Spring注入方式(1)

Spring支持3种依赖注入方式，分别为属性注入、构造器注入和工厂方法注入(很少使用，不推荐)，下面分别对属性注入和构造器注入详细讲解。

1、常量注入

　　属性注入是通过setter方法注入Bean的属性值，属性注入使用<property>元素，使用name属性指定Bean的属性名称，使用value属性或者<value>子节点指定属性值。

beans.xml文件主要内容

<!--通过属性注入方式配置  -->
<bean id="person" class="com.spring.Person">
    <property name="name" value="Tom"></property>
    <property name="age" value="29"></property>
</bean>

Person.java

package com.spring;
public class Person {
	private String name;
	private int age;
	private double height;
	private double weight;

	public Person(String name, int age, double height, double weight) {
		super();
		this.name = name;
		this.age = age;
		this.height = height;
		this.weight = weight;
	}

	public Person() {
		super();
	}

	public double getHeight() {
		return height;
	}

	public void setHeight(double height) {
		this.height = height;
	}

	public double getWeight() {
		return weight;
	}

	public void setWeight(double weight) {
		this.weight = weight;
	}

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + ", height=" + height + ", weight=" + weight + "]";
	}

}

Main.java

package com.spring;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {
	public static void main(String[] args) {
		ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
		Person person = (Person) ctx.getBean("person");
		System.out.println(person);
	}
}

运行结果截图如下：

以上就是属性注入的例子

2、构造器注入

2.1 按照索引匹配

beans.xml

<bean id="person1" class="com.spring.Person">
		<constructor-arg value="Tim" index="0"></constructor-arg>
		<constructor-arg value="30" index="1"></constructor-arg>
		<constructor-arg value="30" index="3"></constructor-arg>
		<constructor-arg value="65" index="2"></constructor-arg>

</bean>

结果：

2.2 按类型匹配

beans.xml

 <bean id="person2" class="com.spring.Person">
         <constructor-arg value="34" type="int"></constructor-arg>
         <constructor-arg value="175" type="double"></constructor-arg>
         <constructor-arg value="Jerry" type="java.lang.String" ></constructor-arg>
         <constructor-arg value="70" type="double"></constructor-arg>
     </bean>

结果：