SpringCloud Hystrix 示例

目标

创建2个service，student service 和 school service，school service 会调用 student service，school service 中集成 hystrix。

启动2个服务，访问 school service，正常情况下调用 student service 返回结果，停掉 student service，返回 hystrix 的处理信息。

创建 student service

https://start.spring.io，Spring Boot 1.5.16，Artifact：hystrix-student，依赖：web, rest repositories, actuator。

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>com.example</groupId>
    <artifactId>hystrix-student</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>hystrix-student</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.16.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>
    </properties>

    <dependencies>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.6</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.9.6</version>
</dependency>

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.9.6</version>
</dependency>
    </dependencies>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.properties

server.port = 8098

StudentServiceController.java

@RestController
public class StudentServiceController {
 
    private static Map<String, List<Student>> schooDB = new HashMap<String, List<Student>>();
 
    static {
        schooDB = new HashMap<String, List<Student>>();
 
        List<Student> lst = new ArrayList<Student>();
        Student std = new Student("Sajal", "Class IV");
        lst.add(std);
        std = new Student("Lokesh", "Class V");
        lst.add(std);
 
        schooDB.put("abcschool", lst);
 
        lst = new ArrayList<Student>();
        std = new Student("Kajal", "Class III");
        lst.add(std);
        std = new Student("Sukesh", "Class VI");
        lst.add(std);
 
        schooDB.put("xyzschool", lst);
 
    }
 
    @RequestMapping(value = "/getStudentDetailsForSchool/{schoolname}", method = RequestMethod.GET)
    public List<Student> getStudents(@PathVariable String schoolname) {
        System.out.println("Getting Student details for " + schoolname);
 
        List<Student> studentList = schooDB.get(schoolname);
        if (studentList == null) {
            studentList = new ArrayList<Student>();
            Student std = new Student("Not Found", "N/A");
            studentList.add(std);
        }
        return studentList;
    }
}

Student.java

public class Student {
 
    private String name;
    private String className;
 
    public Student(String name, String className) {
        super();
        this.name = name;
        this.className = className;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getClassName() {
        return className;
    }
 
    public void setClassName(String className) {
        this.className = className;
    }
}

启动，访问 http://localhost:8098/getStudentDetailsForSchool/abcschool

studentserviceresponse.jpg

创建 school service

Artifact：hystrix-school，依赖：web, rest repositories, actuator, hystrix, hystrix dashboard。

application.properties

server.port = 9098

启动类上开启 hystrix

@EnableHystrixDashboard
@EnableCircuitBreaker

SchoolServiceController.java

@RestController
public class SchoolServiceController {
     
    @Autowired
    StudentServiceDelegate studentServiceDelegate;
 
    @RequestMapping(value = "/getSchoolDetails/{schoolname}", method = RequestMethod.GET)
    public String getStudents(@PathVariable String schoolname) {
        System.out.println("Going to call student service to get data!");
        return studentServiceDelegate.callStudentServiceAndGetData(schoolname);
    }
}

StudentServiceDelegate.java

@Service
public class StudentServiceDelegate {
 
    @Autowired
    RestTemplate restTemplate;
     
    @HystrixCommand(fallbackMethod = "callStudentServiceAndGetData_Fallback")
    public String callStudentServiceAndGetData(String schoolname) {
 
        System.out.println("Getting School details for " + schoolname);
 
        String response = restTemplate
                .exchange("http://localhost:8098/getStudentDetailsForSchool/{schoolname}"
                , HttpMethod.GET
                , null
                , new ParameterizedTypeReference<String>() {
            }, schoolname).getBody();
 
        System.out.println("Response Received as " + response + " -  " + new Date());
 
        return "NORMAL FLOW !!! - School Name -  " + schoolname + " :::  " +
                    " Student Details " + response + " -  " + new Date();
    }
     
    @SuppressWarnings("unused")
    private String callStudentServiceAndGetData_Fallback(String schoolname) {
 
        System.out.println("Student Service is down!!! fallback route enabled...");
 
        return "CIRCUIT BREAKER ENABLED!!! No Response From Student Service at this moment. " +
                    " Service will be back shortly - " + new Date();
    }
 
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

启动，访问 http://localhost:9098/getSchoolDetails/abcschool