Spring2.5依靠注入的方式有三种

Spring2.5依靠注入的方式有三种:
 1.通过setter方法注入;
 2.通过构造方法注入;
 3.通过注解进行注入;

 
第一种方式:通过setter方法注入

Java代码

  package com.test;   
      
    public class UserServiceImplement implements IUserService   
      
    {   
        private IUserDao user;   
      
        public IUserDao getUser() {   
            return user;   
        }   
      
        public void setUser(IUserDao user) {   
            this.user = user;   
        }   
      
        public void saveUser() {   
            user.addUser();   
        }   
    }  

 Xml代码

<?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:lang="http://www.springframework.org/schema/lang"  
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-2.0.xsd">  
        <bean id="userdao" class="com.test.UserDaoImplement"></bean>  
        <bean id="userservice" class="com.test.UserServiceImplement">  
            <property name="user" ref="userdao"></property>  
        </bean>  
    </beans>  

 注重这种方法还可以把XML改成以下方式:

 Xml代码
<?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:lang="http://www.springframework.org/schema/lang"  
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-2.0.xsd">  
        <bean id="userservice" class="com.test.UserServiceImplement"> <!-- <property name="user" ref="userdao"></property>-->  
            <property name="user">  
                <bean class="com.test.UserDaoImplement"></bean>  
            </property>  
        </bean>  
    </beans>  

这两者的区别在于,第二种方式只会注入到当前这个Bean实例中,而不能再注入到其它的Bean中,第一种方式被注入的Bean可以注入到多个Bean当中,这可能会有一些线程安全的问题,因此在最好指定被注入的Bean的作用域。

 另外通过setter方式注入,对应的注入依靠属性,必须要有setter方法。

 
测试代码:

Java代码

  package com.test;   
      
    import org.springframework.context.ApplicationContext;   
    import org.springframework.context.support.ClassPathXmlApplicationContext;   
      
    public class Test {   
        public static void main(String[] args) {   
            ApplicationContext ctx = new ClassPathXmlApplicationContext(   
                    "com/test/bean.xml");   
            IUserService us = (IUserService) ctx.getBean("userservice");   
            us.saveUser();   
        }   
    }  
 

第二种方式:通过构造方法进行注入

Java代码

  package com.test;   
      
    public class UserServiceImplement implements IUserService {   
        private IUserDao user;   
        int age;   
      
        public UserServiceImplement(IUserDao user, int age) {   
            this.user = user;   
            this.age = age;   
        }   
      
        public void saveUser() {   
            user.addUser();   
            System.out.println(this.age);   
        }   
    }  

 

Xml代码

 <beans xmlns="http://www.springframework.org/schema/beans"  
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:lang="http://www.springframework.org/schema/lang"  
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-2.0.xsd">  
        <bean id="userdao" class="com.test.UserDaoImplement"></bean>  
        <bean id="userservice" class="com.test.UserServiceImplement">  
            <constructor-arg index="0" type="com.test.IUserDao"  
                ref="userdao"></constructor-arg>  
            <constructor-arg index="1" value="24"></constructor-arg>  
        </bean>  
    </beans>  

注重

    <construcotr-arg>标签中的index属性假如构造方法只有一个参数的时候可以不指定,它的下标从0开始,表示构造方法参数的索引,假如有构造方法有多个参数必须指定索引。除此之外还有一个type属性,这个属性用来指定被注入的参数的参数类型,一定要跟构造方法中的参数类型一致,假如是一个接口,那么也不答应传它的实现类,这是一个可选属性;
    假如构造函数的的参数类型是基本数据类型,那么就不用ref属性了,而用value属性设置它的值,而且这些数据类型会自动打包和解包;
    同样要注重bean的作用域问题。

 测试代码同上......

 第三种方式:通过java注解进行注入

 使用这种方式进行注入可以用两个标注:

    @Resource
    @Autowired

 两者的区别:1. @Resource标注是由JDK提供的,而@Autowired标注是由Spring提供的,因而@Autowired标注会与Spring紧密耦合,所以推荐使用@Resource标注;

             2. @Resource默认是按照名称来装配注入的,当找不到与名称匹配的bean才会按照类型来装配注入;

             3. @Autowired默认是按照类型装配注入的,假如想按照名称来转配注入,则需要结合@Qualifier一起使用;

             4. @Resource和@Autowired都可以用来标注字段或者setter方法。

 I.使用@Resource标注进行注入

Java代码

  package com.test;   
      
    import javax.annotation.Resource;   
      
    public class UserServiceImplement implements IUserService {   
      
        @Resource  
        private IUserDao user;   
      
        private IUserDao user1;   
      
        public IUserDao getUser1() {   
            return user1;   
        }   
      
        @Resource  
        public void setUser1(IUserDao user1) {   
            this.user1 = user1;   
        }   
      
        public void saveUser() {   
            user.addUser();   
            System.out.println("user注入成功");   
            user1.addUser();   
            System.out.println("user1注入成功");   
        }   
    }  


Xml代码

<?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-2.5.xsd   
               http://www.springframework.org/schema/context   
               http://www.springframework.org/schema/context/spring-context-2.5.xsd">  
        <context:annotation-config />  
      
        <bean id="user" class="com.test.UserDaoImplement"></bean>  
        <bean id="user1" class="com.test.UserDaoImplement"></bean>  
        <bean id="userservice" class="com.test.UserServiceImplement"></bean>  
    </beans>  

 测试类:

Java代码

   package com.test;   
      
    import org.springframework.context.ApplicationContext;   
    import org.springframework.context.support.ClassPathXmlApplicationContext;   
      
    public class Test {   
      
        public static void main(String[] args) {   
            ApplicationContext ctx = new ClassPathXmlApplicationContext(   
                    "com/test/bean.xml");   
            IUserService us = (IUserService) ctx.getBean("userservice");   
            us.saveUser();   
        }   
    }  

 II.使用@Autowired

 Java代码

  package com.test;   
      
    import org.springframework.beans.factory.annotation.Autowired;   
      
    public class UserServiceImplement implements IUserService {   
      
        @Autowired  
        private IUserDao user;   
      
        public IUserDao getUser() {   
            return user;   
        }   
      
        public void setUser(IUserDao user) {   
            this.user = user;   
        }   
      
        public void saveUser() {   
            user.addUser();   
            System.out.println("user注入成功");   
        }   
    }  
 
Xml代码

  <?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-2.5.xsd   
               http://www.springframework.org/schema/context   
               http://www.springframework.org/schema/context/spring-context-2.5.xsd">  
        <context:annotation-config />  
      
        <bean id="user" class="com.test.UserDaoImplement"></bean>  
        <bean id="userservice" class="com.test.UserServiceImplement"></bean>  
    </beans>  

 测试类:

Java代码

package com.test;   
      
    import org.springframework.context.ApplicationContext;   
    import org.springframework.context.support.ClassPathXmlApplicationContext;   
      
    public class Test {   
      
        public static void main(String[] args) {   
            ApplicationContext ctx = new ClassPathXmlApplicationContext(   
                    "com/test/bean.xml");   
            IUserService us = (IUserService) ctx.getBean("userservice");   
            us.saveUser();   
        }   
    }  
原文地址:https://www.cnblogs.com/harbin1900/p/8480932.html