Proto文件如何生成JavaProto对象?

首先安装好Protocol Buffer的编译器

Protocol Buffer:
version:2.6.1
link: 链接直达

根据电脑环境进行下载，Widnwos 32/64位就选择win32是没问题的，楼主亲测

1.proto文件编写

Person.proto

public class Person  {String name;int id;String email;
}

syntax = "proto2";
option java_outer_classname="PersonPOJO";
message Person {required string name = 1;required int32 id = 2;required string email = 3;
}

2.生成PersonProto文件

接下来我们要根据上面编写好的Person.proto文件生成Java对应的Proto对象

运行指令

.\protoc.exe --java_out=. Person.proto

如果没有报错就是成功了，有的运行指令会报错

再仔细核对下上面的proto文件即可，这里采用的proto2版本进行生成的，一定要注意版本号的区别，我们下载的版本号就是2.6.1，不同的编译文件可能会有略微差异，但是不影响。

3.PersonPOJO.java

上面的JavaProto文件类名我指定成了PersonPOJO(也就是JavaProto对象)，这里可以看到，里面生成了很多代码，而我们Person实体类属性才只有3个

// Generated by the protocol buffer compiler.  DO NOT EDIT!
// source: Person.protopublic final class PersonPOJO {private PersonPOJO() {}public static void registerAllExtensions(com.google.protobuf.ExtensionRegistry registry) {}public interface PersonOrBuilder extends// @@protoc_insertion_point(interface_extends:Person)com.google.protobuf.MessageOrBuilder {/*** <code>required string name = 1;</code>*/boolean hasName();/*** <code>required string name = 1;</code>*/java.lang.String getName();/*** <code>required string name = 1;</code>*/com.google.protobuf.ByteStringgetNameBytes();/*** <code>required int32 id = 2;</code>*/boolean hasId();/*** <code>required int32 id = 2;</code>*/int getId();/*** <code>required string email = 3;</code>*/boolean hasEmail();/*** <code>required string email = 3;</code>*/java.lang.String getEmail();/*** <code>required string email = 3;</code>*/com.google.protobuf.ByteStringgetEmailBytes();}/*** Protobuf type {@code Person}*/public static final class Person extendscom.google.protobuf.GeneratedMessage implements// @@protoc_insertion_point(message_implements:Person)PersonOrBuilder {// Use Person.newBuilder() to construct.private Person(com.google.protobuf.GeneratedMessage.Builder<?> builder) {super(builder);this.unknownFields = builder.getUnknownFields();}private Person(boolean noInit) { this.unknownFields = com.google.protobuf.UnknownFieldSet.getDefaultInstance(); }private static final Person defaultInstance;public static Person getDefaultInstance() {return defaultInstance;}public Person getDefaultInstanceForType() {return defaultInstance;}private final com.google.protobuf.UnknownFieldSet unknownFields;@java.lang.Overridepublic final com.google.protobuf.UnknownFieldSetgetUnknownFields() {return this.unknownFields;}private Person(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 10: {com.google.protobuf.ByteString bs = input.readBytes();bitField0_ |= 0x00000001;name_ = bs;break;}case 16: {bitField0_ |= 0x00000002;id_ = input.readInt32();break;}case 26: {com.google.protobuf.ByteString bs = input.readBytes();bitField0_ |= 0x00000004;email_ = bs;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.DescriptorgetDescriptor() {return PersonPOJO.internal_static_Person_descriptor;}protected com.google.protobuf.GeneratedMessage.FieldAccessorTableinternalGetFieldAccessorTable() {return PersonPOJO.internal_static_Person_fieldAccessorTable.ensureFieldAccessorsInitialized(PersonPOJO.Person.class, PersonPOJO.Person.Builder.class);}public static com.google.protobuf.Parser<Person> PARSER =new com.google.protobuf.AbstractParser<Person>() {public Person parsePartialFrom(com.google.protobuf.CodedInputStream input,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws com.google.protobuf.InvalidProtocolBufferException {return new Person(input, extensionRegistry);}};@java.lang.Overridepublic com.google.protobuf.Parser<Person> getParserForType() {return PARSER;}private int bitField0_;public static final int NAME_FIELD_NUMBER = 1;private java.lang.Object name_;/*** <code>required string name = 1;</code>*/public boolean hasName() {return ((bitField0_ & 0x00000001) == 0x00000001);}/*** <code>required string name = 1;</code>*/public java.lang.String getName() {java.lang.Object ref = name_;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()) {name_ = s;}return s;}}/*** <code>required string name = 1;</code>*/public com.google.protobuf.ByteStringgetNameBytes() {java.lang.Object ref = name_;if (ref instanceof java.lang.String) {com.google.protobuf.ByteString