无涯教程-Spring Boot - Hystrix Hystrix是Netflix的Library。 Hystrix隔

Hystrix是Netflix的Library。 Hystrix隔离服务之间的访问点，停止服务之间的级联故障，并提供后备选项。

首先，无涯教程需要在构建配置文件中添加Spring Cloud Starter Hystrix依赖项。

Maven用户可以在pom.xml文件中添加以下依赖项-

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>

Gradle用户可以在build.gradle文件中添加以下依赖项-

compile(org.springframework.cloud:spring-cloud-starter-hystrix)

现在，将@EnableHystrix批注添加到主Spring Boot应用程序类文件中。 @EnableHystrix批注用于将Hystrix功能启用到您的Spring Boot应用程序中。

下面给出了主要的Spring Boot应用程序类文件代码-

package com.learnfk.hystrixapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
@SpringBootApplication
@EnableHystrix
public class HystrixappApplication {
public static void main(String[] args) {
SpringApplication.run(HystrixappApplication.class, args);
}
}

现在编写一个简单的Rest Controller，以便它在请求的时间后3秒钟后返回String。

@RequestMapping(value="/")
public String hello() throws InterruptedException {
   Thread.sleep(3000);
   return "Welcome Hystrix";
}

现在，为Rest API添加@Hystrix命令和@HystrixProperty并定义以毫秒为单位的超时值。

@HystrixCommand(fallbackMethod="fallback_hello", commandProperties={
   @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds", value="1000")
})

接下来，如果请求需要很长时间才能响应，则定义回退方法fallback_hello()。

private String fallback_hello() {
   return "Request fails. It takes long time to response";
}

此处显示了包含REST API和Hystrix属性的完整Rest Controller类文件-

@RequestMapping(value="/")
@HystrixCommand(fallbackMethod="fallback_hello", commandProperties={
   @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds", value="1000")
})
public String hello() throws InterruptedException {
   Thread.sleep(3000);
   return "Welcome Hystrix";
}
private String fallback_hello() {
   return "Request fails. It takes long time to response";
}

在此示例中，REST API编写在主Spring Boot应用程序类文件本身中。

package com.learnfk.hystrixapp;
import org.springframework.boot.SpringApplication;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
@SpringBootApplication
@EnableHystrix
@RestController
public class HystrixappApplication {
public static void main(String[] args) {
SpringApplication.run(HystrixappApplication.class, args);
}
@RequestMapping(value="/")
@HystrixCommand(fallbackMethod="fallback_hello", commandProperties={
@HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds", value="1000")
})
public String hello() throws InterruptedException {
Thread.sleep(3000);
return "Welcome Hystrix";
}
private String fallback_hello() {
return "Request fails. It takes long time to response";
}
}

完整的构建配置文件如下所示。

Maven-pom.xml文件

<?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>com.learnfk</groupId>
<artifactId>hystrixapp</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>hystrixapp</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Edgware.RELEASE</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

Gradle – build.gradle

buildscript {
   ext {
      springBootVersion=1.5.9.RELEASE
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}
apply plugin: java
apply plugin: eclipse
apply plugin: org.springframework.boot
group=com.learnfk
version=0.0.1-SNAPSHOT
sourceCompatibility=1.8
repositories {
mavenCentral()
}
ext {
springCloudVersion=Edgware.RELEASE
}
dependencies {
compile(org.springframework.cloud:spring-cloud-starter-hystrix)
compile(org.springframework.boot:spring-boot-starter-web)
testCompile(org.springframework.boot:spring-boot-starter-test)
}
dependencyManagement {
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
}
}

您可以创建一个可执行的JAR文件，并使用以下Maven或Gradle命令运行Spring Boot应用程序-

对于Maven，使用如下所示的命令-

mvn clean install

在" BUILD SUCCESS"之后，您可以在目标目录下找到JAR文件。

对于Gradle，使用如下所示的命令-

gradle clean build

在" BUILD SUCCESSFUL"之后，您可以在build/libs目录下找到JAR文件。

现在，使用下面给出的命令运行JAR文件:

java –jar <JARFILE>

这将在Tomcat端口8080上启动应用程序，如下所示-

现在，从Web浏览器中访问URL http:// localhost:8080/，然后查看Hystrix响应。该API需要3秒钟来响应，但是Hystrix超时是1秒。

无涯教程-Spring Boot - Hystrix

参考链接