// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package com.google.protobuf;
import static com.google.protobuf.Internal.checkNotNull;
import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
* Main runtime interface for protobuf. Applications should interact with this interface (rather
* than directly accessing internal APIs) in order to perform operations on protobuf messages.
*/
@ExperimentalApi
public final class Protobuf {
private static final Protobuf INSTANCE = new Protobuf();
private final SchemaFactory schemaFactory;
// TODO(nathanmittler): Consider using ClassValue instead.
private final ConcurrentMap<Class<?>, Schema<?>> schemaCache =
new ConcurrentHashMap<Class<?>, Schema<?>>();
/** Gets the singleton instance of the Protobuf runtime. */
public static Protobuf getInstance() {
return INSTANCE;
}
/** Writes the given message to the target {@link Writer}. */
public <T> void writeTo(T message, Writer writer) {
schemaFor(message).writeTo(message, writer);
}
/** Reads fields from the given {@link Reader} and merges them into the message. */
public <T> void mergeFrom(T message, Reader reader) throws IOException {
schemaFor(message).mergeFrom(message, reader);
}
/** Gets the schema for the given message type. */
public <T> Schema<T> schemaFor(Class<T> messageType) {
checkNotNull(messageType, "messageType");
@SuppressWarnings("unchecked")
Schema<T> schema = (Schema<T>) schemaCache.get(messageType);
if (schema == null) {
schema = schemaFactory.createSchema(messageType);
@SuppressWarnings("unchecked")
Schema<T> previous = (Schema<T>) registerSchema(messageType, schema);
if (previous != null) {
// A new schema was registered by another thread.
schema = previous;
}
}
return schema;
}
/** Gets the schema for the given message. */
@SuppressWarnings("unchecked")
public <T> Schema<T> schemaFor(T message) {
return schemaFor((Class<T>) message.getClass());
}
/**
* Registers the given schema for the message type only if a schema was not already registered.
*
* @param messageType the type of message on which the schema operates.
* @param schema the schema for the message type.
* @return the previously registered schema, or {@code null} if the given schema was successfully
* registered.
*/
public Schema<?> registerSchema(Class<?> messageType, Schema<?> schema) {
checkNotNull(messageType, "messageType");
checkNotNull(schema, "schema");
return schemaCache.putIfAbsent(messageType, schema);
}
/**
* Visible for testing only. Registers the given schema for the message type. If a schema was
* previously registered, it will be replaced by the provided schema.
*
* @param messageType the type of message on which the schema operates.
* @param schema the schema for the message type.
* @return the previously registered schema, or {@code null} if no schema was registered
* previously.
*/
public Schema<?> registerSchemaOverride(Class<?> messageType, Schema<?> schema) {
checkNotNull(messageType, "messageType");
checkNotNull(schema, "schema");
return schemaCache.put(messageType, schema);
}
private Protobuf() {
// TODO(nathanmittler): Detect the proper factory for the platform.
SchemaFactory factory = null;
for (String className :
new String[] {
"com.google.frameworks.protobuf.experimental.android.schema.AndroidProto3SchemaFactory",
// TODO(nathanmittler): Remove this once the code has been completely ported over.
"com.google.frameworks.protobuf.experimental.schema.generic.Proto3SchemaFactory",
"com.google.protobuf.Proto3SchemaFactory"
}) {
factory = newSchemaFactory(className);
if (factory != null) {
break;
}
}
if (factory == null) {
throw new IllegalStateException("Unable to locate a default SchemaFactory. Check classpath.");
}
schemaFactory = factory;
}
private static SchemaFactory newSchemaFactory(String className) {
try {
return (SchemaFactory) Class.forName(className).getConstructor().newInstance();
} catch (Throwable e) {
return null;
}
}
}