从一个异常探索spring autowired 的原理
从一个异常探索autowired 的原理。
首先环境是这样的:
public class Boss { @Autowired
private Car car; } //@Component 加上这个注释,上面的Boss 的Autowired car就会失败,出现下面的异常
public class Car {
private String brand;
private double price; }
xml 是这样的:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"
> <context:component-scan base-package="com.baobaotao"></context:component-scan> <!-- 该 BeanPostProcessor 将自动起作用,对标注 @Autowired 的 Bean 进行自动注入 -->
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/> <!-- 移除 boss Bean 的属性注入配置的信息 -->
<bean id="boss" class="com.baobaotao.Boss"/>
<!--
<bean id="office" class="com.baobaotao.Office">
<property name="officeNo" value=""/>
</bean>
<bean id="car" class="com.baobaotao.Car" scope="singleton">
<property name="brand" value=" 红旗 CA72"/>
<property name="price" value=""/>
</bean>--> </beans>
测试类:
import com.baobaotao.Boss;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.AbstractJUnit4SpringContextTests;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; @RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:/beans.xml"})
public class AutowiredlTest extends
AbstractJUnit4SpringContextTests { @Autowired
Boss boss; @Test
public void aaa() {
System.out.println("boss = " + boss); }
}
结果是出现异常:
D:\soft\java\jdk1.\bin\java -Didea.launcher.port= "-Didea.launcher.bin.path=D:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 2016.1.2\bin" -Dfile.encoding=UTF- -classpath "D:\soft\java\jdk1.7\jre\lib\charsets.jar;D:\soft\java\jdk1.7\jre\lib\deploy.jar;D:\soft\java\jdk1.7\jre\lib\ext\access-bridge-64.jar;D:\soft\java\jdk1.7\jre\lib\ext\dnsns.jar;D:\soft\java\jdk1.7\jre\lib\ext\jaccess.jar;D:\soft\java\jdk1.7\jre\lib\ext\localedata.jar;D:\soft\java\jdk1.7\jre\lib\ext\sunec.jar;D:\soft\java\jdk1.7\jre\lib\ext\sunjce_provider.jar;D:\soft\java\jdk1.7\jre\lib\ext\sunmscapi.jar;D:\soft\java\jdk1.7\jre\lib\ext\zipfs.jar;D:\soft\java\jdk1.7\jre\lib\javaws.jar;D:\soft\java\jdk1.7\jre\lib\jce.jar;D:\soft\java\jdk1.7\jre\lib\jfr.jar;D:\soft\java\jdk1.7\jre\lib\jfxrt.jar;D:\soft\java\jdk1.7\jre\lib\jsse.jar;D:\soft\java\jdk1.7\jre\lib\management-agent.jar;D:\soft\java\jdk1.7\jre\lib\plugin.jar;D:\soft\java\jdk1.7\jre\lib\resources.jar;D:\soft\java\jdk1.7\jre\lib\rt.jar;D:\code\ws\spring\hz\spring-learn\target\test-classes;D:\code\ws\spring\hz\spring-learn\target\classes;C:\Users\lkms\.m2\repository\junit\junit\4.12\junit-4.12.jar;C:\Users\lkms\.m2\repository\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-context\4.3.5.RELEASE\spring-context-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-aop\4.3.5.RELEASE\spring-aop-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-beans\4.3.5.RELEASE\spring-beans-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-core\4.3.5.RELEASE\spring-core-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\commons-logging\commons-logging\1.2\commons-logging-1.2.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-expression\4.3.5.RELEASE\spring-expression-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-web\4.3.5.RELEASE\spring-web-4.3.5.RELEASE.jar;C:\Users\lkms\.m2\repository\org\springframework\spring-test\4.3.5.RELEASE\spring-test-4.3.5.RELEASE.jar;D:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 2016.1.2\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain AnnoIoCTest
十一月 , :: 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7a277bd2: startup date [Sat Nov :: CST ]; root of context hierarchy
十一月 , :: 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [beans.xml]
十一月 , :: 下午 org.springframework.context.support.ClassPathXmlApplicationContext refresh
WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'boss': Unsatisfied dependency expressed through field 'car'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.baobaotao.Car' available: expected at least bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'boss': Unsatisfied dependency expressed through field 'car'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.baobaotao.Car' available: expected at least bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:)
at org.springframework.beans.factory.support.AbstractBeanFactory$.getObject(AbstractBeanFactory.java:)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:)
at AnnoIoCTest.main(AnnoIoCTest.java:)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:)
at java.lang.reflect.Method.invoke(Method.java:)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.baobaotao.Car' available: expected at least bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:)
... more Process finished with exit code
spring 的启动过程中会读取配置的xml,注册所有的 beanDefinition,这个是准备过程。 准备完后是 beanfactory 的refresh ,这个时候会 进行注解的处理, 也就是 BeanPostProcessor。 这其中就包含了对 bean 中包含的各种注解的 解析, 比如 Autowired 注解等。 AutowiredAnnotationBeanPostProcessor 的 postProcessPropertyValues 是继承于InstantiationAwareBeanPostProcessor 。 是对它的实现。 如果我们仔细观察这个错误堆栈, 也许我们会从中发现很多很多的细节。
参考:
http://blog.csdn.net/mack415858775/article/details/47721909 写得非常详细,非常好!
