Answers:
更新答案，将近5年后：
原始答案中的代码不再可靠运行，因为来自各种来源的图像有时会返回不同的内容URI，content://而不是file://。更好的解决方案是简单地使用context.getContentResolver().openInputStream(intent.getData())，因为这将返回一个InputStream，您可以根据自己的选择进行处理。
例如，BitmapFactory.decodeStream()在这种情况下可以很好地工作，因为您还可以使用“选项”和“ inSampleSize”字段对大图像进行降采样并避免内存问题。
但是，诸如Google云端硬盘之类的东西会将URI返回到尚未实际下载的图像。因此，您需要在后台线程上执行getContentResolver（）代码。
原始答案：
其他答案解释了如何发送意图，但没有很好地解释如何处理响应。以下是一些有关如何执行此操作的示例代码：
protected void onActivityResult(int requestCode, int resultCode,
Intent imageReturnedIntent) {
super.onActivityResult(requestCode, resultCode, imageReturnedIntent);
switch(requestCode) {
case REQ_CODE_PICK_IMAGE:
if(resultCode == RESULT_OK){
Uri selectedImage = imageReturnedIntent.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(
selectedImage, filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();
Bitmap yourSelectedImage = BitmapFactory.decodeFile(filePath);
}
}
}之后，您将选择的图像存储在“ yourSelectedImage”中，以进行所需的操作。这段代码通过获取图像在ContentResolver数据库中的位置来工作，但仅靠它是不够的。每个图像大约有18列信息，从文件路径到“最后修改日期”再到照片拍摄地的GPS坐标，尽管实际上并未使用许多字段。
为了节省时间，因为您实际上不需要其他字段，所以使用过滤器来进行光标搜索。筛选器的工作方式是指定所需的列名称MediaStore.Images.Media.DATA（即路径），然后将该string []赋予光标查询。游标查询返回路径，但是直到使用columnIndex代码，您才知道它位于哪一列。这只是根据其名称获取列号，该名称与过滤过程中使用的相同。一旦知道了这一点，您就可以使用我给出的最后一行代码将图像解码为位图。
private static final int SELECT_PHOTO = 100;开始意图
Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
photoPickerIntent.setType("image/*");
startActivityForResult(photoPickerIntent, SELECT_PHOTO); 处理结果
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) {
super.onActivityResult(requestCode, resultCode, imageReturnedIntent);
switch(requestCode) {
case SELECT_PHOTO:
if(resultCode == RESULT_OK){
Uri selectedImage = imageReturnedIntent.getData();
InputStream imageStream = getContentResolver().openInputStream(selectedImage);
Bitmap yourSelectedImage = BitmapFactory.decodeStream(imageStream);
}
}
}或者，您也可以降低图像的采样率，以避免OutOfMemory错误。
private Bitmap decodeUri(Uri selectedImage) throws FileNotFoundException {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(getContentResolver().openInputStream(selectedImage), null, o);
// The new size we want to scale to
final int REQUIRED_SIZE = 140;
// Find the correct scale value. It should be the power of 2.
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE) {
break;
}
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
return BitmapFactory.decodeStream(getContentResolver().openInputStream(selectedImage), null, o2);
}int scale = 1; for ( ; bfOptions.outWidth / scale > TARGET_SIZE && bfOptions.outWidth > TARGET_SIZE; scale*=2);
您必须启动图库意图才能获得结果。
Intent i = new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, ACTIVITY_SELECT_IMAGE); 然后在 onActivityForResult，调用intent.getData()获取图像的Uri。然后，您需要从ContentProvider获取图像。
这是一个经过测试的图像和视频代码，适用于所有小于19和大于19的API。
图片：
if (Build.VERSION.SDK_INT <= 19) {
Intent i = new Intent();
i.setType("image/*");
i.setAction(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(i, 10);
} else if (Build.VERSION.SDK_INT > 19) {
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, 10);
}视频：
if (Build.VERSION.SDK_INT <= 19) {
Intent i = new Intent();
i.setType("video/*");
i.setAction(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(i, 20);
} else if (Build.VERSION.SDK_INT > 19) {
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Video.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, 20);
} 。
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK) {
if (requestCode == 10) {
Uri selectedImageUri = data.getData();
String selectedImagePath = getRealPathFromURI(selectedImageUri);
} else if (requestCode == 20) {
Uri selectedVideoUri = data.getData();
String selectedVideoPath = getRealPathFromURI(selectedVideoUri);
}
}
}
public String getRealPathFromURI(Uri uri) {
if (uri == null) {
return null;
}
String[] projection = {MediaStore.Images.Media.DATA};
Cursor cursor = getActivity().getContentResolver().query(uri, projection, null, null, null);
if (cursor != null) {
int column_index = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}
return uri.getPath();
}这样做以启动图库并允许用户选择图像：
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/*");
startActivityForResult(intent, IMAGE_PICK);然后在您onActivityResult()使用返回的图像的URI来在ImageView上设置图像。
public class EMView extends Activity {
ImageView img,img1;
int column_index;
Intent intent=null;
// Declare our Views, so we can access them later
String logo,imagePath,Logo;
Cursor cursor;
//YOU CAN EDIT THIS TO WHATEVER YOU WANT
private static final int SELECT_PICTURE = 1;
String selectedImagePath;
//ADDED
String filemanagerstring;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
img= (ImageView)findViewById(R.id.gimg1);
((Button) findViewById(R.id.Button01))
.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// in onCreate or any event where your want the user to
// select a file
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent,
"Select Picture"), SELECT_PICTURE);
}
});
}
//UPDATED
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == Activity.RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
//OI FILE Manager
filemanagerstring = selectedImageUri.getPath();
//MEDIA GALLERY
selectedImagePath = getPath(selectedImageUri);
img.setImageURI(selectedImageUri);
imagePath.getBytes();
TextView txt = (TextView)findViewById(R.id.title);
txt.setText(imagePath.toString());
Bitmap bm = BitmapFactory.decodeFile(imagePath);
// img1.setImageBitmap(bm);
}
}
}
//UPDATED!
