使用RestTemplate远程调用及基于RestTemplate的服务降级(hystrix)

表结构及测试数据

DROP TABLE IF EXISTS `product`;
CREATE TABLE `product` (
  `productId` bigint(20) NOT NULL AUTO_INCREMENT,
  `productName` varchar(50) DEFAULT NULL,
  `productDesc` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`productId`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of product
-- ----------------------------
INSERT INTO `product` VALUES ('1', '电子锁骨', 'cloud');
INSERT INTO `product` VALUES ('2', 'Springboot', 'cloud');
INSERT INTO `product` VALUES ('3', '水表', 'cloud');
INSERT INTO `product` VALUES ('4', '门禁', 'cloud');
INSERT INTO `product` VALUES ('5', '摄像头', 'cloud');
INSERT INTO `product` VALUES ('8', 'SpringCloud', 'cloud');
INSERT INTO `product` VALUES ('9', 'RestTemplate', 'cloud');

父工程

<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>4.0.0modelVersion>

    <groupId>com.xysd.cloudgroupId>
    <artifactId>cloudexecise2artifactId>
    <packaging>pompackaging>
    <version>1.0-SNAPSHOTversion>
    <modules>
        <module>cloudapimodule>
        <module>cloudproviderproductmodule>
        <module>cloudconsumermodule>
        <module>clouderurekamodule>
    modules>

    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.1.6.RELEASEversion>
    parent>

    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding>
        <java.version>1.8java.version>
    properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-loggingartifactId>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <version>1.18.4version>
            <scope>providedscope>
        dependency>
    dependencies>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>Greenwich.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>

    <build>
        <finalName>cloudexecise2finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>${java.version}source>
                    <target>${java.version}target>
                configuration>
            plugin>
        plugins>
    build>
project>

公共模块，存放实体类，工具类等等

package com.xysd.cloud.entity;

import java.io.Serializable;

public class Product implements Serializable {
    private Long productId;
    private String productName;
    private String productDesc;

    public String getProductDesc() {
        return productDesc;
    }
    public void setProductDesc(String productDesc) {
        this.productDesc = productDesc;
    }
    public String getProductName() {
        return productName;
    }
    public void setProductName(String productName) {
        this.productName = productName;
    }
    public Long getProductId() {
        return productId;
    }
    public void setProductId(Long productId) {
        this.productId = productId;
    }
    @Override
    public String toString() {
        return "Product{" +
                "productId=" + productId +
                ", productName='" + productName + '\'' +
                ", productDesc='" + productDesc + '\'' +
                '}';
    }
}

注册中心cloudeureka

依赖

<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">
    <parent>
        <artifactId>cloudexecise2artifactId>
        <groupId>com.xysd.cloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-erurekaartifactId>

    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
    properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-serverartifactId>
        dependency>
    dependencies>

    <build>
        <finalName>eureka-serverfinalName>
        <plugins>
            <plugin> 
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
                <configuration> 
                    <mainClass>com.xysd.cloud.EurekaAppmainClass>
                configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackagegoal>
                        goals>
                    execution>
                executions>
            plugin>
        plugins>
    build>
project>

配置application.yml

server:
  port: 8761
eureka:
  instance:
    hostname: localhost   # 定义 Eureka 实例所在的主机名称
  client:
    fetch-registry: false #是否从eureka中获取注册信息
    register-with-eureka: false #是否将自己注册到注册中心
    service-url:
      defaultZone: http://localhost:8761/eureka/

代码

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaApp {

    public static void main(String[] args) {
        SpringApplication.run(EurekaApp.class,args);
    }
}

生产主cloudproviderproduct

依赖

<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">
    <parent>
        <artifactId>cloudexecise2artifactId>
        <groupId>com.xysd.cloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-provider-productartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>com.xysd.cloudgroupId>
            <artifactId>cloud-apiartifactId>
            <version>1.0.0version>
        dependency>
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
        dependency>
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>druidartifactId>
            <version>1.0.31version>
        dependency>
        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>1.3.0version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
        dependency>
    
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>

    dependencies>

    <build>
        <finalName>cloud-eurekafinalName>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <filtering>truefiltering>
            resource>
        resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-resources-pluginartifactId>
                <configuration>
                    <delimiters>
                        <delimiter>$delimiter>
                    delimiters>
                configuration>
            plugin>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>${java.version}source>
                    <target>${java.version}target>
                configuration>
            plugin>
        plugins>
    build>
project>

