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Thursday, 1 August 2013

Convert between Uri and file path, and load Bitmap from.

12:30
What return from Android build-in Gallery App is Uri, in the form of "content://media/...". This exercise demonstrate how to convert the Uri to real file path, in the form of "/storage/sdcard0/...". and convert back to Uri, in the form of "file:///storage/sdcard0/...".  All the three form refer to the same file.

And also demonstrate how to load bitmap from the Uri(s) and file path, then display in ImageView.

Convert between Uri and file path, and load Bitmap from.


package com.example.androiduri;

import java.io.File;
import java.io.FileNotFoundException;

import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.provider.MediaStore.Images;
import android.support.v4.content.CursorLoader;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class MainActivity extends Activity {

Button btnSelFile;
TextView text1, text2, text3, note;
ImageView image;

Uri orgUri, uriFromPath;
String convertedPath;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnSelFile = (Button)findViewById(R.id.selfile);
text1 = (TextView)findViewById(R.id.text1);
text2 = (TextView)findViewById(R.id.text2);
text3 = (TextView)findViewById(R.id.text3);
note = (TextView)findViewById(R.id.note);
image = (ImageView)findViewById(R.id.image);

btnSelFile.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View arg0) {
Intent intent = new Intent(Intent.ACTION_PICK,
Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, 0);
}});

text1.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
image.setImageBitmap(null);
note.setText("by Returned Uri");

try {
Bitmap bm = BitmapFactory.decodeStream(
getContentResolver().openInputStream(orgUri));
image.setImageBitmap(bm);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}});

text2.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
image.setImageBitmap(null);
note.setText("by Real Path");
Bitmap bm = BitmapFactory.decodeFile(convertedPath);
image.setImageBitmap(bm);
}});

text3.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
image.setImageBitmap(null);
note.setText("by Back Uri");

try {
Bitmap bm = BitmapFactory.decodeStream(
getContentResolver().openInputStream(uriFromPath));
image.setImageBitmap(bm);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);

if(resultCode == RESULT_OK){

image.setImageBitmap(null);

//Uri return from external activity
orgUri = data.getData();
text1.setText("Returned Uri: " + orgUri.toString() + "\n");

//path converted from Uri
convertedPath = getRealPathFromURI(orgUri);
text2.setText("Real Path: " + convertedPath + "\n");

//Uri convert back again from path
uriFromPath = Uri.fromFile(new File(convertedPath));
text3.setText("Back Uri: " + uriFromPath.toString() + "\n");
}

}

public String getRealPathFromURI(Uri contentUri) {
String[] proj = { MediaStore.Images.Media.DATA };

//This method was deprecated in API level 11
//Cursor cursor = managedQuery(contentUri, proj, null, null, null);

CursorLoader cursorLoader = new CursorLoader(
this,
contentUri, proj, null, null, null);
Cursor cursor = cursorLoader.loadInBackground();

int column_index =
cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}

}


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context=".MainActivity" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="android-er.blogspot.com" />
<Button
android:id="@+id/selfile"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Select File" />
<TextView
android:id="@+id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/text2"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/text3"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/note"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<ImageView
android:id="@+id/image"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</LinearLayout>


Please notice that the code haven't handle resize on the bitmap. If you load with a large picture, OutOfMemoryError will be caused.

download filesDownload the files.

Related: Load picture with Intent.ACTION_GET_CONTENT

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