Spring 学习——Spring注解——Autowiring(自动装配)

装配方式

• 方式一：默认
• 方式二：byName:根据属性名称自动装配。会查找Bean容器内部所有初始化的与属性名成相同的Bean,自动装配。（需要通过set方法注入，注入Bean的id名称需要和实体类的属性名称一致）

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans.xsd"
      default-autowire="byName">
  
      <bean id="autoService" class="com.jing.spring.autowiring.AutoWiringService"></bean>
      <bean id="autoWiringDao" class="com.jing.spring.autowiring.AutoWiringDao"></bean> 
   </beans>

  ackage com.jing.spring.autowiring;
  
  public class AutoWiringService {
  
      private AutoWiringDao autoWiringDao;
  
      public void setAutoWiringDao(AutoWiringDao autoWiringTestDao) {
          this.autoWiringDao = autoWiringTestDao;
      }
  
      public void autoService(String arg){
          System.out.println("AutoWiringService.autoService===="+arg);
          autoWiringDao.autoDao(arg);
      }
  }

• 方式三：byType：根据类型自动装配。如果容器中存在一个与所需Bean类型相同的Bean，则自动装配。如果存在多个相同类型的Bean，报错。找不到相匹配的Bean，什么都不发生。（需要通过set方法注入！！！）

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans.xsd"
      default-autowire="byType">
  
      <bean class="com.jing.spring.autowiring.AutoWiringService"></bean>
      <bean class="com.jing.spring.autowiring.AutoWiringDao"></bean> 
   </beans>

• Constructor：同byType相似。如果找不到匹配的Bean，报错。（需要通过构造方法注入，注入的Bean的id名称需要和实体类的属性名称一致！！！）

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.springframework.org/schema/beans
          http://www.springframework.org/schema/beans/spring-beans.xsd"
      default-autowire="constructor">
  
      <bean id="autoService" class="com.jing.spring.autowiring.AutoWiringService"></bean>
      <bean id="autoWiringDao" class="com.jing.spring.autowiring.AutoWiringDao"></bean>    
   </beans>

  package com.jing.spring.autowiring;
  
  public class AutoWiringService {
  
      private AutoWiringDao autoWiringDao;
  
      public AutoWiringService(AutoWiringDao autoWiringTestDao){
          this.autoWiringDao = autoWiringTestDao;
      }public void autoService(String arg){
          System.out.println("AutoWiringService.autoService===="+arg);
  
          autoWiringDao.autoDao(arg);
      }
  }