protobuf的简单应用，json和protocol Buffer的转换简单例子
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时间：2015年06月09日
Google Protocol Buffer 的使用和原理
Protocol Buffers 是一种轻便高效的结构化数据存储格式，可以用于结构化数据串行化，很适合做数据存储或 RPC 数据交换格式。它可用于通讯协议、数据存储等领域的语言无关、平台无关、可扩展的序列化结构数据格式。目前提供了 C++、Java、Python 三种语言的 API。
简介
什么是 Google Protocol Buffer？ 假如您在网上搜索，应该会得到类似这样的文字介绍：
Google Protocol Buffer( 简称 Protobuf) 是 Google 公司内部的混合语言数据标准，目前已经正在使用的有超过 48,162 种报文格式定义和超过 12,183 个 .proto 文件。他们用于 RPC 系统和持续数据存储系统。
Protocol Buffers 是一种轻便高效的结构化数据存储格式，可以用于结构化数据串行化，或者说序列化。它很适合做数据存储或 RPC 数据交换格式。可用于通讯协议、数据存储等领域的语言无关、平台无关、可扩展的序列化结构数据格式。目前提供了 C++、Java、Python 三种语言的 API。
或许您和我一样，在第一次看完这些介绍后还是不明白 Protobuf 究竟是什么，那么我想一个简单的例子应该比较有助于理解它。
例子:
package org.protob;
import org.protob.W.helloworld;
import com.google.protobuf.InvalidProtocolBufferException;
import com.googlecode.protobuf.format.JsonFormat;
import com.googlecode.protobuf.format.JsonFormat.ParseException;
/**
* 下载 protoc-2.5.0-win32.zip
* cmd: protoc.exe --java_out=./ w.proto
* @author liangrui
*
*/
public class Main {
public static void main(String[] args) throws Exception {
main2(null);
main3(null);
main4(null);
}
//序列化 /返序列化
public static void main2(String[] args) throws InvalidProtocolBufferException {
//序列化
helloworld.Builder builder=helloworld.newBuilder();
builder.setId(10);
builder.setStr("fx");
builder.setOpt(20);
helloworld info=builder.build();
byte[] result=info.toByteArray() ;
//返序列化
helloworld msg = helloworld.parseFrom(result);
System.out.println(msg);
}
//protobuf转json
public static void main3(String[] args) throws InvalidProtocolBufferException {
//序列化
helloworld.Builder builder=helloworld.newBuilder();
builder.setId(10);
builder.setStr("fx");
builder.setOpt(20);
helloworld info=builder.build();
byte[] result=info.toByteArray() ;
//返序列化
helloworld hello = helloworld.parseFrom(result);
System.out.println(hello);
String jsonFormat =JsonFormat.printToString(hello);
System.out.println(jsonFormat);
}
//josn转protobuf
public static void main4(String[] args) throws ParseException {
helloworld.Builder builder =helloworld.newBuilder();
String jsonFormat = "{id:11,str:'xxx',opt:50}";
JsonFormat.merge(jsonFormat, builder);
System.out.println(builder.build());
}
}
/**
output:
id: 10
str: "fx"
opt: 20
id: 10
str: "fx"
opt: 20
{"id": 10,"str": "fx","opt": 20}
id: 11
str: "xxx"
opt: 50
*/
proto文件 w.proto
package org.protob;
message helloworld
{
required int32 id = 1; // ID
required string str = 2; // str
optional int32 opt = 3; //optional field
}生成后的java类
// Generated by the protocol buffer compiler. DO NOT EDIT!
// source: w.proto
package org.protob;
public final class W {
private W() {}
public static void registerAllExtensions(
com.google.protobuf.ExtensionRegistry registry) {
}
public interface helloworldOrBuilder
extends com.google.protobuf.MessageOrBuilder {
// required int32 id = 1;
/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
boolean hasId();
/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
int getId();
// required string str = 2;
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
boolean hasStr();
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
java.lang.String getStr();
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
com.google.protobuf.ByteString
getStrBytes();
// optional int32 opt = 3;
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
boolean hasOpt();
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
int getOpt();
}
/**
* Protobuf type {@code org.protob.helloworld}
*/
public static final class helloworld extends
com.google.protobuf.GeneratedMessage
implements helloworldOrBuilder {
// Use helloworld.newBuilder() to construct.
