Bug 2330278 (b8d46988) · Commits · e / os / android_frameworks_base

core/java/com/google/android/util/SimplePullParser.java

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		/*
		* Copyright (C) 2008 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 com.google.android.util;

		import org.xmlpull.v1.XmlPullParser;
		import org.xmlpull.v1.XmlPullParserException;

		import java.io.IOException;
		import java.io.InputStream;
		import java.io.StringReader;
		import java.io.Reader;
		import java.io.Closeable;

		import android.util.Xml;
		import android.util.Log;

		/**
		* This is an abstraction of a pull parser that provides several benefits:<ul>
		* <li>it is easier to use robustly because it makes it trivial to handle unexpected tags (which
		* might have children)</li>
		* <li>it makes the handling of text (cdata) blocks more convenient</li>
		* <li>it provides convenient methods for getting a mandatory attribute (and throwing an exception
		* if it is missing) or an optional attribute (and using a default value if it is missing)
		* </ul>
		*/
		public class SimplePullParser {
		public static final String TEXT_TAG = "![CDATA[";

		private String mLogTag = null;
		private final XmlPullParser mParser;
		private Closeable source;
		private String mCurrentStartTag;

		/**
		* Constructs a new SimplePullParser to parse the stream
		* @param stream stream to parse
		* @param encoding the encoding to use
		*/
		public SimplePullParser(InputStream stream, String encoding)
		throws ParseException, IOException {
		try {
		XmlPullParser parser = Xml.newPullParser();
		parser.setInput(stream, encoding);
		moveToStartDocument(parser);
		mParser = parser;
		mCurrentStartTag = null;
		source = stream;
		} catch (XmlPullParserException e) {
		throw new ParseException(e);
		}
		}

		/**
		* Constructs a new SimplePullParser to parse the xml
		* @param parser the underlying parser to use
		*/
		public SimplePullParser(XmlPullParser parser) {
		mParser = parser;
		mCurrentStartTag = null;
		source = null;
		}

		/**
		* Constructs a new SimplePullParser to parse the xml
		* @param xml the xml to parse
		*/
		public SimplePullParser(String xml) throws IOException, ParseException {
		this(new StringReader(xml));
		}

		/**
		* Constructs a new SimplePullParser to parse the xml
		* @param reader a reader containing the xml
		*/
		public SimplePullParser(Reader reader) throws IOException, ParseException {
		try {
		XmlPullParser parser = Xml.newPullParser();
		parser.setInput(reader);
		moveToStartDocument(parser);
		mParser = parser;
		mCurrentStartTag = null;
		source = reader;
		} catch (XmlPullParserException e) {
		throw new ParseException(e);
		}
		}

		private static void moveToStartDocument(XmlPullParser parser)
		throws XmlPullParserException, IOException {
		int eventType;
		eventType = parser.getEventType();
		if (eventType != XmlPullParser.START_DOCUMENT) {
		throw new XmlPullParserException("Not at start of response");
		}
		}

		/**
		* Enables logging to the provided log tag. A basic representation of the xml will be logged as
		* the xml is parsed. No logging is done unless this is called.
		*
		* @param logTag the log tag to use when logging
		*/
		public void setLogTag(String logTag) {
		mLogTag = logTag;
		}

		/**
		* Returns the tag of the next element whose depth is parentDepth plus one
		* or null if there are no more such elements before the next start tag. When this returns,
		* getDepth() and all methods relating to attributes will refer to the element whose tag is
		* returned.
		*
		* @param parentDepth the depth of the parrent of the item to be returned
		* @param textBuilder if null then text blocks will be ignored. If
		* non-null then text blocks will be added to the builder and TEXT_TAG
		* will be returned when one is found
		* @return the next of the next child element's tag, TEXT_TAG if a text block is found, or null
		* if there are no more child elements or DATA blocks
		* @throws IOException propogated from the underlying parser
		* @throws ParseException if there was an error parsing the xml.
		*/
		public String nextTagOrText(int parentDepth, StringBuilder textBuilder)
		throws IOException, ParseException {
		while (true) {
		int eventType = 0;
		try {
		eventType = mParser.next();
		} catch (XmlPullParserException e) {
		throw new ParseException(e);
		}
		int depth = mParser.getDepth();
		mCurrentStartTag = null;

