Spring入门初体验

Spring其实就是一个容器，让我们更方便的拿到想要的对象。

1.编写一个service

// userService.java
public interface userService {
    public void insertUser();
}

// xmlImpl.java
public class xmlImpl implements userService{
    @Override
    public void insertUser() {
        System.out.println("insert a user");
    }
}

2.编写Spring核心配置文件，ApplicationContext.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="service.xmlImpl"></bean>
</beans>

3.使用

例如写一个servlet文件，在doGet那调用

public class userView extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取Spring容器context
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        
        // 方式1，靠id拿bean
        userService service = (userService) context.getBean("userService");
        service.insertUser();
        
        // 方式2，靠class拿bean
        userService service2 = context.getBean(userService.class);
        service2.insertUser();
        
        response.getWriter().println("123");
    }
}