java - 如何在 java 中实用地从 jar 中删除特定文件/文件夹

Question

如何在 java 中实用地从 jar 中删除特定文件/文件夹。

我有一个 jar ABC.jar 包含文件、文件夹和另一个 jars 说 child.jar。在 child.jar 下我想删除一个特定的文件。我能怎么做？这样我的 ABC.jar 结构就保持不变。

任何帮助将不胜感激。

提前致谢。

Answer 1

正如@icza 的回答，我们必须遍历原始 jar 文件并删除我们不需要的条目。这是您可以引用的 java 代码。

 public static void main(String[] args) throws IOException {


  String jarName = args[0];
  String fileName = args[1];

  // Create file descriptors for the jar and a temp jar.

  File jarFile = new File(jarName);
  File tempJarFile = new File(jarName + ".tmp");

  // Open the jar file.

  JarFile jar = new JarFile(jarFile);
  System.out.println(jarName + " opened.");

  // Initialize a flag that will indicate that the jar was updated.

  boolean jarUpdated = false;

  try {
     // Create a temp jar file with no manifest. (The manifest will
     // be copied when the entries are copied.)

     Manifest jarManifest = jar.getManifest();
     JarOutputStream tempJar =
        new JarOutputStream(new FileOutputStream(tempJarFile));

     // Allocate a buffer for reading entry data.

     byte[] buffer = new byte[1024];
     int bytesRead;

     try {
        // Open the given file.

        FileInputStream file = new FileInputStream(fileName);

        try {
           // Create a jar entry and add it to the temp jar.

           JarEntry entry = new JarEntry(fileName);
           tempJar.putNextEntry(entry);

           // Read the file and write it to the jar.

           while ((bytesRead = file.read(buffer)) != -1) {
              tempJar.write(buffer, 0, bytesRead);
           }

           System.out.println(entry.getName() + " added.");
        }
        finally {
           file.close();
        }

        // Loop through the jar entries and add them to the temp jar,
        // skipping the entry that was added to the temp jar already.

        for (Enumeration entries = jar.entries(); entries.hasMoreElements(); ) {
           // Get the next entry.

           JarEntry entry = (JarEntry) entries.nextElement();

           // If the entry has not been added already, add it.

           if (! entry.getName().equals(fileName)) {
              // Get an input stream for the entry.

              InputStream entryStream = jar.getInputStream(entry);

              // Read the entry and write it to the temp jar.

              tempJar.putNextEntry(entry);

              while ((bytesRead = entryStream.read(buffer)) != -1) {
                 tempJar.write(buffer, 0, bytesRead);
              }
           }
        }

        jarUpdated = true;
     }
     catch (Exception ex) {
        System.out.println(ex);

        // Add a stub entry here, so that the jar will close without an
        // exception.

        tempJar.putNextEntry(new JarEntry("stub"));
     }
     finally {
        tempJar.close();
     }
  }
  finally {
     jar.close();
     System.out.println(jarName + " closed.");

     // If the jar was not updated, delete the temp jar file.

     if (! jarUpdated) {
        tempJarFile.delete();
     }
  }

  // If the jar was updated, delete the original jar file and rename the
  // temp jar file to the original name.

  if (jarUpdated) {
     jarFile.delete();
     tempJarFile.renameTo(jarFile);
     System.out.println(jarName + " updated.");
  }