive-Button is set
        builder.setPositiveButton("Open Settings", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // The app will redirect to the 'Display over other apps' in Settings.
                // This is an Implicit Intent. This is needed when any Action is needed 
                  // to perform, here it is
                // redirecting to an other app(Settings).
                Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + getPackageName()));
                  
                  // This method will start the intent. It takes two parameter, 
                  // one is the Intent and the other is
                // an requestCode Integer. Here it is -1.
                startActivityForResult(intent, RESULT_OK);
            }
        });
        dialog = builder.create();
        // The Dialog will show in the screen
        dialog.show();
    }

• checkOverlayDisplayPermission() ：此方法实际上检查API级别是否大于23，然后在设置中是否启用了“通过其他应用程序显示”。这是此函数的代码：

Java

private boolean checkOverlayDisplayPermission() {
        // Android Version is lesser than Marshmallow 
          // or the API is lesser than 23
        // doesn't need 'Display over other apps' permission enabling.
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
            // If 'Display over other apps' is not enabled it 
              // will return false or else true
            if (!Settings.canDrawOverlays(this)) {
                return false;
            } else {
                return true;
            }
        } else {
            return true;
        }
    }

• 现在，这里是MainActivity的完整代码。 Java文件。

Java

package com.wheic.floatingedittext;
  
import android.app.ActivityManager;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.Settings;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
  
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
  
import com.wheic.floatingedittext.Common.Common;
  
public class MainActivity extends AppCompatActivity {
  
    // The reference variables for the
    // Button, AlertDialog, EditText 
    // classes are created
    private Button minimizeBtn;
    private AlertDialog dialog;
    private EditText descEditArea;
    private Button save;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
  
        // The Buttons and the EditText are connected with
        // the corresponding component id used in layout file
        minimizeBtn = findViewById(R.id.buttonMinimize);
        descEditArea = findViewById(R.id.descEditText);
        save = findViewById(R.id.saveBtn);
  
        // If the app is started again while the 
        // floating window service is running
        // then the floating window service will stop
        if (isMyServiceRunning()) {
            // onDestroy() method in FloatingWindowGFG
            // class will be called here
            stopService(new Intent(MainActivity.this, FloatingWindowGFG.class));
        }
  
        // currentDesc String will be empty 
        // at first time launch
        // but the text written in floating 
        // window will not gone
        descEditArea.setText(Common.currentDesc);
        descEditArea.setSelection(descEditArea.getText().toString().length());
  
        // The EditText string will be stored in 
        // currentDesc while writing
        descEditArea.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                // Not Necessary
            }
  
            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                Common.currentDesc = descEditArea.getText().toString();
            }
  
            @Override
            public void afterTextChanged(Editable editable) {
                // Not Necessary
            }
        });
  
        // Here the save button is used just to store the 
        // EditText string in saveDesc variable
        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Common.savedDesc = descEditArea.getText().toString();
                descEditArea.setCursorVisible(false);
                descEditArea.clearFocus();
                Toast.makeText(MainActivity.this, "Text Saved!!!", Toast.LENGTH_SHORT).show();
            }
        });
  
        // The Main Button that helps to minimize the app
        minimizeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // First it confirms whether the
                // 'Display over other apps' permission in given
                if (checkOverlayDisplayPermission()) {
                    // FloatingWindowGFG service is started
                    startService(new Intent(MainActivity.this, FloatingWindowGFG.class));
                    // The MainActivity closes here
                    finish();
                } else {
                    // If permission is not given,
                    // it shows the AlertDialog box and
                    // redirects to the Settings
                    requestOverlayDisplayPermission();
                }
            }
        });
    }
  
    private boolean isMyServiceRunning() {
        // The ACTIVITY_SERVICE is needed to retrieve a
        // ActivityManager for interacting with the global system
        // It has a constant String value "activity".
        ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
          
        // A loop is needed to get Service information that 
        // are currently running in the System.
        // So ActivityManager.RunningServiceInfo is used. 
        // It helps to retrieve a
        // particular service information, here its this service.
        // getRunningServices() method returns a list of the 
        // services that are currently running
        // and MAX_VALUE is 2147483647. So at most this many services
        // can be returned by this method.
        for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            // If this service is found as a running, 
            // it will return true or else false.
            if (FloatingWindowGFG.class.getName().equals(service.service.getClassName())) {
                return true;
            }
        }
        return false;
    }
  
    private void requestOverlayDisplayPermission() {
        // An AlertDialog is created
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
          
        // This dialog can be closed, just by taping
        // anywhere outside the dialog-box
        builder.setCancelable(true);
          
        // The title of the Dialog-box is set
        builder.setTitle("Screen Overlay Permission Needed");
          
        // The message of the Dialog-box is set
        builder.setMessage("Enable 'Display over other apps' from System Settings.");
          
        // The event of the Positive-Button is set
        builder.setPositiveButton("Open Settings", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // The app will redirect to the 'Display over other apps' in Settings.
                // This is an Implicit Intent. This is needed when any Action is needed
                // to perform, here it is
                // redirecting to an other app(Settings).
                Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + getPackageName()));
                  
