注释其实很详细。
Parsing
代码语言：javascript复制/*
使用从给定输入流解析的协议缓冲区填充消息。读取错误或输入格式错误时返回false。
成功返回并不表示整个输入已使用，请确保调用ConsumedEntireMessage（）检查是否已使用（如果适用）。
*/
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromCodedStream(
io::CodedInputStream* input);
//跟上面那个功能一样，不过允许 repeated 部分不填充，后面遇到Partial都是这个意思
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromCodedStream(
io::CodedInputStream* input);
// 从给定的零拷贝输入流读取协议缓冲区。如果成功，将使用整个输入。
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromZeroCopyStream(
io::ZeroCopyInputStream* input);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromZeroCopyStream(
io::ZeroCopyInputStream* input);
// Parse a protocol buffer from a file descriptor. If successful, the entire
// input will be consumed.
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromFileDescriptor(
int file_descriptor);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromFileDescriptor(
int file_descriptor);
// Parse a protocol buffer from a C istream. If successful, the entire
// input will be consumed.
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromIstream(std::istream* input);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromIstream(
std::istream* input);
// Read a protocol buffer from the given zero-copy input stream, expecting
// the message to be exactly "size" bytes long. If successful, exactly
// this many bytes will have been consumed from the input.
bool MergePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input,
int size);
// Like ParseFromBoundedZeroCopyStream(), but accepts messages that are
// missing required fields.
bool MergeFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromBoundedZeroCopyStream(
io::ZeroCopyInputStream* input, int size);
// Like ParseFromBoundedZeroCopyStream(), but accepts messages that are
// missing required fields.
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromBoundedZeroCopyStream(
io::ZeroCopyInputStream* input, int size);
// Parses a protocol buffer contained in a string. Returns true on success.
// This function takes a string in the (non-human-readable) binary wire
// format, matching the encoding output by MessageLite::SerializeToString().
// If you'd like to convert a human-readable string into a protocol buffer
// object, see google::protobuf::TextFormat::ParseFromString().
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromString(ConstStringParam data);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromString(
ConstStringParam data);
// Parse a protocol buffer contained in an array of bytes.
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromArray(const void* data,
int size);
PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromArray(const void* data,
int size);
// Reads a protocol buffer from the stream and merges it into this
// Message. Singular fields read from the what is
// already in the Message and repeated fields are appended to those
// already present.
//
// It is the responsibility of the caller to call input->LastTagWas()
// (for groups) or input->ConsumedEntireMessage() (for non-groups) after
// this returns to verify that the message's end was delimited correctly.
//
// ParseFromCodedStream() is implemented as Clear() followed by
// MergeFromCodedStream().
bool MergeFromCodedStream(io::CodedInputStream* input);
// Like MergeFromCodedStream(), but succeeds even if required fields are
// missing in the input.
//
// MergeFromCodedStream() is just implemented as MergePartialFromCodedStream()
// followed by IsInitialized().
bool MergePartialFromCodedStream(io::CodedInputStream* input);
// Merge a protocol buffer contained in a string.
bool MergeFromString(ConstStringParam data);Serialization
Methods for serializing in protocol buffer format. Most of these are just simple wrappers around ByteSize() and SerializeWithCachedSizes().
代码语言：javascript复制 // Write a protocol buffer of this message to the given output. Returns
// false on a write error. If the message is missing required fields,
// this may GOOGLE_CHECK-fail.
bool SerializeToCodedStream(io::CodedOutputStream* output) const;
bool SerializePartialToCodedStream(io::CodedOutputStream* output) const;
// Write the message to the given zero-copy output stream. All required
// fields must be set.
bool SerializeToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
// Serialize the message and store it in the given string. All required
// fields must be set.
bool SerializeToString(std::string* output) const;
bool SerializePartialToString(std::string* output) const;
// Serialize the message and store it in the given byte array. All required
// fields must be set.
bool SerializeToArray(void* data, int size) const;
bool SerializePartialToArray(void* data, int size) const;
// Make a string encoding the message. Is equivalent to calling
// SerializeToString() on a string and using that. Returns the empty
// string if SerializeToString() would have returned an error.
// Note: If you intend to generate many such strings, you may
// reduce heap fragmentation by instead re-using the same string
// object with calls to SerializeToString().
std::string SerializeAsString() const;
std::string SerializePartialAsString() const;
// Serialize the message and write it to the given file descriptor. All
// required fields must be set.
bool SerializeToFileDescriptor(int file_descriptor) const;
bool SerializePartialToFileDescriptor(int file_descriptor) const;
// Serialize the message and write it to the given C ostream. All
// required fields must be set.
bool SerializeToOstream(std::ostream* output) const;
bool SerializePartialToOstream(std::ostream* output) const;
// Like SerializeToString(), but appends to the data to the string's
// existing contents. All required fields must be set.
bool AppendToString(std::string* output) const;
// Like AppendToString(), but allows missing required fields.
bool AppendPartialToString(std::string* output) const;
// Computes the serialized size of the message. This recursively calls
// ByteSizeLong() on all embedded messages.
//
// ByteSizeLong() is generally linear in the number of fields defined for the
// proto.
virtual size_t ByteSizeLong() const = 0;
// Legacy ByteSize() API.
PROTOBUF_DEPRECATED_MSG("Please use ByteSizeLong() instead")
int ByteSize() const { return internal::ToIntSize(ByteSizeLong()); }
// Serializes the message without recomputing the size. The message must not
// have changed since the last call to ByteSize(), and the value returned by
// ByteSize must be non-negative. Otherwise the results are undefined.
void SerializeWithCachedSizes(io::CodedOutputStream* output) const {
output->SetCur(_InternalSerialize(output->Cur(), output->EpsCopy()));
}
// Functions below here are not part of the public interface. It isn't
// enforced, but they should be treated as private, and will be private
// at some future time. Unfortunately the implementation of the "friend"
// keyword in GCC is broken at the moment, but we expect it will be fixed.
// Like SerializeWithCachedSizes, but writes directly to *target, returning
// a pointer to the byte immediately after the last byte written. "target"
// must point at a byte array of at least ByteSize() bytes. Whether to use
// deterministic serialization, e.g., maps in sorted order, is determined by
// CodedOutputStream::IsDefaultSerializationDeterministic().
uint8_t* SerializeWithCachedSizesToArray(uint8_t* target) const;
// Returns the result of the last call to ByteSize(). An embedded message's
// size is needed both to serialize it (because embedded messages are
// length-delimited) and to compute the outer message's size. Caching
// the size avoids computing it multiple times.
//
// ByteSize() does not automatically use the cached size when available
// because this would require invalidating it every time the message was
// modified, which would be too hard and expensive. (E.g. if a deeply-nested
// sub-message is changed, all of its parents' cached sizes would need to be
// invalidated, which is too much work for an otherwise inlined setter
// method.)
virtual int GetCachedSize() const = 0;卷好睡觉。。
