Hystrix 学习 1 : Hello World

本文是本人学习Hystrix总结的第一篇，经典的Hello World应用。本应用特征如下 :

1. 纯 java 项目 ;
   • 暂不涉及结合Spring使用，以便专注于Hystrix自身；
2. 使用junit 观察运行效果 ;
3. 使用 maven 管理依赖;

1. pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>tut.zero</groupId>
    <artifactId>hystrix</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-core</artifactId>
            <version>1.5.18</version>
        </dependency>
        <!-- test -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2. 定义Hello World Hystrix Command

package tut.zero.simple;

import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;

/**
 * 一个简单的 HystrixCommand 实现,执行结果为 String 类型
 */
public class CommandHelloWorld extends HystrixCommand<String> {

    private String name;

    public CommandHelloWorld(String name) {
        super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"));
        this.name = name;
    }

    @Override
    protected String run() {
        return "Hello " + name + "!";
    }
}

3. 测试运行定义的Hystrix Command

package tut.zero;

import tut.zero.middle.MockRemoteService;
import tut.zero.middle.MockRemoteServiceCommand;
import tut.zero.simple.CommandHelloWorld;
import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandProperties;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.netflix.hystrix.exception.HystrixRuntimeException;
import org.junit.Test;

import java.util.concurrent.Future;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.junit.Assert.assertThat;

public class HystrixTest {
    /**
     * 一个简单的 HystrixCommand 的实现 和 调用演示
     */
    @Test
    public void testCommandHelloWorld() throws Exception{
        {// 同步方式调用 HystrixCommand
            String result = new CommandHelloWorld("World").execute();
            assertThat(result, equalTo("Hello World!"));
        }

        {// 异步方式调用 HystrixCommand
            Future<String> result = new CommandHelloWorld("WORLD").queue();
            assertThat(result.get(), equalTo("Hello WORLD!"));
        }
    }
}

该测试执行应该能够正常通过，并且演示了使用HystrixCommand的基本方法 :

1. 同步调用 T execute() (这里T是结果数据类型)
2. 异步调用 Future<T> queue() (这里T是结果数据类型)