Android Camera（二） Camera程序编写

Android Camera 相机程序编写

　　要自己写一个相机应用直接使用相机硬件，首先应用需要一个权限设置，在AndroidManifest.xml中加上使用设备相机的权限：

<uses-permission android:name="android.permission.CAMERA" />

　　为你的应用创建自定义的相机，一般步骤如下：

　　1.检测相机硬件并获取访问

　　2.建立一个Preview类：需要一个相机预览的类，继承 SurfaceView 类，并实现SurfaceHolder接口。

　　3.建立预览的布局。

　　4.为拍照建立监听。

　　5.拍照并且存储文件。

　　6.释放相机。

　　因为相机是一个共享资源，所以应该被谨慎管理，这样应用之间才不会发生冲突。

　　所以使用完相机之后应该调用 Camera.release()来释放相机对象。

　　如果不释放，后续的使用相机请求（其他应用或本应用）都会失败。

检测相机硬件

　　如果你的程序没有在manifest的声明中要求有相机，那么你应该在运行时检查相机的存在与否，主要用了 PackageManager.hasSystemFeature() 方法。比如：

    /** Check if this device has a camera */
    private boolean checkCameraHardware(Context context)
    {
        if (context.getPackageManager().hasSystemFeature(
                PackageManager.FEATURE_CAMERA))
        {
            // this device has a camera
            return true;
        }
        else
        {
            // no camera on this device
            return false;
        }
    }

　　设备上可能有多个相机，Android 2.3以后可以使用 Camera.getNumberOfCameras()来查看相机的数目。

　　如下面这段程序用于检测设备中的相机，并得到默认相机的索引号：

    private int getDefaultCameraId()
    {
        int defaultId = -1;

        // Find the total number of cameras available
        mNumberOfCameras = Camera.getNumberOfCameras();

        // Find the ID of the default camera
        CameraInfo cameraInfo = new CameraInfo();
        for (int i = 0; i < mNumberOfCameras; i++)
        {
            Camera.getCameraInfo(i, cameraInfo);
            if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK)
            {
                defaultId = i;
            }
        }
        if (-1 == defaultId)
        {
            if (mNumberOfCameras > 0)
            {
                // 如果没有后向摄像头
                defaultId = 0;
            }
            else
            {
                // 没有摄像头
                Toast.makeText(getApplicationContext(), R.string.no_camera,
                        Toast.LENGTH_LONG).show();
            }
        }
        return defaultId;
    }

　　看了Camera类的代码实现后，其中不带参数的open()方法：

    public static Camera open()
    {
        int numberOfCameras = getNumberOfCameras();
        CameraInfo cameraInfo = new CameraInfo();
        for (int i = 0; i < numberOfCameras; i++)
        {
            getCameraInfo(i, cameraInfo);
            if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK)
            {
                return new Camera(i);
            }
        }
        return null;
    }

　　说明open方法默认是打开第一个后向摄像头的。

访问相机

　　当检测到设备上有相机之后，必须获取其访问权，获取一个 Camera 类的对象。

　　要获取主要的相机，可以使用 Camera.open() 方法，注意异常处理。

　　在使用这个方法的时候一定要检查异常，如果相机正在被使用或者不存在，没有处理异常，将会使得应用被系统关闭。

　　如：

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance()
    {
        Camera c = null;
        try
        {
            c = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e)
        {
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }

　　Android 2.3之后，可以使用Camera.open(int)来获取特定的相机。

检查相机特性

　　可以使用Camera.getParameters()方法来检查相机的特性。

　　API Level 9之后，可以使用 Camera.getCameraInfo()来查看相机是在设备前面还是后面，还可以得到图像的方向。

建立Preview类

　　为了有效地拍照或录像，用户必须要看到相机能看到的图像。

　　相机的preview类是一个 SurfaceView ，展示了相机正在捕捉的图像。

　　下面是一个预览类的例子（来自官网）：

A basic preview class

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;

    public CameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}

　　注意要设置尺寸的话需要放在surfaceChanged()方法里，调用 setPreviewSize()方法，并且应该使用 getSupportedPreviewSizes()返回的值，而不要使用任意的尺寸。

