负载均衡spring-cloud-starter-openfeign教程

原创已于 2025-10-22 15:26:44 修改 · 174 阅读

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#spring

于 2025-10-18 11:39:55 首次发布

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.5.5</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>com.example</groupId>
  <artifactId>demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>demo</name>
  <description>Demo project for Spring Boot</description>
  <url/>
  <licenses>
    <license/>
  </licenses>
  <developers>
    <developer/>
  </developers>
  <scm>
    <connection/>
    <developerConnection/>
    <tag/>
    <url/>
  </scm>
  <properties>
    <java.version>17</java.version>
    <spring-cloud.version>2025.0.0</spring-cloud.version>

  </properties>
  <dependencies>
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>3.0.5</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
        <version>4.3.0</version>
    </dependency>
      <dependency>
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
          <version>3.3.0</version>
      </dependency>

    <dependency>
      <groupId>com.mysql</groupId>
      <artifactId>mysql-connector-j</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjrt</artifactId>
      <version>1.9.24</version>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter-test</artifactId>
      <version>3.0.5</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
<!--    <dependency>-->
<!--      <groupId>org.springframework.boot</groupId>-->
<!--      <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>-->
<!--      <version>5.0.0</version>-->
<!--    </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.apache.maven.plugins</groupId>-->
  <!--        <artifactId>maven-compiler-plugin</artifactId>-->
  <!--        <version>3.8.1</version>-->
  <!--        <configuration>-->
  <!--          <source>17</source>  &lt;!&ndash; 需与项目JDK版本一致 &ndash;&gt;-->
  <!--          <target>17</target>-->
  <!--          <encoding>UTF-8</encoding>-->
  <!--        </configuration>-->
  <!--      </plugin>-->
  <!--    </plugins>-->
  <!--  </build>-->

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>appassembler-maven-plugin</artifactId>
        <version>2.1.0</version>

        <!-- 如果不配置 generate-daemons，则打包命令为 mvn clean package appassembler:assemble -->
        <!-- 如果配置了 generate-daemons，打包命令可以是 mvn clean package 也可以是 mvn clean package appassembler:assemble -->
        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
              <goal>assemble</goal>
            </goals>
          </execution>
        </executions>

        <configuration>
          <!-- flat与lib共同决定将项目用的的所有jar包复制到lib目录下 -->
          <repositoryLayout>flat</repositoryLayout>
          <!--从哪里copy配置文件-->
          <configurationSourceDirectory>src/main/resources</configurationSourceDirectory>
          <includeConfigurationDirectoryInClasspath>true</includeConfigurationDirectoryInClasspath>
          <!--是否copy配置文件-->
          <copyConfigurationDirectory>true</copyConfigurationDirectory>
          <!--生成的项目的目录位置，这里的client是项目的名称，你可以根据你的需要自己随便命名-->
          <assembleDirectory>${project.build.directory}/client</assembleDirectory>
          <!--配置文件存放在conf目录路径-->
          <configurationDirectory>conf</configurationDirectory>
          <!-- 打包的jar，以及maven依赖的jar放到这个目录里面 -->
          <repositoryName>lib</repositoryName>
          <!-- 可执行脚本的目录 -->
          <binFolder>bin</binFolder>

          <!-- 生成linux, windows两种平台的执行脚本 -->
          <platforms>
            <platform>windows</platform>
            <platform>unix</platform>
          </platforms>

          <!-- 针对不同平台生成不同类型的启动脚本 -->
          <binFileExtensions>
            <unix>.sh</unix>
            <windows>.bat</windows>
          </binFileExtensions>

          <!--编码，日志-->
          <encoding>UTF-8</encoding>
          <logsDirectory>logs</logsDirectory>
          <tempDirectory>tmp</tempDirectory>

          <!--java启动参数-->
          <extraJvmArguments>-Xms128m</extraJvmArguments>

          <programs>
            <program>
              <!--指定主类，脚本名。会生成shell/bat两种类型,也可用platforms指定运行平台-->
              <mainClass>com.example.demo.OpenFeignApplication</mainClass>
              <!-- 生成的脚本文件的名称，比如start.sh,你也可以根据你的需要命名成其他名字 -->
              <name>start</name>
            </program>
          </programs>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

2、application.yml

server:
  port: 8088
spring:
 datasource:
        url: jdbc:mysql://localhost:3306/wscob
        username: root
        password: 123456
        driver-class-name: com.mysql.cj.jdbc.Driver
logging:
      level:
        root: DEBUG

3、启动项

@SpringBootApplication (scanBasePackages = {"com.example.controller","com.example.imp"})
@EnableFeignClients(basePackages = "com.example.imp")
@EnableAspectJAutoProxy(proxyTargetClass = true)  // 启用AOP代理 熔断需要使用
public class OpenFeignApplication {

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

}

4、访问FeignClient配置

@FeignClient(name = "${user.service.name}", url = "${user.service.url}")
public interface UserServiceClient {

    @GetMapping("/hello")
    String sayHello();

}

4、application.properties

spring.application.name=demo
user.service.name=user-service
user.service.url=http://localhost:9081

5、service层



@Service
public class MyService {
    @Autowired
    private UserServiceClient feignClient;
    @CircuitBreaker(name =  "checkCircuitBreaker", fallbackMethod = "fallbackForCallExternalService")
    public String callExternalService(String param) {
        // 模拟调用可能失败的外部服务
        String ss=null;
        try {
            // 可能抛出多种异常的代码
            ss= feignClient.sayHello();
        } catch (FeignException e) {
            // 处理多种异常
            throw new RuntimeException("Service call failed!");
        }

        return ss;
    }

    // 降级方法（参数和返回类型与主方法一致）
    private String fallbackForCallExternalService(String param, Throwable t) {
        // 记录异常或执行备用逻辑

        return "服务连接异常" + t.getMessage();
    }
}

5、controller层

@RestController
public class MyController {
    @Autowired
     private MyService myService;

     @GetMapping("/get-data1")
    public String getData1() {
        
        return myService.callExternalService("fail");
    }
}