Android工具类之GZip

最新推荐文章于 2024-04-13 18:10:15 发布

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最新推荐文章于 2024-04-13 18:10:15 发布

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文章标签： Android GZip

本文链接：https://blog.youkuaiyun.com/u012758497/article/details/90812583

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本文详细探讨了Android中GZip压缩工具类的使用，包括如何进行数据压缩和解压缩，以及在实际开发中如何优化性能。通过实例代码解析，阐述了GZip在Android应用中的关键操作和注意事项。

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public class GzipUtil {

    public static final String GZIP_ENCODE_UTF_8 = "UTF-8";

    public static final String GZIP_ENCODE_ISO_8859_1 = "ISO-8859-1";
    private static final char ARRAY_LEFT = '[';
    private static final char ARRAY_RIGHT = ']';

    public static String compressString(String str) {
        byte[] temp = compress(str);
        return Arrays.toString(temp);
    }

    public static byte[] compress(String str) {
        return compress(str, GZIP_ENCODE_UTF_8);
    }

    /**
     * 字符串压缩为GZIP字节数组
     * @param str
     * @param encoding
     * @return
     */
    public static byte[] compress(String str, String encoding) {
        if (str == null || str.length() == 0) {
            return null;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        GZIPOutputStream gzip;
        try {
            gzip = new GZIPOutputStream(out);
            gzip.write(str.getBytes(encoding));
            gzip.close();
        } catch (IOException e) {
            Log.e("gzip compress error.", e.getMessage());
        }
        return out.toByteArray();
    }

    /**
     * Gzip  byte[] 解压成字符串
     * @param bytes
     * @return
     */
    public static String uncompressToString(byte[] bytes) {
        return uncompressToString(bytes, GZIP_ENCODE_UTF_8);
    }


    /**
     * Gzip  byte[] 解压成字符串
     * @param bytes
     * @param encoding
     * @return
     */
    public static String uncompressToString(byte[] bytes, String encoding) {
        if (bytes == null || bytes.length == 0) {
            return null;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        ByteArrayInputStream in = new ByteArrayInputStream(bytes);
        try {
            GZIPInputStream ungzip = new GZIPInputStream(in);
            byte[] buffer = new byte[256];
            int n;
            while ((n = ungzip.read(buffer)) >= 0) {
                out.write(buffer, 0, n);
            }
            return out.toString(encoding);
        } catch (IOException e) {
            Log.e("gzip compress error.",e.getMessage());
        }
        return null;
    }

    /**
     * 判断byte[]是否是Gzip格式
     * @param data
     * @return
     */
    public static boolean isGzip(byte[] data) {
        int header = (int)((data[0]<<8) | data[1]&0xFF);
        return header == 0x1f8b;
    }

    /**
     * 获取解压缩的字符串
     * @param str 压缩的字符串
     * @return 解压的字符串
     */
    public static String getUncompressedStr(String str) {
        return uncompressToString(getByteArrayFromString(str));
    }

    private static byte[] getByteArrayFromString(String bytesString) {
        int length = bytesString.length();
        byte[] res = null;
        if (bytesString.charAt(0) == ARRAY_LEFT && bytesString.charAt(length - 1) == ARRAY_RIGHT) {
            String substring = bytesString.substring(1, length - 1);
            String[] temp = substring.split(",");
            res = new byte[temp.length];
            for (int i=0; i<temp.length; i++) {
                res[i] = Byte.parseByte(temp[i].trim());
            }
        }
        return res;
    }

}