【小沐学前端】Node.js实现基于Protobuf协议的数据处理-摩杜云开发者社区

1、简介

1.1 node

Node.js 是一个开源的、跨平台的 JavaScript 运行时环境。

Node.js 是一个开源和跨平台的 JavaScript 运行时环境。它是几乎任何类型项目的流行工具！

Node.js 在浏览器之外运行 V8 JavaScript 引擎（Google Chrome 的内核）。这使得 Node.js 非常高效。

2、Protobuf 代码示例

2.1 例子: awesome.proto

awesome.proto的内容定义如下：

// awesome.proto
package awesomepackage;
syntax = "proto3";

message AwesomeMessage {
    string awesome_field = 1; // becomes awesomeField
    string name_field = 2;
}

2.1.1 加载.proto文件方式

测试脚本文件：app_proto001.js

var protobuf = require("protobufjs");

protobuf.load("awesome.proto", function(err, root) {
    if (err)
        throw err;
    var AwesomeMessage = root.lookupType("awesomepackage.AwesomeMessage");

    var payload = { awesomeField: "AwesomeString" };

    var message = AwesomeMessage.create(payload); 

    var buffer = AwesomeMessage.encode(message).finish();
});

var protobuf = require("protobufjs");

protobuf.load("awesome.proto", function(err, root) {
    if (err)
        throw err;

    // Obtain a message type
    var AwesomeMessage = root.lookupType("awesomepackage.AwesomeMessage");

    // Exemplary payload
    var payload = { awesomeField: "AwesomeString" };
    console.log("payload: " + JSON.stringify(payload));

    // Verify the payload if necessary (i.e. when possibly incomplete or invalid)
    var errMsg = AwesomeMessage.verify(payload);
    if (errMsg)
        throw Error(errMsg);

    // Create a new message
    var message = AwesomeMessage.create(payload); // or use .fromObject if conversion is necessary
    console.log("create: " + JSON.stringify(message));

    // Encode a message to an Uint8Array (browser) or Buffer (node)
    var buffer = AwesomeMessage.encode(message).finish();
    // ... do something with buffer
    console.log("encode: " + JSON.stringify(buffer));

    // Decode an Uint8Array (browser) or Buffer (node) to a message
    var message = AwesomeMessage.decode(buffer);
    // ... do something with message
    console.log("decode: " + JSON.stringify(message));

    // If the application uses length-delimited buffers, there is also encodeDelimited and decodeDelimited.

    // Maybe convert the message back to a plain object
    var object = AwesomeMessage.toObject(message, {
        longs: String,
        enums: String,
        bytes: String,
        // see ConversionOptions
    });
    console.log("toObject: " + JSON.stringify(object));
});

执行运行命令如下：

node app_proto001.js

在这里插入图片描述

2.1.2 加载.json文件方式

执行如下命令，将awesome.proto转为awesome.json:

./node_modules/protobufjs/bin/pbjs -t json awesome.proto > awesome.json

自动生成的awesome.json如下：

{
  "nested": {
    "awesomepackage": {
      "nested": {
        "AwesomeMessage": {
          "fields": {
            "awesomeField": {
              "type": "string",
              "id": 1
            },
            "nameField": {
              "type": "string",
              "id": 2
            }
          }
        }
      }
    }
  }
}

编写脚本代码如下：

var protobuf = require("protobufjs");

var jsonDescriptor = require("./awesome.json"); // exemplary for node

var root = protobuf.Root.fromJSON(jsonDescriptor);

// Obtain a message type
var AwesomeMessage = root.lookupType("awesomepackage.AwesomeMessage");

// Exemplary payload
var payload = { awesomeField: "AwesomeString", nameField: "AwesomeName"};
console.log("payload: " + JSON.stringify(payload));

// Verify the payload if necessary (i.e. when possibly incomplete or invalid)
var errMsg = AwesomeMessage.verify(payload);
if (errMsg)
    throw Error(errMsg);

// Create a new message
var message = AwesomeMessage.create(payload); // or use .fromObject if conversion is necessary
console.log("create: " + JSON.stringify(message));

// Encode a message to an Uint8Array (browser) or Buffer (node)
var buffer = AwesomeMessage.encode(message).finish();
// ... do something with buffer
console.log("encode: " + JSON.stringify(buffer));

// Decode an Uint8Array (browser) or Buffer (node) to a message
var message = AwesomeMessage.decode(buffer);
// ... do something with message
console.log("decode: " + JSON.stringify(message));

// If the application uses length-delimited buffers, there is also encodeDelimited and decodeDelimited.

