Spring学习心得(3)——注解装配

Spring学习心得(三)——注解装配

　　在前两篇文章中我大致介绍了Spring框架的搭建、配置文件注入、log4j日志配置和对数据库的操作，虽然利用这些东西我可以使用Spring构建web工程，但是丝毫感受不到Spring的优势所在，而且多了一大堆的配置文件需要编写。本文开始我则从优化WEB工程，简化程序员编码的角度来继续实战Spring。

　　第一步，检查需要的外包，本工程所依赖的jar包有：aopalliance、commons-logging、log4j、

spring-beans、spring-context、spring-context-support、spring-core、spring-tx、spring-web、spring-webmvc。这些包在我前两篇博客的附件中都可以找到，把这些所需要的外包直接复制到“WebRoot/WEB-INF/lib/”中即可。

　　第二步，编写配置文件.

　　1.在web.xml文件中加入Spring所依赖的配置信息，在前一篇文章所编写的基础上还要加上注解自动装配，字符集过滤器、Spring 分发器这些设置。

<filter>  
        <filter-name>CharacterEncodingFilter</filter-name>  
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>  
        <init-param>  
            <param-name>encoding</param-name>  
            <param-value>UTF-8</param-value>  
        </init-param>  
        <init-param>  
            <param-name>forceEncoding</param-name>  
            <param-value>true</param-value>  
        </init-param>  
    </filter>  
    <filter-mapping>  
        <filter-name>CharacterEncodingFilter</filter-name>  
        <url-pattern>/*</url-pattern>  
    </filter-mapping>

　　这几行配置是利用Spring框架中的字符过滤类对所有到达的请求进行字符集过滤，将编码格式统一设置成UTF-8格式。

<servlet>  
        <servlet-name>spring</servlet-name>  
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>  
        <init-param>  
            <param-name>contextConfigLocation</param-name>  
            <param-value>/WEB-INF/servlet.xml</param-value>  
        </init-param>  
    </servlet>  
    <servlet-mapping>  
        <servlet-name>spring</servlet-name>  
        <url-pattern>*.lzy</url-pattern>  
    </servlet-mapping>

　　这几行是配置Spring 分发器，该配置中将拦截所有以.lzy结尾的请求，并使用Spring的DispatcherServlet类进行分发，并依参数形式说明了servlet配置文件的路径。

<context-param>  
        <param-name>contextConfigLocation</param-name>  
        <param-value>/WEB-INF/applicationContext.xml</param-value>  
    </context-param>

　　　这里将Spring全局的配置文件制定为applicationContext.xml来做整体控制。

　　这样完全配置的web.xml文件为：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>MySpringMVC</display-name> 
    <!-- 应用路径 -->  
    <context-param>  
        <param-name>webAppRootKey</param-name>  
        <param-value>spring.webapp.root</param-value>  
    </context-param>  
    <!-- Log4J 配置  -->  
    <context-param>  
        <param-name>log4jConfigLocation</param-name>  
        <param-value>/WEB-INF/conf/log4j.properties</param-value>  
    </context-param>  
    <context-param>  
        <param-name>log4jRefreshInterval</param-name>  
        <param-value>60000</param-value>  
    </context-param>  
    <!--Spring上下文 配置  -->  
    <context-param>  
        <param-name>contextConfigLocation</param-name>  
        <param-value>/WEB-INF/applicationContext.xml</param-value>  
    </context-param>  
    <!-- 字符集 过滤器  -->  
    <filter>  
        <filter-name>CharacterEncodingFilter</filter-name>  
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>  
        <init-param>  
            <param-name>encoding</param-name>  
            <param-value>UTF-8</param-value>  
        </init-param>  
        <init-param>  
            <param-name>forceEncoding</param-name>  
            <param-value>true</param-value>  
        </init-param>  
    </filter>  
    <filter-mapping>  
        <filter-name>CharacterEncodingFilter</filter-name>  
        <url-pattern>/*</url-pattern>  
    </filter-mapping>  
    <!-- Spring 监听器 -->  
    <listener>  
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  
    </listener>  
    <listener>  
        <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>  
    </listener>  
    <!-- Spring 分发器 -->  
    <servlet>  
        <servlet-name>spring</servlet-name>  
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>  
        <init-param>  
            <param-name>contextConfigLocation</param-name>  
            <param-value>/WEB-INF/servlet.xml</param-value>  
        </init-param>  
    </servlet>  
    <servlet-mapping>  
        <servlet-name>spring</servlet-name>  
        <url-pattern>*.lzy</url-pattern>  
    </servlet-mapping>  
  