private helloworld(com.google.protobuf.GeneratedMessage.Builder<?> builder) {
super(builder);
this.unknownFields = builder.getUnknownFields();
}
private helloworld(boolean noInit) { this.unknownFields = com.google.protobuf.UnknownFieldSet.getDefaultInstance(); }
private static final helloworld defaultInstance;
public static helloworld getDefaultInstance() {
return defaultInstance;
}
public helloworld getDefaultInstanceForType() {
return defaultInstance;
}
private final com.google.protobuf.UnknownFieldSet unknownFields;
@java.lang.Override
public final com.google.protobuf.UnknownFieldSet
getUnknownFields() {
return this.unknownFields;
}
private helloworld(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
initFields();
int mutable_bitField0_ = 0;
com.google.protobuf.UnknownFieldSet.Builder unknownFields =
com.google.protobuf.UnknownFieldSet.newBuilder();
try {
boolean done = false;
while (!done) {
int tag = input.readTag();
switch (tag) {
case 0:
done = true;
break;
default: {
if (!parseUnknownField(input, unknownFields,
extensionRegistry, tag)) {
done = true;
}
break;
}
case 8: {
bitField0_ |= 0x00000001;
id_ = input.readInt32();
break;
}
case 18: {
bitField0_ |= 0x00000002;
str_ = input.readBytes();
break;
}
case 24: {
bitField0_ |= 0x00000004;
opt_ = input.readInt32();
break;
}
}
}
} catch (com.google.protobuf.InvalidProtocolBufferException e) {
throw e.setUnfinishedMessage(this);
} catch (java.io.IOException e) {
throw new com.google.protobuf.InvalidProtocolBufferException(
e.getMessage()).setUnfinishedMessage(this);
} finally {
this.unknownFields = unknownFields.build();
makeExtensionsImmutable();
}
}
public static final com.google.protobuf.Descriptors.Descriptor
getDescriptor() {
return org.protob.W.internal_static_org_protob_helloworld_descriptor;
}
protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
internalGetFieldAccessorTable() {
return org.protob.W.internal_static_org_protob_helloworld_fieldAccessorTable
.ensureFieldAccessorsInitialized(
org.protob.W.helloworld.class, org.protob.W.helloworld.Builder.class);
}
public static com.google.protobuf.Parser<helloworld> PARSER =
new com.google.protobuf.AbstractParser<helloworld>() {
public helloworld parsePartialFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return new helloworld(input, extensionRegistry);
}
};
@java.lang.Override
public com.google.protobuf.Parser<helloworld> getParserForType() {
return PARSER;
}
private int bitField0_;
// required int32 id = 1;
public static final int ID_FIELD_NUMBER = 1;
private int id_;
/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
public boolean hasId() {
return ((bitField0_ & 0x00000001) == 0x00000001);
}
/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
public int getId() {
return id_;
}
// required string str = 2;
public static final int STR_FIELD_NUMBER = 2;
private java.lang.Object str_;
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public boolean hasStr() {
return ((bitField0_ & 0x00000002) == 0x00000002);
}
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public java.lang.String getStr() {
java.lang.Object ref = str_;
if (ref instanceof java.lang.String) {
return (java.lang.String) ref;
} else {
com.google.protobuf.ByteString bs =
(com.google.protobuf.ByteString) ref;
java.lang.String s = bs.toStringUtf8();
if (bs.isValidUtf8()) {
str_ = s;
}
return s;
}
}
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public com.google.protobuf.ByteString
getStrBytes() {
java.lang.Object ref = str_;
if (ref instanceof java.lang.String) {
com.google.protobuf.ByteString b =
com.google.protobuf.ByteString.copyFromUtf8(
(java.lang.String) ref);
str_ = b;
return b;
} else {
return (com.google.protobuf.ByteString) ref;
}
}
// optional int32 opt = 3;
public static final int OPT_FIELD_NUMBER = 3;
private int opt_;
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public boolean hasOpt() {
return ((bitField0_ & 0x00000004) == 0x00000004);
}
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public int getOpt() {
return opt_;
}
private void initFields() {
id_ = 0;
str_ = "";
opt_ = 0;
}
private byte memoizedIsInitialized = -1;
public final boolean isInitialized() {
byte isInitialized = memoizedIsInitialized;
if (isInitialized != -1) return isInitialized == 1;
if (!hasId()) {
memoizedIsInitialized = 0;
return false;
}
if (!hasStr()) {
memoizedIsInitialized = 0;
return false;
}
memoizedIsInitialized = 1;
return true;
}
public void writeTo(com.google.protobuf.CodedOutputStream output)
throws java.io.IOException {
getSerializedSize();
if (((bitField0_ & 0x00000001) == 0x00000001)) {
output.writeInt32(1, id_);
}
if (((bitField0_ & 0x00000002) == 0x00000002)) {
output.writeBytes(2, getStrBytes());
}
if (((bitField0_ & 0x00000004) == 0x00000004)) {
output.writeInt32(3, opt_);
}
getUnknownFields().writeTo(output);
}
private int memoizedSerializedSize = -1;
public int getSerializedSize() {
int size = memoizedSerializedSize;
if (size != -1) return size;
size = 0;
if (((bitField0_ & 0x00000001) == 0x00000001)) {