把Preview放在布局里面

　　布局时可以使用FrameLayout，这样其他的按钮或者元素可以叠加在预览图像上。

　　对于大多数设备来说，相机预览的默认方向是横放的（landscape）。

　　从Android 2.2 (API Level 8)开始，可以使用 setDisplayOrientation()来设置预览图像的方向。

　　如果需要在用户改变设备方向的时候改变预览图像的方向，可以在 surfaceChanged()方法中，首先用 Camera.stopPreview() 停止预览，改变方向，然后用Camera.startPreview()开启新的预览。

　　当然你也可以直接在manifest中设置好方向，如下：

<activity android:name=".CameraActivity"
          android:label="@string/app_name"

          android:screenOrientation="landscape">
          <!-- configure this activity to use landscape orientation -->

          <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

拍照

　　在应用里面，必须为用户控制加上监听，来响应用户拍照的动作。

　　为了得到图像，要使用 Camera.takePicture()方法。

　　这个方法接收三个参数，用于从相机获取图像。

　　为了接收到JPEG格式的数据，需要实现Camera.PictureCallback接口用来接收图像数据并且写入文件。

　　下面的代码展示了一个最基本的实现：

private PictureCallback mPicture = new PictureCallback() {

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {

        File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
        if (pictureFile == null){
            Log.d(TAG, "Error creating media file, check storage permissions: " +
                e.getMessage());
            return;
        }

        try {
            FileOutputStream fos = new FileOutputStream(pictureFile);
            fos.write(data);
            fos.close();
        } catch (FileNotFoundException e) {
            Log.d(TAG, "File not found: " + e.getMessage());
        } catch (IOException e) {
            Log.d(TAG, "Error accessing file: " + e.getMessage());
        }
    }
};

　　照相动作可以用按钮控制，如下：

// Add a listener to the Capture button
Button captureButton = (Button) findViewById(id.button_capture);
captureButton.setOnClickListener(
    new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // get an image from the camera
            mCamera.takePicture(null, null, mPicture);
        }
    }
);

释放相机

　　相机是设备资源，被所有应用共享，当应用不使用相机时应当及时释放，应当在Activity.onPause()中释放。

　　如果不及时释放，后续的相机请求（包括你自己的应用和其他的应用发出的）都将失败并且导致应用退出。

实验程序

　　完整的照相程序需要考虑相机切换、预览图像的尺寸设置、焦距变换、缩放、白平衡的相机参数设置。

　　请查阅文后的参考资料进行进一步学习。

　　附上一个粗糙待完善的自定义相机程序（2013/4/6）

　　预览图像类：　

CameraPreview

package com.example.hellocustomcamera;

import java.io.IOException;
import java.util.List;

import android.R.integer;
import android.content.Context;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Size;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/**
 * 相机图片预览类
 * 
 * @author
 * 
 */
public class CameraPreview extends SurfaceView implements
        SurfaceHolder.Callback
{

    private SurfaceHolder mHolder;
    private Camera mCamera;
    Size mPreviewSize;
    List<Size> mSupportedPreviewSizes;

    public CameraPreview(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        init();
    }

    public CameraPreview(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        init();
    }

    public CameraPreview(Context context)
    {
        super(context);
        init();
    }

    /**
     * 初始化工作
     * 
     */
    private void init()
    {
        Log.d(AppConstants.LOG_TAG, "CameraPreview initialize");

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    }

    public void setCamera(Camera camera)
    {

        mCamera = camera;
        if (mCamera != null)
        {
            mSupportedPreviewSizes = mCamera.getParameters()
                    .getSupportedPreviewSizes();
            requestLayout();
        }
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder)
    {
        Log.d(AppConstants.LOG_TAG, "surfaceCreated");
        // The Surface has been created, now tell the camera where to draw the
        // preview.
        try
        {
            if (null != mCamera)
            {
                mCamera.setPreviewDisplay(holder);
            }
        }
        catch (IOException e1)
        {
            e1.printStackTrace();

            Log.d(AppConstants.LOG_TAG,
                    "Error setting camera preview display: " + e1.getMessage());
        }
        try
        {
            if (null != mCamera)
            {
                mCamera.startPreview();
            }

            Log.d(AppConstants.LOG_TAG, "surfaceCreated successfully! ");
        }
        catch (Exception e)
        {
            Log.d(AppConstants.LOG_TAG,
                    "Error setting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height)
    {

        Log.d(AppConstants.LOG_TAG, "surface changed");
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (null == mHolder.getSurface())
        {
            // preview surface does not exist
            return;
        }

