• SpringMVC使用的几个要点


    1.使用 @RequestParam("username") 来对应参数名的时候,这个参数必须要传入,否则会报错。没加@RequestParam则可传可不传

        @RequestMapping("/index")
        public String index(@RequestParam("username") String username, String password) {
            System.out.println(username);
            System.out.println(password);
            return "test/index";
        }

    2.向页面传值,可以用Map也可以用Model,通常都用Model

        @RequestMapping("/index2")
        public String index2(String username, Map<String, Object> context) {
            System.out.println(username);
            context.put("username", username);
            return "test/index";
        }
    
        @RequestMapping("/index3")
        public String index3(String username, Model model) {
            // System.out.println("id:" + id);
            System.out.println(username);
            model.addAttribute("username", "username");
            // 只有一个参数,默认key就是小写的对象名称
            model.addAttribute(new Article());
            return "test/index";
        }

    页面:

    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>test ${username }
    ${article.id }
    </body>
    </html>

    3. method = RequestMethod.GET 代表get方式访问

        @RequestMapping(value = "/index4", method = RequestMethod.GET)
        public String index4(String username, Model model) {
            // System.out.println("id:" + id);
            System.out.println(username);
            model.addAttribute("username", "username");
            // 只有一个参数,默认key就是小写的对象名称
            model.addAttribute(new Article());
            return "test/index";
        }

    4. 通过url传值用 @PathVariable  @RequestMapping value可以直接支持多级目录的路径,不像asp.net mvc需要在global.asax中设置路由

        // www.url.com/test/p1 读取url的地址作为参数
        @RequestMapping(value = "/{username}", method = RequestMethod.GET)
        public String show(@PathVariable String username) {
            System.out.println(username);
            return "test/index";
        }
    
        // www.url.com/test/p1 读取url的地址作为参数
        @RequestMapping(value = "/update/{id}", method = RequestMethod.GET)
        public String show2(@PathVariable String id) {
            System.out.println("show2 " + id);
            return "test/index";
        }
    
        @RequestMapping(value = "/update/detail/{id}", method = RequestMethod.GET)
        public String show3(@PathVariable String id) {
            System.out.println("show3 " + id);
            return "test/index";
        }

    5. (1) 可以通过 bean-validator.jar 对springMVC 做服务端校验,校验时@Validated Menu menu, BindingResult br 参数必须写在一起

        @NotEmpty(message="菜单名单不能为空")
        public String getMenuname() {
            return menuname;
        }

        (2) springMVC上传文件需要使用commons-io-2.2.jar、commons-fileupload-1.3.1.jar两个jar包

              配置文件中需要加入bean代码

    <!-- 设置multipartResolver才能完成文件上传 -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- 限制文件最大值为5M -->
    <property name="maxUploadSize" value="5000000"></property>
    </bean>

        @RequestMapping(value = "/menuadd", method = RequestMethod.POST)
        public String menuadd(@Validated Menu menu, BindingResult br,@RequestParam("attachs") MultipartFile[] attachs, HttpServletRequest req) throws IOException {// 紧跟Validated写验证结果类
            System.out.println(menu.getMenuid() + " " + menu.getMenuname());
            if (br.hasErrors()) {
                System.out.println("验证不通过");
                return "redirect:/test/menuadd";// 客户端跳转
            }
            for (MultipartFile attach : attachs) {
                if (attach.isEmpty())
                    continue;
    
                System.out.println(attach.getName() + "," + attach.getOriginalFilename() + "," + attach.getContentType());
                String path = req.getSession().getServletContext().getRealPath("/WEB-INF/resources/upload");
                System.out.println(path);
                File file = new File(path + "/" + attach.getOriginalFilename());
                FileUtils.copyInputStreamToFile(attach.getInputStream(), file);
            }
    
            return "redirect:/test/index2";// 客户端跳转
        }

    页面:

    <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="UTF-8"%>
    <%@taglib prefix="sf" uri="http://www.springframework.org/tags/form"%>
    
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    
    <sf:form method="post" modelAttribute="menu" enctype="multipart/form-data">
    menuid:<input type="text" name="menuid"><br/>
    menuname:<input type="text" name="menuname"><br>
    <sf:errors path="menuname"></sf:errors><br/>
    file1:<input type="file" name="attachs"><br/>
    file2:<input type="file" name="attachs"><br/>
    file3:<input type="file" name="attachs"><br/>
    <input type="submit" value="提交">
    </sf:form>
    
    </body>
    </html>

    6.跳转页面可以使用  return "redirect:/test/index2";  // 客户端跳转

    7. 返回json数据 加@ResponseBody 并且直接return对象

        params="jj" 代表如果传了jj参数就可以映射到这个方法执行,可以根据params参数执行不同的方法

        @RequestMapping(value = "/update/detail/{id}", method = RequestMethod.GET,params="jj")
        @ResponseBody
        public Menu show4(@PathVariable String id) {
            System.out.println("show4 " + id);
            Menu menu = new Menu(12l, "menuName");
            return menu;
        }

    8. produces解决返回中文到客户端乱码的问题

        /**
         * 启用活动
         */
        @RequestMapping(value = "use/{id}", produces = "text/html;charset=UTF-8")
        @ResponseBody
        public String use(@PathVariable("id") long id) {
            InfoWeixinGoldEggActivity info = service.queryById(id);
            if (info.getStatus()) {
                return "活动已经是启用状态";
            }
            info.setStatus(true);
            service.updateStatus(info);
            return "success";
        }
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  • 原文地址:https://www.cnblogs.com/zhuawang/p/5656935.html
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