• SpingMVC ModelAndView, Model,Control以及参数传递


    1.web.xml 配置:

    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <description>加载/WEB-INF/spring-mvc/目录下的所有XML作为Spring MVC的配置文件</description>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-mvc/*.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>

    这样,所有的.htm的请求,都会被DispatcherServlet处理;

    初始化 DispatcherServlet 时,该框架在 web 应用程序WEB-INF 目录中寻找一个名为[servlet-名称]-servlet.xml的文件,并在那里定义相关的Beans,重写在全局中定义的任何Beans,像上面的web.xml中的代码,对应的是dispatcher-servlet.xml;当然也可以使用<init-param>元素,手动指定配置文件的路径;dispatcher-servlet.xml 配置:

    <?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:mvc="http://www.springframework.org/schema/mvc"
           xmlns:p="http://www.springframework.org/schema/p"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:aop="http://www.springframework.org/schema/aop"
           xmlns:tx="http://www.springframework.org/schema/tx"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
                http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                http://www.springframework.org/schema/context 
                http://www.springframework.org/schema/context/spring-context-3.0.xsd
                http://www.springframework.org/schema/aop 
                http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
                http://www.springframework.org/schema/tx 
                http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
                http://www.springframework.org/schema/mvc 
                http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
                http://www.springframework.org/schema/context 
                http://www.springframework.org/schema/context/spring-context-3.0.xsd">
        <!--
            使Spring支持自动检测组件,如注解的Controller
        -->
        <context:component-scan base-package="com.minx.crm.web.controller"/>
       
        <bean id="viewResolver"
              class="org.springframework.web.servlet.view.InternalResourceViewResolver"
              p:prefix="/WEB-INF/jsp/"
              p:suffix=".jsp" />
    </beans>

    2.spring mvc处理方法支持如下的返回方式:ModelAndView, Model, ModelMap, Map,View, String, void

    ModelAndView

    @RequestMapping("/show1") 
    public ModelAndView show1(HttpServletRequest request, 
               HttpServletResponse response) throws Exception { 
           ModelAndView mav = new ModelAndView("/demo2/show"); 
           mav.addObject("account", "account -1"); 
           return mav; 
       } 

    通过ModelAndView构造方法可以指定返回的页面名称,也可以通过setViewName()方法跳转到指定的页面 , 使用addObject()设置需要返回的值,addObject()有几个不同参数的方法,可以默认和指定返回对象的名字。 调用addObject()方法将值设置到一个名为ModelMap的类属性,ModelMap是LinkedHashMap的子类, 具体请看类。

    Model 是一个接口, 其实现类为ExtendedModelMap,继承了ModelMap类。

    model.addAttribute("pojo", pojo);

    Map 

    @RequestMapping("/demo2/show") 
        public Map<String, String> getMap() { 
            Map<String, String> map = new HashMap<String, String>(); 
            map.put("key1", "value-1"); 
            map.put("key2", "value-2"); 
            return map; 
        } 

    在jsp页面中可直通过${key1}获得到值, map.put()相当于request.setAttribute方法。 写例子时发现,key值包括 - . 时会有问题.

    View 可以返回pdf excel等,暂时没详细了解。

    String 指定返回的视图页面名称,结合设置的返回地址路径加上页面名称后缀即可访问到。

    注意:如果方法声明了注解@ResponseBody ,则会直接将返回值输出到页面。 例如:

    @RequestMapping(value = "/something", method = RequestMethod.GET) 
    @ResponseBody 
    public String helloWorld()  { 
    return"Hello World"; 
    } 

    上面的结果会将文本"Hello World "直接写到http响应流。

    @RequestMapping("/welcome") 
    public String welcomeHandler() { 
      return"center"; 
    } 

    对应的逻辑视图名为“center”,URL= prefix前缀+视图名称 +suffix后缀组成。
    void  如果返回值为空,则响应的视图页面对应为访问地址

    @RequestMapping("/welcome") 
    publicvoid welcomeHandler() {} 

    此例对应的逻辑视图名为"welcome"。

    小结:

    1.使用 String 作为请求处理方法的返回值类型是比较通用的方法,这样返回的逻辑视图名不会和请求 URL 绑定,具有很大的灵活性,而模型数据又可以通过 ModelMap 控制。 2.使用void,map,Model 时,返回对应的逻辑视图名称真实url为:prefix前缀+视图名称 +suffix后缀组成。 3.使用String,ModelAndView返回视图名称可以不受请求的url绑定,ModelAndView可以设置返回的视图名称。

    Model model,HttpServletRequest request, ModelMap map声明变量

    request.getSession().setAttribute("test", "haiwei2Session"); request.setAttribute("test", "haiwei1request"); map.addAttribute("test", "haiweiModelMap"); model.addAttribute("test", "haiweiModel");
    我通过${test}这个方式取值,优先取Model和ModelMap的,Model和ModelMap是同一个东西,谁最后赋值的就取谁的,然后是request,最后是从session中获取

