Spring NoSuchBeanDefinitionException
转http://www.baeldung.com/spring-nosuchbeandefinitionexception
1. Overview
In this article, we are discussing the Springorg.springframework.beans.factory.NoSuchBeanDefinitionException – this is a common exception thrown by the BeanFactory when trying to resolve a bean that simply isn’t defined in the Spring Context.
We will discuss here the possible causes for this problem and the available solutions.
2. Cause: No qualifying bean of type [...] found for dependency
The most common cause of this exception is simply trying to inject a bean that isn’t defined. For example – BeanB is wiring in a collaborator – BeanA:
1
2
3
4
5
6
7
|
@Component public class BeanA { @Autowired private BeanB dependency; ... } |
Now, if the dependency – BeanB – is not defined in the Spring Context, the bootstrap process will fail with the no such bean definition exception:
1
2
3
4
|
org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.baeldung.packageB.BeanB] 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 )} |
The reason is clearly indicated by Spring: “expected at least 1 bean which qualifies as autowire candidate for this dependency“
One reason BeanB may not exist in the context – if beans are picked up automatically byclasspath scanning, and if BeanB is correctly annotated as a bean (@Component,@Repository, @Service, @Controller, etc) – is that it may be defined in a package that is not scanned by Spring:
1
2
3
|
package org.baeldung.packageB; @Component public class BeanB { ...} |
While the classpath scanning may be configured as follows:
1
2
3
4
5
|
@Configuration @ComponentScan ( "org.baeldung.packageA" ) public class ContextWithJavaConfig { ... } |
If beans are not automatically scanned by instead defined manually, then BeanB is simply not defined in the current Spring Context.
3. Cause: No qualifying bean of type [...] is defined
Another cause for the exception is the existence of two bean definitions in the context, instead of one. For example, if an interface – IBeanB is implemented by two beans –BeanB1 and BeanB2:
1
2
3
4
5
6
7
8
|
@Component public class BeanB1 implements IBeanB { // } @Component public class BeanB2 implements IBeanB { // } |
Now, if BeanA autowires this interface, Spring will not know which one of the two implementations to inject:
1
2
3
4
5
6
7
|
@Component public class BeanA { @Autowired private IBeanB dependency; ... } |
And again, this will result in a NoSuchBeanDefinitionException being thrown by theBeanFactory:
1
2
3
|
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [org.baeldung.packageB.IBeanB] is defined: expected single matching bean but found 2: beanB1,beanB2 |
Similarly, Spring clearly indicates the reason for the wiring failure: “expected single matching bean but found 2″.
Notice however, that in this case, the exact exception being thrown is notNoSuchBeanDefinitionException but a subclass – theNoUniqueBeanDefinitionException. This new exception has been introduced in Spring 3.2.1, for exactly this reason – to differentiate between the cause where no bean definition was found and this one – where several definitions are found in the context.
Before this change, the exception above was:
1
2
3
|
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.baeldung.packageB.IBeanB] is defined: expected single matching bean but found 2: beanB1,beanB2 |
One solution to this problem is to use the @Qualifier annotation to specify exactly the name of the bean we want to wire:
1
2
3
4
5
6
7
8
|
@Component public class BeanA { @Autowired @Qualifier ( "beanB2" ) private IBeanB dependency; ... } |
Now Spring has enough information to make the decision of which bean to inject –BeanB1 or BeanB2 (the default name of BeanB2 is beanB2).
4. Cause: No Bean Named [...] is defined
A NoSuchBeanDefinitionException may also be thrown when a bean that isn’t defined isrequested by name from the Spring context:
1
2
3
4
5
6
7
8
9
10
11
|
@Component public class BeanA implements InitializingBean { @Autowired private ApplicationContext context; @Override public void afterPropertiesSet() { context.getBean( "someBeanName" ); } } |
In this case, there is no bean definition for “someBeanName” – leading to the following exception:
1
2
|
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'someBeanName' is defined |
Again, Spring clearly and concisely indicates the reason for the failure: “No bean named X is defined“.
5. Cause: Proxied Beans
When a bean in the context is proxied using the JDK Dynamic Proxy mechanism, then the proxy will not extend the target bean (it will however implement the same interfaces).
Because of this, if the bean is injected by an interface, it will be correctly wired in. If however the bean is injected by the actual class, then Spring will not find a bean definition that matches the class – since the proxy does not actually extend the class.
A very common reason the bean may be proxied is the Spring transactional support – namely beans that are annotated with @Transactional.
For example, if ServiceA injects ServiceB, and both services are transactional, injecting by the class definition will not work:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
@Service @Transactional public class ServiceA implements IServiceA{ @Autowired private ServiceB serviceB; ... } @Service @Transactional public class ServiceB implements IServiceB{ ... } |
The same two services, this time correctly injecting by the interface, will be OK:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
@Service @Transactional public class ServiceA implements IServiceA{ @Autowired private IServiceB serviceB; ... } @Service @Transactional public class ServiceB implements IServiceB{ ... } |
6. Conclusion
This tutorial discussed examples of the possible causes for the commonNoSuchBeanDefinitionException – with a focus on how to address these exceptions in practice.
