Commons Digester example source code file (LoaderFromStream.java)

This example Commons Digester source code file (LoaderFromStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Digester tags/keywords

bytearrayinputstream, bytearrayoutputstream, bytearrayoutputstream, fromxmlruleset, fromxmlruleset, inputsource, inputsource, io, ioexception, loaderfromstream, loaderfromstream, log, override, ruleloader, sax, string

The Commons Digester LoaderFromStream.java source code

/* $Id: LoaderFromStream.java 992107 2010-09-02 20:31:00Z simonetripodi $
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.digester.plugins.strategies;

import java.io.InputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import org.xml.sax.InputSource;

import org.apache.commons.digester.Digester;
import org.apache.commons.digester.plugins.RuleLoader;
import org.apache.commons.digester.plugins.PluginException;
import org.apache.commons.digester.xmlrules.FromXmlRuleSet;
import org.apache.commons.logging.Log;

/**
 * A rule-finding algorithm which loads an xmlplugins-format file.
 * <p>
 * Note that the "include" feature of xmlrules is not supported.
 *
 * @since 1.6
 */

public class LoaderFromStream extends RuleLoader {

    private byte[] input;
    
    /** See {@link #load}. */
    public LoaderFromStream(InputStream s) throws Exception {
        load(s);
    }

    /**
     * The contents of the input stream are loaded into memory, and
     * cached for later use.
     * <p>
     * The caller is responsible for closing the input stream after this
     * method has returned.
     */
    private void load(InputStream s) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buf = new byte[256];
        for(;;) {
            int i = s.read(buf);
            if (i == -1)
                break;
            baos.write(buf, 0, i);
        }
        input = baos.toByteArray();
    }
    
    /**
     * Add the rules previously loaded from the input stream into the
     * specified digester.
     */
    @Override
    public void addRules(Digester d, String path) throws PluginException {
        Log log = d.getLogger();
        boolean debug = log.isDebugEnabled();
        if (debug) {
            log.debug(
                "LoaderFromStream: loading rules for plugin at path [" 
                + path + "]");
        }

        // Note that this input-source doesn't have any idea of its
        // system id, so it has no way of resolving relative URLs
        // such as the "include" feature of xmlrules. This is ok,
        // because that doesn't work well with our approach of
        // caching the input data in memory anyway.

        InputSource source = new InputSource(new ByteArrayInputStream(input));
        FromXmlRuleSet ruleSet = new FromXmlRuleSet(source);
        ruleSet.addRuleInstances(d, path);
    }
}