5. Spring 装配Bean的三种方式，bean作用域

实例化Bean的三种方式

1. 使用构造方法实例化

2. 使用静态工厂方法实例化

3. 使用实例化工厂方法实例化

代码实现：

UserServiceImpl:

public class UserServiceImpl implements IUserService {

    private String name;

    public String getName() {
        return name;
    }

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

    public UserServiceImpl() {
        System.out.println("UserServiceImpl()。。调用了");
    }

    @Override
    public void add() {
        System.out.println("添加用户。。。"+name);
    }
}UserServiceFactory1

UserServiceFactory1

public class UserServiceFactory1 {
    public static IUserService createUservice(){
        return new UserServiceImpl();
    }
}

UserServiceFactory2

public class UserServiceFactory2 {
    public IUserService createUservice(){
        return new UserServiceImpl();
    }
}

 

Beans1.xml

<?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">
    <!--装配bean的三种方式，所谓的装配bean就是在xml写一个bean标签-->
    <!--第一种方式：new 实现类-->
    <bean id="userService" class="com.gyf.service.UserServiceImpl">
        <!--依赖注入数据，调用属性的set方法-->
        <property name="name" value="alex"></property>
    </bean>
    <!--第二种方式：通过静态工厂方法-->
    <bean id="userService1" class="com.gyf.service.UserServiceFactory1" factory-method="createUservice"></bean>

    <!--第三种方式：通过实例工厂方法-->
    <!--创建实例factory2 bean-->
    <bean id="factory" class="com.gyf.service.UserServiceFactory2"></bean>
    <bean id="userService2" factory-bean="factory" factory-method="createUservice"></bean>
</beans>

 

main

public class Run2 {
    @Test()
    public void test2() {

        ApplicationContext context = new ClassPathXmlApplicationContext("beans1.xml");

        // new对象
        //IUserService userService = (IUserService) context.getBean("userService");
        //userService.add();

        //静态工厂
        //IUserService uservice = UserServiceFactory1.createUservice();
        //userService.add();
        //IUserService userService1 = (IUserService)context.getBean("userService1");
        //userService1.add();

        //实例化工厂
        //1.创建工厂
        //UserServiceFactory2 factory2 = new UserServiceFactory2();
        //IUserService userService2 = factory2.createUservice();

        IUserService userService2 = (IUserService)context.getBean("userService2");
        userService2.add();

    }
}

 

bean的作用域

掌握红色两个常用的即可

====================================================================================================

类别                                                          说明               

singleton                                                    在Spring IoC容器中仅存在一个Bean实例，Bean以单例方式存在，默认值

prototype                                                    每次从容器中调用Bean时，都返回一个新的实例，即每次调用getBean（）时，相当于执行new xxxBean()

request　　　　　　　　　　　　　　　每次HTTP请求都会创建一个新的Bean，该作用与仅适用与WebApplicationContext环境

session　　　　　　　　　　　　　　　同一个HTTP Session共享一个Bean，不同Session使用不同Bean，仅适用WebApplicationContext环境

globalSession                                            一般用与Portlet应用环境，该作用域仅用于WebApplicationContext环境

====================================================================================================

□scop="singleton"单例模式（默认）

beans3.xml

<?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">
    <!---->
    <bean id="userService" class="com.gyf.service.UserServiceImpl" scope="singleton">
        <!--依赖注入数据，调用属性的set方法-->
        <property name="name" value="alex"></property>
    </bean>
</beans>

main

public class Run3 {
    @Test()
    public void test2() {

        ApplicationContext context = new ClassPathXmlApplicationContext("beans3.xml");

        // 从容器获取两个bean
        IUserService userService1 = (IUserService) context.getBean("userService");
        IUserService userService2 = (IUserService) context.getBean("userService");
        System.out.println(userService1);
        System.out.println(userService2);

    }
}
================================
结果：
com.gyf.service.UserServiceImpl@192d3247
com.gyf.service.UserServiceImpl@192d3247

□scop="prototype"

beans3.xml

<?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">
    <!---->
    <bean id="userService" class="com.gyf.service.UserServiceImpl" scope="prototype">
        <!--依赖注入数据，调用属性的set方法-->
        <property name="name" value="alex"></property>
    </bean>
</beans>

main

public class Run3 {
    @Test()
    public void test2() {

        ApplicationContext context = new ClassPathXmlApplicationContext("beans3.xml");

        // 从容器获取两个bean
        IUserService userService1 = (IUserService) context.getBean("userService");
        IUserService userService2 = (IUserService) context.getBean("userService");
        System.out.println(userService1);
        System.out.println(userService2);

    }
}
=============================================
结果：
com.gyf.service.UserServiceImpl@8646db9
com.gyf.service.UserServiceImpl@37374a5e