如何将字符串反序列化为Java对象

Question

我尝试从一个用于存储Spring会话的Redis服务器反序列化String到Java对象，并且我想在Spring框架之外反序列化它。我认为Spring Redis序列化器可能使用默认字符集UTF-8来将Java对象序列化为字符串。

Redis中的字符串：

private static void scanKeys(Jedis jedis, String prefix, String hashKey)
        throws IOException, ClassNotFoundException {
    Set<String> keys = jedis.keys(prefix + "*");

    for (String key : keys) {
        if (!key.contains("expir")) {
            Map<String, String> sessionMap = jedis.hgetAll(key);

            for (Entry<String, String> entry : sessionMap.entrySet()) {

                if (entry.getValue() != null && entry.getKey().equals(hashKey)) {
                    System.out.println(entry.getKey());
                    System.out.println(entry.getValue());

                    byte[] output = entry.getValue().getBytes(charset);
                    System.out.println(Arrays.toString(output));    
                    try {
                        Long id = (Long) deserialize(output);
                        System.out.println(id);
                    } catch (EOFException e) {
                        break;
                    }
                }
            }

        }

    }
}

public static Object deserialize(byte[] data) throws IOException, ClassNotFoundException {
    ByteArrayInputStream in = new ByteArrayInputStream(data);
    ObjectInputStream is = new ObjectInputStream(in);
    return is.readObject();
}

错误消息：

java.io.StreamCorruptedException: invalid stream header: EFBFBDEF
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:862)
    at java.io.ObjectInputStream.<init>(ObjectInputStream.java:354)
    at practice.redis.jedis.App.deserialize(App.java:191)
    at practice.redis.jedis.App.scanKeys(App.java:168)
    at practice.redis.jedis.App.main(App.java:77)

我知道用UTF-8在Byte[]和String之间的转换很可能是问题所在，但我还是想问一下，是否有人知道如何在不修改序列化部分的情况下解决这个问题。

Answer 1

我建议您自己解析字符串。它看起来像是转义和未转义字节的简单序列。

String value = "\\xAC\\xED\\x00\\x05sr\\x00\\x0Ejava.lang.Long;\\x8B\\xE4\\x90\\xCC\\x8F#\\xDF\\x02\\x00\\x01J\\x00\\x05valuexr\\x00\\x10java.lang.Number\\x86\\xAC\\x95\\x1D\\x0B\\x94\\xE0\\x8B\\x02\\x00\\x00xp\\x00\\x00\\x00\\x00\\x00\\x00\\xD7";

try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()) {
    int i = 0;
    while (i < value.length()) {
        char ch = value.charAt(i);
        if (ch == '\\') {
            if (value.charAt(i + 1) != 'x') {
                throw new UnsupportedOperationException();
            }
            String hex = value.substring(i + 2, i + 4);
            byteArrayOutputStream.write(Integer.parseInt(hex, 16) & 0xFF);
            i += 4;
        } else {
            byteArrayOutputStream.write(ch);
            i++;
        }
    }

    byte[] output = byteArrayOutputStream.toByteArray();
    Long id = (Long) deserialize(output);
    System.out.println(id);
}