Question

如何在java中以实际方式从jar中删除特定的文件/文件夹。

我有一个罐子ABC.jar包含文件，文件夹和另一个罐子说child.jar。在child.jar下我想删除一个特定的文件。我能怎么做？所以我的ABC.jar结构保持不变。

任何帮助都将不胜感激。

先谢谢。

Answer 1

正如@icza回答的那样，我们必须遍历原始jar文件并删除我们不想要的条目。这是您可以参考的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.");
  }

}

Answer 2

Jar / zip文件不可编辑。您无法从jar / zip文件中删除条目。

你可以做的是“重新创建”这样的jar文件：启动一个新的jar文件，迭代当前jar文件的条目，并将这些条目添加到你不想要的新jar文件中删除。

理论上可以删除这样的条目（但标准的Java lib不适用于此，意味着ZipFile，ZipInputStream，JarFile，{{1} }））：

jar / zip文件中的条目是顺序的。每个条目都有一个标题，其中包含有关条目的信息（可以是文件或文件夹条目）。此标头还包含条目的字节长度。因此，您可以按顺序迭代条目，如果遇到要删除的条目（并且您从其标题中知道其大小），则可以将文件的剩余部分（此条目后的内容）复制到文本的开头。当前条目（显然文件大小应该以当前/已删除条目的长度为准）。

或者您的其他选项包括不通过Java执行此操作，而是使用JarInputStream命令本身等外部工具。

Answer 3

Sun / Oracle bug数据库要求在java api中实现此功能。

检查here

Answer 4

通过在运行时执行命令shell，可以通过一种简单的方法从JAR中删除文件。执行以下命令可以完成工作：

Runtime.getRuntime().exec("zip -d path\my.jar some_file.txt");

其中 path 是jar文件的绝对路径， some_file.txt 是要删除的文件。在此示例中，文件驻留在jar的主文件夹中。如果文件位于不同的文件夹

，则可能需要提供其相对路径

你可能知道的 jar 本身的路径，或者可以根据你执行命令shell的类来找到它的路径：

String path = SomeClass.class.getProtectionDomain().getCodeSource().getLocation().getPath();

您可以通过收听可用的流来跟踪流程的执行情况：

    Process p = Runtime.getRuntime().exec("zip -d path\my.jar some_file.txt");
    BufferedReader reader = 
            new BufferedReader(new InputStreamReader(p.getInputStream()));

       String line = "";    
       StringBuilder sb = new StringBuilder();
       while ((line = reader.readLine())!= null) {
           sb.append(line + "\n");
           System.out.println(line);
       }
       System.out.println(sb.toString());

Answer 5

    public static void filterJar(Path jarInFileName, String skipRegex, Path jarOutFileName) throws IOException {
        ZipEntry entry;
        ZipInputStream zis = null;
        JarOutputStream os = null;
        FileInputStream is = null;
        try {
            is = new FileInputStream(jarInFileName.toFile());
            Pattern pattern = Pattern.compile(skipRegex);
            zis = new ZipInputStream(is);
            os = new JarOutputStream(new FileOutputStream(jarOutFileName.toFile())); 
            while ((entry = zis.getNextEntry()) != null) {
                if (pattern.matcher(entry.getName()).matches()) continue;
                os.putNextEntry(entry);
                if (!entry.isDirectory()) {
                    byte[] bytes = toBytes(zis);
                    os.write(bytes);
                }
            }
        }
        catch (Exception ex) {
           throw new IOException("unable to filter jar:" + ex.getMessage());
        }
        finally {
            closeQuietly(is);
            closeQuietly(os);
        }
    }
    public static void closeQuietly(final Closeable closeable) {
        try {
            if (closeable != null) {
                closeable.close();
            }
        }
        catch (final Exception e) {}
    }
    public static byte[] toBytes(InputStream aInput) throws IOException {
        byte[] bucket = new byte[5 * 1024];
        ByteArrayOutputStream result = null;
        result = new ByteArrayOutputStream(bucket.length);
        int bytesRead = 0;
        while (bytesRead != -1) {
            bytesRead = aInput.read(bucket);
            if (bytesRead > 0) {
                result.write(bucket, 0, bytesRead);
            }
        }
        return result.toByteArray();
    }

public static void main(String[] args) throws IOException {
  filterJar(Paths.get("./old.jar"), "BOOT-INF/lib.*", Paths.get("./new.jar"));
}

如何在java中以实际方式从jar中删除特定的文件/文件夹

5 个答案: