Apache Thrift基本使用介绍

基本介绍

Thrift 是用于点对点 RPC 实现的轻量级、独立于语言的软件堆栈。 Thrift 为数据传输、数据序列化和应用程序级处理提供了清晰的抽象和实现。代码生成系统将简单的定义语言作为输入，并生成跨编程语言的代码，这些编程语言使用抽象堆栈来构建可互操作的 RPC 客户端和服务器。

Thrift 使以不同编程语言编写的程序可以轻松共享数据和调用远程过程。 Thrift 支持 28 种编程语言，很有可能支持您当前使用的语言。

Thrift 专门设计用于支持跨客户端和服务器代码的非原子版本更改。这使您可以升级服务器，同时仍然能够为旧客户端提供服务；或让较新的客户端向较旧的服务器发出请求。在 Thrift Missing Guide 中可以找到社区提供的关于在版本化 API 时节俭和兼容性的优秀文章。

下载与编译thrift

在使用Thrift之前，还需要安装编译器，如果是windows系统，那么可以直接下载二进制版本的thrift编译器，例如下述为0.16.0 windwos版本的thrift编译器

Thrift compiler for Windows (thrift-0.16.0.exe)

而如果你使用的是linux系统，那么你可以从源码进行编译安装，源码下载地址以及源码编译方法可见如下链接：

源码下载地址：thrift-0.16.0.tar.gz
源码编译方法：https://thrift.apache.org/docs/BuildingFromSource

当然，如果你使用的是Java语言，那么还需要在你的项目中添加如下依赖以完全使用thrift提供的能力。

<dependency>
  <groupId>org.apache.thrift</groupId>
  <artifactId>libthrift</artifactId>
  <version>0.16.0</version>
</dependency>

下面以Java语言的maven项目为例，讲述从头构建一个基本的thrift应用。

如果您对如何使用thrift定义语言不太了解，那么可以参考文章：Thrift接口定义语言

而对于thrift中所使用的基本类型，您可以参考文章：Thrift数据类型

构建thrift基本应用

在安装了Thrift编译器之后，我们需要创建一个.thrift文件，该文件是一个接口定义，由 thrift 类型和 Services 组成。在此文件中定义的服务由服务端实现并由任何客户端调用。 Thrift 编译器用于将您的 Thrift 文件生成为源代码，供不同的客户端库和您编写的服务端使用。

Apache Thrift 允许您在一个简单的定义文件中定义数据类型和服务接口。将该文件作为输入，编译器生成代码，用于轻松构建跨编程语言无缝通信的 RPC 客户端和服务器。无需编写大量样板代码来序列化和传输对象并调用远程方法，您可以直接开始工作。

您可以通过如下方式生成源代码：

thrift --gen <language> <Thrift filename>

本文中，由于我们使用的是maven项目，我们可以使用maven插件来完成.thrift文件编译工作。

我们定义两个.thrift文件，一个名为shared.thrift，另一个名为tutorial.thrift，以此说明如何编写.thrift文件。

shared.thrift

/**
 * This Thrift file can be included by other Thrift files that want to share
 * these definitions.
 */

namespace java com.zh.ch.bigdata.thrift.tutorial

struct SharedStruct {
  1: i32 key
  2: string value
}

service SharedService {
  SharedStruct getStruct(1: i32 key)
}

tutorial.thrift

# Thrift Tutorial
# Mark Slee (mcslee@facebook.com)
#
# This file aims to teach you how to use Thrift, in a .thrift file. Neato. The
# first thing to notice is that .thrift files support standard shell comments.
# This lets you make your thrift file executable and include your Thrift build
# step on the top line. And you can place comments like this anywhere you like.
#
# Before running this file, you will need to have installed the thrift compiler
# into /usr/local/bin.

/**
 * The first thing to know about are types. The available types in Thrift are:
 *
 *  bool        Boolean, one byte
 *  i8 (byte)   Signed 8-bit integer
 *  i16         Signed 16-bit integer
 *  i32         Signed 32-bit integer
 *  i64         Signed 64-bit integer
 *  double      64-bit floating point value
 *  string      String
 *  binary      Blob (byte array)
 *  map<t1,t2>  Map from one type to another
 *  list<t1>    Ordered list of one type
 *  set<t1>     Set of unique elements of one type
 *
 * Did you also notice that Thrift supports C style comments?
 */

// Just in case you were wondering... yes. We support simple C comments too.

