com.google.protobuf
Class CodedInputStream

java.lang.Object
  extended by com.google.protobuf.CodedInputStream

public final class CodedInputStream
extends Object

Reads and decodes protocol message fields. This class contains two kinds of methods: methods that read specific protocol message constructs and field types (e.g. readTag() and readInt32()) and methods that read low-level values (e.g. readRawVarint32() and readRawBytes(int)). If you are reading encoded protocol messages, you should use the former methods, but if you are reading some other format of your own design, use the latter.


Method Summary
 void checkLastTagWas(int value)
          Verifies that the last call to readTag() returned the given tag value.
static int decodeZigZag32(int n)
          Decode a ZigZag-encoded 32-bit value.
static long decodeZigZag64(long n)
          Decode a ZigZag-encoded 64-bit value.
 int getBytesUntilLimit()
          Returns the number of bytes to be read before the current limit.
 int getTotalBytesRead()
          The total bytes read up to the current position.
 boolean isAtEnd()
          Returns true if the stream has reached the end of the input.
static CodedInputStream newInstance(byte[] buf)
          Create a new CodedInputStream wrapping the given byte array.
static CodedInputStream newInstance(byte[] buf, int off, int len)
          Create a new CodedInputStream wrapping the given byte array slice.
static CodedInputStream newInstance(InputStream input)
          Create a new CodedInputStream wrapping the given InputStream.
 void popLimit(int oldLimit)
          Discards the current limit, returning to the previous limit.
 int pushLimit(int byteLimit)
          Sets currentLimit to (current position) + byteLimit.
 boolean readBool()
          Read a bool field value from the stream.
 ByteString readBytes()
          Read a bytes field value from the stream.
 double readDouble()
          Read a double field value from the stream.
 int readEnum()
          Read an enum field value from the stream.
 int readFixed32()
          Read a fixed32 field value from the stream.
 long readFixed64()
          Read a fixed64 field value from the stream.
 float readFloat()
          Read a float field value from the stream.
 void readGroup(int fieldNumber, MessageLite.Builder builder, ExtensionRegistryLite extensionRegistry)
          Read a group field value from the stream.
<T extends MessageLite>
T
readGroup(int fieldNumber, Parser<T> parser, ExtensionRegistryLite extensionRegistry)
          Read a group field value from the stream.
 int readInt32()
          Read an int32 field value from the stream.
 long readInt64()
          Read an int64 field value from the stream.
 void readMessage(MessageLite.Builder builder, ExtensionRegistryLite extensionRegistry)
          Read an embedded message field value from the stream.
<T extends MessageLite>
T
readMessage(Parser<T> parser, ExtensionRegistryLite extensionRegistry)
          Read an embedded message field value from the stream.
 byte readRawByte()
          Read one byte from the input.
 byte[] readRawBytes(int size)
          Read a fixed size of bytes from the input.
 int readRawLittleEndian32()
          Read a 32-bit little-endian integer from the stream.
 long readRawLittleEndian64()
          Read a 64-bit little-endian integer from the stream.
 int readRawVarint32()
          Read a raw Varint from the stream.
static int readRawVarint32(int firstByte, InputStream input)
          Like readRawVarint32(InputStream), but expects that the caller has already read one byte.
 long readRawVarint64()
          Read a raw Varint from the stream.
 int readSFixed32()
          Read an sfixed32 field value from the stream.
 long readSFixed64()
          Read an sfixed64 field value from the stream.
 int readSInt32()
          Read an sint32 field value from the stream.
 long readSInt64()
          Read an sint64 field value from the stream.
 String readString()
          Read a string field value from the stream.
 int readTag()
          Attempt to read a field tag, returning zero if we have reached EOF.
 int readUInt32()
          Read a uint32 field value from the stream.
 long readUInt64()
          Read a uint64 field value from the stream.
 void readUnknownGroup(int fieldNumber, MessageLite.Builder builder)
          Deprecated. UnknownFieldSet.Builder now implements MessageLite.Builder, so you can just call readGroup(int, com.google.protobuf.MessageLite.Builder, com.google.protobuf.ExtensionRegistryLite).
 void resetSizeCounter()
          Resets the current size counter to zero (see setSizeLimit(int)).
 int setRecursionLimit(int limit)
          Set the maximum message recursion depth.
 int setSizeLimit(int limit)
          Set the maximum message size.
 boolean skipField(int tag)
          Reads and discards a single field, given its tag value.
 void skipMessage()
          Reads and discards an entire message.
 void skipRawBytes(int size)
          Reads and discards size bytes.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

newInstance

public static CodedInputStream newInstance(InputStream input)
Create a new CodedInputStream wrapping the given InputStream.


newInstance

public static CodedInputStream newInstance(byte[] buf)
Create a new CodedInputStream wrapping the given byte array.


newInstance

public static CodedInputStream newInstance(byte[] buf,
                                           int off,
                                           int len)
Create a new CodedInputStream wrapping the given byte array slice.


readTag

public int readTag()
            throws IOException
Attempt to read a field tag, returning zero if we have reached EOF. Protocol message parsers use this to read tags, since a protocol message may legally end wherever a tag occurs, and zero is not a valid tag number.

