构造器注入和setting注入的区别

首先分析说明是构造器注入和setting注入

一、构造器注入

创建AccountServiceImpl继承AccountService

 
 
import org.com.service.IAccountService;
 
import java.util.Date;
 
 
public class AccountServiceImpl implements AccountService {
 
 
 
    private String name;
    private  Integer age;
    private Date time;
 
    public AccountServiceImpl(String name, Integer age, Date time) {
        this.name = name;
        this.age = age;
        this.time = time;
    }
 
    public void saveAccount() {
        System.out.println("service"+name+age+time);
 
    }
}

配置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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">
 
    <bean id="accountService" class="org.com.service.impl.AccountServiceImpl">
    <constructor-arg name="name" value="mys"></constructor-arg>
    <constructor-arg name="age" value="21"></constructor-arg>
    <constructor-arg name="time" ref="now"></constructor-arg>
 
    </bean>
    <bean id="now" class="java.util.Date"></bean>
 
</beans>

二、setting注入

创建Account类

 
 
import org.com.service.IAccountService;
 
import java.util.Date;
 
 
public class AccountServiceImpl {
 
 
 
    private String name;

    public void setName(String name){
      this.name=name
    }

    public String getName){
      return this.name;
    }

}

配置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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">
 
    <bean id="account" class="org.com.Account">
       <property name="name" value="mxl"></property>
    </bean>
 
</beans>

​

相比之下，setting注入具有如下的优点：

与传统的JavaBean的写法更相似，程序开发人员更容易理解、接受。通过setter方法设定依赖关系显得更加直观、自然。

对于复杂的依赖关系，如果采用构造注入，会导致构造器过于臃肿，难以阅读。Spring在创建Bean实例时，需要同时实例化其依赖的全部实例，因而导致性能下降。而使用设值注入，则能避免这些问题。

尤其是在某些属性可选的情况下，多参数的构造器更加笨重。