Apache Thrift 简单实例

Php rpc 服务端提供计算器服务（加减乘除），Java rpc 客户端通过 thrift api 对其进行调用。改编自thrift官方教程，主要是为了看起来更加简单。

1. 编写接口描述文件 calculator.thrift

namespace java app.rpc.learn
namespace php App.Rpc.Learn

enum Operation {
  ADD = 1,
  SUBTRACT = 2,
  MULTIPLY = 3,
  DIVIDE = 4
}

exception InvalidOperation {
  1: i32 whatOp,
  2: string why
}

service Calculator {
   double calculate(1:double num1, 2:double num2, 3:Operation op) throws (1:InvalidOperation ouch),
}

2. 使用 thrift编译器生成 PHP服务端及Java客户端基础代码

// 服务端命令
thrift -gen php:server calculator.thrift 

// 客户端命令
thrift -gen java calculator.thrift

3. php 服务端实现计算器服务

<?php
/**
 * Created by PhpStorm.
 * Date: 18-1-6
 * Time: 下午9:26
 */

namespace App\Services;

use App\Rpc\Learn\CalculatorIf;
use App\Rpc\Learn\Operation;
use App\Rpc\Learn\InvalidOperation;


class CalculatorService implements CalculatorIf {
    /**
     * @param double $num1
     * @param double $num2
     * @param int $op
     * @return double
     * @throws InvalidOperation
     */
    public function calculate($num1, $num2, $op) {
        switch ($op) {
            case Operation::ADD:
                $val = $num1 + $num2;
                break;
            case Operation::SUBTRACT:
                $val = $num1 - $num2;
                break;
            case Operation::MULTIPLY:
                $val = $num1 * $num2;
                break;
            case Operation::DIVIDE:
                if ($num2 == 0) {
                    $io = new InvalidOperation();
                    $io->whatOp = $op;
                    $io->why = "Cannot divide by 0";
                    throw $io;
                }
                $val = $num1 / $num2;
                break;
            default:
                $io = new InvalidOperation();
                $io->whatOp = $op;
                $io->why = "Invalid Operation";
                throw $io;
        }
        return $val;
    }
}

4. 搭建并开启服务
   本文使用了laravel 5.5 框架来搭建php 测试服务器，由composer管理系统依赖，为了引入 thrift 依赖，在项目根目录下执行以下命令即可：

composer require apache/thrift

编写 RpcController：

<?php
/**
 * Created by PhpStorm.
 * Date: 18-1-6
 * Time: 下午9:16
 */

namespace App\Http\Controllers;


use App\Rpc\Learn\CalculatorProcessor;
use App\Services\CalculatorService;
use Illuminate\Http\Request;
use Thrift\Protocol\TBinaryProtocol;
use Thrift\Transport\TBufferedTransport;
use Thrift\Transport\TPhpStream;

class RpcController extends Controller
{
    function handleRequest(Request $request) {
        header('Content-Type', 'application/x-thrift');
        $handler = new CalculatorService();
        $processor = new CalculatorProcessor($handler);

        $transport = new TBufferedTransport(new TPhpStream(TPhpStream::MODE_R | TPhpStream::MODE_W));
        $protocol = new TBinaryProtocol($transport, true, true);

        $transport->open();
        $processor->process($protocol, $protocol);
        $transport->close();
    }
}

在 routes/api.php 文件中配置路由：

Route::post('/rpc', [
    'as' => 'rpc',
    'uses' => 'RpcController@handleRequest'
]);

在项目根目录下执行以下命令启动测试服务器：

php artisan serve

5. 编写 Java rpc 客户端
   thrift 0.11.0 版本目前尚未加入maven 仓库，因此使用以下方式将无法下载到thrift 0.11.0版本的依赖包

<dependency>
  <groupId>org.apache.thrift</groupId>
  <artifactId>libthrift</artifactId>
  <version>0.11.0</version>
</dependency>

目前如果要使用0.11.0版，在编译构建thrift源代码后，lib/java/build 目录下有所有需要依赖的jar包，将其加入类路径即可。

该例子中的客户端代码非常简单：

package app;

import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.THttpClient;
import org.apache.thrift.transport.TTransport;

import app.rpc.learn.Calculator;
import app.rpc.learn.InvalidOperation;
import app.rpc.learn.Operation;

public class RpcClient {

    public static void main(String[] args) {
        TTransport transport = null;
        try {
            transport = new THttpClient("http://localhost:8000/api/rpc");
            TProtocol protocol = new TBinaryProtocol(transport, true, true);
            Calculator.Client rpcCalculator = new Calculator.Client(protocol);
            System.out.println("Start Access Calculate Service From PHP Rpc Server...");
            System.out.print("12 + 5 = ");
            System.out.println(rpcCalculator.calculate(12, 5, Operation.ADD));
            System.out.print("12 - 5 = ");
            System.out.println(rpcCalculator.calculate(12, 5, Operation.SUBTRACT));
            System.out.print("12 * 5 = ");
            System.out.println(rpcCalculator.calculate(12, 5, Operation.MULTIPLY));
            System.out.print("12 / 5 = ");
            System.out.println(rpcCalculator.calculate(12, 5, Operation.DIVIDE));
            System.out.print("1 / 0 = ");
            System.out.println(rpcCalculator.calculate(1, 0, Operation.DIVIDE));
        } catch (InvalidOperation e) {
            System.out.println("Exception: " + e.why);
        } catch (Exception e) {
            System.out.println(e.getMessage());
        } finally {
            if (transport != null) {
                transport.close();
            }
        }   
    }
}

运行结果：

Start Access Calculate Service From PHP Rpc Server...
12 + 5 = 17.0
12 - 5 = 7.0
12 * 5 = 60.0
12 / 5 = 2.4
1 / 0 = Exception: Cannot divide by 0

最后感谢伟大的markdown让写文档如此方便！