  
  
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

　　　　　2.applicationContext.xml文件

<?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"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
	<import
		resource="service.xml" />
	<import
		resource="dao.xml" />
</beans>

　　applicationContext.xml什么都不干，它只管涉及到整体需要的配置，并且集中管理。这里引入了两个配置文件service.xml和dao.xml分别用于业务、数据处理。

　　3.service.xml

<?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"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

	<context:component-scan
		base-package="service" />
</beans>

　　这里通过<context:component-scan />标签指定了业务层的基础包路径——“service”,有了该配置Spring就可以对该包下的类进行自动扫描,并将有@Service、@Repository、@Controller、@Component 标注的类解析Spring Bean，不需要在XML文件中显示声明。

　　4.dao.xml

<?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:aop="http://www.springframework.org/schema/aop"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
	<context:component-scan
		base-package="dao" />
		

</beans>

　　该文件作用同上。

　　５.servlet/xml

<?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"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
	<context:component-scan
		base-package="controller" />
	<bean
		id="urlMapping"
		class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />
	<bean
		class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
</beans>

　　　该文件重要的是后面两个配置，这将使得注解生效。

　　５.eclipse类图说明

　　第三步，写后端代码测试

　　　　１.UserController

package controller;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.ServletRequestUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import service.UserService;


/**
 * 
 * @author zhiyuan.lv
 *
 */
@Controller
@RequestMapping("/account.lzy")
public class UserController {

	@Autowired
	private UserService accountService;
	

	@RequestMapping(method = RequestMethod.GET)
	public Map hello(HttpServletRequest request, HttpServletResponse response , ModelMap model)
			throws Exception {

		String username = ServletRequestUtils.getRequiredStringParameter(
				request, "username");
		String password = ServletRequestUtils.getRequiredStringParameter(
				request, "password");
		System.out.println(accountService.verify(username, password));
		
		model.put("msg", username);  
		
		return model;
	}
}

　　　2.UserDao

/**
 * 2010-1-23
 */
package dao;

import main.User;


/**
 * 
 * @author zhiyuan.lv
 *
 */
public interface UserDao {

	/**
	 * 读取用户信息
	 * 
	 * @param username
	 * @return
	 */
	User read(String username);

}

　　　3.UserDaoImpl

package dao;

import main.User;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Repository;


/**
 * 
 * @author zhiyuan.lv
 *
 */
@Repository
public class UserDaoImpl implements UserDao {
	
	/* (non-Javadoc)
	 * @see org.zlex.spring.dao.AccountDao#read(java.lang.String)
	 */
	@Override
	public User read(String username) {
	
		return new User(username,"wolf");
	}

}

　　　4.User

package main;

import java.io.Serializable;

/**
 * 
 * @author zhiyuan.lv
 *
 */
public class User implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = -533698031946372178L;

	private String username;
	private String password;

	/**
	 * @param username
	 * @param password
	 */
	public User(String username, String password) {
		this.username = username;
		this.password = password;
	}

	/**
	 * @return the username
	 */
	public String getUsername() {
		return username;
	}

	/**
	 * @param username the username to set
	 */
	public void setUsername(String username) {
		this.username = username;
	}

	/**
	 * @return the password
	 */
	public String getPassword() {
		return password;
	}

	/**
	 * @param password the password to set
	 */
	public void setPassword(String password) {
		this.password = password;
	}
	
	
}

　　　 5.UserService

package service;

/**
 * 
 * @author zhiyuan.lv
 *
 */
public interface UserService {

	/**
	 * 验证用户身份
	 * 
	 * @param username
	 * @param password
	 * @return
	 */
	boolean verify(String username, String password);

}

　　　6.UserServiceImpl

package service;

import main.User;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import dao.UserDao;


/**
 * 
 * @author zhiyuan.lv
 *
 */
@Service
@Transactional
public class UserServiceImpl implements UserService {

	@Autowired
	private UserDao accountDao;

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.zlex.spring.service.AccountService#verify(java.lang.String,
	 * java.lang.String)
	 */
	@Override
	public boolean verify(String username, String password) {

