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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.sdklib.xml;
     18 
     19 import com.android.sdklib.SdkConstants;
     20 
     21 import java.util.ArrayList;
     22 import java.util.Iterator;
     23 import java.util.List;
     24 
     25 import javax.xml.XMLConstants;
     26 import javax.xml.namespace.NamespaceContext;
     27 import javax.xml.xpath.XPath;
     28 import javax.xml.xpath.XPathFactory;
     29 
     30 /**
     31  * XPath factory with automatic support for the android name space.
     32  */
     33 public class AndroidXPathFactory {
     34     /** Default prefix for android name space: 'android' */
     35     public final static String DEFAULT_NS_PREFIX = "android"; //$NON-NLS-1$
     36 
     37     private final static XPathFactory sFactory = XPathFactory.newInstance();
     38 
     39     /** Name space context for Android resource XML files. */
     40     private static class AndroidNamespaceContext implements NamespaceContext {
     41         private final static AndroidNamespaceContext sThis = new AndroidNamespaceContext(
     42                 DEFAULT_NS_PREFIX);
     43 
     44         private final String mAndroidPrefix;
     45         private final List<String> mAndroidPrefixes = new ArrayList<String>();
     46 
     47         /**
     48          * Returns the default {@link AndroidNamespaceContext}.
     49          */
     50         private static AndroidNamespaceContext getDefault() {
     51             return sThis;
     52         }
     53 
     54         /**
     55          * Construct the context with the prefix associated with the android namespace.
     56          * @param androidPrefix the Prefix
     57          */
     58         public AndroidNamespaceContext(String androidPrefix) {
     59             mAndroidPrefix = androidPrefix;
     60             mAndroidPrefixes.add(mAndroidPrefix);
     61         }
     62 
     63         public String getNamespaceURI(String prefix) {
     64             if (prefix != null) {
     65                 if (prefix.equals(mAndroidPrefix)) {
     66                     return SdkConstants.NS_RESOURCES;
     67                 }
     68             }
     69 
     70             return XMLConstants.NULL_NS_URI;
     71         }
     72 
     73         public String getPrefix(String namespaceURI) {
     74             if (SdkConstants.NS_RESOURCES.equals(namespaceURI)) {
     75                 return mAndroidPrefix;
     76             }
     77 
     78             return null;
     79         }
     80 
     81         public Iterator<?> getPrefixes(String namespaceURI) {
     82             if (SdkConstants.NS_RESOURCES.equals(namespaceURI)) {
     83                 return mAndroidPrefixes.iterator();
     84             }
     85 
     86             return null;
     87         }
     88     }
     89 
     90     /**
     91      * Creates a new XPath object, specifying which prefix in the query is used for the
     92      * android namespace.
     93      * @param androidPrefix The namespace prefix.
     94      */
     95     public static XPath newXPath(String androidPrefix) {
     96         XPath xpath = sFactory.newXPath();
     97         xpath.setNamespaceContext(new AndroidNamespaceContext(androidPrefix));
     98         return xpath;
     99     }
    100 
    101     /**
    102      * Creates a new XPath object using the default prefix for the android namespace.
    103      * @see #DEFAULT_NS_PREFIX
    104      */
    105     public static XPath newXPath() {
    106         XPath xpath = sFactory.newXPath();
    107         xpath.setNamespaceContext(AndroidNamespaceContext.getDefault());
    108         return xpath;
    109     }
    110 }
    111