		if (eventType == XmlPullParser.START_TAG && depth == parentDepth + 1) {
		mCurrentStartTag = mParser.getName();
		if (mLogTag != null && Log.isLoggable(mLogTag, Log.DEBUG)) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < depth; i++) sb.append(" ");
		sb.append("<").append(mParser.getName());
		int count = mParser.getAttributeCount();
		for (int i = 0; i < count; i++) {
		sb.append(" ");
		sb.append(mParser.getAttributeName(i));
		sb.append("=\"");
		sb.append(mParser.getAttributeValue(i));
		sb.append("\"");
		}
		sb.append(">");
		Log.d(mLogTag, sb.toString());
		}
		return mParser.getName();
		}

		if (eventType == XmlPullParser.END_TAG && depth == parentDepth) {
		if (mLogTag != null && Log.isLoggable(mLogTag, Log.DEBUG)) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < depth; i++) sb.append(" ");
		sb.append("</>"); // Not quite valid xml but it gets the job done.
		Log.d(mLogTag, sb.toString());
		}
		return null;
		}

		if (eventType == XmlPullParser.END_DOCUMENT && parentDepth == 0) {
		// we could just rely on the caller calling close(), which it should, but try
		// to auto-close for clients that might have missed doing so.
		if (source != null) {
		source.close();
		source = null;
		}
		return null;
		}

		if (eventType == XmlPullParser.TEXT && depth == parentDepth) {
		if (textBuilder == null) {
		continue;
		}
		String text = mParser.getText();
		textBuilder.append(text);
		return TEXT_TAG;
		}
		}
		}

		/**
		* The same as nextTagOrTexxt(int, StringBuilder) but ignores text blocks.
		*/
		public String nextTag(int parentDepth) throws IOException, ParseException {
		return nextTagOrText(parentDepth, null /* ignore text */);
		}

		/**
		* Returns the depth of the current element. The depth is 0 before the first
		* element has been returned, 1 after that, etc.
		*
		* @return the depth of the current element
		*/
		public int getDepth() {
		return mParser.getDepth();
		}

		/**
		* Consumes the rest of the children, accumulating any text at this level into the builder.
		*
		* @param textBuilder the builder to contain any text
		* @throws IOException propogated from the XmlPullParser
		* @throws ParseException if there was an error parsing the xml.
		*/
		public void readRemainingText(int parentDepth, StringBuilder textBuilder)
		throws IOException, ParseException {
		while (nextTagOrText(parentDepth, textBuilder) != null) {
		}
		}

		/**
		* Returns the number of attributes on the current element.
		*
		* @return the number of attributes on the current element
		*/
		public int numAttributes() {
		return mParser.getAttributeCount();
		}

		/**
		* Returns the name of the nth attribute on the current element.
		*
		* @return the name of the nth attribute on the current element
		*/
		public String getAttributeName(int i) {
		return mParser.getAttributeName(i);
		}

		/**
		* Returns the namespace of the nth attribute on the current element.
		*
		* @return the namespace of the nth attribute on the current element
		*/
		public String getAttributeNamespace(int i) {
		return mParser.getAttributeNamespace(i);
		}

		/**
		* Returns the string value of the named attribute.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute
		* @param defaultValue the value to return if the attribute is not specified
		* @return the value of the attribute
		*/
		public String getStringAttribute(
		String namespace, String name, String defaultValue) {
		String value = mParser.getAttributeValue(namespace, name);
		if (null == value) return defaultValue;
		return value;
		}