                // This method will start the intent. It takes two parameter, one is the Intent and the other is
                // an requestCode Integer. Here it is -1.
                startActivityForResult(intent, RESULT_OK);
            }
        });
        dialog = builder.create();
        // The Dialog will 
        // show in the screen
        dialog.show();
    }
  
    private boolean checkOverlayDisplayPermission() {
        // Android Version is lesser than Marshmallow or
        // the API is lesser than 23
        // doesn't need 'Display over other apps' permission enabling.
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
            // If 'Display over other apps' is not enabled
            // it will return false or else true
            if (!Settings.canDrawOverlays(this)) {
                return false;
            } else {
                return true;
            }
        } else {
            return true;
        }
    }
}

4.c：开始在FloatingWindowGFG上工作。 Java文件

• 创建另一个名为FloatingWindowGFG的类。转到项目包路径(对我来说是com.wheic.floatingedittext ) ->新建-> Java类，然后会给出任何预期的名称(对我来说是FloatingWindowGFG )。
• 该类继承Service类。
• 现在，由于该类是从Service类继承的，因此可以将该类用作清单文件中的服务。因此，在AndroidManifest.xml中，在活动块之后和应用程序块结束之前添加此行。

• 现在，这里是FloatingWindowGFG的代码。 Java的。添加了注释以便更好地解释：

Java

package com.wheic.floatingedittext;
  
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.Build;
import android.os.IBinder;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
  
import androidx.annotation.Nullable;
  
import com.wheic.floatingedittext.Common.Common;
  
public class FloatingWindowGFG extends Service {
  
    // The reference variables for the
    // ViewGroup, WindowManager.LayoutParams, 
    // WindowManager, Button, EditText classes are created
    private ViewGroup floatView;
    private int LAYOUT_TYPE;
    private WindowManager.LayoutParams floatWindowLayoutParam;
    private WindowManager windowManager;
    private Button maximizeBtn;
    private EditText descEditArea;
    private Button saveBtn;
  
    // As FloatingWindowGFG inherits Service class, 
    // it actually overrides the onBind method
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
  
    @Override
    public void onCreate() {
        super.onCreate();
  
        // The screen height and width are calculated, cause
        // the height and width of the floating window is set depending on this
        DisplayMetrics metrics = getApplicationContext().getResources().getDisplayMetrics();
        int width = metrics.widthPixels;
        int height = metrics.heightPixels;
  
        // To obtain a WindowManager of a different Display,
        // we need a Context for that display, so WINDOW_SERVICE is used
        windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
  
        // A LayoutInflater instance is created to retrieve the 
        // LayoutInflater for the floating_layout xml
        LayoutInflater inflater = (LayoutInflater) getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);
          
        // inflate a new view hierarchy from the floating_layout xml
        floatView = (ViewGroup) inflater.inflate(R.layout.floating_layout, null);
  
        // The Buttons and the EditText are connected with
        // the corresponding component id used in floating_layout xml file
        maximizeBtn = floatView.findViewById(R.id.buttonMaximize);
        descEditArea = floatView.findViewById(R.id.descEditText);
        saveBtn = floatView.findViewById(R.id.saveBtn);
  
        // Just like MainActivity, the text written 
        // in Maximized will stay
        descEditArea.setText(Common.currentDesc);
        descEditArea.setSelection(descEditArea.getText().toString().length());
        descEditArea.setCursorVisible(false);
  
        // WindowManager.LayoutParams takes a lot of parameters to set the
        // the parameters of the layout. One of them is Layout_type.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            // If API Level is more than 26, we need TYPE_APPLICATION_OVERLAY
            LAYOUT_TYPE = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
        } else {
            // If API Level is lesser than 26, then we can 
            // use TYPE_SYSTEM_ERROR,
            // TYPE_SYSTEM_OVERLAY, TYPE_PHONE, TYPE_PRIORITY_PHONE.
            // But these are all
            // deprecated in API 26 and later. Here TYPE_TOAST works best.
            LAYOUT_TYPE = WindowManager.LayoutParams.TYPE_TOAST;
        }
  
        // Now the Parameter of the floating-window layout is set.
        // 1) The Width of the window will be 55% of the phone width.
        // 2) The Height of the window will be 58% of the phone height.
        // 3) Layout_Type is already set.
        // 4) Next Parameter is Window_Flag. Here FLAG_NOT_FOCUSABLE is used. But
        // problem with this flag is key inputs can't be given to the EditText.
        // This problem is solved later.
        // 5) Next parameter is Layout_Format. System chooses a format that supports 
        // translucency by PixelFormat.TRANSLUCENT
        floatWindowLayoutParam = new WindowManager.LayoutParams(
                (int) (width * (0.55f)),
                (int) (height * (0.58f)),
                LAYOUT_TYPE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );
  
        // The Gravity of the Floating Window is set. 
        // The Window will appear in the center of the screen
        floatWindowLayoutParam.gravity = Gravity.CENTER;
          
        // X and Y value of the window is set
        floatWindowLayoutParam.x = 0;
        floatWindowLayoutParam.y = 0;
  
