调用摄像头和相册（调用摄像头拍照和从相册中选择图片）

public class MainActivity extends Activity {public static final int TAKE_PHOTO=1;public static final int CROP_PHOTO=0;public static final int CHOOSE_PHOTO=3;private ImageView picture;private Button chooseFromAlbum;private Button takePhoto;private Uri imageUri;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);takePhoto=(Button)findViewById(R.id.take_photo);chooseFromAlbum=(Button)findViewById(R.id.choose_from_ablum);picture=(ImageView)findViewById(R.id.picture);takePhoto.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {File outputImage=new File(Environment.getExternalStorageDirectory(), "output_image.jpg");try {if(outputImage.exists()){outputImage.delete();}outputImage.createNewFile();} catch (Exception e) {e.printStackTrace();}imageUri=Uri.fromFile(outputImage);Intent intent=new Intent("android.media.action.IMAGE_CAPTURE");intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);startActivityForResult(intent,TAKE_PHOTO);}});chooseFromAlbum.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {Intent intent=new Intent("android.intent.action.GET_CONTENT");intent.setType("image/*");startActivityForResult(intent, CHOOSE_PHOTO);}});} @Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {switch (requestCode) {case TAKE_PHOTO:if(resultCode==RESULT_OK){Intent intent=new Intent("com.android.camera.action.CROP");intent.setDataAndType(imageUri, "image/*");//intent.putExtra("scale", true);intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);startActivityForResult(intent, CROP_PHOTO);}break;case CROP_PHOTO:if(resultCode==RESULT_OK){try {Bitmap bitmap=BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));picture.setImageBitmap(bitmap);} catch (Exception e) {e.printStackTrace();}}case CHOOSE_PHOTO:if(resultCode==RESULT_OK){//判断手机系统版本号if(Build.VERSION.SDK_INT>=19){//4.4及以上系统使用这个方法处理图片handleImageOnkitKat(data);}else{handleImageBeforekitKat(data);//4.4及以下系统使用这个方法处理图片}}default:break;}super.onActivityResult(requestCode, resultCode, data);}//API 19以下private void handleImageBeforekitKat(Intent data) {}   //API 19private void handleImageOnkitKat(Intent data) {String imagePath=null;Uri uri=data.getData();if(DocumentsContract.isDocumentUri(MainActivity.this, uri)){String docId=DocumentsContract.getDocumentId(uri);if("com.android.providers.media.documents".equals(uri.getAuthority())){String id=docId.split(":")[1];String selection=MediaStore.Images.Media._ID+"="+id;imagePath=getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,selection);}else if("com.android.providers.downloads.documents".equals(uri.getAuthority())){Uri contentUri=ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),Long.valueOf(docId));imagePath=getImagePath(contentUri,null);}}else if("content".equalsIgnoreCase(uri.getScheme())){imagePath=getImagePath(uri, null);}displayImage(imagePath);}private void displayImage(String imagePath) {if(imagePath!=null){Bitmap bitmap=BitmapFactory.decodeFile(imagePath);picture.setImageBitmap(bitmap);}else{Toast.makeText(this, "failed to get image", Toast.LENGTH_SHORT).show();}}private String getImagePath(Uri uri, String selection) {String path=null;Cursor cursor=getContentResolver().query(uri, null, selection, null, null);if(cursor!=null){if(cursor.moveToFirst()){path=cursor.getString(cursor.getColumnIndex(Media.DATA));}cursor.close();}return path;}