     第一个Controller

    package com.minx.crm.web.controller;  
      
    import org.springframework.stereotype.Controller;  
    import org.springframework.web.bind.annotation.RequestMapping;  
    @Controller  
    public class IndexController {  
        @RequestMapping("/index")  
        public String index() {  
            return "index";  
        }  
    }  
    package com.minx.crm.web.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    @Controller
    public class IndexController {
        @RequestMapping("/index")
        public String index() {
            return "index";
        }
    }

    @Controller注解标识一个控制器,@RequestMapping注解标记一个访问的路径(/index.htm),return "index"标记返回视图(index.jsp);

    注:如果@RequestMapping注解在类级别上,则表示一相对路径,在方法级别上,则标记访问的路径;

    从@RequestMapping注解标记的访问路径中获取参数:

    Spring MVC 支持RESTful风格的URL参数,如:

    @Controller  
    public class IndexController {  
      
        @RequestMapping("/index/{username}")  
        public String index(<span style="color: rgb(255, 0, 0);">@PathVariable</span>("username") String username) {  
            System.out.print(username);  
            return "index";  
        }  
    }  
    @Controller
    public class IndexController {
    
        @RequestMapping("/index/{username}")
        public String index(@PathVariable("username") String username) {
            System.out.print(username);
            return "index";
        }
    }

    @RequestMapping中定义访问页面的URL模版,使用{}传入页面参数,使用@PathVariable 获取传入参数,即可通过地址:http://localhost:8080/crm/index/tanqimin.htm 访问;

    根据不同的Web请求方法,映射到不同的处理方法:

    使用登陆页面作示例,定义两个方法分辨对使用GET请求和使用POST请求访问login.htm时的响应。可以使用处理GET请求的方法显示视图,使用POST请求的方法处理业务逻辑;

    @Controller  
    public class LoginController {  
        @RequestMapping(value = "/login", method = RequestMethod.GET)  
        public String login() {  
            return "login";  
        }  
        @RequestMapping(value = "/login", method = RequestMethod.POST)  
        public String login2(HttpServletRequest request) {  
                String username = request.getParameter("username").trim();  
                System.out.println(username);  
            return "login2";  
        }  
    }  
    @Controller
    public class LoginController {
        @RequestMapping(value = "/login", method = RequestMethod.GET)
        public String login() {
            return "login";
        }
        @RequestMapping(value = "/login", method = RequestMethod.POST)
        public String login2(HttpServletRequest request) {
                String username = request.getParameter("username").trim();
                System.out.println(username);
            return "login2";
        }
    }

    在视图页面,通过地址栏访问login.htm,是通过GET请求访问页面,因此,返回登陆表单视图login.jsp;当在登陆表单中使用POST请求提交数据时,则访问login2方法,处理登陆业务逻辑;

    防止重复提交数据,可以使用重定向视图:

    return "redirect:/login2"  
    return "redirect:/login2"

    可以传入方法的参数类型:

    <strong>@RequestMapping(value = "login", method = RequestMethod.POST)  
    public String testParam(HttpServletRequest request, HttpServletResponse response, HttpSession session) {  
        String username = request.getParameter("username");  
        System.out.println(username);  
        return null;  
    }</strong>  
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public String testParam(HttpServletRequest request, HttpServletResponse response, HttpSession session) {
    	String username = request.getParameter("username");
    	System.out.println(username);
    	return null;
    }

    可以传入HttpServletRequestHttpServletResponseHttpSession,值得注意的是,如果第一次访问页面,HttpSession没被创建,可能会出错;

    其中,String username = request.getParameter("username");可以转换为传入的参数:

    @RequestMapping(value = "login", method = RequestMethod.POST)  
    public String testParam(HttpServletRequest request, HttpServletResponse response, HttpSession session,@RequestParam("username") String username) {  
        String username = request.getParameter("username");  
        System.out.println(username);  
        return null;  
    }  
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public String testParam(HttpServletRequest request, HttpServletResponse response, HttpSession session,@RequestParam("username") String username) {
        String username = request.getParameter("username");
        System.out.println(username);
        return null;
    }
     
    
    使用@RequestParam 注解获取GET请求或POST请求提交的参数;
    
    获取Cookie的值:使用@CookieValue :
    获取printwriter:
    可以直接在Controller的方法中传入PrintWriter对象,就可以在方法中使用:
    @RequestMapping(value = "login", method = RequestMethod.POST)  
    public String testParam(PrintWriter out, <span style="color: rgb(255, 0, 0);">@RequestParam</span>("username") String username) {  
        out.println(username);  
        return null;  
    }  
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public String testParam(PrintWriter out, @RequestParam("username") String username) {
    	out.println(username);
    	return null;
    }

