初学android自定义Camera拍照并查看图片

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1.打开相机
a.预览拍摄图片，需用到SurfaceView，并且实现其回调函数implements SurfaceHolder.Callback；
activity_camera.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <SurfaceView        android:id="@+id/sv"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1" />    <Button        android:id="@+id/btn_camera"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="拍照" /></LinearLayout>

2.获取相机并开启预览

/**     * 获取系统相机     *      * @return     */    private Camera getcCamera() {        Camera camera = null;        try {            camera = Camera.open();        } catch (Exception e) {            camera = null;        }        return camera;    }

/**     * 显示相机预览图片     *      * @return     */    private void showCameraView(Camera camera,SurfaceHolder holder)    {        try {            camera.setPreviewDisplay(holder);            camera.setDisplayOrientation(90);            camera.startPreview();        }catch (Exception e){            e.printStackTrace();        };    }

/**** 实现界面回调处理*/    @Override    public void surfaceCreated(SurfaceHolder holder) {        showCameraView(mCamera, holder);    }    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {        mCamera.stopPreview();        showCameraView(mCamera, holder);    }    @Override    public void surfaceDestroyed(SurfaceHolder holder) {        clearCamera();    }}

3,相机主页面处理

public class CameraActivity extends AppCompatActivity implements SurfaceHolder.Callback{    private SurfaceView sv;    private Camera mCamera;    private SurfaceHolder holder;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_camera);        sv = (SurfaceView)findViewById(R.id.sv);        holder = sv.getHolder();        holder.addCallback(this);        findViewById(R.id.btn_camera).setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // 获取当前相机参数                Camera.Parameters parameters = mCamera.getParameters();                // 设置相片格式                parameters.setPictureFormat(ImageFormat.JPEG);                // 设置预览大小                parameters.setPreviewSize(800, 480);                // 设置对焦方式，这里设置自动对焦                parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);                mCamera.autoFocus(new Camera.AutoFocusCallback() {                    @Override                    public void onAutoFocus(boolean success, Camera camera) {                        // 判断是否对焦成功                        if (success) {                            // 拍照 第三个参数为拍照回调                            mCamera.takePicture(null, null, new Camera.PictureCallback() {                                @Override                                public void onPictureTaken(byte[] data, Camera camera) {                                    // data为完整数据                                    File file = new File("/sdcard/photo.png");                                    // 使用流进行读写                                    try {                                        FileOutputStream fos = new FileOutputStream(file);                                        try {                                            fos.write(data);                                            // 关闭流                                            fos.close();                                            // 查看图片                                            Intent intent = new Intent();                                            // 传递路径                                            intent.putExtra("path", file.getAbsolutePath());                                            setResult(0,intent);                                            finish();                                        } catch (IOException e) {                                            // TODO Auto-generated catch block                                            e.printStackTrace();                                        }                                    } catch (FileNotFoundException e) {                                        // TODO Auto-generated catch block                                        e.printStackTrace();                                    }                                }                            });                        }                    }                });            }        });    }

  @Override    protected void onResume() {        super.onResume();        if (mCamera == null) {            mCamera = getCamera();            if (holder != null) {                showCameraView(mCamera, holder);            }        }    }    @Override    protected void onPause() {        // TODO Auto-generated method stub        super.onPause();        // activity暂停时我们释放相机内存        clearCamera();    }    @Override    protected void onDestroy() {        super.onDestroy();    }    /**     * 释放相机的内存     */    private void clearCamera() {        // 释放hold资源        if (mCamera != null) {            // 停止预览            mCamera.stopPreview();            mCamera.setPreviewCallback(null);            // 释放相机资源            mCamera.release();            mCamera = null;        }    }

4.启动activity（设置拍照完图片路径返回显示图片处理，一定要对图片进行采样率操作（很可能拍照的图片太多而无法显示，又不报任何异常））

public class MainActivity extends AppCompatActivity {    private ImageView cameraIv;    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        if(resultCode == 0 && requestCode == 100)        {            String path = data.getStringExtra("path");            BitmapFactory.Options options = new BitmapFactory.Options();            options.inJustDecodeBounds = true;            BitmapFactory.decodeFile(path, options);            ImageSize imageSize = getImageViewSize(cameraIv);            options.inSampleSize = caculateInSampleSize(options,                    imageSize.width, imageSize.height);            // 使用获得到的InSampleSize再次解析图片            options.inJustDecodeBounds = false;            Bitmap bitmap = BitmapFactory.decodeFile(path, options);            cameraIv.setImageBitmap(bitmap);        }        super.onActivityResult(requestCode, resultCode, data);    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button openButton = (Button) findViewById(R.id.button);        cameraIv = (ImageView) findViewById(R.id.imageView);        openButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                Intent intent = new Intent(MainActivity.this,CameraActivity.class);                startActivityForResult(intent,100);            }        });    }      /* 根据需求的宽和高以及图片实际的宽和高计算SampleSize     *             * @param options     * @param width     * @param height     * @return             */    public static int caculateInSampleSize(BitmapFactory.Options options, int reqWidth,                                           int reqHeight)    {        int width = options.outWidth;        int height = options.outHeight;        int inSampleSize = 1;        if (width > reqWidth || height > reqHeight)        {            int widthRadio = Math.round(width * 1.0f / reqWidth);            int heightRadio = Math.round(height * 1.0f / reqHeight);            inSampleSize = Math.max(widthRadio, heightRadio);        }        return inSampleSize;    }    public static ImageSize getImageViewSize(ImageView imageView)    {        ImageSize imageSize = new ImageSize();        DisplayMetrics displayMetrics = imageView.getContext().getResources()                .getDisplayMetrics();        LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)imageView.getLayoutParams();        int width = imageView.getWidth();// 获取imageview的实际宽度        if (width <= 0)        {            width = lp.width;// 获取imageview在layout中声明的宽度        }        if (width <= 0)        {            width = displayMetrics.widthPixels;        }        int height = imageView.getHeight();// 获取imageview的实际高度        if (height <= 0)        {            height = lp.height;// 获取imageview在layout中声明的宽度        }        if (height <= 0)        {            height = displayMetrics.heightPixels;        }        imageSize.width = width;        imageSize.height = height;        return imageSize;    }    public static class ImageSize    {        int width;        int height;    }}

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