com.google.protobuf.CodedInputStream# pushLimit ( ) 源码实例Demo

private static String getCompiledFileMd5(File file) {
    String md5;
    try (InputStream is = new BufferedInputStream(new FileInputStream(file))) {
        CodedInputStream codedInputStream = CodedInputStream.newInstance(is);
        int numFiles = codedInputStream.readRawLittleEndian32();
        // Preconditions.checkState(numFiles == 1, "inline xml not implemented yet");
        long pbSize = codedInputStream.readRawLittleEndian64();
        codedInputStream.pushLimit((int)pbSize);
        CompiledFile compiledFile = CompiledFile.parser().parsePartialFrom(codedInputStream);
        md5 = MD5Util.getFileMD5(compiledFile.getSourcePath());
        // codedInputStream.popLimit((int)pbSize);
        // codedInputStream.pushLimit(0);
        return md5;
    } catch (IOException e) {
        throw new UncheckedIOException(e);
    }
}
 

/**
 * Parses the field.
 *
 * @param <T> the generic type
 * @param input the input
 * @param extensionRegistry the extension registry
 * @param type the type
 * @param value the value
 * @return the t
 * @throws IOException Signals that an I/O exception has occurred.
 */
@SuppressWarnings("unchecked")
static <T> T parseField(CodedInputStream input, ExtensionRegistryLite extensionRegistry, WireFormat.FieldType type,
        T value) throws IOException {
    switch (type) {
        case MESSAGE:
            int length = input.readRawVarint32();
            final int oldLimit = input.pushLimit(length);
            Codec<? extends Object> codec = ProtobufProxy.create(value.getClass());
            T ret = (T) codec.decode(input.readRawBytes(length));
            input.popLimit(oldLimit);
            return ret;
        case ENUM:
            return (T) (java.lang.Integer) input.readEnum();
        case GROUP:
            throw new RuntimeException("Groups are not allowed in maps.");
        default:
            return (T) CodedConstant.readPrimitiveField(input, type, true);
    }
}
 

private OnlineSectioningLog.ExportedLog readLog(CodedInputStream cin) throws IOException {
	if (cin.isAtEnd()) return null;
	int size = cin.readInt32();
	int limit = cin.pushLimit(size);
	OnlineSectioningLog.ExportedLog ret = OnlineSectioningLog.ExportedLog.parseFrom(cin);
	cin.popLimit(limit);
	cin.resetSizeCounter();
	return ret;
}
 

public static TableData.Table readTable(CodedInputStream cin) throws IOException {
	if (cin.isAtEnd()) return null;
	int size = cin.readInt32();
	int limit = cin.pushLimit(size);
	TableData.Table ret = TableData.Table.parseFrom(cin);
	cin.popLimit(limit);
	cin.resetSizeCounter();
	return ret;
}
 

/**
 * Parses an entry off of the input into the map. This helper avoids allocaton of a {@link MapEntryLite} by parsing
 * directly into the provided {@link MapFieldLite}.
 *
 * @param map the map
 * @param input the input
 * @param extensionRegistry the extension registry
 * @throws IOException Signals that an I/O exception has occurred.
 */
public void parseInto(MapFieldLite<K, V> map, CodedInputStream input, ExtensionRegistryLite extensionRegistry)
        throws IOException {
    int length = input.readRawVarint32();
    final int oldLimit = input.pushLimit(length);
    K key = metadata.defaultKey;
    V value = metadata.defaultValue;

    while (true) {
        int tag = input.readTag();
        if (tag == 0) {
            break;
        }
        if (tag == CodedConstant.makeTag(KEY_FIELD_NUMBER, metadata.keyType.getWireType())) {
            key = parseField(input, extensionRegistry, metadata.keyType, key);
        } else if (tag == CodedConstant.makeTag(VALUE_FIELD_NUMBER, metadata.valueType.getWireType())) {
            value = parseField(input, extensionRegistry, metadata.valueType, value);
        } else {
            if (!input.skipField(tag)) {
                break;
            }
        }
    }

    input.checkLastTagWas(0);
    input.popLimit(oldLimit);
    map.put(key, value);
}
 

@NonNull
@Override
public FileDataSource loadData(InputStream inputStream, String filePath) throws Exception {
    long propertiesOffset = 0L;
    Track track = new Track();
    CodedInputStream input = CodedInputStream.newInstance(inputStream);
    boolean done = false;
    while (!done) {
        long offset = input.getTotalBytesRead();
        int tag = input.readTag();
        int field = WireFormat.getTagFieldNumber(tag);
        switch (field) {
            case 0:
                done = true;
                break;
            default: {
                throw new com.google.protobuf.InvalidProtocolBufferException("Unsupported proto field: " + tag);
            }
            case FIELD_VERSION: {
                // skip version
                input.skipField(tag);
                break;
            }
            case FIELD_POINT: {
                int length = input.readRawVarint32();
                int oldLimit = input.pushLimit(length);
                readPoint(track, input);
                input.popLimit(oldLimit);
                input.checkLastTagWas(0);
                break;
            }
            case FIELD_NAME: {
                propertiesOffset = offset;
                track.name = input.readBytes().toStringUtf8();
                break;
            }
            case FIELD_COLOR: {
                track.style.color = input.readUInt32();
                break;
            }
            case FIELD_WIDTH: {
                track.style.width = input.readFloat();
                break;
            }
        }
    }
    inputStream.close();
    track.id = 31 * filePath.hashCode() + 1;
    FileDataSource dataSource = new FileDataSource();
    dataSource.name = track.name;
    dataSource.tracks.add(track);
    track.source = dataSource;
    dataSource.propertiesOffset = propertiesOffset;
    return dataSource;
}