Spring C/P 命名空间的使用和区别

名称空间p和c的使用

Spring2.0以后提供了xml命名空间。

P名称空间

C名称空间
首先它们不是真正的名称空间，是虚拟的。它是嵌入到spring内核中的。

使用p名称空间可以解决我们setter注入时简化

使用c名称空间可以解决我们构造器注入时简化

Demo：

Dog.java

package com.test.p;

public class Dog {
	
	private String name;
	private String color;
	
	public Dog() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	public Dog(String name, String color) {
		super();
		this.name = name;
		this.color = color;
	}

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getColor() {
		return color;
	}
	public void setColor(String color) {
		this.color = color;
	}
	@Override
	public String toString() {
		return "Dog [name=" + name + ", color=" + color + "]";
	}
	
}

Person.java

package com.test.p;

public class Person {
	private String name;
	private Dog dog;
	
	public Person() {
		super();
		// TODO Auto-generated constructor stub
	}

	public Person(String name, Dog dog) {
		super();
		this.name = name;
		this.dog = dog;
	}

	public String getName() {
		return name;
	}

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

	public Dog getDog() {
		return dog;
	}

	public void setDog(Dog dog) {
		this.dog = dog;
	}

	@Override
	public String toString() {
		return "Person [name=" + name + ", dog.name=" + dog.getName() + " dog.color" + dog.getColor() + "]";
	}
}

以上是Demo使用的两个类

接下来我们来写applicationContext.xml的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- 传统方式注入 -->
    <bean id="dog1" class="com.test.p.Dog">
    	<property name="name" value="吉娃娃" />
    	<property name="color" value="黄色" />
    </bean>
    
    <!-- P命名空间方式的注入 简化上述操作-->
    <bean id="dog2" class="com.test.p.Dog" p:name="金毛" p:color="黄色"></bean>
	
	<!-- 传统构造器注入 -->
	<bean id="dog3" class="com.test.p.Dog">
		<constructor-arg index="0" value="藏獒" />
		<constructor-arg index="1" value="黑色" />
	</bean>
	
	<!-- 使用C名称空间来简化构造器注入 -->
	<bean id="dog4" class="com.test.p.Dog" c:name="哈士奇" c:color="彩色"></bean>
	<!-- 
		ref的使用
		这个人叫张三，他有一只哈士奇，是彩色的
  	-->
	<bean id="person" class="com.test.p.Person" p:name="张三" p:dog-ref="dog4"></bean>
</beans>

为了更加直观的看到他们之间的区别，我们将传统方式和c、p命名空间的方式都写了，并在接下来的test中进行调用，我们来观察它的执行结果

package com.test.p;

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

public class DogTest {
	
	@Test
	public void test1() {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Dog dog1 = (Dog)context.getBean("dog1");
		System.out.println(dog1);
	}
	
	@Test
	public void test2() {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Dog dog2 = (Dog)context.getBean("dog2");
		System.out.println(dog2);
	}
	
	@Test
	public void test3() {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Dog dog3 = (Dog)context.getBean("dog3");
		System.out.println(dog3);
	}
	
	@Test
	public void test4() {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Dog dog4 = (Dog)context.getBean("dog4");
		System.out.println(dog4);
	}
	
	@Test
	public void test5() {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Person p1 = (Person)context.getBean("person");
		System.out.println(p1);
	}
}

我们来观察它们最后的执行结果：

Test1

Test2

Test3

Test4

Test5