Spring 04 MVC

Maven Eclipse 整合SSM

新建工程选择webapp

创建目录结构

• src/main/java
• src/main/resources
  • mappers
    • XXXMapper.xml
  • applicationContext.xml
  • springmvc.xml
  • sqlMapConfig.xml
• src/main/webapp/WEB-INF
  • jsp
    • XXX. jsp
  • web.xml
• pom.xml

xml文件

• pom.xml 引入依赖和插件：Spring Springmvc Mybatis / JDBC相关：SQL驱动，连接池 / jackson Tomcat插件 jdk版本等等
• XXXMapper.xml sql语句在此拼接
• applicationContext.xml Mybatis 详细配置

	<!-- 配置数据源 -->
	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="driverClass" value="com.mysql.jdbc.Driver"></property>
		<property name="jdbcUrl" value="jdbc:mysql:///ssmdb"></property>
		<property name="user" value="root"></property>
		<property name="password" value="123456"></property>
	</bean>
	
	<!-- 整合MyBatis -->
	<!-- 配置SqlSessionFactory -->
	<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
		<property name="dataSource" ref="dataSource"></property>
		<property name="configLocation" value="classpath:/sqlMapConfig.xml"></property>
		<property name="mapperLocations" value="classpath:/mappers/*.xml"></property>
	</bean>
	<!-- MyBatis MapperBean扫描器，负责为MapperBean生成实现类 -->
	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="cn.zjn.mapper"></property>
	</bean>
	
	<!-- 声明式事务处理 -->
	<!-- 配置事务管理器 -->
	<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource"></property>
	</bean>
	<!-- 开启注解方式控制事务 -->
	<tx:annotation-driven/>
	
</beans>

• springmvc.xml 视图解析器

<!-- 配置包扫描 -->
	<context:component-scan base-package="cn.zjn.controller"></context:component-scan>
	<!-- 配置注解方式mvc -->
	<mvc:annotation-driven></mvc:annotation-driven>
	<!-- 配置视图解析器 -->
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/jsp/"></property>
		<property name="suffix" value=".jsp"></property>
	</bean>	

• sqlMapConfig.xml
• web.xml 监听器 前端控制器

<web-app>
	
	<!-- 配置Spring启动的监听器 -->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:/applicationContext.xml</param-value>
	</context-param>
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	
	<!-- 配置SpringMVC的前端控制器 -->
	<servlet>
		<servlet-name>springmvc</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:springmvc.xml</param-value>
		</init-param>
	</servlet>  
	<servlet-mapping>
		<servlet-name>springmvc</servlet-name>
		<url-pattern>*.action</url-pattern>	
	</servlet-mapping>
  
</web-app>

开发

• 控制层
• 服务层
• 持久层
• 配置run

---

MVC概念

Module:模型–封装数据
View:视图–展示数据
Controller:控制器

---

Spring MVC原理 — 请求驱动

1. 客户端发出请求，请求提交到DispatcherServlet
2. DispatcherServlet查询HandlerMapping，得到Handler路径
3. HandlerAdapter调用真正的Handler处理请求
4. Handler处理完成，返回ModelAndView对象给DispatcherServlet
5. ViewResolver [resolve：解决(问题或困难); 决心],接收DispatcherServlet的ModelAndView，根据映射关系得到真正的view
6. DispatchServlet中的Model数据嵌入到视图解析器解析之后的view
7. 将最终的view返回给客户端，显示给用户
   

---

使用

前端控制器

• 配置前端控制器 在 web.xml

<web-app>
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>*.action</url-pattern>
    </servlet-mapping>
</web-app>

• 其他的bean

---

视图解析 ModelAndView

• 配置视图解析器 在 springmvc.xml
  Spring MVC中所有控制器的处理器方法都要返回一个逻辑视图的名字。如下：如果返回一个叫example的逻辑视图名，视图解析器会将请求转发到 /WEB-INF/jsp/example.jsp 视图去渲染。

<?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">
	<!-- 配置包扫描 -->
	<!--如果某个类的头上带有特定的注解
    @Component，@Repository，@Service，@Controller，就会将这个对象作为Bean注册进Spring容器。-->
	<context:component-scan base-package="查找指定包中的component组件"></context:component-scan>
	<!-- 配置注解方式mvc -->
	<mvc:annotation-driven></mvc:annotation-driven>
	<!-- 配置视图解析器 -->
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/jsp/"></property>
		<property name="suffix" value=".jsp"></property>
	</bean>	
</beans>

---

注解初识

• Controller
• RestController
• RequestMapping
• RequestBody
• ResponseBody

---

@RestController

• 使用了这个注解，不能返回jsp、html页面
• 使用了这个注解以后如果要返回json数据，那么就不需要加@ResponseBody注解
• 属于Spring MVC 不是Spring Boot特有的注解。
  @RestController = @ResponseBody + @Controller

@Controller
@ResponseBody
public @interface RestController {

	/**
	  The value may indicate a suggestion for a logical component name,
	  值可能表示一个逻辑组件名
	  to be turned into a Spring bean in case of an autodetected component.
	  被自动检测的组件被转化成Spring的bean
	  @return the suggested component name, if any
	   返回一个逻辑组件名 艹翻译不通
	  @since 4.0.1
	 */
	String value() default "";

}

---

@ResponseBody 与 @RequestBody

HttpMessageConverter 实现转换
https://blog.csdn.net/justry_deng/article/details/80972817
https://blog.csdn.net/ff906317011/article/details/78552426#commentBox

