Protobuf2使用

背景

博主最近在研究sofa-jraft的时候，看到jraft使用的protobuf，所以单独拎出来单独理解一下。

 

Protobuf语法

 

使用案例

1 添加proto文件

syntax="proto2";

package jraft;

import "enum.proto";

option java_package="com.alipay.sofa.jraft.entity1";
option java_outer_classname = "RaftOutter1";


message EntryMeta {
    required int64 term = 1;
    required EntryType type = 2;
    repeated string peers = 3;
    optional int64 data_len = 4;
    // Don't change field id of `old_peers' in the consideration of backward
    // compatibility
    repeated string old_peers = 5;
    // Checksum fot this log entry, since 1.2.6, added by [e-mail]
    optional int64 checksum = 6;
    repeated string learners = 7;
    repeated string old_learners = 8;
};

message SnapshotMeta {
    required int64 last_included_index = 1;
    required int64 last_included_term = 2;
    repeated string peers = 3;
    repeated string old_peers = 4;
    repeated string learners = 5;
    repeated string old_learners = 6;
}

2 下载protoc.exe   执行：

protoc ./raft.proto --java_out=../java/

会看到在entity1目录下生成

 

3 测试

package com.alipay.sofa.jraft.entity1;

import com.alipay.sofa.jraft.entity.EnumOutter;
import com.google.protobuf.InvalidProtocolBufferException;

import java.util.Arrays;

public class PB2Byte {
    public static void main(String[] args) throws InvalidProtocolBufferException {
        RaftOutter1.EntryMeta.Builder builder = RaftOutter1.EntryMeta.newBuilder();
        // ====================================赋值================================
        builder.setType(EnumOutter.EntryType.ENTRY_TYPE_UNKNOWN);
        builder.setChecksum(4354734L);
        builder.setTerm(1);
        // builder.setPeers(0, "1");
        builder.addPeers("gdghfhf");
        builder.addOldPeers("gdghfhf1");

        builder.addLearners("7");
        builder.addOldLearners("8");
        // ====================================build对象================================
        RaftOutter1.EntryMeta entryMeta = builder.build();
        // ====================================对象序列化================================
        byte[] byteArray = entryMeta.toByteArray();
        System.out.println(Arrays.toString(byteArray));

        // ====================================反序列化================================
        RaftOutter1.EntryMeta newEntryMeta = RaftOutter1.EntryMeta.parseFrom(byteArray);
        System.out.println("newEntryMeta:" + newEntryMeta.toString());
    }
}

 

4 结果