【Java异常】Spring boot启动失败@org.springframework.beans.factory.annotation.Autowired(required=true)

本文目录

一、背景描述

二、报错信息

三、错误原因

四、解决方案

4.1 方案一：扩大注解 @EnableFeignClients扫描的包的范围

4.2 方案二：在注解@EnableFeignClients指定clients

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一、背景描述

微服务项目，spring boot (v2.1.5.RELEASE) ，今天在ServiceA微服务里添加一个功能，通过FeignClient调用ServiceB的接口。

在本项目里通过@Autowired自动注入方式注入客户端接口

@Autowired
private ScreenSaverClient screenSaverClient;

然后启动项目，结果就报 APPLICATION FAILED TO START 项目启动失败。

二、报错信息

报错内容如下图所示：

三、错误原因

报这个错，是因为启动类里的注解 @EnableFeignClients没有扫描到这个包，在本项目里是没有扫描到com.iot.basic.iotsmarthome.api.client.screensaver.ScreenSaverClient这个。

以下是本项目的错误的启动类代码：

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@EnableDiscoveryClient
@ComponentScan(basePackages = {"com.uiotsoft.back","com.uiotsoft.framework"})
@EnableFeignClients(basePackages = {"com.uiotsoft.back.operation.facade.feign"})
@ServletComponentScan(basePackages ={"com.uiotsoft.back.operation.config"} )
@EnableSwagger2
@EnableHystrix
@EnableConfigurationProperties
public class OperationApplication {
	
	public static void main(String[] args) throws Exception {
		SpringApplication.run(OperationApplication.class, args);
	}
	
}

四、解决方案

方案有多种，这里先写两种，以后再更新：

4.1 方案一：扩大注解 @EnableFeignClients扫描的包的范围

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@EnableDiscoveryClient
@ComponentScan(basePackages = {"com.uiotsoft.back","com.uiotsoft.framework"})
@EnableFeignClients(basePackages = {"com.uiotsoft"})
@ServletComponentScan(basePackages ={"com.uiotsoft.back.operation.config"} )
@EnableSwagger2
@EnableHystrix
@EnableConfigurationProperties
public class OperationApplication {
	
	public static void main(String[] args) throws Exception {
		SpringApplication.run(OperationApplication.class, args);
	}
	
}

网上有说“将 FeignClient 这个 bean 放在和 Application 启动类同级目录”，其道理和作用是和方案一相同的。

4.2 方案二：在注解@EnableFeignClients指定clients

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@EnableDiscoveryClient
@ComponentScan(basePackages = {"com.uiotsoft.back","com.uiotsoft.framework"})
@EnableFeignClients(basePackages = {"com.uiotsoft.back.operation.facade.feign"}, clients = ScreenSaverClient.class)
@ServletComponentScan(basePackages ={"com.uiotsoft.back.operation.config"} )
@EnableSwagger2
@EnableHystrix
@EnableConfigurationProperties
public class OperationApplication {
	
	public static void main(String[] args) throws Exception {
		SpringApplication.run(OperationApplication.class, args);
	}
	
}

当然方案二有个弊端，就是项目里存在多个clients（需要调用很多其他的服务时）的时候，就需要指定很多个，所以如果通过FeignClient调用多个服务的时候，用方案一比较合适。

完结！

以下不用看，只是方便被搜索到

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of constructor in com.uiotsoft.back.operation.facade.service.impl.ScreenSaverClientServiceImpl required a bean of type 'com.uiotsoft.basic.iotsmarthome.api.client.screensaver.ScreenSaverClient' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)

Action:

Consider defining a bean of type 'com.uiotsoft.basic.iotsmarthome.api.client.screensaver.ScreenSaverClient' in your configuration.