public String getPath(Uri uri) {
String[] projection = { MediaColumns.DATA };
Cursor cursor = managedQuery(uri, projection, null, null, null);
column_index = cursor
.getColumnIndexOrThrow(MediaColumns.DATA);
cursor.moveToFirst();
imagePath = cursor.getString(column_index);
return cursor.getString(column_index);
}
}public class BrowsePictureActivity extends Activity {
private static final int SELECT_PICTURE = 1;
private String selectedImagePath;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
((Button) findViewById(R.id.Button01))
.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent,
"Select Picture"), SELECT_PICTURE);
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
selectedImagePath = getPath(selectedImageUri);
}
}
}
public String getPath(Uri uri) {
if( uri == null ) {
return null;
}
// this will only work for images selected from gallery
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = managedQuery(uri, projection, null, null, null);
if( cursor != null ){
int column_index = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}
return uri.getPath();
}
}由于某些原因，该线程中的所有答案都将onActivityResult()尝试对接收到的内容进行后处理Uri，例如获取图像的真实路径，然后使用BitmapFactory.decodeFile(path)来获取Bitmap。
此步骤是不必要的。该ImageView班有一个叫方法setImageURI(uri)。将您的uri传递给它，您应该已完成。
Uri imageUri = data.getData();
imageView.setImageURI(imageUri);对于完整的工作示例，您可以在此处查看：http : //androidbitmaps.blogspot.com/2015/04/loading-images-in-android-part-iii-pick.html
PS：如果要加载的图像太大而无法容纳在内存中，则必须
使用Bitmap单独的变量OurOfMemoryError，如@siamii答案所示，必须进行缩小操作以防止出现这种情况。
像这样调用chooseImage方法
public void chooseImage(ImageView v)
{
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*");
startActivityForResult(intent, SELECT_PHOTO);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, imageReturnedIntent);
if(imageReturnedIntent != null)
{
Uri selectedImage = imageReturnedIntent.getData();
switch(requestCode) {
case SELECT_PHOTO:
if(resultCode == RESULT_OK)
{
Bitmap datifoto = null;
temp.setImageBitmap(null);
Uri picUri = null;
picUri = imageReturnedIntent.getData();//<- get Uri here from data intent
if(picUri !=null){
try {
datifoto = android.provider.MediaStore.Images.Media.getBitmap(this.getContentResolver(), picUri);
temp.setImageBitmap(datifoto);
} catch (FileNotFoundException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
} catch (OutOfMemoryError e) {
Toast.makeText(getBaseContext(), "Image is too large. choose other", Toast.LENGTH_LONG).show();
}
}
}
break;
}
}
else
{
//Toast.makeText(getBaseContext(), "data null", Toast.LENGTH_SHORT).show();
}
}#initialize in main activity
path = Environment.getExternalStorageDirectory()
+ "/images/make_machine_example.jpg"; #
ImageView image=(ImageView)findViewById(R.id.image);
//--------------------------------------------------||
public void FromCamera(View) {
Log.i("camera", "startCameraActivity()");
File file = new File(path);
Uri outputFileUri = Uri.fromFile(file);
Intent intent = new Intent(
android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
startActivityForResult(intent, 1);
}
public void FromCard() {
Intent i = new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, 2);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 2 && resultCode == RESULT_OK
&& null != data) {
Uri selectedImage = data.getData();
String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(selectedImage,
filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String picturePath = cursor.getString(columnIndex);
cursor.close();
bitmap = BitmapFactory.decodeFile(picturePath);
image.setImageBitmap(bitmap);
if (bitmap != null) {
ImageView rotate = (ImageView) findViewById(R.id.rotate);
}
} else {
Log.i("SonaSys", "resultCode: " + resultCode);
switch (resultCode) {
case 0:
Log.i("SonaSys", "User cancelled");
break;
case -1:
onPhotoTaken();
break;
}
}
}
protected void onPhotoTaken() {
// Log message
Log.i("SonaSys", "onPhotoTaken");
taken = true;
imgCapFlag = true;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4;
bitmap = BitmapFactory.decodeFile(path, options);
image.setImageBitmap(bitmap);
}