b = com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);name_ = b;return b;} else {return (com.google.protobuf.ByteString) ref;}}public static final int ID_FIELD_NUMBER = 2;private int id_;/*** <code>required int32 id = 2;</code>*/public boolean hasId() {return ((bitField0_ & 0x00000002) == 0x00000002);}/*** <code>required int32 id = 2;</code>*/public int getId() {return id_;}public static final int EMAIL_FIELD_NUMBER = 3;private java.lang.Object email_;/*** <code>required string email = 3;</code>*/public boolean hasEmail() {return ((bitField0_ & 0x00000004) == 0x00000004);}/*** <code>required string email = 3;</code>*/public java.lang.String getEmail() {java.lang.Object ref = email_;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()) {email_ = s;}return s;}}/*** <code>required string email = 3;</code>*/public com.google.protobuf.ByteStringgetEmailBytes() {java.lang.Object ref = email_;if (ref instanceof java.lang.String) {com.google.protobuf.ByteString b = com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);email_ = b;return b;} else {return (com.google.protobuf.ByteString) ref;}}private void initFields() {name_ = "";id_ = 0;email_ = "";}private byte memoizedIsInitialized = -1;public final boolean isInitialized() {byte isInitialized = memoizedIsInitialized;if (isInitialized == 1) return true;if (isInitialized == 0) return false;if (!hasName()) {memoizedIsInitialized = 0;return false;}if (!hasId()) {memoizedIsInitialized = 0;return false;}if (!hasEmail()) {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.writeBytes(1, getNameBytes());}if (((bitField0_ & 0x00000002) == 0x00000002)) {output.writeInt32(2, id_);}if (((bitField0_ & 0x00000004) == 0x00000004)) {output.writeBytes(3, getEmailBytes());}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.computeBytesSize(1, getNameBytes());}if (((bitField0_ & 0x00000002) == 0x00000002)) {size += com.google.protobuf.CodedOutputStream.computeInt32Size(2, id_);}if (((bitField0_ & 0x00000004) == 0x00000004)) {size += com.google.protobuf.CodedOutputStream.computeBytesSize(3, getEmailBytes());}size += getUnknownFields().getSerializedSize();memoizedSerializedSize = size;return size;}private static final long serialVersionUID = 0L;@java.lang.Overrideprotected java.lang.Object writeReplace()throws java.io.ObjectStreamException {return super.writeReplace();}public static PersonPOJO.Person parseFrom(com.google.protobuf.ByteString data)throws com.google.protobuf.InvalidProtocolBufferException {return PARSER.parseFrom(data);}public static PersonPOJO.Person parseFrom(com.google.protobuf.ByteString data,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws com.google.protobuf.InvalidProtocolBufferException {return PARSER.parseFrom(data, extensionRegistry);}public static PersonPOJO.Person parseFrom(byte[] data)throws com.google.protobuf.InvalidProtocolBufferException {return PARSER.parseFrom(data);}public static PersonPOJO.Person parseFrom(byte[] data,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws com.google.protobuf.InvalidProtocolBufferException {return PARSER.parseFrom(data, extensionRegistry);}public static PersonPOJO.Person parseFrom(java.io.InputStream input)throws java.io.IOException {return PARSER.parseFrom(input);}public static PersonPOJO.Person parseFrom(java.io.InputStream input,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws java.io.IOException {return PARSER.parseFrom(input, extensionRegistry);}public static PersonPOJO.Person parseDelimitedFrom(java.io.InputStream input)throws java.io.IOException {return PARSER.parseDelimitedFrom(input);}public static PersonPOJO.Person parseDelimitedFrom(java.io.InputStream input,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws java.io.IOException {return PARSER.parseDelimitedFrom(input, extensionRegistry);}public static PersonPOJO.Person parseFrom(com.google.protobuf.CodedInputStream input)throws java.io.IOException {return PARSER.parseFrom(input);}public static PersonPOJO.Person 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(PersonPOJO.Person prototype) {return newBuilder().mergeFrom(prototype);}public Builder toBuilder() { return newBuilder(this); }@java.lang.Overrideprotected Builder