		User account = accountDao.read(username);
		
		if (password.equals(account.getPassword())) {
			return true;
		} else {
			return false;
		}
	}

}

　　后记：1.本人在开发时使用的是JDK1.8，在确定代码和配置都没有问题后，tomcat启动时却一直报错：

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Failed to import bean definitions from relative location [service.xml]
Offending resource: ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/service.xml]; nested exception is java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher
	at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:68)
	at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:85)
	at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:76)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.importBeanDefinitionResource(DefaultBeanDefinitionDocumentReader.java:201)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:147)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:132)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:92)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:507)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:398)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:92)
	at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:123)
	at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:422)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:352)
	at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4729)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5167)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/service.xml]; nested exception is java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:420)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.importBeanDefinitionResource(DefaultBeanDefinitionDocumentReader.java:190)
	... 27 more
Caused by: java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher
	at org.springframework.context.config.ContextNamespaceHandler$1.parse(ContextNamespaceHandler.java:65)
	at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:69)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1297)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1287)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:135)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:92)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:507)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:398)
	... 30 more

　　根据首行错误提升 available on JDK 1.5 and higher，Spring的某个类需要JDK1.5及以上的版本，但我的JDK是1.8，怎么会不行呢。查了大量的资料，看了不少的代码才知道我使用的Spring3.2.0系类的jar包只支持到JDK1.7，根本识别不了1.8.如下图：

一向喜欢最新版的我就从网上大量搜寻新版的JAR包，发现直到目前最新版的4.1.4系列才支持JDK1.8.我就跟换了spring core包。

　　２.跟换了core包后，我以为没有问题了，结果又出现了新的问题：

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
java.lang.NoSuchMethodError: org.springframework.core.CollectionFactory.createConcurrentMapIfPossible(I)Ljava/util/Map;
	at org.springframework.web.context.ContextLoader.<clinit>(ContextLoader.java:153)
	at org.springframework.web.context.ContextLoaderListener.createContextLoader(ContextLoaderListener.java:53)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:44)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4729)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5167)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

　　这是由于我使用的j众多jar包版本不一致造成的，我就索性把所有的jar包都换成最新的，就开始从网上翻山倒海的搜寻。

　　3.把所有的jar包都换成最新的后，我以为大功告成没结果有一个新的问题：

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Failed to import bean definitions from relative location [service.xml]
Offending resource: ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\zhiyuan.lv\myspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\MySpringMVC\WEB-INF\classes\service\UserService.class]; nested exception is java.lang.IncompatibleClassChangeError: class org.springframework.core.type.classreading.ClassMetadataReadingVisitor has interface org.springframework.asm.ClassVisitor as super class
	at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:70)
	at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:85)
	at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:76)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.importBeanDefinitionResource(DefaultBeanDefinitionDocumentReader.java:261)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:186)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:171)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:144)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:100)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:510)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)
	at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129)
	at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:452)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4729)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5167)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\zhiyuan.lv\myspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\MySpringMVC\WEB-INF\classes\service\UserService.class]; nested exception is java.lang.IncompatibleClassChangeError: class org.springframework.core.type.classreading.ClassMetadataReadingVisitor has interface org.springframework.asm.ClassVisitor as super class
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:303)
	at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:248)
	at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:87)
	at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:74)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1427)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1417)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:174)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:144)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:100)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:510)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.importBeanDefinitionResource(DefaultBeanDefinitionDocumentReader.java:245)
	... 28 more
Caused by: java.lang.IncompatibleClassChangeError: class org.springframework.core.type.classreading.ClassMetadataReadingVisitor has interface org.springframework.asm.ClassVisitor as super class
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2476)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:857)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1282)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1164)
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2476)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:857)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1282)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1164)
	at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:63)
	at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:98)
	at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102)
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:279)
	... 41 more

　　在网上搜了好久也没有查到错误的原因，只好自己读报的错误了。在查看我引入的jar包时，我发现asm包还是3.14系列，并且在网上没有它的更新包了。再加上tomcat报错的提示，我发现4.14系列的jar包，把asm的功能加入到了core中，现在我引了两个，所以导致错误。直接把asm删掉就行了。

　　终于大功告成了，我把目前最新版的spring jar包（4.14）系列防止本文的附件中了，方便大家下载使用。

Spring学习心得(3)——注解装配

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