spring_Dependency injection

Dependency injection(依赖注入)

     DI exists in two major variants, Constructor-based dependency injection and Setter-based dependency injection.

案例分析：

  1、创建EmployeeBean类 代码如下:

package www.csdn.spring.constructor.bean;public class EmployeeBean {private String name;private Double salary;private Dept dept;private String sex;// 构造器函数public EmployeeBean(String name, Double salary, Dept dept, String sex) {super();this.name = name;this.salary = salary;this.dept = dept;this.sex = sex;}@Overridepublic String toString() {return "EmployeeBean [name=" + name + ", salary=" + salary + ", dept="+ dept + ", sex=" + sex + "]";}}

2、创建Dept类 代码如下:

package www.csdn.spring.constructor.bean;public class Dept {private String name;private String deptno;public void setName(String name) {this.name = name;}public void setDeptno(String deptno) {this.deptno = deptno;}@Overridepublic String toString() {return "Dept [name=" + name + ", deptno=" + deptno + "]";}}

3、创建配置文件

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans           http://www.springframework.org/schema/beans/spring-beans.xsd">        <!-- 一、构造函数依赖注入(Constructor-based dependency injection) --><!-- 1、通过构造函数注入 (Constructor argument resolution)--><bean id="employeeBean1" class="www.csdn.spring.constructor.bean.EmployeeBean"><constructor-arg value="王晓而" /><constructor-arg value="100.0" /><constructor-arg ref="dept" /><constructor-arg value="男" /></bean><!-- 2、根据构造器参数的类型(Constructor argument type matching) --><bean id="employeeBean2" class="www.csdn.spring.constructor.bean.EmployeeBean"><constructor-arg type="java.lang.String" value="陈红均" /><constructor-arg type="java.lang.String" value="男" /><constructor-arg type="java.lang.Double" value="100.0" /><constructor-arg type="www.csdn.spring.constructor.bean.Dept"ref="dept" /></bean><!-- 3、通过构造函数根据索引index注入(Constructor argument index) --><bean id="employeeBean3" class="www.csdn.spring.constructor.bean.EmployeeBean"><constructor-arg index="0" value="陈红均" /><constructor-arg index="1" value="100.0" /><constructor-arg index="2" ref="dept" /><constructor-arg index="3" value="女" /></bean><!-- 4、通过构造函数根据name注入(Constructor argument name) --><bean id="employeeBean4" class="www.csdn.spring.constructor.bean.EmployeeBean"><constructor-arg name="name" value="陈红均" /><constructor-arg name="salary" value="100.0" /><constructor-arg name="dept" ref="dept" /><constructor-arg name="sex" value="男" /></bean>        <!-- 二、Setter方法依赖注入(Setter-based dependency injection) --><bean id="dept" class="www.csdn.spring.constructor.bean.Dept">    <!-- 根据setter注入 --><property name="name" value="CSDN教育事业部" /><property name="deptno" value="0x0001" /></bean></beans>

4、创建测试代码：

@Testpublic void testBean(){ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-null.xml");MemberBean bean = context.getBean("memberBean1", MemberBean.class);System.out.println(bean.name);System.out.println(bean.member);System.out.println(bean.email);}

5、自己运行观看结果