    获取表单中提交的值,并封装到POJO中,传入Controller的方法里:

    POJO如下(User.java):

    public class User{  
        private long id;  
        private String username;  
        private String password;  
      
        …此处省略getter,setter...  
    }  
    public class User{
    	private long id;
    	private String username;
    	private String password;
    
    	…此处省略getter,setter...
    }

    通过表单提交,直接可以把表单值封装到User对象中:

    @RequestMapping(value = "login", method = RequestMethod.POST)  
    public String testParam(PrintWriter out, User user) {  
        out.println(user.getUsername());  
        return null;  
    }  
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public String testParam(PrintWriter out, User user) {
    	out.println(user.getUsername());
    	return null;
    }

    可以把对象,put 入获取的Map对象中,传到对应的视图:

    <strong>@RequestMapping(value = "login", method = RequestMethod.POST)  
    public String testParam(User user, Map model) {  
        model.put("user",user);  
        return "view";  
    }</strong>  
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public String testParam(User user, Map model) {
    	model.put("user",user);
    	return "view";
    }

    在返回的view.jsp中,就可以根据key来获取user的值(通过EL表达式,${user }即可);

    Controller中方法的返回值:

    void:多数用于使用PrintWriter输出响应数据;

    String 类型:返回该String对应的View Name

    任意类型对象:

    返回ModelAndView

    自定义视图(JstlView,ExcelView):

     拦截器(Inteceptors):

    <strong>public class MyInteceptor implements HandlerInterceptor {  
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o)   
            throws Exception {  
            return false;  
        }  
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView mav)   
            throws Exception {  
        }  
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object o, Exception excptn)   
            throws Exception {  
        }  
    }</strong>  
    public class MyInteceptor implements HandlerInterceptor {
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) 
    		throws Exception {
    		return false;
    	}
    	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView mav) 
    		throws Exception {
    	}
    	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object o, Exception excptn) 
    		throws Exception {
    	}
    }

    拦截器需要实现HandleInterceptor接口,并实现其三个方法:

    preHandle:拦截器的前端,执行控制器之前所要处理的方法,通常用于权限控制、日志,其中,Object o表示下一个拦截器;

    postHandle:控制器的方法已经执行完毕,转换成视图之前的处理;

    afterCompletion:视图已处理完后执行的方法,通常用于释放资源;

    MVC的配置文件中,配置拦截器与需要拦截的URL

    <mvc:interceptors>  
        <mvc:interceptor>  
            <mvc:mapping path="/index.htm" />  
            <bean class="com.minx.crm.web.interceptor.MyInterceptor" />  
        </mvc:interceptor>  
    </mvc:interceptors> 
    <mvc:interceptors>
    	<mvc:interceptor>
    		<mvc:mapping path="/index.htm" />
    		<bean class="com.minx.crm.web.interceptor.MyInterceptor" />
    	</mvc:interceptor>
    </mvc:interceptors>

    国际化:

    MVC配置文件中,配置国际化属性文件:

    <bean id="messageSource"  
        class="org.springframework.context.support.ResourceBundleMessageSource"  
        p:basename="message">  
    </bean>  
    <bean id="messageSource"
    	class="org.springframework.context.support.ResourceBundleMessageSource"
    	p:basename="message">
    </bean>

    那么,Spring就会在项目中搜索相关的国际化属性文件,如:message.propertiesmessage_zh_CN.properties

    VIEW中,引入Spring标签:<%@taglib uri="http://www.springframework.org/tags" prefix="spring" %>,使用<spring:message code="key" />调用,即可;

    如果一种语言,有多个语言文件,可以更改MVC配置文件为:

    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">  
        <property name="basenames">  
            <list>  
                <value>message01</value>  
                <value>message02</value>  
                <value>message03</value>  
            </list>  
        </property>  
    </bean>  
  • 相关阅读:
    Linux(Debian、Ubuntu、Deepin等)安装最新版Chrome Unstable
    JavaScript根据经纬度获取距离信息
    CSS滚动条样式定制
    Linux下 Apache Vhost 配置 防止403
    Unity减小安装包的体积(210MB减小到7MB)
    Ubuntu17.04配置LNMP(Nginx+PHP7+MySQL)简单教程 快速 易学 简单易懂
    Yii2项目实现Markdown功能 在线Markdown编辑器
    Gradle全局代理配置
    Angular4.0从入门到实战打造在线竞拍网站学习笔记之三依赖注入
    Python使用PyMysql操作数据库
  • 原文地址:https://www.cnblogs.com/zhoudi/p/5977078.html
Copyright © 2020-2023  润新知