博客

bean 的基础配置

bean别名配置

项目结构

applicationContext.xml

<bean id="bookService" name="ss" class="com.service.impl.BookServiceImpl" >

aa.java

 BookServiceImpl bookService = (BookServiceImpl) ctx.getBean("ss");

如

aa.java

 BookServiceImpl bookService = (BookServiceImpl) ctx.getBean("ss1");

则

bean作用范围配置

为什么bean默认为单例

单例作用范围

applicationContext.xml

<bean id="bookDao" class="com.dao.impl.BookDaoimpl" scope="singleton">
        <property name="databasesName" value="mysql"/>
        <property name="connectionNum" value="100"/>
    </bean>

app.java

 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        BookDao bookDao1=(BookDao) ctx.getBean("bookDao");
        BookDao bookDao2=(BookDao) ctx.getBean("bookDao");
        System.out.println(bookDao1);
        System.out.println(bookDao2);

非单例作用范围

applicationContext.xml

<bean id="bookDao" class="com.dao.impl.BookDaoimpl" scope="prototype">
        <property name="databasesName" value="mysql"/>
        <property name="connectionNum" value="100"/>
    </bean>

app.java

 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        BookDao bookDao1=(BookDao) ctx.getBean("bookDao");
        BookDao bookDao2=(BookDao) ctx.getBean("bookDao");
        System.out.println(bookDao1);
        System.out.println(bookDao2);

适合交给容器进行管理的bean

表现层对象

业务层对象

数据层对象

工具对象

不适合交给容器进行管理的bean

封装实体的域对象