Spring中Bean容器

红太狼 2022-05-29 04:06 211阅读 0赞

bean中的属性：  
id：表示在Spring的BeanFacotry中的标识，通过这个id去找。  
class:表示的是类名

bean的两种注入方式：（把bean注入Spring的bean容器）  
一、在xml中配置  
又分为三种：  
1、属性注入：即通过setXxx()方法注入Bean的属性值或依赖对象

import org.springframework.beans.factory.BeanNameAware;
    public class LogonService implements **BeanNameAware**{
        private UserDao userDao;
        public void setUserDao(UserDao userDao) {
            this.userDao = userDao;
        }
        public void setLogDao(LogDao logDao) {
            this.logDao = logDao;
        }
    
        public LogDao getLogDao() {
            return logDao;
        }
        public UserDao getUserDao() {
            return userDao;
        }
    
        public void setBeanName(String beanName) {
            System.out.println("beanName:"+beanName);        
        }
    
        public void initMethod1(){
            System.out.println("initMethod1");
        }
        public void initMethod2(){
            System.out.println("initMethod2");
        }
    
    }
    xml中对应部分：
    <?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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"
           default-autowire="byName"
             >
        <bean id="userDao" class="com.baobaotao.anno.UserDao"/>
       <bean class="com.baobaotao.anno.LogonService">
           <property name="userDao" ref="userDao"></property>
       </bean>
    </beans>

2、构造函数注入：使用构造函数注入的前提是Bean必须提供带参数的构造函数

package com.baobaotao.anno;
    
    import org.springframework.beans.factory.BeanNameAware;
    
    public class LogonService implements BeanNameAware{
        private LogDao logDao;
        private UserDao userDao;
        public LogonService(){}
        //必须写
        **public LogonService(LogDao logDao, UserDao userDao) {
            this.logDao = logDao;
            this.userDao = userDao;
        }**
        public void setUserDao(UserDao userDao) {
            this.userDao = userDao;
        }
        public void setLogDao(LogDao logDao) {
            this.logDao = logDao;
        }
    
        public LogDao getLogDao() {
            return logDao;
        }
        public UserDao getUserDao() {
            return userDao;
        }       
    }
    
    对应xml中：
    <?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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"
           default-autowire="byName">
    
        <bean id="logDao" class="com.baobaotao.anno.LogDao"/>
        <bean id="userDao" class="com.baobaotao.anno.UserDao"/>
       <bean class="com.baobaotao.anno.LogonService">
          <constructor-arg  ref="logDao"></constructor-arg>
           <constructor-arg ref="userDao"></constructor-arg>
       </bean>
    
    </beans>

3、工厂注入
     略

二、注解注入  
使用@Autowired进行自动注入。或者@Resource(name=”xxx”) 按指定名称  
直接写在需要注入的Bean上面即可。  
让@Autowired可以生效的几种方式：只要满足一下任意一种都可使用。  
1、在xml配置文件中显式指定

<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />   
    
          
        <bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" />

或  
2、在xml配置文件中使用context:annotation-config

<context:annotation-config />

或  
3、在xml配置文件中使用context:component-scan

<context:component-scan base-package="com.baobaotao.anno"/>