Java压缩和解压缩文件

在对EJB进行部署的过程中，需要将ejb的jar文件解压缩到一个临时目录下，添加或修改它的基于特定应用服务器的专有部署文件，再将修改后的文件夹打包成jar放到应用服务器上完成整个部署流程。在这里需要用到Java的压缩和解压缩文件操作，其中，解压缩文件的代码如下：

private boolean releaseZipToFile(String source, String outFile) throws IOException{
    ZipFile zfile = new ZipFile(source);
    Enumeration zList = zfile.entries();
    ZipEntry ze = null;
    byte[] buf = new byte[1024];
    while (zList.hasMoreElements()) {
        ze = (ZipEntry)zList.nextElement();
        if (ze.isDirectory()){
            continue;
        }
        OutputStream os = new BufferedOutputStream(new FileOutputStream(getRealFileName(outFile, ze.getName())));
        InputStream is = new BufferedInputStream(zfile.getInputStream(ze));
        int readLen = 0;
        while ((readLen = is.read(buf, 0, 1024)) != -1) {
            os.write(buf, 0, readLen);
        }
        is.close();
        os.close();
        System.out.println("Extracted: " + ze.getName());
    }
    zfile.close();
}

private File getRealFileName(String baseDir, String absFileName) {
    String[] dirs = absFileName.split("/");
    File ret = new File(baseDir);
    if (dirs.length > 1) {
        for (int i = 0; i < dirs.length - 1; i++) {
            ret = new File(ret, dirs[i]);
        }
    }
    if (!ret.exists()) {
        ret.mkdirs();
    }
    ret = new File(ret, dirs[dirs.length - 1]);
    return ret;
}

原理很简单，就是将压缩文件读入，遇到目录就进入目录，遍历它的每个文件，并且在目标目录中建立相同名称的文件，并将字节从源文件读取写入到目标文件中。压缩文件的代码如下所示：

public void createZip(String sourceDir, String zipFileName) throws Exception { 
    File folderObject = new File(sourceDir);
    if (folderObject.exists()) {
        ArrayList<File> fileList = getSubFiles(new File(sourceDir));
        ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(zipFileName));
        ZipEntry ze = null;
        byte[] buf = new byte[1024];
        int readLen = 0;
        for (int i = 0; i < fileList.size(); i++) {
            File f = (File)fileList.get(i);
            System.out.println("Adding: " + f.getPath() + f.getName());
        ze = new ZipEntry(getAbsFileName(sourceDir, f));
        ze.setSize(f.length());
        ze.setTime(f.lastModified());
        zos.putNextEntry(ze);
        InputStream is = new BufferedInputStream(new FileInputStream(f));
        while ((readLen = is.read(buf, 0, 1024)) != -1) {
            zos.write(buf, 0, readLen);
        }
        is.close();
        System.out.println("done...");
    }
    zos.close();
} else {
    throw new Exception("The folder is not exist");
    }
}

private ArrayList<File> getSubFiles(File baseDir) {
    ArrayList<File> ret = new ArrayList<File>();
    File[] tmp = baseDir.listFiles();
    for (int i = 0; i < tmp.length; i++) {
        if (tmp[i].isFile()) {
            ret.add(tmp[i]);
        }
        if (tmp[i].isDirectory()) {
            ret.addAll(getSubFiles(tmp[i]));
        }
    }
    return ret;
}

private String getAbsFileName(String baseDir, File realFileName) {
    File real = realFileName;
    File base = new File(baseDir);
    String ret = real.getName();
    while (true) {
        real = real.getParentFile();
        if (real == null)
            break;
        if (real.equals(base))
            break;
        else {
            ret = real.getName() + "/" + ret;
        }
    }
    return ret;
}

代码首先判断源目录是否存在，然后获得它的文件列表，然后利用压缩目标文件的名称创建一个Zip输出流，将每个文件写到这个流中，从而完成整个压缩工作。