Spring的基础篇

Posted 2021-01-15 没昵称可用

搭建Spring实例

　　持久层

import org.springframework.stereotype.Repository;

@Repository   //将该类的对象创建为userDao实例
public class UserDao{
	public String findUserByName(String userName) {
		return "abc";
	}
}

　　业务层

import com.baobaotao.dao.UserDao;
import com.sun.istack.internal.FinalArrayList;
@Service        //通常作用在业务层,主要将业务层的类自动注册到spring容器
public class UserService{
	@Autowired   //自动将bean注册到该对象
	private UserDao userDao;
	private TransactionTemplate transactionTemplate;
	public String login(final String name,final String password) {
		return   transactionTemplate.execute(new TransactionCallback(){
			public Object doInTransaction(TransactionStatus status) {
			Object result;
			try {
			result = userDao.findUserByName(name);
			} catch (Exception e) {
			status.setRollbackOnly();
			result = false;
			System.out.println("Transfer Error!");
			}
			return result;
			}
			});
	}
}

　　控制层

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletRequest;
import com.baobaotao.domain.User;
import com.baobaotao.service.UserService;

@Controller   //将该类注册为一个控制层的Bean实例
public class UserController{
	@Autowired  //自动注入spring容器的bean实例
	private UserService userService;
	@RequestMapping(value="login")    //
	public String login(HttpServletRequest request,User user){
		System.out.println("=========aaaaaaaa====");
		String result = userService.login(user.getUserName(), user.getPassword());
		return "success";
	}

　　Spring容器配置文件

　　　

<?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:context="http://www.springframework.org/schema/context"
xmlns:c="http://www.springframework.org/schema/c"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
 http://www.springframework.org/schema/aop 
 http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx 
http://www.springframework.org/schema/tx/spring-tx-4.3.xsd
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context-4.3.xsd">
<!-- 扫描类包，将通过注解的类转换为Bean实例 -->
<context:component-scan base-package="com.baobaotao.dao"></context:component-scan>
<context:component-scan base-package="com.baobaotao.service"></context:component-scan>
<context:component-scan base-package="com.baobaotao.controller"></context:component-scan>
<context:component-scan base-package="testpackage"></context:component-scan>
</beans>

　　SpringMVC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:context="http://www.springframework.org/schema/context"  
       xmlns:mvc="http://www.springframework.org/schema/mvc"  
       xsi:schemaLocation="http://www.springframework.org/schema/beans  
       http://www.springframework.org/schema/beans/spring-beans.xsd  
       http://www.springframework.org/schema/context  
       http://www.springframework.org/schema/context/spring-context.xsd  
       http://www.springframework.org/schema/mvc  
       http://www.springframework.org/schema/mvc/spring-mvc.xsd">  
    <mvc:annotation-driven/>  
    <context:component-scan base-package="com.baobaotao.controller"/>
    <!-- 配置视图解析器，将ModelAndView及字符串解析为具体页面 -->  
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">  
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />  
        <property name="prefix" value="/WEB-INF/views/"/>  
        <property name="suffix" value=".jsp"/>  
    </bean>  
</beans>

　　web.xml文件配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>baobaotao</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <!-- 从类路径下面加载Spring配置文件 -->
  <context-param>
  <param-name>contextConfigLocation</param-name>
  <param-value>classpath:applicationContext.xml</param-value>
  </context-param>
  
  <!-- 加载配置文件的监听器 -->
  <listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  
  <!-- SpringMVC的配置文件加载，这里定义了一个servlet，servlet名自己取后面要用到，class固定的，不可改变。
  	然后就是初始化init后要加载的xml文件，默认名为servlet名-servlet.xml，这个是要加载到webroot-webinf-classes下的 -->
  <servlet>
        <servlet-name>baobaotao</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
         <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:baobaotao-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>baobaotao</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

注解详解

　　@Repository，标识Dao层的Bean实例。可以设置为@Repository(“XXX”)。

　　@Service(“XXX”)，就相当于将业务层的类定义为一个 bean，其中，XXX 即为 bean 的名称。如果不设置bean的名字，会默认为类名作为实例名。

　　@Controller,用于标注控制层组件。可以设置为@Controller("XXX")。

　　@Component，泛指任何一层的bean实例，可以设置为@Component("XXX)。