        // stop preview before making changes
        try
        {
            if (null != mCamera)
            {
                mCamera.stopPreview();
            }
        }
        catch (Exception e)
        {
            // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here

        if (null != mCamera)
        {
            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);

            requestLayout();

            mCamera.setParameters(parameters);
            mCamera.setDisplayOrientation(90);
            Log.d(AppConstants.LOG_TAG, "camera set parameters successfully!: "
                    + parameters);

        }
        // 这里可以用来设置尺寸

        // start preview with new settings
        try
        {
            if (null != mCamera)
            {

                mCamera.setPreviewDisplay(mHolder);
                mCamera.startPreview();
            }

        }
        catch (Exception e)
        {
            Log.d(AppConstants.LOG_TAG,
                    "Error starting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder)
    {
        Log.d(AppConstants.LOG_TAG, "surfaceDestroyed");

        if (null != mCamera)
        {
            mCamera.stopPreview();
        }

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        // We purposely disregard child measurements because act as a
        // wrapper to a SurfaceView that centers the camera preview instead
        // of stretching it.
        final int width = resolveSize(getSuggestedMinimumWidth(),
                widthMeasureSpec);
        final int height = resolveSize(getSuggestedMinimumHeight(),
                heightMeasureSpec);
        setMeasuredDimension(width, height);

        if (mSupportedPreviewSizes != null)
        {
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width,
                    height);
        }
    }

    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h)
    {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null)
            return null;

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes)
        {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
                continue;
            if (Math.abs(size.height - targetHeight) < minDiff)
            {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null)
        {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes)
            {
                if (Math.abs(size.height - targetHeight) < minDiff)
                {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

}

　　主要的Activity类：

HelloCustomCameraActivity

package com.example.hellocustomcamera;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.Toast;

public class HelloCustomCameraActivity extends Activity
{

    private Camera mCamera;
    private CameraPreview mPreview;

    int mNumberOfCameras;
    int mCameraCurrentlyLocked;

    // The first rear facing camera
    int mDefaultCameraId;

    int mScreenWidth, mScreenHeight;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        Log.d(AppConstants.LOG_TAG, "onCreate");
        super.onCreate(savedInstanceState);

        // 无标题栏的窗口
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        // 设置布局
        setContentView(R.layout.activity_hello_custom_camera);

        // 得到屏幕的大小
        WindowManager wManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        Display display = wManager.getDefaultDisplay();
        mScreenHeight = display.getHeight();
        mScreenWidth = display.getWidth();

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this);

        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);

        // 将相机预览图加入帧布局里面
        preview.addView(mPreview, 0);

        // 使用按钮进行拍摄动作监听
        Button captureButton = (Button) findViewById(R.id.button_capture);
        captureButton.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                // get an image from the camera
                mCamera.takePicture(null, null, mPicture);
            }
        });

        // 得到默认的相机ID
        mDefaultCameraId = getDefaultCameraId();
        mCameraCurrentlyLocked = mDefaultCameraId;

    }

    @Override
    protected void onResume()
    {
        Log.d(AppConstants.LOG_TAG, "onResume");
        super.onResume();

        // Open the default i.e. the first rear facing camera.
        mCamera = getCameraInstance(mCameraCurrentlyLocked);
        
        mPreview.setCamera(mCamera);
    }

    @Override
    protected void onPause()
    {
        Log.d(AppConstants.LOG_TAG, "onPause");
        super.onPause();

        // Because the Camera object is a shared resource, it's very
        // important to release it when the activity is paused.
        if (mCamera != null)
        {
            mPreview.setCamera(null);
            Log.d(AppConstants.LOG_TAG, "onPause --> Realease camera");
            mCamera.release();
            mCamera = null;
        }

    }

    @Override
    protected void onDestroy()
    {
        Log.d(AppConstants.LOG_TAG, "onDestroy");
        super.onDestroy();

    }

    /**
     * 得到默认相机的ID
     * 
     * @return
     */
    private int getDefaultCameraId()
    {
        Log.d(AppConstants.LOG_TAG, "getDefaultCameraId");
        int defaultId = -1;

        // Find the total number of cameras available
        mNumberOfCameras = Camera.getNumberOfCameras();

        // Find the ID of the default camera
        CameraInfo cameraInfo = new CameraInfo();
        for (int i = 0; i < mNumberOfCameras; i++)
        {
            Camera.getCameraInfo(i, cameraInfo);
            Log.d(AppConstants.LOG_TAG, "camera info: " + cameraInfo.orientation);
            if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK)
            {
                defaultId = i;
            }
        }
        if (-1 == defaultId)
        {
            if (mNumberOfCameras > 0)
            {
                // 如果没有后向摄像头
                defaultId = 0;
            }
            else
            {
                // 没有摄像头
                Toast.makeText(getApplicationContext(), R.string.no_camera,
                        Toast.LENGTH_LONG).show();
            }
        }
        return defaultId;
    }

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance(int cameraId)
    {
        Log.d(AppConstants.LOG_TAG, "getCameraInstance");
        Camera c = null;
        try
        {
            c = Camera.open(cameraId); // attempt to get a Camera instance
        }
        catch (Exception e)
        {
            // Camera is not available (in use or does not exist)
            e.printStackTrace();
            Log.e(AppConstants.LOG_TAG, "Camera is not available");
        }
        return c; // returns null if camera is unavailable
    }

    public static final int MEDIA_TYPE_IMAGE = 1;
    public static final int MEDIA_TYPE_VIDEO = 2;

    /** Create a File for saving an image or video */
    private static File getOutputMediaFile(int type)
    {
        Log.d(AppConstants.LOG_TAG, "getOutputMediaFile");
        // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.

        File mediaStorageDir = null;
        try
        {
            // This location works best if you want the created images to be
            // shared
            // between applications and persist after your app has been
            // uninstalled.
            mediaStorageDir = new File(
                    Environment
                            .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
                    "MyCameraApp");

            Log.d(AppConstants.LOG_TAG,
                    "Successfully created mediaStorageDir: " + mediaStorageDir);

        }
        catch (Exception e)
        {
            e.printStackTrace();
            Log.d(AppConstants.LOG_TAG, "Error in Creating mediaStorageDir: "
                    + mediaStorageDir);
        }

        // Create the storage directory if it does not exist
        if (!mediaStorageDir.exists())
        {
            if (!mediaStorageDir.mkdirs())
            {
                // 在SD卡上创建文件夹需要权限：
                // <uses-permission
                // android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
                Log.d(AppConstants.LOG_TAG,
                        "failed to create directory, check if you have the WRITE_EXTERNAL_STORAGE permission");
                return null;
            }
        }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
                .format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE)
        {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator
                    + "IMG_" + timeStamp + ".jpg");
        }
        else if (type == MEDIA_TYPE_VIDEO)
        {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator
                    + "VID_" + timeStamp + ".mp4");
        }
        else
        {
            return null;
        }

        return mediaFile;
    }

    private PictureCallback mPicture = new PictureCallback()
    {

        @Override
        public void onPictureTaken(byte[] data, Camera camera)
        {
            Log.d(AppConstants.LOG_TAG, "onPictureTaken");

            File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
            if (pictureFile == null)
            {
                Log.d(AppConstants.LOG_TAG,
                        "Error creating media file, check storage permissions: ");
                return;
            }

            try
            {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            }
            catch (FileNotFoundException e)
            {
                Log.d(AppConstants.LOG_TAG, "File not found: " + e.getMessage());
            }
            catch (IOException e)
            {
                Log.d(AppConstants.LOG_TAG,
                        "Error accessing file: " + e.getMessage());
            }

            // 拍照后重新开始预览
            mCamera.stopPreview();
            mCamera.startPreview();
        }
    };

    /** Check if this device has a camera */
    private boolean checkCameraHardware(Context context)
    {
        if (context.getPackageManager().hasSystemFeature(
                PackageManager.FEATURE_CAMERA))
        {
            // this device has a camera
            return true;
        }
        else
        {
            // no camera on this device
            return false;
        }
    }



}

　　布局文件：

activity_hello_custom_camera.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <FrameLayout
        android:id="@+id/camera_preview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" >

    <Button
        android:id="@+id/button_capture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|center"
        android:text="Capture" />

    </FrameLayout>

</LinearLayout>

　　Manifest文件：

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.hellocustomcamera"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="9"
        android:targetSdkVersion="15" />

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.CAMERA" />

    <uses-feature android:name="android.hardware.camera" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".HelloCustomCameraActivity"
            android:label="@string/title_activity_hello_custom_camera" >

            <!-- android:screenOrientation="landscape" -->
            <!-- configure this activity to use landscape orientation -->

            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>