Get resource from Jar file : JarFile « File « Java Tutorial

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/**
 * 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.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
import java.util.zip.ZipInputStream;

public final class JarResource {

  public List<String> getJarContents(URL jarLocation) throws IOException {
    return getJarContents(jarLocation.openStream());
  }

  public List<String> getJarContents(InputStream is) throws IOException {
    return load(is);
  }

  public List<String> getJarContents(String jarLocation) throws IOException {
    return getJarContents(new File(jarLocation));
  }

  public List<String> getJarContents(File jarFile) throws IOException {
    return load(jarFile);
  }

  private List<String> load(File jarFile) throws IOException {
    List<String> jarContents = new ArrayList<String>();
    try {
      ZipFile zf = new ZipFile(jarFile);
      for (Enumeration e = zf.entries(); e.hasMoreElements();) {
        ZipEntry ze = (ZipEntry) e.nextElement();
        if (ze.isDirectory()) {
          continue;
        }
        jarContents.add(ze.getName());
      }
    } catch (NullPointerException e) {
      System.out.println("done.");
    } catch (ZipException ze) {
      ze.printStackTrace();
    }
    return jarContents;
  }

  private List<String> load(InputStream is) throws IOException {
    List<String> jarContents = new ArrayList<String>();
    try {
      ZipInputStream zis = new ZipInputStream(is);
      ZipEntry ze = zis.getNextEntry();
      while (ze != null) {
        if (ze.isDirectory()) {
          continue;
        }
        jarContents.add(ze.getName());
        ze = zis.getNextEntry();
      }
    } catch (NullPointerException e) {
      System.out.println("done.");
    }

    return jarContents;
  }
}