// Maybe convert the message back to a plain object
var object = AwesomeMessage.toObject(message, {
    longs: String,
    enums: String,
    bytes: String,
    // see ConversionOptions
});
console.log("toObject: " + JSON.stringify(object));

运行结果如下：在这里插入图片描述

2.1.3 加载.js文件方式

通过如下命令转为.proto为对应的.js文件

C:\Users\tomcat\Desktop\test>C:\Users\tomcat\Desktop\protobuf.js-protobufjs-v7.2.5\node_modules\.bin\pbjs  -t static-module -w commonjs -o awesome.js awesome.proto

生成的awesome.js 部分内容如下：在这里插入图片描述编写测试脚本代码如下：

var protobuf = require("protobufjs");

var awesomeProto = require("./awesome.js"); // exemplary for node
var AwesomeUtils = awesomeProto.awesomepackage.AwesomeMessage;

// Exemplary payload
var payload = { awesomeField: "AwesomeString", nameField: "AwesomeName"};
console.log("payload: " + JSON.stringify(payload));

// Verify the payload if necessary (i.e. when possibly incomplete or invalid)
var errMsg = AwesomeUtils.verify(payload);
if (errMsg)
    throw Error(errMsg);

// Create a new message
var message = AwesomeUtils.create(payload); // or use .fromObject if conversion is necessary
console.log("create: " + JSON.stringify(message));

// Encode a message to an Uint8Array (browser) or Buffer (node)
var buffer = AwesomeUtils.encode(message).finish();
// ... do something with buffer
console.log("encode: " + JSON.stringify(buffer));

// Decode an Uint8Array (browser) or Buffer (node) to a message
var message = AwesomeUtils.decode(buffer);
// ... do something with message
console.log("decode: " + JSON.stringify(message));

// If the application uses length-delimited buffers, there is also encodeDelimited and decodeDelimited.

// Maybe convert the message back to a plain object
var object = AwesomeUtils.toObject(message, {
    longs: String,
    enums: String,
    bytes: String,
    // see ConversionOptions
});
console.log("toObject: " + JSON.stringify(object));

运行脚本文件如下：

node app_awesome.js

在这里插入图片描述

2.2 例子：account.proto

account.proto

// account.proto
package yxy;
syntax = "proto3";

message Account{
    required string name = 1; //帐号名
    required string pwd = 2; //帐号密码
}

message AccountList{
    required int32 index = 1;
    repeated Account list = 2;
}

2.2.1 create(...)创建对象

app_account.js

var ProtoBufJs = require("protobufjs");
var root = ProtoBufJs.loadSync("./account.proto");
var AccountList = root.lookupType("yxy.AccountList");
var Account = root.lookupType("yxy.Account");
var accountListObj = AccountList.create();

for(var i = 0; i < 10; i++){
    var accountObj = Account.create();
    accountObj.name = "杨小羊_"+i;
    accountObj.pwd = "pwd_"+i;
    accountListObj.list.push(accountObj);
}

var buffer = AccountList.encode(accountListObj).finish();

console.log("data: " + JSON.stringify(accountListObj));
console.log("encode: " + JSON.stringify(buffer));

执行命令如下：

node app_account.js

在这里插入图片描述

2.2.2 fromObject(...)创建对象

var ProtoBufJs = require("protobufjs");
var root = ProtoBufJs.loadSync("./account.proto");
var AccountList = root.lookupType("yxy.AccountList");
var Account = root.lookupType("yxy.Account");

var accountObj1 = Account.fromObject({pwd:"666", name:"杨小羊"});
var accountObj2 = Account.fromObject({pwd:"777", name:"杨大羊"});
var accountObj3 = Account.fromObject({pwd:"888", name:"杨胖羊"});
var accountListObj = AccountList.fromObject({index:"0", list:[accountObj1,accountObj2,accountObj3]});
var buffer = AccountList.encode(accountListObj).finish();

console.log("data: " + JSON.stringify(accountListObj));
console.log("encode: " + JSON.stringify(buffer));

执行结果如下：在这里插入图片描述

结语

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