compress | decompress| read | write file and decode | encode

最新推荐文章于 2025-04-01 22:25:35 发布

liliugen

最新推荐文章于 2025-04-01 22:25:35 发布

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分类专栏： Java核心技术文章标签： Java OS

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本文介绍了一系列用于文件压缩及对象序列化的实用方法，包括将字节数组压缩为.gz文件、从.gz文件中解压获取原始字节数组、Base64编码与解码字符串、将对象存储到磁盘文件以及从磁盘文件读取对象等。这些方法适用于Java应用程序的数据处理。

public static File compressFile(byte[] buff, String fileName)
    {
        if (buff == null || fileName == null)
            return null;

        try
        {

            File zipFile = new File(fileName+".gz");

            GZIPOutputStream os = new GZIPOutputStream(new FileOutputStream(zipFile));

            BufferedInputStream is = new BufferedInputStream(new ByteArrayInputStream(buff));
            int count;
            byte data[] = new byte[1024];
            while ((count = is.read(data, 0, 1024)) != -1)
            {
                os.write(data, 0, count);
            }
            is.close();
            os.close();

            return zipFile;
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        return null;
    }

    public static byte[] decompressFile(File zipFile)
    {
        if (!zipFile.exists())
            return null;

        try
        {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            GZIPInputStream is = new GZIPInputStream(new FileInputStream(zipFile));

            int count;
            byte data[] = new byte[1024];
            while ((count = is.read(data, 0, 1024)) != -1)
            {
                baos.write(data, 0, count);
            }
            is.close();

            byte[] buff = baos.toByteArray();

            baos.close();

            return buff;
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        return null;
    }

    public static String getBase64(String str)
    {
        if (str == null)
            return null;

        try
        {
            return BASE64_ENCODER.encode(str.getBytes("UTF-8"));
        }
        catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }
        return null;
    }


    public static String reverseFromBase64(String base64Str)
    {
        if (base64Str == null)
            return null;

        try
        {
            return new String(BASE64_DECODER.decodeBuffer(base64Str),"UTF-8");
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        return null;
    }

    // store  an object to the file of the disk 
    public static void storeToDisk(Serializable object, File file)
    {
        java.io.ObjectOutputStream outputStream;
        try
        {
            if (!file.getParentFile().exists())
                file.getParentFile().mkdirs();

            outputStream = new java.io.ObjectOutputStream(
                            new java.io.FileOutputStream(file));
            outputStream.writeObject(object);
            outputStream.close();
        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
      // get an object from the file of the disk 
    public static Serializable getObjectFromDisk(File file)
    {
        java.io.ObjectInputStream inputStream;
        try
        {
            inputStream = new java.io.ObjectInputStream(
                            new java.io.FileInputStream(file));
            Object obj = inputStream.readObject();
            inputStream.close();
            return (Serializable) obj;
        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (ClassNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

    /**
     * Write the context into the given file.
     * 
     * @param context
     *            The context.
     * @param theFileName
     *            The file name to write to.
     * @throws IOException
     *             Exception when create the file.
     */
    public static void writeToFile(String context, String theFileName)
                    throws IOException
    {

        if (theFileName != null && !"".equals(theFileName.trim()))
        {
            createFilePath(theFileName);
            BufferedWriter aWriter = new BufferedWriter(new FileWriter(
                            theFileName));
            aWriter.write(context);
            aWriter.close();
        }
        else
        {
            throw new IllegalArgumentException("Invalid file name!");
        }
    }

    public static void createFilePath(String fileName)
    {
        createFilePath(new File(fileName));
    }

    public static void createFilePath(File file)
    {
        if (!file.getParentFile().exists())
        {
            file.getParentFile().mkdirs();
        }

    }