		/**
		* Returns the string value of the named attribute. An exception will
		* be thrown if the attribute is not present.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute @return the value of the attribute
		* @throws ParseException thrown if the attribute is missing
		*/
		public String getStringAttribute(String namespace, String name) throws ParseException {
		String value = mParser.getAttributeValue(namespace, name);
		if (null == value) {
		throw new ParseException(
		"missing '" + name + "' attribute on '" + mCurrentStartTag + "' element");
		}
		return value;
		}

		/**
		* Returns the string value of the named attribute. An exception will
		* be thrown if the attribute is not a valid integer.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute
		* @param defaultValue the value to return if the attribute is not specified
		* @return the value of the attribute
		* @throws ParseException thrown if the attribute not a valid integer.
		*/
		public int getIntAttribute(String namespace, String name, int defaultValue)
		throws ParseException {
		String value = mParser.getAttributeValue(namespace, name);
		if (null == value) return defaultValue;
		try {
		return Integer.parseInt(value);
		} catch (NumberFormatException e) {
		throw new ParseException("Cannot parse '" + value + "' as an integer");
		}
		}

		/**
		* Returns the string value of the named attribute. An exception will
		* be thrown if the attribute is not present or is not a valid integer.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute @return the value of the attribute
		* @throws ParseException thrown if the attribute is missing or not a valid integer.
		*/
		public int getIntAttribute(String namespace, String name)
		throws ParseException {
		String value = getStringAttribute(namespace, name);
		try {
		return Integer.parseInt(value);
		} catch (NumberFormatException e) {
		throw new ParseException("Cannot parse '" + value + "' as an integer");
		}
		}

		/**
		* Returns the string value of the named attribute. An exception will
		* be thrown if the attribute is not a valid long.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute @return the value of the attribute
		* @throws ParseException thrown if the attribute is not a valid long.
		*/
		public long getLongAttribute(String namespace, String name, long defaultValue)
		throws ParseException {
		String value = mParser.getAttributeValue(namespace, name);
		if (null == value) return defaultValue;
		try {
		return Long.parseLong(value);
		} catch (NumberFormatException e) {
		throw new ParseException("Cannot parse '" + value + "' as a long");
		}
		}

		/**
		* Close this SimplePullParser and any underlying resources (e.g., its InputStream or
		* Reader source) used by this SimplePullParser.
		*/
		public void close() {
		if (source != null) {
		try {
		source.close();
		} catch (IOException ioe) {
		// ignore
		}
		}
		}

		/**
		* Returns the string value of the named attribute. An exception will
		* be thrown if the attribute is not present or is not a valid long.
		*
		* @param namespace the namespace of the attribute
		* @param name the name of the attribute @return the value of the attribute
		* @throws ParseException thrown if the attribute is missing or not a valid long.
		*/
		public long getLongAttribute(String namespace, String name)
		throws ParseException {
		String value = getStringAttribute(namespace, name);
		try {
		return Long.parseLong(value);
		} catch (NumberFormatException e) {
		throw new ParseException("Cannot parse '" + value + "' as a long");
		}
		}

		public static final class ParseException extends Exception {
		public ParseException(String message) {
		super(message);
		}

		public ParseException(String message, Throwable cause) {
		super(message, cause);
		}

		public ParseException(Throwable cause) {
		super(cause);
		}
		}
		}

tests/AndroidTests/src/com/android/unit_tests/SimplePullParserTest.java

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		/*
		* Copyright (C) 2007 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 com.android.unit_tests;

		import com.google.android.util.SimplePullParser;
		import junit.framework.TestCase;
		import android.test.suitebuilder.annotation.SmallTest;

		public class SimplePullParserTest extends TestCase {
		@SmallTest
		public void testTwoLevels() throws Exception {
		String xml = ""
		+ "<top a='1' b='hello'>\n"
		+ " <next c='2' d='there'/>\n"
		+ " <next c='3' d='bye'/>\n"
		+ "</top>";
		SimplePullParser parser = new SimplePullParser(xml);
		int depth0 = parser.getDepth();
		assertEquals(0, depth0);
		assertEquals("top", parser.nextTag(depth0));
		assertEquals(1, parser.getIntAttribute(null, "a"));
		assertEquals("hello", parser.getStringAttribute(null, "b"));

		int depth1 = parser.getDepth();
		assertEquals(1, depth1);
		assertEquals("next", parser.nextTag(depth1));
		assertEquals(2, parser.getIntAttribute(null, "c"));
		assertEquals("there", parser.getStringAttribute(null, "d"));
		assertEquals("next", parser.nextTag(depth1));
		assertEquals(3, parser.getIntAttribute(null, "c"));
		assertEquals("bye", parser.getStringAttribute(null, "d"));
		assertNull(parser.nextTag(depth1));

		assertNull(parser.nextTag(depth0));
		}

		@SmallTest
		public void testAttributes() throws Exception {
		String xml = "<top a='1' b='hello'/>";
		SimplePullParser parser = new SimplePullParser(xml);
		int depth = parser.getDepth();
		parser.nextTag(depth);

		assertEquals(2, parser.numAttributes());
		assertEquals("a", parser.getAttributeName(0));
		assertEquals("b", parser.getAttributeName(1));

		assertEquals(1, parser.getIntAttribute(null, "a"));
		assertEquals(5, parser.getIntAttribute(null, "c", 5));
		assertEquals("hello", parser.getStringAttribute(null, "b"));
		assertEquals("not", parser.getStringAttribute(null, "d", "not"));
		}

		@SmallTest
		public void testRecovery() throws Exception {
		String xml = ""
		+ "<top a='1' b='hello'>\n"
		+ " <middle c='2' d='there'>\n"
		+ " <inner/>\n"
		+ " <inner2/>\n"
		+ " <inner3/>\n"
		+ " </middle>\n"
		+ " <middle2/>\n"
		+ "</top>";
		SimplePullParser parser = new SimplePullParser(xml);
		assertEquals(0, parser.getDepth());
		assertEquals("top", parser.nextTag(0));
		assertEquals(1, parser.getDepth());
		assertEquals("middle", parser.nextTag(1));
		assertEquals(2, parser.getDepth());
		assertEquals("inner", parser.nextTag(2));
		// Now skip some elements.
		assertEquals("middle2", parser.nextTag(1));
		}

		@SmallTest
		public void testCdata() throws Exception {
		StringBuilder cdataBuilder;
		String xml = ""
		+ "<top>"
		+ "<![CDATA[data0]]>"
		+ "<next0/>"
		+ "<![CDATA[data1]]>"
		+ "<next1/>"
		+ "<![CDATA[data2]]>"
		+ "<next2/>"
		+ "<![CDATA[data3]]>"
		+ "<next3/>"
		+ "<![CDATA[data4]]>"
		+ "<next4/>"
		+ "<![CDATA[data5]]>"
		+ "</top>";
		SimplePullParser parser = new SimplePullParser(xml);
		assertEquals("top", parser.nextTag(0));

		// We can ignore cdata by not passing a cdata builder.
		assertEquals("next0", parser.nextTag(1));

		// We can get the most recent cdata by passing an empty cdata builder.
		cdataBuilder = new StringBuilder();
		assertSame(SimplePullParser.TEXT_TAG, parser.nextTagOrText(1, cdataBuilder));
		assertEquals("data1", cdataBuilder.toString());
		assertEquals("next1", parser.nextTag(1));

		// We can join multiple cdatas by reusing a builder.
		cdataBuilder = new StringBuilder();
		assertSame(SimplePullParser.TEXT_TAG, parser.nextTagOrText(1, cdataBuilder));
		assertEquals("next2", parser.nextTag(1));
		assertSame(SimplePullParser.TEXT_TAG, parser.nextTagOrText(1, cdataBuilder));
		assertEquals("data2data3", cdataBuilder.toString());
		assertEquals("next3", parser.nextTag(1));

		// We can read all of the remaining cdata while ignoring any elements.
		cdataBuilder = new StringBuilder();
		parser.readRemainingText(1, cdataBuilder);
		assertEquals("data4data5", cdataBuilder.toString());
		}
		}