Throws:
IOException

checkLastTagWas

public void checkLastTagWas(int value)
                     throws InvalidProtocolBufferException
Verifies that the last call to readTag() returned the given tag value. This is used to verify that a nested group ended with the correct end tag.

Throws:
InvalidProtocolBufferException - value does not match the last tag.

skipField

public boolean skipField(int tag)
                  throws IOException
Reads and discards a single field, given its tag value.

Returns:
false if the tag is an endgroup tag, in which case nothing is skipped. Otherwise, returns true.
Throws:
IOException

skipMessage

public void skipMessage()
                 throws IOException
Reads and discards an entire message. This will read either until EOF or until an endgroup tag, whichever comes first.

Throws:
IOException

readDouble

public double readDouble()
                  throws IOException
Read a double field value from the stream.

Throws:
IOException

readFloat

public float readFloat()
                throws IOException
Read a float field value from the stream.

Throws:
IOException

readUInt64

public long readUInt64()
                throws IOException
Read a uint64 field value from the stream.

Throws:
IOException

readInt64

public long readInt64()
               throws IOException
Read an int64 field value from the stream.

Throws:
IOException

readInt32

public int readInt32()
              throws IOException
Read an int32 field value from the stream.

Throws:
IOException

readFixed64

public long readFixed64()
                 throws IOException
Read a fixed64 field value from the stream.

Throws:
IOException

readFixed32

public int readFixed32()
                throws IOException
Read a fixed32 field value from the stream.

Throws:
IOException

readBool

public boolean readBool()
                 throws IOException
Read a bool field value from the stream.

Throws:
IOException

readString

public String readString()
                  throws IOException
Read a string field value from the stream.

Throws:
IOException

readGroup

public void readGroup(int fieldNumber,
                      MessageLite.Builder builder,
                      ExtensionRegistryLite extensionRegistry)
               throws IOException
Read a group field value from the stream.

Throws:
IOException

readGroup

public <T extends MessageLite> T readGroup(int fieldNumber,
                                           Parser<T> parser,
                                           ExtensionRegistryLite extensionRegistry)
                                throws IOException
Read a group field value from the stream.

Throws:
IOException

readUnknownGroup

@Deprecated
public void readUnknownGroup(int fieldNumber,
                                        MessageLite.Builder builder)
                      throws IOException
Deprecated. UnknownFieldSet.Builder now implements MessageLite.Builder, so you can just call readGroup(int, com.google.protobuf.MessageLite.Builder, com.google.protobuf.ExtensionRegistryLite).

Reads a group field value from the stream and merges it into the given UnknownFieldSet.

Throws:
IOException

readMessage

public void readMessage(MessageLite.Builder builder,
                        ExtensionRegistryLite extensionRegistry)
                 throws IOException
Read an embedded message field value from the stream.

Throws:
IOException

readMessage

public <T extends MessageLite> T readMessage(Parser<T> parser,
                                             ExtensionRegistryLite extensionRegistry)
                                  throws IOException
Read an embedded message field value from the stream.

Throws:
IOException

readBytes

public ByteString readBytes()
                     throws IOException
Read a bytes field value from the stream.

Throws:
IOException

readUInt32

public int readUInt32()
               throws IOException
Read a uint32 field value from the stream.

Throws:
IOException

readEnum

public int readEnum()
             throws IOException
Read an enum field value from the stream. Caller is responsible for converting the numeric value to an actual enum.

Throws:
IOException

readSFixed32

public int readSFixed32()
                 throws IOException
Read an sfixed32 field value from the stream.

Throws:
IOException

readSFixed64

public long readSFixed64()
                  throws IOException
Read an sfixed64 field value from the stream.

Throws:
IOException

readSInt32

public int readSInt32()
               throws IOException
Read an sint32 field value from the stream.

Throws:
IOException

readSInt64

public long readSInt64()
                throws IOException
Read an sint64 field value from the stream.

