2、熔断器 Netflix Hystrix 之开始使用

矫情吗；* 2023-01-07 13:25 96阅读 0赞

## 1、添加依赖 ##

Maven、Ivy、Gradle和其他工具的二进制文件和依赖信息可以在 `http://search.maven.org` 上找到。

**Maven的例子:**

<dependency>
        <groupId>com.netflix.hystrix</groupId>
        <artifactId>hystrix-core</artifactId>
        <version>x.y.z</version>
    </dependency>

**Ivy 的例子：**

如果你需要下载jar文件，而不是使用构建系统，创建一个Maven pom文件，如下所示:

<?xml version="1.0"?>
    <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>com.netflix.hystrix.download</groupId>
    	<artifactId>hystrix-download</artifactId>
    	<version>1.0-SNAPSHOT</version>
    	<name>Simple POM to download hystrix-core and dependencies</name>
    	<url>http://github.com/Netflix/Hystrix</url>
    	<dependencies>
    		<dependency>
    			<groupId>com.netflix.hystrix</groupId>
    			<artifactId>hystrix-core</artifactId>
    			<version>x.y.z</version>
    			<scope/>
    		</dependency>
    	</dependencies>
    </project>

然后排除：

mvn -f download-hystrix-pom.xml dependency:copy-dependencies

它将下载 `hystrix-core-*.jar` 及其依赖项到 `./target/dependency/`。

您需要 Java 6 或更高版本。

## 2、Hello World! ##

Hystrix 的最简单用法如下:

public class CommandHelloWorld extends HystrixCommand<String> { 
    
        private final String name;
    
        public CommandHelloWorld(String name) { 
            super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"));
            this.name = name;
        }
    
        @Override
        protected String run() { 
            // a real example would do work like a network call here
            return "Hello " + name + "!";
        }
    }

[View Source][]

这个命令可以这样使用:

String s = new CommandHelloWorld("Bob").execute();
    Future<String> s = new CommandHelloWorld("Bob").queue();
    Observable<String> s = new CommandHelloWorld("Bob").observe();

更多的例子和信息可以在如何使用一节中找到。

示例源代码可以在 [hystrix-examples][] 模块中找到。

## 3、项目构建 ##

检出源代码并构建:

$ git clone git@github.com:Netflix/Hystrix.git
    $ cd Hystrix/
    $ ./gradlew build

简单的构建:

$ ./gradlew clean build

构建结果类似如下:

$ ./gradlew build
    :hystrix-core:compileJava
    :hystrix-core:processResources UP-TO-DATE
    :hystrix-core:classes
    :hystrix-core:jar
    :hystrix-core:sourcesJar
    :hystrix-core:signArchives SKIPPED
    :hystrix-core:assemble
    :hystrix-core:licenseMain UP-TO-DATE
    :hystrix-core:licenseTest UP-TO-DATE
    :hystrix-core:compileTestJava
    :hystrix-core:processTestResources UP-TO-DATE
    :hystrix-core:testClasses
    :hystrix-core:test
    :hystrix-core:check
    :hystrix-core:build
    :hystrix-examples:compileJava
    :hystrix-examples:processResources UP-TO-DATE
    :hystrix-examples:classes
    :hystrix-examples:jar
    :hystrix-examples:sourcesJar
    :hystrix-examples:signArchives SKIPPED
    :hystrix-examples:assemble
    :hystrix-examples:licenseMain UP-TO-DATE
    :hystrix-examples:licenseTest UP-TO-DATE
    :hystrix-examples:compileTestJava
    :hystrix-examples:processTestResources UP-TO-DATE
    :hystrix-examples:testClasses
    :hystrix-examples:test
    :hystrix-examples:check
    :hystrix-examples:build
    
    BUILD SUCCESSFUL
    
    Total time: 30.758 secs

在一个干净的构建中，你会看到单元测试运行，看起来像这样:

> Building > :hystrix-core:test > 147 tests completed

[View Source]: https://github.com/Netflix/Hystrix/blob/master/hystrix-examples/src/main/java/com/netflix/hystrix/examples/basic/CommandHelloWorld.java
[hystrix-examples]: https://github.com/Netflix/Hystrix/tree/master/hystrix-examples/src/main/java/com/netflix/hystrix/examples