配置application.yml

server:
 port: 8080
mybatis:  #mybatyis的配置
  mapper-locations: classpath:mapper/*.xml
spring:
 datasource:
   type: com.alibaba.druid.pool.DruidDataSource # 配置当前要使用的数据源的操作类型
   driver-class-name: com.mysql.cj.jdbc.Driver # 配置MySQL的驱动程序类
   url: jdbc:mysql://localhost:3306/cloud?serverTimezone=GMT%2B8 # 数据库连接地址
   username: root # 数据库用户名
   password: root # 数据库连接密码
 application:
   name: cloudproviderproduct
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    instance-id: cloudproviderproduct
    prefer-ip-address: true #显示ip
info:
  app.name: cloudproviderproduct
  company.name: xysd
  build.artifactId: $project.artifactId$
  build.modelVersion: $project.modelVersion$

代码

package com.xysd.cloud.mapper;

import com.xysd.cloud.entity.Product;

import java.util.List;

public interface ProductMapper {
    boolean create(Product product);
    public Product findById(Long id);
    public List<Product> findAll();
}

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xysd.cloud.mapper.ProductMapper">

    <resultMap id="productResult" type="com.xysd.cloud.entity.Product">
        <id column="productId" property="productId"/>
        <result column="productName" property="productName"/>
        <result column="productDesc" property="productDesc"/>
    resultMap>
    <select id="findById" resultMap="productResult" parameterType="long">
        select productId,productName,productDesc from product WHERE productId=#{id} ;
    select>
    <select id="findAll" resultMap="productResult">
        SELECT productId,productName,productDesc from product;
    select>
    <insert id="create" parameterType="com.xysd.cloud.entity.Product">
        INSERT INTO product(productName,productDesc) VALUES (#{productName},database()) ;
    insert>
mapper>

package com.xysd.cloud.service;

import com.xysd.cloud.entity.Product;

import java.util.List;

public interface ProductService {
    Product get(long id);
    boolean add(Product product);
    List<Product> list();
}

package com.xysd.cloud.service.impl;

import com.xysd.cloud.entity.Product;
import com.xysd.cloud.mapper.ProductMapper;
import com.xysd.cloud.service.ProductService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;
@Service
public class ProductServiceImpl implements ProductService {

    @Resource
    private ProductMapper productMapper;

    @Override
    public Product get(long id) {
        return productMapper.findById(id);
    }

    @Override
    public boolean add(Product product) {
        System.out.println(product);
        return productMapper.create(product);
    }

    @Override
    public List<Product> list() {
        return productMapper.findAll();
    }
}

package com.xysd.cloud.controller;

import com.xysd.cloud.entity.Product;
import com.xysd.cloud.service.ProductService;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;

@RestController
@RequestMapping("/product")
public class ProductController {

    @Resource
    private ProductService productService;

    @RequestMapping(value = "/get/{id}",method = RequestMethod.GET)
    public Object get(@PathVariable("id") long id) {
        return this.productService.get(id);
    }

    @RequestMapping(value = "/add")
    public Object add(@RequestBody Product product) {
        return this.productService.add(product);
    }

    @RequestMapping(value = "/list")
    public Object list() {
        return this.productService.list();
    }
}

消费者cloudconsumer

依赖

<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">
    <parent>
        <artifactId>cloudexecise2artifactId>
        <groupId>com.xysd.cloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-consumerartifactId>
    <dependencies>
        <dependency>
            <groupId>com.xysd.cloudgroupId>
            <artifactId>cloud-apiartifactId>
            <version>1.0.0version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>

    dependencies>

    <build>
        <finalName>cloud-eurekafinalName>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <filtering>truefiltering>
            resource>
        resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-resources-pluginartifactId>
                <configuration>
                    <delimiters>
                        <delimiter>$delimiter>
                    delimiters>
                configuration>
            plugin>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>${java.version}source>
                    <target>${java.version}target>
                configuration>
            plugin>
        plugins>
    build>
project>

配置application.yml

server:
  port: 8083

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    instance-id: cloudconsumerproduct
    prefer-ip-address: true #显示ip
spring:
  application:
    name: cloudconsumerproduct
info:
  app.name: cloudproviderproduct
  company.name: xysd
  build.artifactId: $project.artifactId$
  build.modelVersion: $project.modelVersion$

代码

package com.xysd.cloud.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;


@Configuration
public class RestConfig {

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

package com.xysd.cloud.controller;

import com.xysd.cloud.entity.Product;
import com.xysd.cloud.service.ProductFeignClient;
import org.springframework.http.HttpHeaders;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.util.List;

@RestController
@RequestMapping("/consumer")
public class ConsumerProductController {
    public static final String PRODUCT_GET_URL = "http://cloudproviderproduct/product/get/";
    public static final String PRODUCT_LIST_URL="http://cloudproviderproduct/product/list/";
    public static final String PRODUCT_ADD_URL = "http://cloudproviderproduct/product/add/";
    
    @Resource //必须使用应用名(服务名大小写都可以)作为代替ip:端口，
    private RestTemplate restTemplate;

    @RequestMapping("/product/get")
    public Object getProduct(@RequestParam(value = "id") long id) {
        String url = PRODUCT_GET_URL + id;
        System.out.println(url);
        Product product = restTemplate.getForObject(url, Product.class);
     return  product;
    }

