XmlDocumentProvider moved to the XmlAdapter sample code (171c60e8) · Commits · e / os / android_frameworks_base

core/java/android/content/XmlDocumentProvider.java

deleted100644 → 0

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		/*
		* Copyright (C) 2010 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package android.content;

		import org.apache.http.HttpEntity;
		import org.apache.http.HttpResponse;
		import org.apache.http.HttpStatus;
		import org.apache.http.client.methods.HttpGet;
		import org.xmlpull.v1.XmlPullParser;
		import org.xmlpull.v1.XmlPullParserException;
		import org.xmlpull.v1.XmlPullParserFactory;

		import android.content.ContentResolver.OpenResourceIdResult;
		import android.database.Cursor;
		import android.database.MatrixCursor;
		import android.net.Uri;
		import android.net.http.AndroidHttpClient;
		import android.util.Log;
		import android.widget.CursorAdapter;

		import java.io.FileNotFoundException;
		import java.io.IOException;
		import java.io.InputStream;
		import java.util.BitSet;
		import java.util.Stack;
		import java.util.regex.Pattern;

		/**
		* @hide -- not yet ready to support, should be provided just as a static lib.
		*
		* A read-only content provider which extracts data out of an XML document.
		*
		* <p>A XPath-like selection pattern is used to select some nodes in the XML document. Each such
		* node will create a row in the {@link Cursor} result.</p>
		*
		* Each row is then populated with columns that are also defined as XPath-like projections. These
		* projections fetch attributes values or text in the matching row node or its children.
		*
		* <p>To add this provider in your application, you should add its declaration to your application
		* manifest:
		* <pre class="prettyprint">
		* <provider android:name="android.content.XmlDocumentProvider" android:authorities="xmldocument" />
		* </pre>
		* </p>
		*
		* <h2>Node selection syntax</h2>
		* The node selection syntax is made of the concatenation of an arbitrary number (at least one) of
		* <code>/node_name</code> node selection patterns.
		*
		* <p>The <code>/root/child1/child2</code> pattern will for instance match all nodes named
		* <code>child2</code> which are children of a node named <code>child1</code> which are themselves
		* children of a root node named <code>root</code>.</p>
		*
		* Any <code>/</code> separator in the previous expression can be replaced by a <code>//</code>
		* separator instead, which indicated a <i>descendant</i> instead of a child.
		*
		* <p>The <code>//node1//node2</code> pattern will for instance match all nodes named
		* <code>node2</code> which are descendant of a node named <code>node1</code> located anywhere in
		* the document hierarchy.</p>
		*
		* Node names can contain namespaces in the form <code>namespace:node</code>.
		*
		* <h2>Projection syntax</h2>
		* For every selected node, the projection will then extract actual data from this node and its
		* descendant.
		*
		* <p>Use a syntax similar to the selection syntax described above to select the text associated
		* with a child of the selected node. The implicit root of this projection pattern is the selected
		* node. <code>/</code> will hence refer to the text of the selected node, while
		* <code>/child1</code> will fetch the text of its child named <code>child1</code> and
		* <code>//child1</code> will match any <i>descendant</i> named <code>child1</code>. If several
		* nodes match the projection pattern, their texts are appended as a result.</p>
		*
		* A projection can also fetch any node attribute by appending a <code>@attribute_name</code>
		* pattern to the previously described syntax. <code>//child1@price</code> will for instance match
		* the attribute <code>price</code> of any <code>child1</code> descendant.
		*
		* <p>If a projection does not match any node/attribute, its associated value will be an empty
		* string.</p>
		*
		* <h2>Example</h2>
		* Using the following XML document:
		* <pre class="prettyprint">
		* <library>
		* <book id="EH94">
		* <title>The Old Man and the Sea</title>
		* <author>Ernest Hemingway</author>
		* </book>
		* <book id="XX10">
		* <title>The Arabian Nights: Tales of 1,001 Nights</title>
		* </book>
		* <no-id>
		* <book>
		* <title>Animal Farm</title>
		* <author>George Orwell</author>
		* </book>
		* </no-id>
		* </library>
		* </pre>
		* A selection pattern of <code>/library//book</code> will match the three book entries (while
		* <code>/library/book</code> will only match the first two ones).
		*
		* <p>Defining the projections as <code>/title</code>, <code>/author</code> and <code>@id</code>
		* will retrieve the associated data. Note that the author of the second book as well as the id of
		* the third are empty strings.
		*/
		public class XmlDocumentProvider extends ContentProvider {
		/*
		* Ideas for improvement:
		* - Expand XPath-like syntax to allow for [nb] child number selector
		* - Address the starting . bug in AbstractCursor which prevents a true XPath syntax.
		* - Provide an alternative to concatenation when several node match (list-like).
		* - Support namespaces in attribute names.
		* - Incremental Cursor creation, pagination
		*/
		private static final String LOG_TAG = "XmlDocumentProvider";
		private AndroidHttpClient mHttpClient;

