Android content provider example

Joined:
07/27/2010: Posts:
128

May 17, 2011 11:13:17 Last update: May 17, 2011 11:13:17

This is an odd-ball content provider in that it doesn't provide database records, but provides a resource as a stream. It can be used to provide media files or XML resources.

Start the project with:

tools/android create project --package com.android.cptest \
--activity Dummy --target 2 --path ContentProvider

Create assets directory and add an XML file (assets/demo.xml):

<? xml version="1.0" encoding="UTF-8"?>
<people>
    <person id="1">
	<first-name>Jack</first-name>
	<last-name>Smith</last-name>
    </person>

    <person id="2">
	<first-name>Steve</first-name>
	<last-name>Jones</last-name>
    </person>
</people>

Edit the layout (res/layout/main.xml):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/content"
    />
</LinearLayout>

Edit src/com/android/cptest/Dummy.java:

package com.android.cptest;

import java.io.*;

import android.app.Activity;
import android.content.ContentResolver;
import android.os.Bundle;
import android.net.Uri;
import android.util.Log;
import android.widget.TextView;

public class Dummy extends Activity
{
    private static final String TAG = "Dummy";

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
	try {
	    ContentResolver r = getContentResolver();
	    InputStream in = r.openInputStream(Uri.parse("content://com.android.cptest.XmlResource"));
	    ByteArrayOutputStream out = new ByteArrayOutputStream();
	    byte[] buffer = new byte[4096];
	    int n = in.read(buffer);
	    while (n >= 0) {
		out.write(buffer, 0, n);
		n = in.read(buffer);
	    }
	    in.close();

	    TextView content = (TextView) findViewById(R.id.content);
	    content.setText(out.toString());
	}
	catch (Exception e) {
	    e.printStackTrace();
	    Log.e(TAG, "ERROR: " + e);
	}
    }
}

Add content provider (src/com/android/cptest/XmlResource.java):

package com.android.cptest;

import java.io.*;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.net.Uri;
import android.util.Log;

public class XmlResource extends ContentProvider {
    private static final String TAG = "XmlResource";

    @Override
    public boolean onCreate() {
	return true;
    }

    @Override
    public String getType(Uri uri) {
	return null;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
	return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
	return null;
    }

    @Override
    public int delete(Uri uri, String selection, String[] aelectionArgs) {
	return 0;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
	return 0;
    }

    @Override
    public AssetFileDescriptor openAssetFile(Uri uri, String mode) throws FileNotFoundException {
	Log.d(TAG, "Uri: " + uri);
	Log.d(TAG, "mode: " + mode);
	try {
	    return getContext().getAssets().openFd("demo.xml");
	}
	catch (IOException e) {
	    e.printStackTrace();
	    Log.e(TAG, "ERROR: " + e);
	    throw new FileNotFoundException(e.getMessage());
	}
    }
}

Update AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.android.cptest"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:label="@string/app_name" android:icon="@drawable/icon">
        <activity android:name="Dummy"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

	<provider android:name="XmlResource"
		  android:authorities="com.android.cptest.XmlResource"/>
    </application>
</manifest>

Add this section to the end of build.xml:

<target name="-package-resources">
    <echo>Packaging resources!!!</echo>
    <aapt executable="${aapt}"
	command="package"
	versioncode="${version.code}"
	debug="${build.packaging.debug}"
	manifest="AndroidManifest.xml"
	assets="${asset.absolute.dir}"
	androidjar="${android.jar}"
	apkfolder="${out.absolute.dir}"
	resourcefilename="${resource.package.file.name}"
	resourcefilter="${aapt.resource.filter}">
	<res path="${resource.absolute.dir}" />
	<nocompress extension="xml" /> 
    </aapt>
</target>

Build and install:
```
ant install
```
Screenshot:

Remove the Dummy activity (AndroidManifest.xml):

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.android.cptest"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:label="@string/app_name" android:icon="@drawable/icon">
	<provider android:name="XmlResource"
		  android:authorities="com.android.cptest.XmlResource"/>
    </application>
</manifest>

Create a new project for the content consumer:

tools/android create project --package com.android.cctest \
--activity ContentConsumer --target 2 --path ContentConsumer

Copy the layout from the previous project:

cp ../ContentProvider/res/layout/main.xml res/layout/main.xml

Copy the Activity code from the previous project (src/com/android/cctest/ContentConsumer.java):

package com.android.cctest;

import java.io.*;

import android.app.Activity;
import android.content.ContentResolver;
import android.os.Bundle;
import android.net.Uri;
import android.util.Log;
import android.widget.TextView;

public class ContentConsumer extends Activity
{
    private static final String TAG = "ContentConsumer";

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
	try {
	    ContentResolver r = getContentResolver();
	    InputStream in = r.openInputStream(Uri.parse("content://com.android.cptest.XmlResource"));
	    ByteArrayOutputStream out = new ByteArrayOutputStream();
	    byte[] buffer = new byte[4096];
	    int n = in.read(buffer);
	    while (n >= 0) {
		out.write(buffer, 0, n);
		n = in.read(buffer);
	    }
	    in.close();

	    TextView content = (TextView) findViewById(R.id.content);
	    content.setText(out.toString());
	}
	catch (Exception e) {
	    e.printStackTrace();
	    Log.e(TAG, "ERROR: " + e);
	}
    }
}

Install ContentConsumer:
```
ant install
```
Now we have a content consumer in a separate APK from the content provider.

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