/**
 * Thrift files can reference other Thrift files to include common struct
 * and service definitions. These are found using the current path, or by
 * searching relative to any paths specified with the -I compiler flag.
 *
 * Included objects are accessed using the name of the .thrift file as a
 * prefix. i.e. shared.SharedObject
 */
include "shared.thrift"

/**
 * Thrift files can namespace, package, or prefix their output in various
 * target languages.
 */

namespace java com.zh.ch.bigdata.thrift.tutorial

/**
 * Thrift lets you do typedefs to get pretty names for your types. Standard
 * C style here.
 */
typedef i32 MyInteger

/**
 * Thrift also lets you define constants for use across languages. Complex
 * types and structs are specified using JSON notation.
 */
const i32 INT32CONSTANT = 9853
const map<string,string> MAPCONSTANT = {'hello':'world', 'goodnight':'moon'}

/**
 * You can define enums, which are just 32 bit integers. Values are optional
 * and start at 1 if not supplied, C style again.
 */
enum Operation {
  ADD = 1,
  SUBTRACT = 2,
  MULTIPLY = 3,
  DIVIDE = 4
}

/**
 * Structs are the basic complex data structures. They are comprised of fields
 * which each have an integer identifier, a type, a symbolic name, and an
 * optional default value.
 *
 * Fields can be declared "optional", which ensures they will not be included
 * in the serialized output if they aren't set.  Note that this requires some
 * manual management in some languages.
 */
struct Work {
  1: i32 num1 = 0,
  2: i32 num2,
  3: Operation op,
  4: optional string comment,
}

/**
 * Structs can also be exceptions, if they are nasty.
 */
exception InvalidOperation {
  1: i32 whatOp,
  2: string why
}

/**
 * Ahh, now onto the cool part, defining a service. Services just need a name
 * and can optionally inherit from another service using the extends keyword.
 */
service Calculator extends shared.SharedService {

  /**
   * A method definition looks like C code. It has a return type, arguments,
   * and optionally a list of exceptions that it may throw. Note that argument
   * lists and exception lists are specified using the exact same syntax as
   * field lists in struct or exception definitions.
   */

   void ping(),

   i32 add(1:i32 num1, 2:i32 num2),

   i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),

   /**
    * This method has a oneway modifier. That means the client only makes
    * a request and does not listen for any response at all. Oneway methods
    * must be void.
    */
   oneway void zip()

}

/**
 * That just about covers the basics. Take a look in the test/ folder for more
 * detailed examples. After you run this file, your generated code shows up
 * in folders with names gen-<language>. The generated code isn't too scary
 * to look at. It even has pretty indentation.
 */

tutorial.thrift基本介绍：

include "shared.thrift"表示tutorial.thrift文件引入了shared.thrift
Java语言的命名空间设置为namespace java com.zh.ch.bigdata.thrift.tutorial ，也就是说，使用thrift编译器编译上述文件后，生成的代码在上述包中
typedef i32 MyInteger 表示用MyInteger表示i32数据类型
下述代码表示定义常量

const i32 INT32CONSTANT = 9853
const map<string,string> MAPCONSTANT = {'hello':'world', 'goodnight':'moon'}

下述代码表示定义枚举

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

下述代码表示定义结构

struct Work {
  1: i32 num1 = 0,
  2: i32 num2,
  3: Operation op,
  4: optional string comment,
}

下述代码表示定义异常

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

下述代码定义基本的服务。表示服务端提供的基本功能。

service Calculator extends shared.SharedService {

  /**
   * A method definition looks like C code. It has a return type, arguments,
   * and optionally a list of exceptions that it may throw. Note that argument
   * lists and exception lists are specified using the exact same syntax as
   * field lists in struct or exception definitions.
   */

   void ping(),

   i32 add(1:i32 num1, 2:i32 num2),

   i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),

   /**
    * This method has a oneway modifier. That means the client only makes
    * a request and does not listen for any response at all. Oneway methods
    * must be void.
    */
   oneway void zip()

}

有了thrift，我们只需要按照thrift接口规范定义好.thrift文件，然后实现其基本功能即可，而不需要关心数据如何传输。

所以，我们定义CalculatorHandler类来实现Calculator服务

/*
 * Copyright © 2020 https://www.lrting.top/ All rights reserved.
 */

package com.zh.ch.bigdata.handler;

import com.zh.ch.bigdata.thrift.tutorial.Calculator;

import com.zh.ch.bigdata.thrift.tutorial.*;

import java.util.HashMap;

/**
 * @author: bigDataToAi
 * @date: 2022/3/21
 * @description:
 * @modifiedBy:
 * @version: 1.0
 */
public class CalculatorHandler implements Calculator.Iface {

    private HashMap<Integer,SharedStruct> log;

    public CalculatorHandler() {
        log = new HashMap<Integer, SharedStruct>();
    }

    public void ping() {
        System.out.println("ping()");
    }

    public int add(int n1, int n2) {
        System.out.println("add(" + n1 + "," + n2 + ")");
        return n1 + n2;
    }

    public int calculate(int logid, Work work) throws InvalidOperation {
        System.out.println("calculate(" + logid + ", {" + work.op + "," + work.num1 + "," + work.num2 + "})");
        int val = 0;
        switch (work.op) {
            case ADD:
                val = work.num1 + work.num2;
                break;
            case SUBTRACT:
                val = work.num1 - work.num2;
                break;
            case MULTIPLY:
                val = work.num1 * work.num2;
                break;
            case DIVIDE:
                if (work.num2 == 0) {
                    InvalidOperation io = new InvalidOperation();
                    io.whatOp = work.op.getValue();
                    io.why = "Cannot divide by 0";
                    throw io;
                }
                val = work.num1 / work.num2;
                break;
            default:
                InvalidOperation io = new InvalidOperation();
                io.whatOp = work.op.getValue();
                io.why = "Unknown operation";
                throw io;
        }

