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Diffstat (limited to 'java/src/main/java/com/google/protobuf/MessageLite.java')
| -rw-r--r-- | java/src/main/java/com/google/protobuf/MessageLite.java | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/java/src/main/java/com/google/protobuf/MessageLite.java b/java/src/main/java/com/google/protobuf/MessageLite.java new file mode 100644 index 00000000..3001f360 --- /dev/null +++ b/java/src/main/java/com/google/protobuf/MessageLite.java @@ -0,0 +1,331 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// http://code.google.com/p/protobuf/ +// +// 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 +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// TODO(kenton): Use generics? E.g. Builder<BuilderType extends Builder>, then +// mergeFrom*() could return BuilderType for better type-safety. + +package com.google.protobuf; + +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; + +/** + * Abstract interface implemented by Protocol Message objects. + * + * <p>This interface is implemented by all protocol message objects. Most + * users will be more interested in the Message interface, which is a subclass + * of MessageLite. Use MessageLite instead when you only need the subset of + * features which it supports -- namely, nothing that uses descriptors or + * reflection. You can instruct the protocol compiler to generate classes + * which implement only MessageLite, not the full Message interface, by adding + * the follow line to the .proto file: + * <pre> + * option optimize_for = LITE_RUNTIME; + * </pre> + * + * <p>This is particularly useful on resource-constrained systems where the + * full protocol buffers runtime library is too big. + * + * <p>Note that on non-constrained systems (e.g. servers) when you need to link + * in lots of protocol definitions, a better way to reduce total code footprint + * is to use {@code optimize_for = CODE_SIZE}. This will make the generated + * code smaller while still supporting all the same features (at the expense of + * speed). {@code optimize_for = LITE_RUNTIME} is best when you only have a + * small number of message types linked into your binary, in which case the + * size of the protocol buffers runtime itself is the biggest problem. + * + * @author kenton@google.com Kenton Varda + */ +public interface MessageLite { + /** + * Get an instance of the type with all fields set to their default values. + * This may or may not be a singleton. This differs from the + * {@code getDefaultInstance()} method of generated message classes in that + * this method is an abstract method of the {@code MessageLite} interface + * whereas {@code getDefaultInstance()} is a static method of a specific + * class. They return the same thing. + */ + MessageLite getDefaultInstanceForType(); + + /** + * Returns true if all required fields in the message and all embedded + * messages are set, false otherwise. + */ + boolean isInitialized(); + + /** + * Serializes the message and writes it to {@code output}. This does not + * flush or close the stream. + */ + void writeTo(CodedOutputStream output) throws IOException; + + /** + * Get the number of bytes required to encode this message. The result + * is only computed on the first call and memoized after that. + */ + int getSerializedSize(); + + // ----------------------------------------------------------------- + // Convenience methods. + + /** + * Serializes the message to a {@code ByteString} and returns it. This is + * just a trivial wrapper around + * {@link #writeTo(CodedOutputStream)}. + */ + ByteString toByteString(); + + /** + * Serializes the message to a {@code byte} array and returns it. This is + * just a trivial wrapper around + * {@link #writeTo(CodedOutputStream)}. + */ + byte[] toByteArray(); + + /** + * Serializes the message and writes it to {@code output}. This is just a + * trivial wrapper around {@link #writeTo(CodedOutputStream)}. This does + * not flush or close the stream. + * <p> + * NOTE: Protocol Buffers are not self-delimiting. Therefore, if you write + * any more data to the stream after the message, you must somehow ensure + * that the parser on the receiving end does not interpret this as being + * part of the protocol message. This can be done e.g. by writing the size + * of the message before the data, then making sure to limit the input to + * that size on the receiving end (e.g. by wrapping the InputStream in one + * which limits the input). Alternatively, just use + * {@link #writeDelimitedTo(OutputStream)}. + */ + void writeTo(OutputStream output) throws IOException; + + /** + * Like {@link #writeTo(OutputStream)}, but writes the size of the message + * as a varint before writing the data. This allows more data to be written + * to the stream after the message without the need to delimit the message + * data yourself. Use {@link Builder#mergeDelimitedFrom(InputStream)} (or + * the static method {@code YourMessageType.parseDelimitedFrom(InputStream)}) + * to parse messages written by this method. + */ + void writeDelimitedTo(OutputStream output) throws IOException; + + // ================================================================= + // Builders + + /** + * Constructs a new builder for a message of the same type as this message. + */ + Builder newBuilderForType(); + + /** + * Constructs a builder initialized with the current message. Use this to + * derive a new message from the current one. + */ + Builder toBuilder(); + + /** + * Abstract interface implemented by Protocol Message builders. + */ + interface Builder extends Cloneable { + /** Resets all fields to their default values. */ + Builder clear(); + + /** + * Construct