newBuilderForType(com.google.protobuf.GeneratedMessage.BuilderParent parent) {Builder builder = new Builder(parent);return builder;}/*** Protobuf type {@code Person}*/public static final class Builder extendscom.google.protobuf.GeneratedMessage.Builder<Builder> implements// @@protoc_insertion_point(builder_implements:Person)PersonPOJO.PersonOrBuilder {public static final com.google.protobuf.Descriptors.DescriptorgetDescriptor() {return PersonPOJO.internal_static_Person_descriptor;}protected com.google.protobuf.GeneratedMessage.FieldAccessorTableinternalGetFieldAccessorTable() {return PersonPOJO.internal_static_Person_fieldAccessorTable.ensureFieldAccessorsInitialized(PersonPOJO.Person.class, PersonPOJO.Person.Builder.class);}// Construct using PersonPOJO.Person.newBuilder()private Builder() {maybeForceBuilderInitialization();}private Builder(com.google.protobuf.GeneratedMessage.BuilderParent parent) {super(parent);maybeForceBuilderInitialization();}private void maybeForceBuilderInitialization() {if (com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders) {}}private static Builder create() {return new Builder();}public Builder clear() {super.clear();name_ = "";bitField0_ = (bitField0_ & ~0x00000001);id_ = 0;bitField0_ = (bitField0_ & ~0x00000002);email_ = "";bitField0_ = (bitField0_ & ~0x00000004);return this;}public Builder clone() {return create().mergeFrom(buildPartial());}public com.google.protobuf.Descriptors.DescriptorgetDescriptorForType() {return PersonPOJO.internal_static_Person_descriptor;}public PersonPOJO.Person getDefaultInstanceForType() {return PersonPOJO.Person.getDefaultInstance();}public PersonPOJO.Person build() {PersonPOJO.Person result = buildPartial();if (!result.isInitialized()) {throw newUninitializedMessageException(result);}return result;}public PersonPOJO.Person buildPartial() {PersonPOJO.Person result = new PersonPOJO.Person(this);int from_bitField0_ = bitField0_;int to_bitField0_ = 0;if (((from_bitField0_ & 0x00000001) == 0x00000001)) {to_bitField0_ |= 0x00000001;}result.name_ = name_;if (((from_bitField0_ & 0x00000002) == 0x00000002)) {to_bitField0_ |= 0x00000002;}result.id_ = id_;if (((from_bitField0_ & 0x00000004) == 0x00000004)) {to_bitField0_ |= 0x00000004;}result.email_ = email_;result.bitField0_ = to_bitField0_;onBuilt();return result;}public Builder mergeFrom(com.google.protobuf.Message other) {if (other instanceof PersonPOJO.Person) {return mergeFrom((PersonPOJO.Person)other);} else {super.mergeFrom(other);return this;}}public Builder mergeFrom(PersonPOJO.Person other) {if (other == PersonPOJO.Person.getDefaultInstance()) return this;if (other.hasName()) {bitField0_ |= 0x00000001;name_ = other.name_;onChanged();}if (other.hasId()) {setId(other.getId());}if (other.hasEmail()) {bitField0_ |= 0x00000004;email_ = other.email_;onChanged();}this.mergeUnknownFields(other.getUnknownFields());return this;}public final boolean isInitialized() {if (!hasName()) {return false;}if (!hasId()) {return false;}if (!hasEmail()) {return false;}return true;}public Builder mergeFrom(com.google.protobuf.CodedInputStream input,com.google.protobuf.ExtensionRegistryLite extensionRegistry)throws java.io.IOException {PersonPOJO.Person parsedMessage = null;try {parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);} catch (com.google.protobuf.InvalidProtocolBufferException e) {parsedMessage = (PersonPOJO.Person) e.getUnfinishedMessage();throw e;} finally {if (parsedMessage != null) {mergeFrom(parsedMessage);}}return this;}private int bitField0_;private java.lang.Object name_ = "";/*** <code>required string name = 1;</code>*/public boolean hasName() {return ((bitField0_ & 0x00000001) == 0x00000001);}/*** <code>required string name = 1;</code>*/public java.lang.String getName() {java.lang.Object ref = name_;if (!