从一个异常探索spring autowired 的原理的更多相关文章
- Spring异步调用原理及SpringAop拦截器链原理
一.Spring异步调用底层原理 开启异步调用只需一个注解@EnableAsync @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTI ...
- Spring Security 入门原理及实战
目录 从一个Spring Security的例子开始 创建不受保护的应用 加入spring security 保护应用 关闭security.basic ,使用form表单页面登录 角色-资源 访问控 ...
- Spring Boot启动原理解析
Spring Boot启动原理解析http://www.cnblogs.com/moonandstar08/p/6550758.html 前言 前面几章我们见识了SpringBoot为我们做的自动配置 ...
- spring boot 启动原理详细解析
我们开发任何一个Spring Boot项目,都会用到如下的启动类 1 @SpringBootApplication 2 public class Application { 3 public stat ...
- [转帖]Spring Cloud底层原理
拜托!面试不要再问我Spring Cloud底层原理 https://mp.weixin.qq.com/s/ZH-3JK90mhnJPfdsYH2yDA 毫无疑问,Spring Cloud 是目前微服 ...
- struts1,struts2,hibernate,spring的运行原理结构图
一.struts1运行原理 1.初始化:struts框架的总控制器ActionServlet是一个Servlet,它在web.xml中配置成自动启动的Servlet,在启动时总控制器会读取配置文件(s ...
- 何为代理?jdk动态代理与cglib代理、spring Aop代理原理浅析
原创声明:本博客来源为本人原创作品,绝非他处摘取,转摘请联系博主 代理(proxy)的定义:为某对象提供代理服务,拥有操作代理对象的功能,在某些情况下,当客户不想或者不能直接引用另一个对象,而代理对象 ...
- 拜托!面试请不要再问我Spring Cloud底层原理[z]
[z]https://juejin.im/post/5be13b83f265da6116393fc7 拜托!面试请不要再问我Spring Cloud底层原理 欢迎关注微信公众号:石杉的架构笔记(id: ...
- spring Mvc 执行原理 及 xml注解配置说明 (六)
Spring MVC 执行原理 在 Spring Mvc 访问过程里,每个请求都首先经过 许多的过滤器,经 DispatcherServlet 处理; 一个Spring MVC工程里,可以配置多个的 ...
随机推荐
- python打包为独立可执行程序
linux下 pip install pyinstaller 针对需要的项目 pyinstaller -F -w ./xxx.py 即可
- php 安装mongo扩展(其他扩展同理)
很多次安装mogo扩展不成功,总结出来,无非就是一个原因.对应的版本选择不正确 简单来说这篇文章就是来教你如何选择php对应的mongo.ll版本 查看phpinfo https://pecl.php ...
- Intellij IDEA神器值得收藏的小技巧
概述 Intellij IDEA真是越用越觉得它强大,它总是在我们写代码的时候,不时给我们来个小惊喜.出于对Intellij IDEA的喜爱,我决定写一个与其相关的专栏或者系列,把一些好用的Intel ...
- linux上mongodb的安装与卸载
安装 1.下载安装包 wget http://fastdl.mongodb.org/linux/mongodb-linux-i686-1.8.2.tgz 下载完成后解压缩压缩包 tar zxf mon ...
- Dubbo(5)优化:接口抽取以及依赖版本统一
优化点: 1.在上面provider和consumer程序中都存在DemoProviderService接口了,两个项目中存在同样的东西,代码多余以及不方便管理: 正式的项目中存在很多的接口的,将统一 ...
- 峰Redis学习(1)Redis简介和安装
是从博客:http://blog.java1234.com/blog/articles/310.html参考过来的: 第一节:Redis 简介 为什么需要NoSQL,主要应对以下问题,传统关系型数据库 ...
- Java学习——读写txt文件
package HHH; import java.io.*; import static java.lang.System.out; public class OpenFile { public st ...
- [UE4]Text Block文字字体偏移
这样看起来就像是真正的垂直居中对齐了.
- Win7删除缓存垃圾文件
del /s /f /q C:\*.tmp
- 家庭版Windows设置远程连接
家庭版Windows设置远程连接1. windows+R 打开运行,输入 regedit 打开注册表 2.依次打开路径 计算机\HKEY_LOCAL_MACHINE\SOFTWARE\Microsof ...