Java匹配文件流特定数据块方法

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本文链接： https://blog.csdn.net/qq_19734597/article/details/102568846

最近工作中涉及到匹配文件流，并替换其中数据块的内容，特此记录便于日后查阅，代码如下：

public static Map<String, Integer> search_pattern(byte[] content, byte[] pattern) {
    Integer content_len = content.length;
    Map<String, Integer> ret = Maps.newHashMap();
    Integer count = 0;
    for (int i = 16; i <= content_len; i++) {
        if ((content[i - 0x10] == pattern[0x00]) &&
                (content[i - 0x0f] == pattern[0x01]) &&
                (content[i - 0x0e] == pattern[0x02]) &&
                (content[i - 0x0d] == pattern[0x03]) &&
                (content[i - 0x0c] == pattern[0x04]) &&
                (content[i - 0x0b] == pattern[0x05]) &&
                (content[i - 0x0a] == pattern[0x06]) &&
                (content[i - 0x09] == pattern[0x07]) &&
                (content[i - 0x08] == pattern[0x08]) &&
                (content[i - 0x07] == pattern[0x09]) &&
                (content[i - 0x06] == pattern[0x0a]) &&
                (content[i - 0x05] == pattern[0x0b])
        ) {
            ret.put("pattern_len", (content[i - 0x04] << 24) + (content[i - 0x03] << 16) + (content[i - 0x02] << 8) + (content[i - 0x01]));
            if (ret.get("pattern_len") + i - 16 <= content_len) {
                ret.put("count", ++count);
                ret.put("pattern_offset", i - 16);
                i += ret.get("pattern_len") - 1;
            }
        }
    }
    return ret;
}

注意，上述数据块的字节大小必须是 16 的倍数，否则需要 &0xFF

文件和byte数组转换，代码如下：

/**
 * 将文件转为byte数组
 *
 * @param filename
 * @return byte[]
 * @author zxzhang
 * @date 2019/10/8
 */
public static byte[] file2ByteArray(String filename) throws IOException {

    FileChannel fc = null;
    try {
        fc = new RandomAccessFile(filename, "r").getChannel();
        MappedByteBuffer byteBuffer = fc.map(FileChannel.MapMode.READ_ONLY, 0,
                fc.size()).load();
        byte[] result = new byte[(int) fc.size()];
        if (byteBuffer.remaining() > 0) {
            byteBuffer.get(result, 0, byteBuffer.remaining());
        }
        return result;
    } catch (IOException e) {
        e.printStackTrace();
        throw e;
    } finally {
        try {
            fc.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

/**
 * 将Byte数组转换成文件
 *
 * @param bytes
 * @param filePath
 * @param fileName
 * @return void
 * @author zxzhang
 * @date 2019/10/8
 */
public static void byteArray2File(byte[] bytes, String filePath, String fileName) {
    BufferedOutputStream bos = null;
    FileOutputStream fos = null;
    File file = null;
    try {
        File dir = new File(filePath);
        if (!dir.exists()) {// 判断文件目录是否存在
            dir.mkdirs();
        }
        file = new File(filePath + BootstrapConst.PATH_SEPARATOR + fileName);
        fos = new FileOutputStream(file);
        bos = new BufferedOutputStream(fos);
        bos.write(bytes);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (bos != null) {
            try {
                bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (fos != null) {
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}