spring的依赖注入DI

依赖注入的方式：
1.构造函数依赖注入
2.setter方法依赖注入

p名称空间的使用
Spring2.5 版本，引入p名称空间，作用简化 setter方法注入的配置
第一步： 在xml配置文件中，配置p名称空间
xmlns:p = “http://www.springframework.org/schema/p”
第二步： 通过p名称空间语法，简化setter方式属性注入
 p:<属性名>=“xxx” 引入常量值
 p:<属性名>-ref=“xxx” 引用其它Bean对象

		
		
		

改造为 

	

2） SpEL 表达式使用
Spring Expression Language Spring表达式语言， 从3.0版本开始提供
语法格式 #{…} 主要用于spring配置文件
引入对象， 引用对象属性， 引用对象方法

代码示例：
Car.java

package com.my.di;

//轿车 （构造器 依赖注入）
public class Car {

	private String name;
	private double price ;

	// 在构造Car对象时，将name和price 属性注入car对象
	public Car(String name, double price) {
		super();
		this.name = name;
		this.price = price;
	}

	@Override
	public String toString() {
		return "Car [name=" + name + ", price=" + price + "]";
	}
	
}

Car2.java

package com.my.di;

//轿车 通过setter方法完成属性注入
public class Car2 {

	private String name;
	private double price ;

	public String getName() {
		return name;
	}

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

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		this.price = price;
	}

	@Override
	public String toString() {
		return "Car [name=" + name + ", price=" + price + "]";
	}
	
}

Employee.java

package com.my.di;

public class Employee {
	
	private Car car ;
	private String name;
	
	public void setCar(Car car) {
		this.car = car;
	}
	public void setName(String name) {
		this.name = name;
	}
	
	public Employee(Car car, String name) {
		super();
		this.car = car;
		this.name = name;
	}
	
	public Employee() {
	}
	
	@Override
	public String toString() {
		return "Employee [car=" + car + ", name=" + name + "]";
	} 
	

}

applicationContext.xml

?xml version="1.0" encoding="UTF-8"?>

		
	
	
		
		
		
		
	
	
	
	
		
		
		
	
	
	
		
		
		
	
	
	
	
	
	
	
	
	

Test.java

package com.my.di;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;


public class Test {

	@org.junit.Test
	// 测试构造函数注入
	public void demo1(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Car car = (Car) applicationContext.getBean("car");
		System.out.println(car);
	}

	@org.junit.Test
	// 测试setter方法注入
	public void demo2(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Car2 car2 = (Car2) applicationContext.getBean("car2");
		System.out.println(car2);
	}
	
	@org.junit.Test
	// 测试setter方法注入 (复杂属性)
	public void demo3(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Employee employee = (Employee) applicationContext.getBean("employee");
		System.out.println(employee);
	}
	
	@org.junit.Test
	// 测试setter方法注入 (p名称空间)
	public void demo4(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Employee employee2 = (Employee) applicationContext.getBean("employee2");
		System.out.println(employee2);
	}
	
	@org.junit.Test
	// 测试setter方法注入 (spEL使用)
	public void demo5(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Car2 mycar = (Car2) applicationContext.getBean("mycar");
		System.out.println(mycar);
		Employee employee = (Employee) applicationContext.getBean("myemployee");
		System.out.println(employee);
	}
	
}

运行结果：

集合属性 的注入
Spring 提供集合对象注入 四个标签
代码示例：

CollectionBean.java

package com.my.collection;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import com.my.di.Car;

//注入 集合类型 属性 
public class CollectionBean {
	
	private List hobbies;
	private List cars;
	private Set scores;
	private Map map;
	private Properties properties;
	
	public void setHobbies(List hobbies) {
		this.hobbies = hobbies;
	}
	public void setCars(List cars) {
		this.cars = cars;
	}
	public void setScores(Set scores) {
		this.scores = scores;
	}
	@Override
	public String toString() {
		return "CollectionBean [ hobbies=" + hobbies + ",\n cars=" + cars
				+ ", scores=" + scores + ",\n map=" + map + ",\n properties="
				+ properties + " ]";
	}
	
	public void setMap(Map map) {
		this.map = map;
	}
	public void setProperties(Properties properties) {
		this.properties = properties;
	}


}

applicationContext.xml

	
	
		
			
				音乐
				体育
			
		
		
			
				
			
		
		
			
				100
				90
			
		
		
			
		
		
			
				北京
				20
			
		
	
	

Test.java

package com.my.collection;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;


public class Test {

	@org.junit.Test
	public void test() {
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		CollectionBean bean = (CollectionBean) applicationContext.getBean("collectionBean");
		System.out.println(bean);
	}

}

运行结果：