Throws:
IOException

readRawVarint32

public int readRawVarint32()
                    throws IOException
Read a raw Varint from the stream. If larger than 32 bits, discard the upper bits.

Throws:
IOException

readRawVarint32

public static int readRawVarint32(int firstByte,
                                  InputStream input)
                           throws IOException
Like readRawVarint32(InputStream), but expects that the caller has already read one byte. This allows the caller to determine if EOF has been reached before attempting to read.

Throws:
IOException

readRawVarint64

public long readRawVarint64()
                     throws IOException
Read a raw Varint from the stream.

Throws:
IOException

readRawLittleEndian32

public int readRawLittleEndian32()
                          throws IOException
Read a 32-bit little-endian integer from the stream.

Throws:
IOException

readRawLittleEndian64

public long readRawLittleEndian64()
                           throws IOException
Read a 64-bit little-endian integer from the stream.

Throws:
IOException

decodeZigZag32

public static int decodeZigZag32(int n)
Decode a ZigZag-encoded 32-bit value. ZigZag encodes signed integers into values that can be efficiently encoded with varint. (Otherwise, negative values must be sign-extended to 64 bits to be varint encoded, thus always taking 10 bytes on the wire.)

Parameters:
n - An unsigned 32-bit integer, stored in a signed int because Java has no explicit unsigned support.
Returns:
A signed 32-bit integer.

decodeZigZag64

public static long decodeZigZag64(long n)
Decode a ZigZag-encoded 64-bit value. ZigZag encodes signed integers into values that can be efficiently encoded with varint. (Otherwise, negative values must be sign-extended to 64 bits to be varint encoded, thus always taking 10 bytes on the wire.)

Parameters:
n - An unsigned 64-bit integer, stored in a signed int because Java has no explicit unsigned support.
Returns:
A signed 64-bit integer.

setRecursionLimit

public int setRecursionLimit(int limit)
Set the maximum message recursion depth. In order to prevent malicious messages from causing stack overflows, CodedInputStream limits how deeply messages may be nested. The default limit is 64.

Returns:
the old limit.

setSizeLimit

public int setSizeLimit(int limit)
Set the maximum message size. In order to prevent malicious messages from exhausting memory or causing integer overflows, CodedInputStream limits how large a message may be. The default limit is 64MB. You should set this limit as small as you can without harming your app's functionality. Note that size limits only apply when reading from an InputStream, not when constructed around a raw byte array (nor with ByteString.newCodedInput()).

If you want to read several messages from a single CodedInputStream, you could call resetSizeCounter() after each one to avoid hitting the size limit.

Returns:
the old limit.

resetSizeCounter

public void resetSizeCounter()
Resets the current size counter to zero (see setSizeLimit(int)).


pushLimit

public int pushLimit(int byteLimit)
              throws InvalidProtocolBufferException
Sets currentLimit to (current position) + byteLimit. This is called when descending into a length-delimited embedded message.

Note that pushLimit() does NOT affect how many bytes the CodedInputStream reads from an underlying InputStream when refreshing its buffer. If you need to prevent reading past a certain point in the underlying InputStream (e.g. because you expect it to contain more data after the end of the message which you need to handle differently) then you must place a wrapper around your InputStream which limits the amount of data that can be read from it.

Returns:
the old limit.
Throws:
InvalidProtocolBufferException

popLimit

public void popLimit(int oldLimit)
Discards the current limit, returning to the previous limit.

Parameters:
oldLimit - The old limit, as returned by pushLimit.

getBytesUntilLimit

public int getBytesUntilLimit()
Returns the number of bytes to be read before the current limit. If no limit is set, returns -1.


isAtEnd

public boolean isAtEnd()
                throws IOException
Returns true if the stream has reached the end of the input. This is the case if either the end of the underlying input source has been reached or if the stream has reached a limit created using pushLimit(int).

Throws:
IOException

getTotalBytesRead

public int getTotalBytesRead()
The total bytes read up to the current position. Calling resetSizeCounter() resets this value to zero.


readRawByte

public byte readRawByte()
                 throws IOException
Read one byte from the input.

Throws:
InvalidProtocolBufferException - The end of the stream or the current limit was reached.
IOException

readRawBytes

public byte[] readRawBytes(int size)
                    throws IOException
Read a fixed size of bytes from the input.

Throws:
InvalidProtocolBufferException - The end of the stream or the current limit was reached.
IOException

skipRawBytes

public void skipRawBytes(int size)
                  throws IOException
Reads and discards size bytes.

Throws:
InvalidProtocolBufferException - The end of the stream or the current limit was reached.
IOException