拍照后直接使用 BitmapFactory.decodeStream(...) 进行创建 Bitmap 并显示是有问题的。

Bitmap 是个简单对象，它只存储实际像素数据，也就是说，即使原始照片已压缩过，但存入 Bitmap 对象时，文件并不会同样压缩，导致图片无法显示，所以需要进行缩放位图。

缩放位图代码如下：

PictureUtils.java

package club.seliote.camerademo; import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Point;import android.net.Uri; import java.io.File; public class PictureUtils { public static Bitmap getScaledBitmap(Uri uri, int destWidth, int destHeight) { // read in the dimensions of the image on disk BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory.decodeFile(uri.getPath(), options); float srcWidth = options.outWidth; float srcHeight = options.outHeight; // figure out how much to scale down by int inSampleSize = 1; if (srcWidth > destHeight || srcHeight > destHeight) { inSampleSize = Math.round((srcWidth / destWidth) > (srcHeight / destHeight) ? (srcWidth / destWidth) : (srcHeight / destHeight)); } // create a bitmap options = new BitmapFactory.Options(); options.inSampleSize = inSampleSize; return BitmapFactory.decodeFile(uri.getPath(), options); } public static Bitmap getScaledBitmap(Uri uri, Activity activity) { Point point = new Point(); activity.getWindowManager().getDefaultDisplay().getSize(point); return PictureUtils.getScaledBitmap(uri, point.x, point.y); } }

拍照并显示的代码:

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="club.seliote.camerademo"> <uses-permission android:name="android.permission.CAMERA"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <provider android:name="android.support.v4.content.FileProvider" android:authorities="club.seliote.camerademo.fileprovider" android:exported="false" android:grantUriPermissions="true"> <meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/file_paths"/> </provider> </application> </manifest>

activity_main.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"> <Button android:id="@+id/take_photo_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Take a photo" android:layout_gravity="center_horizontal" android:textAllCaps="false"/> <Button android:id="@+id/choose_from_album_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Choose from album" android:layout_gravity="center_horizontal" android:textAllCaps="false"/> <ImageView android:id="@+id/picture_image_view" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal"/> </LinearLayout>

xml/file_paths.xml

<?xml version="1.0" encoding="utf-8"?><paths xmlns:android="http://schemas.android.com/apk/res/android" > <external-path name="images" path="." /></paths>

MainActivity.java

package club.seliote.camerademo; import android.Manifest;import android.annotation.TargetApi;import android.app.Activity;import android.content.ContentUris;import android.content.Intent;import android.content.pm.PackageManager;import android.database.Cursor;import android.net.Uri;import android.os.Build;import android.provider.DocumentsContract;import android.provider.MediaStore;import android.support.annotation.NonNull;import android.support.annotation.Nullable;import android.support.v4.app.ActivityCompat;import android.support.v4.content.ContextCompat;import android.support.v4.content.FileProvider;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.ImageView;import android.widget.Toast; import java.io.File;import java.io.IOException; public class MainActivity extends AppCompatActivity { private static final int CAMERA_INTENT_REQUEST_CODE = 0; private static final int ALBUM_INTENT_REQUEST_CODE = 1; private static final int WRITE_EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE = 0; private String mPictureName; private Uri mPictureUri; private Button mTakePhotoButton; private Button mChooseFromAlbum; private ImageView mImageView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.activity_main); mTakePhotoButton = this.findViewById(R.id.take_photo_button); mChooseFromAlbum = this.findViewById(R.id.choose_from_album_button); mImageView = this.findViewById(R.id.picture_image_view); mTakePhotoButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { MainActivity.this.takePhoto(); } }); mChooseFromAlbum.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) { ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, MainActivity.WRITE_EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE); } else { MainActivity.this.openAlbum(); } } }); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); switch (requestCode) { case MainActivity.CAMERA_INTENT_REQUEST_CODE : if (resultCode == Activity.RESULT_OK) { /*try { // Bitmap is too big to display in screen Bitmap bitmap = BitmapFactory.decodeStream(this.getContentResolver().openInputStream(mPictureUri)); mImageView.setImageBitmap(bitmap); } catch (FileNotFoundException exp) { exp.printStackTrace(); }*/ mImageView.setImageBitmap(PictureUtils.getScaledBitmap(mPictureUri, this)); } break; case MainActivity.ALBUM_INTENT_REQUEST_CODE : if (resultCode == Activity.RESULT_OK) { this.handlePictureFromAlbum(data); } break; default : break; } } @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { super.onRequestPermissionsResult(requestCode, permissions, grantResults); switch (requestCode) { case MainActivity.WRITE_EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE : if (permissions.length > 0 && permissions[0] == Manifest.permission.WRITE_EXTERNAL_STORAGE && grantResults[0] == PackageManager.PERMISSION_GRANTED) { this.openAlbum(); } else { Toast.makeText(this, "Permisson deny!", Toast.LENGTH_LONG).show(); } } } private void takePhoto() { // create file File file = new File(this.getExternalCacheDir(), mPictureName = (System.currentTimeMillis() + ".jpg")); try { if (file.exists()) { file.delete(); } file.createNewFile(); } catch (IOException exp) { exp.printStackTrace(); } // wrap File to Uri if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { // if version more then API 24, not use true path mPictureUri = FileProvider.getUriForFile(this, "club.seliote.camerademo.fileprovider", file); } else { mPictureUri = Uri.fromFile(file); } // start camera activity Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT, mPictureUri); startActivityForResult(intent, MainActivity.CAMERA_INTENT_REQUEST_CODE); } private void openAlbum() { Intent intent = new Intent(Intent.ACTION_GET_CONTENT); intent.setType("image/*"); startActivityForResult(intent, MainActivity.ALBUM_INTENT_REQUEST_CODE); } // only for Android KitKat(4.4) or later @TargetApi(19) private void handlePictureFromAlbum(Intent intent) { String imagePath = null; Uri uri = intent.getData(); if (DocumentsContract.isDocumentUri(this, uri)) { String docId = DocumentsContract.getDocumentId(uri); if ("com.android.providers.media.media.documents".equalsIgnoreCase(uri.getAuthority())) { String id = docId.split(":")[1]; String selection = MediaStore.Images.Media.EXTERNAL_CONTENT_URI + "=" + id; imagePath = this.getPathFormUri(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection); } else if ("com.android.providers.downloads.documents".equalsIgnoreCase(uri.getAuthority())) { Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(docId)); imagePath = getPathFormUri(contentUri, null); } } else if ("content".equalsIgnoreCase(uri.getScheme())) { imagePath = this.getPathFormUri(uri, null); } else if ("file".equalsIgnoreCase(uri.getScheme())) { imagePath = uri.getPath(); } if (imagePath != null) { mImageView.setImageBitmap(PictureUtils.getScaledBitmap(Uri.fromFile(new File(imagePath)), this)); } else { Toast.makeText(this, "Filed to get image", Toast.LENGTH_LONG).show(); } } @Nullable // use uri get picture true path private String getPathFormUri(Uri uri, String selection) { String path = null; Cursor cursor = this.getContentResolver().query(uri, null, selection, null, null); if (cursor != null && cursor.moveToFirst()) { path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA)); cursor.close(); } return path; }}