(ref instanceof java.lang.String)) {com.google.protobuf.ByteString bs =(com.google.protobuf.ByteString) ref;java.lang.String s = bs.toStringUtf8();if (bs.isValidUtf8()) {name_ = s;}return s;} else {return (java.lang.String) ref;}}/*** <code>required string name = 1;</code>*/public com.google.protobuf.ByteStringgetNameBytes() {java.lang.Object ref = name_;if (ref instanceof String) {com.google.protobuf.ByteString b = com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);name_ = b;return b;} else {return (com.google.protobuf.ByteString) ref;}}/*** <code>required string name = 1;</code>*/public Builder setName(java.lang.String value) {if (value == null) {throw new NullPointerException();}bitField0_ |= 0x00000001;name_ = value;onChanged();return this;}/*** <code>required string name = 1;</code>*/public Builder clearName() {bitField0_ = (bitField0_ & ~0x00000001);name_ = getDefaultInstance().getName();onChanged();return this;}/*** <code>required string name = 1;</code>*/public Builder setNameBytes(com.google.protobuf.ByteString value) {if (value == null) {throw new NullPointerException();}bitField0_ |= 0x00000001;name_ = value;onChanged();return this;}private int id_ ;/*** <code>required int32 id = 2;</code>*/public boolean hasId() {return ((bitField0_ & 0x00000002) == 0x00000002);}/*** <code>required int32 id = 2;</code>*/public int getId() {return id_;}/*** <code>required int32 id = 2;</code>*/public Builder setId(int value) {bitField0_ |= 0x00000002;id_ = value;onChanged();return this;}/*** <code>required int32 id = 2;</code>*/public Builder clearId() {bitField0_ = (bitField0_ & ~0x00000002);id_ = 0;onChanged();return this;}private java.lang.Object email_ = "";/*** <code>required string email = 3;</code>*/public boolean hasEmail() {return ((bitField0_ & 0x00000004) == 0x00000004);}/*** <code>required string email = 3;</code>*/public java.lang.String getEmail() {java.lang.Object ref = email_;if (!(ref instanceof java.lang.String)) {com.google.protobuf.ByteString bs =(com.google.protobuf.ByteString) ref;java.lang.String s = bs.toStringUtf8();if (bs.isValidUtf8()) {email_ = s;}return s;} else {return (java.lang.String) ref;}}/*** <code>required string email = 3;</code>*/public com.google.protobuf.ByteStringgetEmailBytes() {java.lang.Object ref = email_;if (ref instanceof String) {com.google.protobuf.ByteString b = com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);email_ = b;return b;} else {return (com.google.protobuf.ByteString) ref;}}/*** <code>required string email = 3;</code>*/public Builder setEmail(java.lang.String value) {if (value == null) {throw new NullPointerException();}bitField0_ |= 0x00000004;email_ = value;onChanged();return this;}/*** <code>required string email = 3;</code>*/public Builder clearEmail() {bitField0_ = (bitField0_ & ~0x00000004);email_ = getDefaultInstance().getEmail();onChanged();return this;}/*** <code>required string email = 3;</code>*/public Builder setEmailBytes(com.google.protobuf.ByteString value) {if (value == null) {throw new NullPointerException();}bitField0_ |= 0x00000004;email_ = value;onChanged();return this;}// @@protoc_insertion_point(builder_scope:Person)}static {defaultInstance = new Person(true);defaultInstance.initFields();}// @@protoc_insertion_point(class_scope:Person)}private static final com.google.protobuf.Descriptors.Descriptorinternal_static_Person_descriptor;private staticcom.google.protobuf.GeneratedMessage.FieldAccessorTableinternal_static_Person_fieldAccessorTable;public static com.google.protobuf.Descriptors.FileDescriptorgetDescriptor() {return descriptor;}private static com.google.protobuf.Descriptors.FileDescriptordescriptor;static {java.lang.String[] descriptorData = {"\n\014Person.proto\"1\n\006Person\022\014\n\004name\030\001 \002(\t\022\n" +"\n\002id\030\002 \002(\005\022\r\n\005email\030\003 \002(\tB\014B\nPersonPOJO"};com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner assigner =new com.google.protobuf.Descriptors.FileDescriptor.    InternalDescriptorAssigner() {public com.google.protobuf.ExtensionRegistry assignDescriptors(com.google.protobuf.Descriptors.FileDescriptor root) {descriptor = root;return null;}};com.google.protobuf.Descriptors.FileDescriptor.internalBuildGeneratedFileFrom(descriptorData,new com.google.protobuf.Descriptors.FileDescriptor[] {}, assigner);internal_static_Person_descriptor =getDescriptor().getMessageTypes().get(0);internal_static_Person_fieldAccessorTable = newcom.google.protobuf.GeneratedMessage.FieldAccessorTable(internal_static_Person_descriptor,new java.lang.String[] { "Name", "Id", "Email", });}// @@protoc_insertion_point(outer_class_scope)
}