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

		/**
		* Query data from the XML document referenced in the URI.
		*
		* <p>The XML document can be a local resource or a file that will be downloaded from the
		* Internet. In the latter case, your application needs to request the INTERNET permission in
		* its manifest.</p>
		*
		* The URI will be of the form <code>content://xmldocument/?resource=R.xml.myFile</code> for a
		* local resource. <code>xmldocument</code> should match the authority declared for this
		* provider in your manifest. Internet documents are referenced using
		* <code>content://xmldocument/?url=</code> followed by an encoded version of the URL of your
		* document (see {@link Uri#encode(String)}).
		*
		* <p>The number of columns of the resulting Cursor is equal to the size of the projection
		* array plus one, named <code>_id</code> which will contain a unique row id (allowing the
		* Cursor to be used with a {@link CursorAdapter}). The other columns' names are the projection
		* patterns.</p>
		*
		* @param uri The URI of your local resource or Internet document.
		* @param projection A set of patterns that will be used to extract data from each selected
		* node. See class documentation for pattern syntax.
		* @param selection A selection pattern which will select the nodes that will create the
		* Cursor's rows. See class documentation for pattern syntax.
		* @param selectionArgs This parameter is ignored.
		* @param sortOrder The row order in the resulting cursor is determined from the node order in
		* the XML document. This parameter is ignored.
		* @return A Cursor or null in case of error.
		*/
		@Override
		public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
		String sortOrder) {

		XmlPullParser parser = null;
		mHttpClient = null;

		final String url = uri.getQueryParameter("url");
		if (url != null) {
		parser = getUriXmlPullParser(url);
		} else {
		final String resource = uri.getQueryParameter("resource");
		if (resource != null) {
		Uri resourceUri = Uri.parse(ContentResolver.SCHEME_ANDROID_RESOURCE + "://" +
		getContext().getPackageName() + "/" + resource);
		parser = getResourceXmlPullParser(resourceUri);
		}
		}

		if (parser != null) {
		XMLCursor xmlCursor = new XMLCursor(selection, projection);
		try {
		xmlCursor.parseWith(parser);
		return xmlCursor;
		} catch (IOException e) {
		Log.w(LOG_TAG, "I/O error while parsing XML " + uri, e);
		} catch (XmlPullParserException e) {
		Log.w(LOG_TAG, "Error while parsing XML " + uri, e);
		} finally {
		if (mHttpClient != null) {
		mHttpClient.close();
		}
		}
		}

		return null;
		}

		/**
		* Creates an XmlPullParser for the provided URL. Can be overloaded to provide your own parser.
		* @param url The URL of the XML document that is to be parsed.
		* @return An XmlPullParser on this document.
		*/
		protected XmlPullParser getUriXmlPullParser(String url) {
		XmlPullParser parser = null;
		try {
		XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
		factory.setNamespaceAware(true);
		parser = factory.newPullParser();
		} catch (XmlPullParserException e) {
		Log.e(LOG_TAG, "Unable to create XmlPullParser", e);
		return null;
		}

		InputStream inputStream = null;
		try {
		final HttpGet get = new HttpGet(url);
		mHttpClient = AndroidHttpClient.newInstance("Android");
		HttpResponse response = mHttpClient.execute(get);
		if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
		final HttpEntity entity = response.getEntity();
		if (entity != null) {
		inputStream = entity.getContent();
		}
		}
		} catch (IOException e) {
		Log.w(LOG_TAG, "Error while retrieving XML file " + url, e);
		return null;
		}

		try {
		parser.setInput(inputStream, null);
		} catch (XmlPullParserException e) {
		Log.w(LOG_TAG, "Error while reading XML file from " + url, e);
		return null;
		}

		return parser;
		}

		/**
		* Creates an XmlPullParser for the provided local resource. Can be overloaded to provide your
		* own parser.
		* @param resourceUri A fully qualified resource name referencing a local XML resource.
		* @return An XmlPullParser on this resource.
		*/
		protected XmlPullParser getResourceXmlPullParser(Uri resourceUri) {
		OpenResourceIdResult resourceId;
		try {
		resourceId = getContext().getContentResolver().getResourceId(resourceUri);
		return resourceId.r.getXml(resourceId.id);
		} catch (FileNotFoundException e) {
		Log.w(LOG_TAG, "XML resource not found: " + resourceUri.toString(), e);
		return null;
		}
		}

		/**
		* Returns "vnd.android.cursor.dir/xmldoc".
		*/
		@Override
		public String getType(Uri uri) {
		return "vnd.android.cursor.dir/xmldoc";
		}

		/**
		* This ContentProvider is read-only. This method throws an UnsupportedOperationException.
		**/
		@Override
		public Uri insert(Uri uri, ContentValues values) {
		throw new UnsupportedOperationException();
		}

		/**
		* This ContentProvider is read-only. This method throws an UnsupportedOperationException.
		**/
		@Override
		public int delete(Uri uri, String selection, String[] selectionArgs) {
		throw new UnsupportedOperationException();
		}