size += com.google.protobuf.CodedOutputStream
.computeInt32Size(1, id_);
}
if (((bitField0_ & 0x00000002) == 0x00000002)) {
size += com.google.protobuf.CodedOutputStream
.computeBytesSize(2, getStrBytes());
}
if (((bitField0_ & 0x00000004) == 0x00000004)) {
size += com.google.protobuf.CodedOutputStream
.computeInt32Size(3, opt_);
}
size += getUnknownFields().getSerializedSize();
memoizedSerializedSize = size;
return size;
}
private static final long serialVersionUID = 0L;
@java.lang.Override
protected java.lang.Object writeReplace()
throws java.io.ObjectStreamException {
return super.writeReplace();
}
public static org.protob.W.helloworld parseFrom(
com.google.protobuf.ByteString data)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data);
}
public static org.protob.W.helloworld parseFrom(
com.google.protobuf.ByteString data,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data, extensionRegistry);
}
public static org.protob.W.helloworld parseFrom(byte[] data)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data);
}
public static org.protob.W.helloworld parseFrom(
byte[] data,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data, extensionRegistry);
}
public static org.protob.W.helloworld parseFrom(java.io.InputStream input)
throws java.io.IOException {
return PARSER.parseFrom(input);
}
public static org.protob.W.helloworld parseFrom(
java.io.InputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return PARSER.parseFrom(input, extensionRegistry);
}
public static org.protob.W.helloworld parseDelimitedFrom(java.io.InputStream input)
throws java.io.IOException {
return PARSER.parseDelimitedFrom(input);
}
public static org.protob.W.helloworld parseDelimitedFrom(
java.io.InputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return PARSER.parseDelimitedFrom(input, extensionRegistry);
}
public static org.protob.W.helloworld parseFrom(
com.google.protobuf.CodedInputStream input)
throws java.io.IOException {
return PARSER.parseFrom(input);
}
public static org.protob.W.helloworld parseFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return PARSER.parseFrom(input, extensionRegistry);
}
public static Builder newBuilder() { return Builder.create(); }
public Builder newBuilderForType() { return newBuilder(); }
public static Builder newBuilder(org.protob.W.helloworld prototype) {
return newBuilder().mergeFrom(prototype);
}
public Builder toBuilder() { return newBuilder(this); }
@java.lang.Override
protected Builder newBuilderForType(
com.google.protobuf.GeneratedMessage.BuilderParent parent) {
Builder builder = new Builder(parent);
return builder;
}
/**
* Protobuf type {@code org.protob.helloworld}
*/
public static final class Builder extends
com.google.protobuf.GeneratedMessage.Builder<Builder>
implements org.protob.W.helloworldOrBuilder {
public static final com.google.protobuf.Descriptors.Descriptor
getDescriptor() {
return org.protob.W.internal_static_org_protob_helloworld_descriptor;
}
protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
internalGetFieldAccessorTable() {
return org.protob.W.internal_static_org_protob_helloworld_fieldAccessorTable
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org.protob.W.helloworld.class, org.protob.W.helloworld.Builder.class);
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// Construct using org.protob.W.helloworld.newBuilder()
private Builder() {
maybeForceBuilderInitialization();
}
private Builder(
com.google.protobuf.GeneratedMessage.BuilderParent parent) {
super(parent);
maybeForceBuilderInitialization();
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private void maybeForceBuilderInitialization() {
if (com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders) {
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private static Builder create() {
return new Builder();
}
public Builder clear() {
super.clear();
id_ = 0;
bitField0_ = (bitField0_ & ~0x00000001);
str_ = "";
bitField0_ = (bitField0_ & ~0x00000002);
opt_ = 0;
bitField0_ = (bitField0_ & ~0x00000004);
return this;
}
public Builder clone() {
return create().mergeFrom(buildPartial());
}
public com.google.protobuf.Descriptors.Descriptor
getDescriptorForType() {
return org.protob.W.internal_static_org_protob_helloworld_descriptor;
}
public org.protob.W.helloworld getDefaultInstanceForType() {
return org.protob.W.helloworld.getDefaultInstance();
}
public org.protob.W.helloworld build() {
org.protob.W.helloworld result = buildPartial();
if (!result.isInitialized()) {
throw newUninitializedMessageException(result);
}
return result;
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public org.protob.W.helloworld buildPartial() {
org.protob.W.helloworld result = new org.protob.W.helloworld(this);
int from_bitField0_ = bitField0_;
int to_bitField0_ = 0;
if (((from_bitField0_ & 0x00000001) == 0x00000001)) {
to_bitField0_ |= 0x00000001;
}
result.id_ = id_;
if (((from_bitField0_ & 0x00000002) == 0x00000002)) {
to_bitField0_ |= 0x00000002;
