我正在将Uri传递给新活动并尝试使用它在新活动中创建imageView。我使用InputStream和BitmapFactory来实现这一点。不过，我的照片显示为黑色，我不知道为什么。
First_Page：
public void galleryClicked(View view){
Intent intent = new Intent(Intent.ACTION_PICK);
File pictureDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
String pictureDirectoryPath = pictureDirectory.getPath();
Uri data = Uri.parse(pictureDirectoryPath);
intent.setDataAndType(data, "image/*");
startActivityForResult(intent, GALLERY_REQUEST);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(resultCode == RESULT_OK ){
Intent intent = new Intent(this, Tattoo_Page.class);
intent.putExtra("picture", data.getData());
startActivity(intent);
}
}
Tattoo_Page：
public class Tattoo_Page extends Activity {
private ImageView picture;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tattoo_page);
Bundle extras = getIntent().getExtras();
picture = (ImageView) findViewById(R.id.picture);
Uri imageUri = (Uri) extras.get("picture");
try {
InputStream inputStream = getContentResolver().openInputStream(imageUri);
Bitmap image = BitmapFactory.decodeStream(inputStream);
picture.setImageBitmap(image);
} catch (FileNotFoundException e) {
e.printStackTrace();
Toast.makeText(this, "Unable to open image", Toast.LENGTH_LONG).show();
}
}
}
XML：
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/picture"
android:scaleType="fitCenter"/>
清单：
<?xml version="1.0" encoding="utf-8"?>
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-feature android:name="android.hardware.camera2" />
<uses-feature android:name="android.hardware.camera.any" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/Theme.AppCompat.NoActionBar"
android:screenOrientation="portrait">
<activity android:name=".First_Page">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Tattoo_Page"> </activity>
</application>
答案 0 :(得分：2)
您可以使用以下代码执行确切的任务：
public void galleryClicked(View v){
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), 0);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 0 && resultCode == getActivity().RESULT_OK) {
Uri selectedImageUri = data.getData();
String[] fileColumns = {MediaStore.Images.Media.DATA};
Cursor cursor = getActivity().getContentResolver().query(selectedImageUri, fileColumns, null, null, null);
cursor.moveToFirst();
int cIndex = cursor.getColumnIndex(fileColumns[0]);
String picturePath = cursor.getString(cIndex);
cursor.close();
if (picturePath != null) {
Intent intent = new Intent(this, Tattoo_Page.class);
intent.putExtra("picture", picturePath);
startActivity(intent);
}
}
}
Tatoo_Page活动
public class Tattoo_Page extends Activity {
public static int IMAGE_MAX_WIDTH=1024;
public static int IMAGE_MAX_HEIGHT=768;
private ImageView picture;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tattoo_page);
Bundle extras = getIntent().getExtras();
picture = (ImageView) findViewById(R.id.picture);
String imagePath = extras.getStringExtra("picture");
new Thread(new Runnable() {
@Override
public void run() {
try {
final Bitmap bitmap = decodeFile(new File(picturePath));
if (bitmap != null) {
Tatoo_Page.this.runOnUiThread(new Runnable() {
@Override
public void run() {
picture.setImageBitmap(bitmap);
}
});
}else{
Toast.makeText(Tatoo_page.this,"Error",Toast.LENGTH_SHORT).show();
}
}catch(Exception e){
e.printStackTrace();
Toast.makeText(ProfileFragment.this.getActivity(),"Problem loading file",Toast.LENGTH_SHORT).show();
}
}
}).start();
}
//This function will decode the file stream from path with appropriate size you need.
//Specify the max size in the class
private Bitmap decodeFile(File f) throws Exception{
Bitmap b = null;
//Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream fis = new FileInputStream(f);
BitmapFactory.decodeStream(fis, null, o);
fis.close();
int scale = 1;
int IMAGE_MAX_SIZE=Math.max(IMAGE_MAX_HEIGHT,IMAGE_MAX_WIDTH);
if (o.outHeight > IMAGE_MAX_HEIGHT || o.outWidth > IMAGE_MAX_WIDTH) {
scale = (int)Math.pow(2, (int) Math.ceil(Math.log(IMAGE_MAX_SIZE /
(double) Math.max(o.outHeight, o.outWidth)) / Math.log(0.5)));
}
//Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
fis = new FileInputStream(f);
b = BitmapFactory.decodeStream(fis, null, o2);
fis.close();
return b;
}
答案 1 :(得分：1)
您正在访问主线程中的图像。它非常不合适，因为它可能会降低您的应用速度，并可能会降低帧速率，直到内存加载完成。
有一个很棒的库，可以在子线程中抽象整个过程并将其应用到布局中。
输入Picasso。通过将compile 'com.squareup.picasso:picasso:2.5.2'添加到项目依赖项中，将它包含到项目中，然后只需编写这个简单的行来从Web下载图像：
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
在处理磁盘映像时，您可能需要使用此加载程序：
Picasso.with(context).load(new File(...)).into(imageView);
就是这样。你完成了。
作为奖励，Picasso自动处理Android上许多常见的图像加载陷阱::
ImageView回收和下载取消。此外，它非常快速和轻巧。比那里的几乎任何实现快得多（如果不是更快），整个jar文件只有118 kb。
<强> TL; DR：
使用Picasso。所有很酷的孩子都在这样做。