4.性能比较

再验证之前pom.xml文件需要导入和我们上面protoc.exe一样的版本号，否则可能会出错，上面的protoc.exe使用的是2.6.1，pom文件也用2.6.1

        <dependency><groupId>com.google.protobuf</groupId><artifactId>protobuf-java</artifactId><version>2.6.1</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.66</version></dependency>

这里我们再加上FASTJSON，进行三者之间的对比

package cn.tuling.nettybasic.serializable.protobuf;import com.alibaba.fastjson.JSON;import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;public class PerformTest {public static void main(String[] args) throws IOException {long start1 = System.currentTimeMillis();PersonOuterClass.Person person = PersonOuterClass.Person.newBuilder().setId(1).setName("Cover").setEmail("[e-mail]").build();byte[] result = person.toByteArray();long end1 = System.currentTimeMillis();System.out.println("Proto serialize length:" + result.length + ", time :" + (end1 - start1));// FAST JSONlong start3 = System.currentTimeMillis();Person person2 = new Person();person2.id = 2;person2.name = "Cover";person2.email = "[e-mail]";byte[] bytes = JSON.toJSONString(person2).getBytes();long end3 = System.currentTimeMillis();System.out.println("FASTJSON serialize length: " + bytes.length + ", time :" + (end3 - start3));// JDKlong start2 = System.currentTimeMillis();Person person1 = new Person();person1.id = 2;person1.name = "Cover";person1.email = "[e-mail]";ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();ObjectOutputStream out = new ObjectOutputStream(arrayOutputStream);out.writeObject(person1);long end2 = System.currentTimeMillis();System.out.println("JDK serialize length:" + arrayOutputStream.toByteArray().length + ", time :" + (end2 - start2));}
}

5.序列化结果展示

可以看到，Proto性能在空间复杂度和时间复杂度上总体要比FASTJSON和JDK要有优势，其实还有很多框架序列化和反序列化的性能也不错，下期我们再介绍其他几种框架，Proto的方式相比其他框架要麻烦一点，需要下载特定的编译器才行。它这样做的目的是为了方便地支持跨语言。