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result.str_ = str_;
if (((from_bitField0_ & 0x00000004) == 0x00000004)) {
to_bitField0_ |= 0x00000004;
}
result.opt_ = opt_;
result.bitField0_ = to_bitField0_;
onBuilt();
return result;
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public Builder mergeFrom(com.google.protobuf.Message other) {
if (other instanceof org.protob.W.helloworld) {
return mergeFrom((org.protob.W.helloworld)other);
} else {
super.mergeFrom(other);
return this;
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}
public Builder mergeFrom(org.protob.W.helloworld other) {
if (other == org.protob.W.helloworld.getDefaultInstance()) return this;
if (other.hasId()) {
setId(other.getId());
}
if (other.hasStr()) {
bitField0_ |= 0x00000002;
str_ = other.str_;
onChanged();
}
if (other.hasOpt()) {
setOpt(other.getOpt());
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this.mergeUnknownFields(other.getUnknownFields());
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public final boolean isInitialized() {
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if (!hasStr()) {
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return true;
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public Builder mergeFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
org.protob.W.helloworld parsedMessage = null;
try {
parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
} catch (com.google.protobuf.InvalidProtocolBufferException e) {
parsedMessage = (org.protob.W.helloworld) e.getUnfinishedMessage();
throw e;
} finally {
if (parsedMessage != null) {
mergeFrom(parsedMessage);
}
}
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private int bitField0_;
// required int32 id = 1;
private int id_ ;
/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
public boolean hasId() {
return ((bitField0_ & 0x00000001) == 0x00000001);
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/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
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/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
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bitField0_ |= 0x00000001;
id_ = value;
onChanged();
return this;
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/**
* <code>required int32 id = 1;</code>
*
* <pre>
* ID
* </pre>
*/
public Builder clearId() {
bitField0_ = (bitField0_ & ~0x00000001);
id_ = 0;
onChanged();
return this;
}
// required string str = 2;
private java.lang.Object str_ = "";
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public boolean hasStr() {
return ((bitField0_ & 0x00000002) == 0x00000002);
}
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public java.lang.String getStr() {
java.lang.Object ref = str_;
if (!(ref instanceof java.lang.String)) {
java.lang.String s = ((com.google.protobuf.ByteString) ref)
.toStringUtf8();
str_ = s;
return s;
} else {
return (java.lang.String) ref;
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/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public com.google.protobuf.ByteString
getStrBytes() {
java.lang.Object ref = str_;
if (ref instanceof String) {
com.google.protobuf.ByteString b =
com.google.protobuf.ByteString.copyFromUtf8(
(java.lang.String) ref);
str_ = b;
return b;
} else {
return (com.google.protobuf.ByteString) ref;
}
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/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public Builder setStr(
java.lang.String value) {
if (value == null) {
throw new NullPointerException();
}
bitField0_ |= 0x00000002;
str_ = value;
onChanged();
return this;
}
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public Builder clearStr() {
bitField0_ = (bitField0_ & ~0x00000002);
str_ = getDefaultInstance().getStr();
onChanged();
return this;
}
/**
* <code>required string str = 2;</code>
*
* <pre>
* str
* </pre>
*/
public Builder setStrBytes(
com.google.protobuf.ByteString value) {
if (value == null) {
throw new NullPointerException();
}
bitField0_ |= 0x00000002;
str_ = value;
onChanged();
return this;
}
// optional int32 opt = 3;
private int opt_ ;
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public boolean hasOpt() {
return ((bitField0_ & 0x00000004) == 0x00000004);
}
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public int getOpt() {
return opt_;
}
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public Builder setOpt(int value) {
bitField0_ |= 0x00000004;
opt_ = value;
onChanged();
return this;
}
/**
* <code>optional int32 opt = 3;</code>
*
* <pre>
*optional field
* </pre>
*/
public Builder clearOpt() {
bitField0_ = (bitField0_ & ~0x00000004);
opt_ = 0;
onChanged();
return this;
}
// @@protoc_insertion_point(builder_scope:org.protob.helloworld)
}
static {
defaultInstance = new helloworld(true);
defaultInstance.initFields();
}
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}
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一个很好的例子：不过是c++
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