    @RequestMapping("/product/list")
    public  Object listProduct() {
        List<Product> list = restTemplate.getForObject(PRODUCT_LIST_URL, List.class);
        return  list;
    }

    @RequestMapping("/product/add")
    public Object addPorduct(@RequestBody Product product) {
        System.out.println(product);
        Boolean result = restTemplate.postForObject(PRODUCT_ADD_URL, product, Boolean.class);
       return  result;
    }
}

测试

先启动cloudeureka，在启动cloudproviderproduct，如何启动cloudconsumer，访问http://localhost:8083/consumer/product/get?id=1

服务降级

在消费者端操作

依赖

 
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-hystrixartifactId>
        dependency>

配置

hystrix:
  command:
    default:
      execution:
        isolation:
          strategy: ExecutionIsolationStrategy.SEMAPHORE #信号量隔离
          thread:
            timeoutInMilliseconds: 1000 #默认的连接超时时间1秒,若1秒没有返回数据,自动的触发降级逻辑

代码

基于方法降级

package com.xysd.cloud.controller;

import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.xysd.cloud.entity.Product;
import com.xysd.cloud.service.ProductFeignClient;
import org.springframework.http.HttpHeaders;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.util.List;

@RestController
@RequestMapping("/consumer")
public class ConsumerProductController {
    public static final String PRODUCT_GET_URL = "http://cloudproviderproduct/product/get/";
    public static final String PRODUCT_LIST_URL="http://cloudproviderproduct/product/list/";
    public static final String PRODUCT_ADD_URL = "http://cloudproviderproduct/product/add/";
    
    @Resource //必须使用应用名作为代替ip:端口，
    private RestTemplate restTemplate;

    @HystrixCommand(fallbackMethod = "getProductFallBack")
    @RequestMapping("/product/get")
    public Object getProduct(@RequestParam(value = "id") long id) {
        String url = PRODUCT_GET_URL + id;
        System.out.println(url);
        Product product = restTemplate.getForObject(url, Product.class);
        return  product;
    }

    /**
     * 降级方法
     *  和需要收到保护的方法的返回值一致
     *  方法参数一致
     */
    public Object getProductFallBack(@RequestParam(value = "id") long id){
        Product product = new Product();
        product.setProductDesc("测试hystrix降级方法");
        product.setProductName("hystrix");
        return product;
    }

    @RequestMapping("/product/list")
    public  Object listProduct() {
        List<Product> list = restTemplate.getForObject(PRODUCT_LIST_URL, List.class);
        return  list;
    }

    @RequestMapping("/product/add")
    public Object addPorduct(@RequestBody Product product) {
        System.out.println(product);
        Boolean result = restTemplate.postForObject(PRODUCT_ADD_URL, product, Boolean.class);
        return  result;
    }
}

基于类服务降级

package com.xysd.cloud.controller;

import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.xysd.cloud.entity.Product;
import com.xysd.cloud.service.ProductFeignClient;
import org.springframework.http.HttpHeaders;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.util.List;
/**
 * @DefaultProperties : 指定此接口中公共的熔断设置
 *      如果过在@DefaultProperties指定了公共的降级方法
 *      在@HystrixCommand不需要单独指定了
 * 		这就要求该controller中的所有方法返回值都一样
 */
@DefaultProperties(defaultFallback = "getProductFallBack")
@RestController
@RequestMapping("/consumer")
public class ConsumerProductController {
    public static final String PRODUCT_GET_URL = "http://cloudproviderproduct/product/get/";
    public static final String PRODUCT_LIST_URL="http://cloudproviderproduct/product/list/";
    public static final String PRODUCT_ADD_URL = "http://cloudproviderproduct/product/add/";
    @Resource //必须使用应用名作为代替ip:端口，
    private RestTemplate restTemplate;

    @RequestMapping("/product/get")
    public Object getProduct(@RequestParam(value = "id") long id) {
        String url = PRODUCT_GET_URL + id;
        System.out.println(url);
        Product product = restTemplate.getForObject(url, Product.class);
      return  product;
    }

    /**
     * 降级方法
     *  和需要收到保护的方法的返回值一致
     *  方法参数一致
     */
    public Object getProductFallBack(@RequestParam(value = "id") long id){
        Product product = new Product();
        product.setProductDesc("测试hystrix降级方法");
        product.setProductName("hystrix");
        return product;
    }

    @RequestMapping("/product/list")
    public  Object listProduct() {
        List<Product> list = restTemplate.getForObject(PRODUCT_LIST_URL, List.class);
     return  list;
    }

    @RequestMapping("/product/add")
    public Object addPorduct(@RequestBody Product product) {
        System.out.println(product);
        Boolean result = restTemplate.postForObject(PRODUCT_ADD_URL, product, Boolean.class);
        return  result;
    }
}