        // The ViewGroup that inflates the floating_layout.xml is
        // added to the WindowManager with all the parameters
        windowManager.addView(floatView, floatWindowLayoutParam);
  
        // The button that helps to maximize the app
        maximizeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // stopSelf() method is used to stop the service if
                // it was previously started
                stopSelf();
                  
                // The window is removed from the screen
                windowManager.removeView(floatView);
                  
                // The app will maximize again. So the MainActivity 
                // class will be called again.
                Intent backToHome = new Intent(FloatingWindowGFG.this, MainActivity.class);
                  
                // 1) FLAG_ACTIVITY_NEW_TASK flag helps activity to start a new task on the history stack.
                // If a task is already running like the floating window service, a new activity will not be started.
                // Instead the task will be brought back to the front just like the MainActivity here
                // 2) FLAG_ACTIVITY_CLEAR_TASK can be used in the conjunction with FLAG_ACTIVITY_NEW_TASK. This flag will
                // kill the existing task first and then new activity is started.
                backToHome.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
                startActivity(backToHome);
            }
        });
  
        // The EditText string will be stored 
        // in currentDesc while writing
        descEditArea.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                // Not Necessary
            }
  
            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                Common.currentDesc = descEditArea.getText().toString();
            }
  
            @Override
            public void afterTextChanged(Editable editable) {
                // Not Necessary
            }
        });
  
        // Another feature of the floating window is, the window is movable.
        // The window can be moved at any position on the screen.
        floatView.setOnTouchListener(new View.OnTouchListener() {
            final WindowManager.LayoutParams floatWindowLayoutUpdateParam = floatWindowLayoutParam;
            double x;
            double y;
            double px;
            double py;
  
            @Override
            public boolean onTouch(View v, MotionEvent event) {
  
                switch (event.getAction()) {
                    // When the window will be touched, 
                    // the x and y position of that position
                    // will be retrieved
                    case MotionEvent.ACTION_DOWN:
                        x = floatWindowLayoutUpdateParam.x;
                        y = floatWindowLayoutUpdateParam.y;
                          
                        // returns the original raw X 
                        // coordinate of this event
                        px = event.getRawX();
                          
                        // returns the original raw Y 
                        // coordinate of this event
                        py = event.getRawY();
                        break;
                    // When the window will be dragged around, 
                    // it will update the x, y of the Window Layout Parameter
                    case MotionEvent.ACTION_MOVE:
                        floatWindowLayoutUpdateParam.x = (int) ((x + event.getRawX()) - px);
                        floatWindowLayoutUpdateParam.y = (int) ((y + event.getRawY()) - py);
  
                        // updated parameter is applied to the WindowManager
                        windowManager.updateViewLayout(floatView, floatWindowLayoutUpdateParam);
                        break;
                }
                return false;
            }
        });
  
        // Floating Window Layout Flag is set to FLAG_NOT_FOCUSABLE, 
        // so no input is possible to the EditText. But that's a problem.
        // So, the problem is solved here. The Layout Flag is 
        // changed when the EditText is touched.
        descEditArea.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                descEditArea.setCursorVisible(true);
                WindowManager.LayoutParams floatWindowLayoutParamUpdateFlag = floatWindowLayoutParam;
                // Layout Flag is changed to FLAG_NOT_TOUCH_MODAL which 
                // helps to take inputs inside floating window, but
                // while in EditText the back button won't work and 
                // FLAG_LAYOUT_IN_SCREEN flag helps to keep the window
                // always over the keyboard
                floatWindowLayoutParamUpdateFlag.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
                  
                // WindowManager is updated with the Updated Parameters
                windowManager.updateViewLayout(floatView, floatWindowLayoutParamUpdateFlag);
                return false;
            }
        });
  
  
        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // saves the text in savedDesc variable
                Common.savedDesc = descEditArea.getText().toString();
                descEditArea.setCursorVisible(false);
                WindowManager.LayoutParams floatWindowLayoutParamUpdateFlag = floatWindowLayoutParam;
                floatWindowLayoutParamUpdateFlag.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
                  
                // The Layout Flag is changed back to FLAG_NOT_FOCUSABLE. and the Layout is updated with new Flag
                windowManager.updateViewLayout(floatView, floatWindowLayoutParamUpdateFlag);
                  
                // INPUT_METHOD_SERVICE with Context is used 
                // to retrieve a InputMethodManager for
                // accessing input methods which is the soft keyboard here
                InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                  
                // The soft keyboard slides back in
                inputMethodManager.hideSoftInputFromWindow(floatView.getApplicationWindowToken(), 0);
                  
                // A Toast is shown when the text is saved
                Toast.makeText(FloatingWindowGFG.this, "Text Saved!!!", Toast.LENGTH_SHORT).show();
            }
        });
    }
  
    // It is called when stopService() 
    // method is called in MainActivity
    @Override
    public void onDestroy() {
        super.onDestroy();
        stopSelf();
        // Window is removed from the screen
        windowManager.removeView(floatView);
    }
}

输出：

终于，项目准备好了。您可以在此GitHub链接中检查该项目。

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