org.apache.maven.plugins.shade.resource.ServicesResourceTransformer.java Source code

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Here is the source code for org.apache.maven.plugins.shade.resource.ServicesResourceTransformer.java

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package org.apache.maven.plugins.shade.resource;

/*
 * 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.
 */

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringReader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;

import org.apache.commons.io.IOUtils;
import org.apache.maven.plugins.shade.relocation.Relocator;

import com.google.common.io.LineReader;
import org.apache.maven.plugins.shade.resource.jar.ConsistentJarEntry;

/**
 * Resources transformer that relocates classes in META-INF/services and appends entries in META-INF/services resources
 * into a single resource. For example, if there are several META-INF/services/org.apache.maven.project.ProjectBuilder
 * resources spread across many JARs the individual entries will all be concatenated into a single
 * META-INF/services/org.apache.maven.project.ProjectBuilder resource packaged into the resultant JAR produced by the
 * shading process.
 */
public class ServicesResourceTransformer implements ResourceTransformer {

    private static final String SERVICES_PATH = "META-INF/services";

    private Map<String, ServiceStream> serviceEntries = new HashMap<String, ServiceStream>();

    private List<Relocator> relocators;

    public boolean canTransformResource(String resource) {
        if (resource.startsWith(SERVICES_PATH)) {
            return true;
        }

        return false;
    }

    public void processResource(String resource, InputStream is, final List<Relocator> relocators)
            throws IOException {
        ServiceStream out = serviceEntries.get(resource);
        if (out == null) {
            out = new ServiceStream();
            serviceEntries.put(resource, out);
        }

        final ServiceStream fout = out;

        final String content = IOUtils.toString(is);
        StringReader reader = new StringReader(content);
        LineReader lineReader = new LineReader(reader);
        String line;
        while ((line = lineReader.readLine()) != null) {
            String relContent = line;
            for (Relocator relocator : relocators) {
                if (relocator.canRelocateClass(relContent)) {
                    relContent = relocator.applyToSourceContent(relContent);
                }
            }
            fout.append(relContent + "\n");
        }

        if (this.relocators == null) {
            this.relocators = relocators;
        }
    }

    public boolean hasTransformedResource() {
        return serviceEntries.size() > 0;
    }

    public void modifyOutputStream(JarOutputStream jos, boolean consistentDates) throws IOException {
        for (Map.Entry<String, ServiceStream> entry : serviceEntries.entrySet()) {
            String key = entry.getKey();
            ServiceStream data = entry.getValue();

            if (relocators != null) {
                key = key.substring(SERVICES_PATH.length() + 1);
                for (Relocator relocator : relocators) {
                    if (relocator.canRelocateClass(key)) {
                        key = relocator.relocateClass(key);
                        break;
                    }
                }

                key = SERVICES_PATH + '/' + key;
            }

            JarEntry jarEntry = new ConsistentJarEntry(key, consistentDates);
            jos.putNextEntry(jarEntry);

            //read the content of service file for candidate classes for relocation
            PrintWriter writer = new PrintWriter(jos);
            InputStreamReader streamReader = new InputStreamReader(data.toInputStream());
            BufferedReader reader = new BufferedReader(streamReader);
            String className;

            while ((className = reader.readLine()) != null) {

                if (relocators != null) {
                    for (Relocator relocator : relocators) {
                        //if the class can be relocated then relocate it
                        if (relocator.canRelocateClass(className)) {
                            className = relocator.applyToSourceContent(className);
                            break;
                        }
                    }
                }

                writer.println(className);
                writer.flush();
            }

            reader.close();
            data.reset();
        }
    }

    static class ServiceStream extends ByteArrayOutputStream {

        public ServiceStream() {
            super(1024);
        }

        public void append(String content) throws IOException {
            if (count > 0 && buf[count - 1] != '\n' && buf[count - 1] != '\r') {
                write('\n');
            }

            byte[] contentBytes = content.getBytes("UTF-8");
            this.write(contentBytes);
        }

        public InputStream toInputStream() {
            return new ByteArrayInputStream(buf, 0, count);
        }

    }

}