the final message. Once this is called, the Builder is no + * longer valid, and calling any other method will result in undefined + * behavior and may throw a NullPointerException. If you need to continue + * working with the builder after calling {@code build()}, {@code clone()} + * it first. + * @throws UninitializedMessageException The message is missing one or more + * required fields (i.e. {@link #isInitialized()} returns false). + * Use {@link #buildPartial()} to bypass this check. + */ + MessageLite build(); + + /** + * Like {@link #build()}, but does not throw an exception if the message + * is missing required fields. Instead, a partial message is returned. + * Once this is called, the Builder is no longer valid, and calling any + * will result in undefined behavior and may throw a NullPointerException. + * + * If you need to continue working with the builder after calling + * {@code buildPartial()}, {@code clone()} it first. + */ + MessageLite buildPartial(); + + /** + * Clones the Builder. + * @see Object#clone() + */ + Builder clone(); + + /** + * Returns true if all required fields in the message and all embedded + * messages are set, false otherwise. + */ + boolean isInitialized(); + + /** + * Parses a message of this type from the input and merges it with this + * message, as if using {@link Builder#mergeFrom(MessageLite)}. + * + * <p>Warning: This does not verify that all required fields are present in + * the input message. If you call {@link #build()} without setting all + * required fields, it will throw an {@link UninitializedMessageException}, + * which is a {@code RuntimeException} and thus might not be caught. There + * are a few good ways to deal with this: + * <ul> + * <li>Call {@link #isInitialized()} to verify that all required fields + * are set before building. + * <li>Parse the message separately using one of the static + * {@code parseFrom} methods, then use {@link #mergeFrom(MessageLite)} + * to merge it with this one. {@code parseFrom} will throw an + * {@link InvalidProtocolBufferException} (an {@code IOException}) + * if some required fields are missing. + * <li>Use {@code buildPartial()} to build, which ignores missing + * required fields. + * </ul> + * + * <p>Note: The caller should call + * {@link CodedInputStream#checkLastTagWas(int)} after calling this to + * verify that the last tag seen was the appropriate end-group tag, + * or zero for EOF. + */ + Builder mergeFrom(CodedInputStream input) throws IOException; + + /** + * Like {@link Builder#mergeFrom(CodedInputStream)}, but also + * parses extensions. The extensions that you want to be able to parse + * must be registered in {@code extensionRegistry}. Extensions not in + * the registry will be treated as unknown fields. + */ + Builder mergeFrom(CodedInputStream input, + ExtensionRegistryLite extensionRegistry) + throws IOException; + + /** + * Get the message's type's default instance. + * See {@link MessageLite#getDefaultInstanceForType()}. + */ + MessageLite getDefaultInstanceForType(); + + // --------------------------------------------------------------- + // Convenience methods. + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream)}. + */ + Builder mergeFrom(ByteString data) throws InvalidProtocolBufferException; + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}. + */ + Builder mergeFrom(ByteString data, + ExtensionRegistryLite extensionRegistry) + throws InvalidProtocolBufferException; + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream)}. + */ + Builder mergeFrom(byte[] data) throws InvalidProtocolBufferException; + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream)}. + */ + Builder mergeFrom(byte[] data, int off, int len) + throws InvalidProtocolBufferException; + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}. + */ + Builder mergeFrom(byte[] data, + ExtensionRegistryLite extensionRegistry) + throws InvalidProtocolBufferException; + + /** + * Parse {@code data} as a message of this type and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}. + */ + Builder mergeFrom(byte[] data, int off, int len, + ExtensionRegistryLite extensionRegistry) + throws InvalidProtocolBufferException; + + /** + * Parse a message of this type from {@code input} and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream)}. Note that this method always + * reads the <i>entire</i> input (unless it throws an exception). If you + * want it to stop earlier, you will need to wrap your input in some + * wrapper stream that limits reading. Or, use + * {@link MessageLite#writeDelimitedTo(OutputStream)} to write your message + * and {@link #mergeDelimitedFrom(InputStream)} to read it. + * <p> + * Despite usually reading the entire input, this does not close the stream. + */ + Builder mergeFrom(InputStream input) throws IOException; + + /** + * Parse a message of this type from {@code input} and merge it with the + * message being built. This is just a small wrapper around + * {@link #mergeFrom(CodedInputStream,ExtensionRegistry)}. + */ + Builder mergeFrom(InputStream input, + ExtensionRegistryLite extensionRegistry) + throws IOException; + + /** + * Like {@link #mergeFrom(InputStream)}, but does not read until EOF. + * Instead, the size of the message (encoded as a varint) is read first, + * then the message data. Use + * {@link MessageLite#writeDelimitedTo(OutputStream)} to write messages in + * this format. + */ + Builder mergeDelimitedFrom(InputStream input) + throws IOException; + + /** + * Like {@link #mergeDelimitedFrom(InputStream)} but supporting extensions. + */ + Builder mergeDelimitedFrom(InputStream input, + ExtensionRegistryLite extensionRegistry) + throws IOException; + } +} |