java - 为什么从字节数组而非 InputStream 创建 Message.Builder 时会收到 InvalidProtocolBufferException？

Question

我正在处理 Servlet 并尝试记录请求。导致错误的代码的关键部分如下:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    StringWriter writer = new StringWriter();
    IOUtils.copy(request.getInputStream(), writer);
    Message.Builder builder = something of type com.google.protobuf.GeneratedMessage.Builder;
    builder.mergeFrom(writer.toString().getBytes());
}

上面最后一行代码导致以下异常:

com.google.protobuf.InvalidProtocolBufferException: Protocol message tag had invalid wire type.

但是，当代码切换为:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    Message.Builder builder = something of type com.google.protobuf.GeneratedMessage.Builder;
    builder.mergeFrom(request.getInputStream());
}

没有错误，一切正常。可能是什么问题？我似乎需要类似于第一个代码片段的东西，因为我需要第二次使用输入流(一次将其写入文件，一次处理实际请求)。

Answer 1

这个怎么样？

InputStream inputStream = request.getInputStream();

byte[] data = IOUtils.toByteArray(inputStream);
Message.Builder builder = something of type com.google.protobuf.GeneratedMessage.Builder;
builder.mergeFrom(data);

// then use inputStream for something else