整理android调用系统相机的方法及遇到的问题

在项目中遇到需要调用系统相机的功能点，整理方法如下

1.拍照完成之后直接存图片

   Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);   intent.putExtra("crop", "true");// crop=true 有这句才能出来最后的裁剪页面.   intent.putExtra("aspectX", 5); // 这两项为裁剪框的比例.   intent.putExtra("aspectY", 4);      intent.putExtra("output", Uri.fromFile(new File("SDCard/1.jpg")));//输出地址   intent.putExtra("outputFormat", "JPEG");//返回格式    startActivityForResult(intent, REQUEST_CAMERA);

获取图片直接在onActivityForResult中

BitmapFactory.decodeFile(fileName, opts);

 

2.拍照完成后读取intent中的数据，在onActivityForResult中

Uri uri = data.getData();ContentResolver cr = this.getContentResolver();try {bitmap = BitmapFactory.decodeStream(cr.openInputStream(uri));} catch (FileNotFoundException e) {e.printStackTrace();}

但是这种方法在测试过程中，海信手机会报空指针异常，也许是相机处理机制的问题，我没有深究

3.最后一种是当前项目正用到的方法 目前在各种手机上使用正常

String sdStatus = Environment.getExternalStorageState();      if (!sdStatus.equals(Environment.MEDIA_MOUNTED)) { // 检测sd是否可用       LogUtils.i("TestFile",         "SD card is not avaiable/writeable right now.");       return;      }      String name = new DateFormat().format(        "yyyyMMdd_hhmmss",        Calendar.getInstance(Locale.CHINA))        + ".jpg";      Bundle bundle = data.getExtras();      Bitmap bitmap = (Bitmap) bundle.get("data");//      LogUtils.d(CommitCommentActivity.this,        bitmap == null ? "bitmap is null"          : "bitmap is not null");      FileOutputStream fos = null;      File file = new File(IMAGE_PATH);      file.mkdirs();// 创建文件夹      final String fileName = IMAGE_PATH + name;      LogUtils.i("fangdd", "Onresult path:" + fileName);      try {       fos = new FileOutputStream(fileName);       bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);// 把数据写入文件      } catch (FileNotFoundException e) {       e.printStackTrace();      } finally {       if (!bitmap.isRecycled()) {        bitmap.recycle();        System.gc();       }       try {        fos.flush();        fos.close();       } catch (IOException e) {        e.printStackTrace();       }      }

 这种方式是将图片资源取出之后存入文件，并不在activity中直接保存bitmap 仅在用到时加载 避免内存溢出

 

下面记录一下开发中遇到的问题，说道这里不得不吐槽一下三星的相机，调用之后系统会调用ondestroy导致activity被销毁重建，原因是系统调用了一次横竖屏切换，解决方法如下

方法一：刚开始调用了onSaveInstanceState(Bundle savedInstanceState)和onRestoreInstanceState(Bundle savedInstanceState)这个方法来实现，虽然方法比较笨，但是可以通过在onSaveInstanceState中保存一些你需要的变量，在onCreate()方法中判断savedInstanceState是否为null，不为null则调用onRestoreInstanceState（）方法取出之前存的变量来使用，这相当于重新加载了一边当前activity。

方法二：上面的方法可行，但并不是解决问题的根本办法，后来通过查看发现在调用相机时，activity从竖屏切换到了横屏，在横竖屏切换导致了activity重新装载，找到根本原因后，在activity中通过android:configChanges="orientation|keyboardHidden" 这个属性，可以约束调用相机时，保持当前activity竖屏状态不变，从而解决了activity重新加载的问题。

 

 另外关于图片压缩的代码也一并贴在这里以便以后查看

private Bitmap getDiskBitmap(String pathString) {Bitmap bitmap = null;Bitmap bMapRotate = null;try {File file = new File(pathString);if (file.exists()) {BitmapFactory.Options opt = new BitmapFactory.Options();opt.inPreferredConfig = Bitmap.Config.RGB_565;opt.inPurgeable = true;opt.inInputShareable = true;opt.inTempStorage = new byte[1024 * 1024 * 10];long length = file.length();LogUtils.d(this, "file.length() = " + length);if (length / (1024 * 1024) > 4) {opt.inSampleSize = 16;LogUtils.d(this, "opt.inSampleSize = 16;");} else if (length / (1024 * 1024) >= 1) {opt.inSampleSize = 8;LogUtils.d(this, "opt.inSampleSize = 8;");} else if (length / (1024 * 512) >= 1) {opt.inSampleSize = 4;LogUtils.d(this, "opt.inSampleSize = 4;");} else if (length / (1024 * 256) >= 1) {opt.inSampleSize = 2;LogUtils.d(this, "opt.inSampleSize = 2;");} else {opt.inSampleSize = 1;LogUtils.d(this, "opt.inSampleSize = 1;");}bitmap = BitmapFactory.decodeFile(pathString, opt);LogUtils.i("fangdd", "图片旋转度数：" + readPictureDegree(pathString));// ///////////// if(pathString.contains("floor/imgs")){// YLog.i("fangdd", "处理旋转:"+isGetImage);int orientation = readPictureDegree(pathString);/* * if(bitmap.getHeight() < bitmap.getWidth()){ orientation = 90; * } else { orientation = 0; } */if (orientation != 0) {Matrix matrix = new Matrix();matrix.postRotate(orientation);bMapRotate = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(),bitmap.getHeight(), matrix, true);} else {bMapRotate = Bitmap.createScaledBitmap(bitmap,bitmap.getWidth(), bitmap.getHeight(), true);}// }// //////////////}} catch (Exception e) {e.printStackTrace();}if (bMapRotate != null) {return bMapRotate;}return bitmap;}/** * 读取图片属性：旋转的角度 *  * @param path *            图片绝对路径 * @return degree旋转的角度 */public static int readPictureDegree(String path) {int degree = 0;try {ExifInterface exifInterface = new ExifInterface(path);int orientation = exifInterface.getAttributeInt(ExifInterface.TAG_ORIENTATION,ExifInterface.ORIENTATION_NORMAL);switch (orientation) {case ExifInterface.ORIENTATION_ROTATE_90:degree = 90;break;case ExifInterface.ORIENTATION_ROTATE_180:degree = 180;break;case ExifInterface.ORIENTATION_ROTATE_270:degree = 270;break;}} catch (IOException e) {e.printStackTrace();}return degree;}