02 Spring框架 简单配置和三种bean的创建方式
上一节学习了如何搭建SpringIOC的环境,下一步我们就来讨论一下如何利用ioc来管理对象和维护对象关系。
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns:util="http://www.springframework.org/schema/util" 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-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd"> </beans>
这个是applicationContext.xml的 dtd。(补充上一节)
我们知道有以下集几种方法来创建对象:
- 采用new关键字创建对象
- 静态工厂方法,例如:Calendar cal=Calendar.getInstance();
- 对象(现有)工厂方法
所以ioc中在aplicationContext.xml中也对应了三种创建对象的途径:
<bean id="" class="">① <bean id="" class="" factory-method="">② <bean id="" factory-bean="" factory-method="">③
id可以自定义
Class需要自己在工程中创建
接下来写一个简单的demo
①
applicationContext.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns:util="http://www.springframework.org/schema/util" 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-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd"> <bean id="c1" class="com.Spring.Demo.HelloWorld"> </beans>
HelloWorld.java :
package com.Spring.Demo; public class HelloWorld { public void show(){ System.out.println("欢迎Spring!"); } }
接下来写一个测试
TestHelloWorld.java :
package com.Spring.Demo; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class TestHelloWorld { public static void main(String[] args){ ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml"); HelloWorld hw=(HelloWorld)context.getBean("c1"); hw.show(); } }
运行后控制台输出为:
欢迎Spring!
这是第一种创建对象的方式,下面我们继续看看怎么使用动态工厂创建对象。
②
<!--静态工厂创建对象配置文件--> <?xml version="1.0" encoding="UTF-8"?> <beans xmlns:util="http://www.springframework.org/schema/util" 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-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd"> <bean id="service" class="dynamicFactory.ServiceFactory" factory-method="getService"/> </beans>
//需要创建的对象,实现的接口(接口化编程,降低耦合度) package staticFactory; public interface SomeServices { String doFirst(); void doSecond(); }
//实现类,实现上面的接口 package staticFactory; public class SomeServiceImp implements SomeServices{ @Override public String doFirst() { System.out.println("print first"); return null; } @Override public void doSecond() { System.out.println("print second"); } }
//静态工厂,产生上面类的实例 package staticFactory; public class ServiceFactory { public static SomeServiceImp getService() { return new SomeServiceImp(); } }
//测试类(Junit) public class test { @Test public void Test01() { String resource = "staticFactory/applicationContext.xml"; ApplicationContext ac = new ClassPathXmlApplicationContext(resource); SomeServices service = (SomeServices)ac.getBean("service"); service.doFirst(); service.doSecond(); } }
控制台输出:
print first
print second
上面的是静态工厂bean的创建方式,接下来我们来看普通工厂对象创建方式:
③
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns:util="http://www.springframework.org/schema/util" 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-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd"> <bean id="serviceFactory" class="dynamicFactory.ServiceFactory"></bean> <!--普通工厂bean,factory-bean填的是上面的serviceFactory--> <bean id="service" factory-bean="serviceFactory" factory-method="getService"/> </beans>
//需要创建的对象,实现的接口(接口化编程,降低耦合度) package dynamicFactory; public interface SomeServices { String doFirst(); void doSecond(); }
//实现类,实现上面的接口 package dynamicFactory; public class SomeServiceImp implements SomeServices{ @Override public String doFirst() { System.out.println("print first"); return null; } @Override public void doSecond() { System.out.println("print second"); } }
//这个和第二种不同,这里的工厂类方法是非静态的 package dynamicFactory; public class ServiceFactory { public SomeServiceImp getService() { return new SomeServiceImp(); } }
//测试类(Junit) public class test { @Test public void Test01() { String resource = "dynamicFactory/applicationContext.xml"; ApplicationContext ac = new ClassPathXmlApplicationContext(resource); SomeServices service = (SomeServices)ac.getBean("service"); service.doFirst(); service.doSecond(); } }
控制台输出:
print first
print second
这样我们的三种创建方式就说完了。
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