        SharedStruct entry = new SharedStruct();
        entry.key = logid;
        entry.value = Integer.toString(val);
        log.put(logid, entry);

        return val;
    }

    public SharedStruct getStruct(int key) {
        System.out.println("getStruct(" + key + ")");
        return log.get(key);
    }

    public void zip() {
        System.out.println("zip()");
    }

}

接下来我们便可以定义服务端和客户端。

/*
 * Copyright © 2020 https://www.lrting.top/ All rights reserved.
 */

package com.zh.ch.bigdata.handler;

import com.zh.ch.bigdata.thrift.tutorial.*;
import org.apache.thrift.server.TServer;
import org.apache.thrift.server.TServer.Args;
import org.apache.thrift.server.TSimpleServer;
import org.apache.thrift.transport.TServerSocket;
import org.apache.thrift.transport.TServerTransport;

/**
 * @author: bigDataToAi
 * @date: 2022/3/21
 * @description:
 * @modifiedBy:
 * @version: 1.0
 */
public class JavaServer {

    public static CalculatorHandler handler;

    public static Calculator.Processor processor;

    public static void main(String [] args) {
        try {
            handler = new CalculatorHandler();
            processor = new Calculator.Processor(handler);

            Runnable simple = new Runnable() {
                public void run() {
                    simple(processor);
                }
            };

            new Thread(simple).start();
        } catch (Exception x) {
            x.printStackTrace();
        }
    }

    public static void simple(Calculator.Processor processor) {
        try {
            TServerTransport serverTransport = new TServerSocket(9090);
            TServer server = new TSimpleServer(new Args(serverTransport).processor(processor));

            // Use this for a multithreaded server
            // TServer server = new TThreadPoolServer(new TThreadPoolServer.Args(serverTransport).processor(processor));

            System.out.println("Starting the simple server...");
            server.serve();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

/*
 * Copyright © 2020 https://www.lrting.top/ All rights reserved.
 */

package com.zh.ch.bigdata.handler;

import org.apache.thrift.TException;
import org.apache.thrift.transport.TSSLTransportFactory;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TSSLTransportFactory.TSSLTransportParameters;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;

import com.zh.ch.bigdata.thrift.tutorial.*;

/**
 * @author: bigDataToAi
 * @date: 2022/3/21
 * @description:
 * @modifiedBy:
 * @version: 1.0
 */
public class JavaClient {

    public static void main(String [] args) {
        try {
            TTransport transport;
            transport = new TSocket("localhost", 9090);
            transport.open();
            TProtocol protocol = new TBinaryProtocol(transport);
            Calculator.Client client = new Calculator.Client(protocol);

            perform(client);

            transport.close();
        } catch (TException x) {
            x.printStackTrace();
        }
    }

    private static void perform(Calculator.Client client) throws TException
    {
        client.ping();
        System.out.println("ping()");

        int sum = client.add(1,1);
        System.out.println("1+1=" + sum);

        Work work = new Work();

        work.op = Operation.DIVIDE;
        work.num1 = 1;
        work.num2 = 0;
        try {
            int quotient = client.calculate(1, work);
            System.out.println("Whoa we can divide by 0");
        } catch (InvalidOperation io) {
            System.out.println("Invalid operation: " + io.why);
        }

        work.op = Operation.SUBTRACT;
        work.num1 = 15;
        work.num2 = 10;
        try {
            int diff = client.calculate(1, work);
            System.out.println("15-10=" + diff);
        } catch (InvalidOperation io) {
            System.out.println("Invalid operation: " + io.why);
        }

        SharedStruct log = client.getStruct(1);
        System.out.println("Check log: " + log.value);
    }

}

由上述可知，我们在服务端启动了一个9090端口的thrift服务以监听客户端的请求。于是，便可以在客户端通过连接该端口执行请求。

thrift-maven-plugin使用

在maven项目中使用可以使用如下插件来编译thrift文件从而生成java代码。

      <plugin>
        <groupId>org.apache.thrift.tools</groupId>
        <artifactId>maven-thrift-plugin</artifactId>
        <version>0.1.11</version>
        <configuration>
          <thriftExecutable>C:\\softwareInstall\\thrift-0.16.0\\thrift</thriftExecutable>
          <thriftSourceRoot>src/main/thrift</thriftSourceRoot>
          <outputDirectory>src/main/java</outputDirectory>
          <generator>java</generator>
        </configuration>
        <executions>
          <execution>
            <id>thrift-sources</id>
            <phase>generate-sources</phase>
            <goals>
              <goal>compile</goal>
            </goals>
          </execution>
        </executions>
      </plugin>

在使用上述插件之前，需要先在本地安装thrift编译器，并由thriftExecutable配置项指定。