在启动期间运行 Spring Boot 应用程序时出现异常:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'testController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.web.client.RestTemplate com.micro.test.controller.TestController.restTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.web.client.RestTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
我在我的 TestController 中自动装配 RestTemplate。我正在使用 Maven 进行依赖管理。
TestMicroServiceApplication.java
package com.micro.test; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class TestMicroServiceApplication { public static void main(String[] args) { SpringApplication.run(TestMicroServiceApplication.class, args); } }
TestController.java
package com.micro.test.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.MediaType; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.client.RestTemplate; @RestController public class TestController { @Autowired private RestTemplate restTemplate; @RequestMapping(value="/micro/order/{id}", method=RequestMethod.GET, produces=MediaType.ALL_VALUE) public String placeOrder(@PathVariable("id") int customerId){ System.out.println("Hit ===> PlaceOrder"); Object[] customerJson = restTemplate.getForObject("http://localhost:8080/micro/customers", Object[].class); System.out.println(customerJson.toString()); return "false"; } }
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.micro.test</groupId> <artifactId>Test-MicroService</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>Test-MicroService</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.3.3.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <java.version>1.8</java.version> </properties> <dependencies> <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> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
这正是错误所说的。您没有创建任何RestTemplatebean,因此它无法自动装配任何 bean。如果你需要一个RestTemplate,你必须提供一个。例如,将以下内容添加到 TestMicroServiceApplication.java :
RestTemplate
@Bean public RestTemplate restTemplate() { return new RestTemplate(); }
从 Spring boot 1.4 开始,还有一个方便的构建器,您可以自动装配并使用它来创建RestTemplatebean。好处是您可以使用构建器模式来注册拦截器、定制器……。
@Bean public RestTemplate restTemplate(RestTemplateBuilder builder) { return builder.build(); }
请注意,在 Eureka 的 Spring cloud starter 的早期版本中,RestTemplate为您创建了一个 bean,但这不再是真的。