spring mvc中下拉框的复习

  spring mvc中下拉框,其实是很简单的了,但简单的东西还是应该多复习,这次来复习下.


1)controller:

  

@RequestMapping(value="/phone-page")
	private ModelAndView selectTag() {
		ModelAndView mav = new ModelAndView("phone-form");
		
		Map<String, String> phones = new HashMap<String, String>();
		phones.put("samsung", "SAMSUNG");
		phones.put("nokia", "NOKIA");
		phones.put("iphone", "IPHONE");
		
		mav.addObject("phonesMap", phones);
		mav.addObject("smartphone", new Smartphone());
		
		return mav;
	}

    这里其实用HashMap去装载下拉列表,然后放到modelandview中去,然后前端的页面jsp

Select phone:
<form:form method="POST" commandName="smartphone" action="phone-result.html">
<table>
    <tr>
    <td>
	    [list]
	    	<form:select path="phone" items="${phonesMap}"/>
	    [/list]
    </td>
    </tr>
    <tr>
        <td>
            <input type="submit" value="Submit"/>
        </td>
    </tr>
</table>  
</form:form>

    这里的submit演示了选择某个选项后,提交到phone-result这个方法控制器中,
控制器中的方法代码为:

  

@RequestMapping(value="/phone-result")
	private ModelAndView processPhone(@ModelAttribute Smartphone smartphone) {
		ModelAndView mav = new ModelAndView("phone-result");
		mav.addObject("smartphone", smartphone);		
		return mav;
	}

   可以看到<form:form method="POST" commandName="smartphone" action="phone-result.html">,而接受的参数中,用@ModelAttribute Smartphone smartphone接收住了.


2) 第2种方法是在JSP页面中硬编码下拉选项,如:
  

<form:form method="POST" commandname="smartphone" action="phone-result.html">
<table>
    <tbody><tr>
    <td>
	    [list]
	    	<form:select path="phone">
	    		<form:option value="samsung">SAMSUNG</form:option>
	    		<form:option value="nokia">NOKIA</form:option>
	    		<form:option selected="selected" value="htc">HTC</form:option>
	    		<form:option value="iphone">IPHONE</form:option>
	    	</form:select>
	    [/list]
    </td>
    </tr>
    <tr>
        <td>
            <input value="Submit" type="submit">
        </td>
    </tr>
</tbody></table>  
</form:form>

  
   当然呈现这个jsp的控制层为:
 

@RequestMapping(value="/phone-option-page")
	private ModelAndView optionTag() {		
		return new ModelAndView("phone-option-form", "smartphone", new Smartphone());
	}

3 最后一个看<form:options>的用法

控制器方法:
  

@RequestMapping(value="/phone-options-page")
	private ModelAndView optionsTag() {
		ModelAndView mav = new ModelAndView("phone-options-form");

		Map< String, String > phones = new HashMap();
		phones.put("samsung", "SAMSUNG");
		phones.put("nokia", "NOKIA");
		phones.put("iphone", "IPHONE");
		phones.put("bberry", "BLACKBERRY");
		phones.put("htc", "HTC");

		mav.addObject("phonesMap", phones);
		mav.addObject("smartphone", new Smartphone());

		return mav;
	}

  注意页面JSP为:
 

Select phone:
<form:form method="POST" commandname="smartphone" action="phone-result.html">
<table>
    <tbody><tr>
    <td>
	    [list]
	    	<form:select path="phone">
		    	<form:option value="-" label="--Select phone">
	            <form:options items="${phonesMap}">
	    	</form:options></form:option></form:select>
	    [/list]
    </td>
    </tr>
    <tr>
        <td>
            <input value="Submit" type="submit">
        </td>
    </tr>
</tbody></table>  
</form:form>