The implementation of all these exceptions examples can be found in the github project – this is an Eclipse based project, so it should be easy to import and run as it is.
Spring NoSuchBeanDefinitionException的更多相关文章
- Spring NoSuchBeanDefinitionException原因分析
摘要:摘要:本文译自EugenParaschiv文章SpringNoSuchBeanDefinitionException原文链接:/2014th7cj/d/file/p/20161012/dv5o0 ...
- Spring NoSuchBeanDefinitionException六大原因总结
1. Overview In this article, we are discussing the Springorg.springframework.beans.factory.NoSuchBea ...
- Atitit s2018 s4 doc list dvchomepc dvccompc.docx .docx \s2018 s4 doc compc dtS44 \s2018 s4 doc dvcCompc dtS420 \s2018 s4f doc homepc \s2018 s4 doc compc dtS44\(5 封私信 _ 44 条消息)WebSocket 有没有可能取代 AJAX
Atitit s2018 s4 doc list dvchomepc dvccompc.docx .docx \s2018 s4 doc compc dtS44 \s2018 s4 doc dvcCo ...
- spring Boot异步操作报错误: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.self.spring.springboot.Jeep' available
我也是最近开始学习Spring Boot,在执行异步操作的时候总是汇报如下的错误: Exception in thread "main" org.springframework.b ...
- Spring Boot 调用 MongoRepository时报org.springframework.beans.factory.NoSuchBeanDefinitionException错误的解决办法
这个问题整整折腾了我两天,现在记录下来,希望可以帮助和我一样,遇到相同问题的小伙伴. 项目是分层的(Intellij IDEA中的模块Module),有API(Core)层,Service&D ...
- Spring报NoSuchBeanDefinitionException
org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 上述可以看出Ac ...
- spring源码分析之freemarker整合
FreeMarker是一款模板引擎: 即一种基于模板和要改变的数据, 并用来生成输出文本(HTML网页.电子邮件.配置文件.源代码等)的通用工具. 它不是面向最终用户的,而是一个Java类库,是一款程 ...
- [Spring]04_最小化Spring XML配置
4.1 自动装配 Bean Spring 装配 bean 时,有时非常明确,就是需要将某个 bean 的引用装配给指定属性. 例如,若应用上下文中只有一个 javax.sql.DataSource 类 ...
- Spring中常见的bean创建异常
Spring中常见的bean创建异常 1. 概述 本次我们将讨论在spring中BeanFactory创建bean实例时经常遇到的异常 org.springframework.beans.fa ...
随机推荐
- zabbix server源码安装
一.准备工作 yum -y install net-snmp-devel php-bcmath php-ctype php-xml php-xmlreader php-xmlwriter php-se ...
- spring学习(03)之bean实例化的三种方式
bean实体例化的三种方式 在spring中有三中实例化bean的方式: 一.使用构造器实例化:(通常使用的一个方法,重点) 二.使用静态工厂方法实例化: 三.使用实例化工厂方法实例化 第一种.使用构 ...
- private static final Logger logger= LoggerFactory.getLogger(WhMainBusi.class);
LoggerFactory.getLogger(WhMainBusi.class):指定类初始化日志对象,在日志输出的时候,将会打印日志信息所在的类.如: logger.info("日志信息 ...
- VS Code 添加移除asp.net core项目引用
可以通过编辑.csproj文件来添加或者移除项目引用. 注意这里并没有智能提示, 最好是在Nuget网站(https://www.nuget.org/)搜索好相关包之后填写进来. 编辑结束之后, vs ...
- MySQL前缀索引和索引选择性
有时候需要索引很长的字符列,这会让索引变得大且慢.通常可以索引开始的部分字符,这样可以大大节约索引空间,从而提高索引效率.但这样也会降低索引的选择性.索引的选择性是指不重复的索引值(也称为基数,car ...
- Pycharm快捷键大全(windows + Mac)
Windows快捷键 1.编辑 Ctrl + Space 基本的代码完成(类.方法.属性) Ctrl + Alt + Space 快速导入任意类 Ctrl + Shift + Enter ...
- IE8“开发人员工具”(上)
认识“开发人员工具” 开发人员工具在IE8的工具菜单下,或者直接点击F12快捷键也可以呼叫出来. 提供一系列的小工具,让你可以方便的查找页面的bug,包括html代码.css代码和JavaScript ...
- 20165236实验一 Java开发环境的熟悉
课程:Java 姓名:郭金涛 学号:20165236 实验日期:2018/04/01 指导老师:娄嘉鹏 实验名称:Java开发环境的熟悉 实验要求: 1. 建立“自 ...
- vue-底部导航栏
<template> <div class="bottom"> <div class="bottom_button iconfont ico ...
- log4j。日志输出
log4j.rootLogger = debug , stdout , D , E log4j.appender.stdout = org.apache.log4j.ConsoleAppender l ...