		/**
		* This ContentProvider is read-only. This method throws an UnsupportedOperationException.
		**/
		@Override
		public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
		throw new UnsupportedOperationException();
		}

		private static class XMLCursor extends MatrixCursor {
		private final Pattern mSelectionPattern;
		private Pattern[] mProjectionPatterns;
		private String[] mAttributeNames;
		private String[] mCurrentValues;
		private BitSet[] mActiveTextDepthMask;
		private final int mNumberOfProjections;

		public XMLCursor(String selection, String[] projections) {
		super(projections);
		// The first column in projections is used for the _ID
		mNumberOfProjections = projections.length - 1;
		mSelectionPattern = createPattern(selection);
		createProjectionPattern(projections);
		}

		private Pattern createPattern(String input) {
		String pattern = input.replaceAll("//", "/(.*/\|)").replaceAll("^/", "^/") + "$";
		return Pattern.compile(pattern);
		}

		private void createProjectionPattern(String[] projections) {
		mProjectionPatterns = new Pattern[mNumberOfProjections];
		mAttributeNames = new String[mNumberOfProjections];
		mActiveTextDepthMask = new BitSet[mNumberOfProjections];
		// Add a column to store _ID
		mCurrentValues = new String[mNumberOfProjections + 1];

		for (int i=0; i<mNumberOfProjections; i++) {
		mActiveTextDepthMask[i] = new BitSet();
		String projection = projections[i + 1]; // +1 to skip the _ID column
		int atIndex = projection.lastIndexOf('@', projection.length());
		if (atIndex >= 0) {
		mAttributeNames[i] = projection.substring(atIndex+1);
		projection = projection.substring(0, atIndex);
		} else {
		mAttributeNames[i] = null;
		}

		// Conforms to XPath standard: reference to local context starts with a .
		if (projection.charAt(0) == '.') {
		projection = projection.substring(1);
		}
		mProjectionPatterns[i] = createPattern(projection);
		}
		}

		public void parseWith(XmlPullParser parser) throws IOException, XmlPullParserException {
		StringBuilder path = new StringBuilder();
		Stack<Integer> pathLengthStack = new Stack<Integer>();

		// There are two parsing mode: in root mode, rootPath is updated and nodes matching
		// selectionPattern are searched for and currentNodeDepth is negative.
		// When a node matching selectionPattern is found, currentNodeDepth is set to 0 and
		// updated as children are parsed and projectionPatterns are searched in nodePath.
		int currentNodeDepth = -1;

		// Index where local selected node path starts from in path
		int currentNodePathStartIndex = 0;

		int eventType = parser.getEventType();
		while (eventType != XmlPullParser.END_DOCUMENT) {

		if (eventType == XmlPullParser.START_TAG) {
		// Update path
		pathLengthStack.push(path.length());
		path.append('/');
		String prefix = null;
		try {
		// getPrefix is not supported by local Xml resource parser
		prefix = parser.getPrefix();
		} catch (RuntimeException e) {
		prefix = null;
		}
		if (prefix != null) {
		path.append(prefix);
		path.append(':');
		}
		path.append(parser.getName());

		if (currentNodeDepth >= 0) {
		currentNodeDepth++;
		} else {
		// A node matching selection is found: initialize child parsing mode
		if (mSelectionPattern.matcher(path.toString()).matches()) {
		currentNodeDepth = 0;
		currentNodePathStartIndex = path.length();
		mCurrentValues[0] = Integer.toString(getCount()); // _ID
		for (int i = 0; i < mNumberOfProjections; i++) {
		// Reset values to default (empty string)
		mCurrentValues[i + 1] = "";
		mActiveTextDepthMask[i].clear();
		}
		}
		}

		// This test has to be separated from the previous one as currentNodeDepth can
		// be modified above (when a node matching selection is found).
		if (currentNodeDepth >= 0) {
		final String localNodePath = path.substring(currentNodePathStartIndex);
		for (int i = 0; i < mNumberOfProjections; i++) {
		if (mProjectionPatterns[i].matcher(localNodePath).matches()) {
		String attribute = mAttributeNames[i];
		if (attribute != null) {
		mCurrentValues[i + 1] =
		parser.getAttributeValue(null, attribute);
		} else {
		mActiveTextDepthMask[i].set(currentNodeDepth, true);
		}
		}
		}
		}

		} else if (eventType == XmlPullParser.END_TAG) {
		// Pop last node from path
		final int length = pathLengthStack.pop();
		path.setLength(length);

		if (currentNodeDepth >= 0) {
		if (currentNodeDepth == 0) {
		// Leaving a selection matching node: add a new row with results
		addRow(mCurrentValues);
		} else {
		for (int i = 0; i < mNumberOfProjections; i++) {
		mActiveTextDepthMask[i].set(currentNodeDepth, false);
		}
		}
		currentNodeDepth--;
		}

		} else if ((eventType == XmlPullParser.TEXT) && (!parser.isWhitespace())) {
		for (int i = 0; i < mNumberOfProjections; i++) {
		if ((currentNodeDepth >= 0) &&
		(mActiveTextDepthMask[i].get(currentNodeDepth))) {
		mCurrentValues[i + 1] += parser.getText();
		}
		}
		}

		eventType = parser.next();
		}
		}
		}
		}