---

RequestBody – 接收请求体

• ajax传送json对象，@RequestBody接收json字符串
• 接收json字符串，反序列化→java对象
• 用来接收前端传递给后端的json字符串中的数据（请求实体中的数据）！！！请求体中的数据，即如果数据放到请求体中要有@RequestBody才能接收到
• 使用@RequestBody接收数据时，前端不能使用GET方式提交数据，要使用POST方式进行提交
• 一个请求只能有一个RequestBody
• json字符串中如果value是"",后端对应属性如果是String类型的，那么接受到的就是""，如果是后端属性的类型是Integer、Double等，那么接收到的就是null

RequestBody如何将json转化为java对象

BeanDeserializerBase

public abstract Object deserializeFromObject(JsonParser p, DeserializationContext ctxt)
        throws IOException;

class BeanDeserializer extends BeanDeserializerBase

public class BeanDeserializer extends BeanDeserializerBase implements java.io.Serializable {
	@Autowired
	User bean = null;
	protected BeanDeserializer(BeanDeserializerBase src) {
		super(src);
		// TODO Auto-generated constructor stub
	}	
	@Override
	public Object deserializeFromObject(JsonParser p, DeserializationContext ctxt) throws IOException {
		// 获取json字符串的key
		String propName = p.getCurrentName();
		
		do {
			p.nextToken();
			//查询模型中是否有对应属性的setter方法
			SettableBeanProperty prop = _beanProperties.find(propName);
			//如果有
			if(prop != null) {
				try {
					//反序列化并且设置java对象
					prop.deserializeAndSet(p, ctxt,bean);
				} catch (Exception e) {
					// TODO: handle exception
					wrapAndThrow(e, bean, propName, ctxt);
				}
				continue;
			}
			//如果没有
	   /* if (_ignorableProps != null && _ignorableProps.contains(propName)) {
	        //setter是空 忽略
            handleIgnoredProperty(p, ctxt, bean, propName);
            } 
            else if (_anySetter != null) { 
            //setter不是空 设置
                 try {
                     // should we consider return type of any setter?
                     _anySetter.deserializeAndSet(p, ctxt, bean, propName); 
                 } catch (Exception e) {
                     wrapAndThrow(e, bean, propName, ctxt);
                 }
            } else {
            // Unknown: let's call handler method
            handleUnknownProperty(p, ctxt, bean, propName);         
        }
		*/
			handleUnknownVanilla(p,ctxt,bean,propName);
			
			//一次获取下一个key，重复逻辑,进而完成json到java对象的转换
		}while((propName = p.nextFieldName())!=null);
		return bean;
	}

}

用法实例

在这里插入代码片

@ResponseBody

• 将控制器返回的对象转换为指定格式（json、xml），通过Response响应给客户端。

/**
 * Annotation that indicates a method return value should be bound to the web
 * response body. Supported for annotated handler methods in Servlet environments.
 *
 * <p>As of version 4.0 this annotation can also be added on the type level in
 * which case it is inherited and does not need to be added on the method level.
 *
 * @author Arjen Poutsma
 * @since 3.0
 * @see RequestBody
 * @see RestController
 */
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ResponseBody {

}

@Controller
@RequestMapping("/order")
public class OrderController {
	@Autowired
	private OrderService orderService = null;
	@ResponseBody
	@RequestMapping("/pay.action")
	public String pay(String orderId){
		try{
			orderService.payOrder(orderId);
			return "1";
		}catch (Exception e) {
			e.printStackTrace();
			return "0";
		}
	}
}

---

@RequestMapping

@AliasFor注解

public @interface RequestMapping {

	/**
	 * Assign（分配） a name to this mapping.
	 * with "#" as separator.
	 */
	String name() default "";

	/**
	 * The primary mapping expressed by this annotation.
	 * <p>In a Servlet environment this is an alias for {@link #path}.
	 * For example {@code @RequestMapping("/foo")} is equivalent to
	 * {@code @RequestMapping(path="/foo")}.
	 */
	@AliasFor("path")
	String[] value() default {};

	/**
	 * In a Servlet environment only: the path mapping URIs (e.g. "/myPath.do").
	 * Ant-style path patterns are also supported (e.g. "/myPath/*.do").
	 * At the method level, relative paths (e.g. "edit.do") are supported within
	 * the primary mapping expressed at the type level. Path mapping URIs may
	 * contain placeholders（占位符） (e.g. "/${connect}")
	 */
	@AliasFor("value")
	String[] path() default {};

	/**
	 * The HTTP request methods to map to, narrowing the primary mapping:
	 * GET, POST, HEAD, OPTIONS, PUT, PATCH, DELETE, TRACE.
	 * <p><b>Supported at the type level as well as at the method level!</b>
	 * When used at the type level, all method-level mappings inherit（继承）
	 * this HTTP method restriction（限定，法规） (i.e. the type-level restriction
	 * gets checked before the handler method is even resolved).
	 */
	RequestMethod[] method() default {};

• URI模板
• http://www.example.com/owners/{ownerId} → http://www.example.com/owners/fred
  URI模板"/owners/{ownerId}"指定了一个变量，名为ownerId。当控制器处理这个请求的时候，ownerId的值就会被URI模板中对应部分的值所填充。比如说，如果请求的URI是/owners/fred，此时变量ownerId的值就是fred. `

@RequestMapping(path="/owners/{ownerId}", method=RequestMethod.GET)
public String findOwner(@PathVariable String ownerId, Model model) {
    Owner owner = ownerService.findOwner(ownerId);
    model.addAttribute("owner", owner);
    return "displayOwner";
}

---