基于Spring MVC的Web应用开发(10) - Views --Form

在FileUpload一文中，我们初步了解了SpringMVC中View的用法，在例子中，通过给Model添加一个属性（model.addAttribute()），View对应的JSP就可以获取该值。本文再介绍一些View对应JSP取值的方式。

增加一个Controller，ViewsController：

Java代码

package org.springframework.samples.mvc.views;
import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
@RequestMapping("/views/*")
public class ViewsController {
@RequestMapping(value="html", method=RequestMethod.GET)
public String prepare(Model model) {
model.addAttribute("foo", "bar");
model.addAttribute("fruit", "apple");
return "views/html";
}
@RequestMapping(value="/viewName", method=RequestMethod.GET)
public void usingRequestToViewNameTranslator(Model model) {
model.addAttribute("foo", "bar");
model.addAttribute("fruit", "apple");
}
@RequestMapping(value="pathVariables/{foo}/{fruit}", method=RequestMethod.GET)
public String pathVars(@PathVariable String foo, @PathVariable String fruit) {
// No need to add @PathVariables "foo" and "fruit" to the model
// They will be merged in the model before rendering
return "views/html";
}
@RequestMapping(value="dataBinding/{foo}/{fruit}", method=RequestMethod.GET)
public String dataBinding(@Valid JavaBean javaBean, Model model) {
// JavaBean "foo" and "fruit" properties populated from URI variables
return "views/dataBinding";
}
}

package org.springframework.samples.mvc.views;

import javax.validation.Valid;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("/views/*")
public class ViewsController {

	@RequestMapping(value="html", method=RequestMethod.GET)
	public String prepare(Model model) {
		model.addAttribute("foo", "bar");
		model.addAttribute("fruit", "apple");
		return "views/html";
	}
	
	@RequestMapping(value="/viewName", method=RequestMethod.GET)
	public void usingRequestToViewNameTranslator(Model model) {
		model.addAttribute("foo", "bar");
		model.addAttribute("fruit", "apple");
	}

	@RequestMapping(value="pathVariables/{foo}/{fruit}", method=RequestMethod.GET)
	public String pathVars(@PathVariable String foo, @PathVariable String fruit) {
		// No need to add @PathVariables "foo" and "fruit" to the model
		// They will be merged in the model before rendering
		return "views/html";
	}

	@RequestMapping(value="dataBinding/{foo}/{fruit}", method=RequestMethod.GET)
	public String dataBinding(@Valid JavaBean javaBean, Model model) {
		// JavaBean "foo" and "fruit" properties populated from URI variables 
		return "views/dataBinding";
	}

}

1. 访问"http://localhost:8080/web/views/html"，返回到"webapp/WEB-INF/views/views/html.jsp"：

Html代码

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
<title>My HTML View</title>
<link href="<c:url value="/resources/form.css" />" rel="stylesheet" type="text/css" />
</head>
<body>
<div class="success">
<h3>foo: "${foo}"</h3>
<h3>fruit: "${fruit}"</h3>
</div>
</body>
</html>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
	<title>My HTML View</title>
	<link href="<c:url value="/resources/form.css" />" rel="stylesheet"  type="text/css" />		
</head>
<body>
<div class="success">
	<h3>foo: "${foo}"</h3>
	<h3>fruit: "${fruit}"</h3>
</div>
</body>
</html>

prepare(Model model)同FileUpload一样，通过model.addAttribite("foo", "bar");，JSP的${foo}就能获得"bar"。

2. 访问"http://localhost:8080/web/views/viewName"，返回到"webapp/WEB-INF/views/views/viewName.jsp"，这个jsp文件和html.jsp一样。

usingRequestToViewNameTranslator(Model model)和prepare(Model model)稍有不同，该方法的返回值为void，SpringMVC认为返回值为void的View名字就是@RequestMapping中映射的完整路径，即"views/viewName"。

3. 访问"http://localhost:8080/web/views/pathVariables/bar/orange"，返回到"webapp/WEB-INF/views/views/html.jsp"

pathVars方法多了@PathVariable注解，该注解解析URL路径，并赋值给带有@PathVaribale的变量，View对应的JSP可以直接读取到这个变量的值。

4. 访问"http://localhost:8080/web/views/dataBinding/bar/orange"，返回到"webapp/WEB-INF/views/views/dataBinding.jsp"

Html代码

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
<title>Data Binding with URI Template Variables</title>
<link href="<c:url value="/resources/form.css" />" rel="stylesheet" type="text/css" />
</head>
<body>
<div class="success">
<h3>javaBean.foo: ${javaBean.foo}</h3>
<h3>javaBean.fruit: ${javaBean.fruit}</h3>
</div>
</body>
</html>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
	<title>Data Binding with URI Template Variables</title>
	<link href="<c:url value="/resources/form.css" />" rel="stylesheet"  type="text/css" />		
</head>
<body>
<div class="success">
	<h3>javaBean.foo: ${javaBean.foo}</h3>
	<h3>javaBean.fruit: ${javaBean.fruit}</h3>
</div>
</body>
</html>

dataBinding(@Valid JavaBean javaBean, Model model)的方法参数中有个自定义的Java类，SpringMVC会自动解析URL路径，并且感知foo和fruit是否为JavaBean的属性，如果是，则将它赋值给JavaBean，非常智能。JSP现在得到的就是一个JavaBean，因此需要使用${javaBean.foo}获取具体值。

=================================================================================

本节介绍SpringMVC中的表单，demo演示访问一个表单提交页面，填写表单的内容后使用jQuery的Ajax提交表单，将返回的文本信息显示出来。

记得在Struts1中有个FormBean的东西封装表单内容，在SpringMVC中也有，只不过SpringMVC更松耦合，只要写一个POJO就可以了，而不需要继承框架关联的类，看一下这个FormBean（只列出了主要属性）：

Java代码

public class FormBean {
@NotEmpty
private String name;
@Min(21)
private int age;
@DateTimeFormat(iso=ISO.DATE)
@Past
private Date birthDate;
@MaskFormat("(###) ###-####")
private String phone;
@NumberFormat(pattern="$###,###.00")
private BigDecimal currency;
@NumberFormat(style=Style.PERCENT)
private BigDecimal percent;
private InquiryType inquiry;
private String inquiryDetails;
private boolean subscribeNewsletter;
private Map<String, String> additionalInfo;
...
}

public class FormBean {
	
	@NotEmpty
	private String name;
	
	@Min(21)
	private int age;

	@DateTimeFormat(iso=ISO.DATE)
	@Past
	private Date birthDate;

	@MaskFormat("(###) ###-####")
	private String phone;

	@NumberFormat(pattern="$###,###.00")
	private BigDecimal currency;

	@NumberFormat(style=Style.PERCENT)
	private BigDecimal percent;
	
	private InquiryType inquiry;
	
	private String inquiryDetails;
	
	private boolean subscribeNewsletter;
	
	private Map<String, String> additionalInfo;
...
}

需要一个Controller，FormController：

Java代码

package org.springframework.samples.mvc.form;
import javax.validation.Valid;
import org.springframework.mvc.extensions.ajax.AjaxUtils;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
@Controller
@RequestMapping("/form")
@SessionAttributes("formBean")
public class FormController {
// Invoked on every request
@ModelAttribute
public void ajaxAttribute(WebRequest request, Model model) {
model.addAttribute("ajaxRequest", AjaxUtils.isAjaxRequest(request));
}
// Invoked initially to create the "form" attribute
// Once created the "form" attribute comes from the HTTP session (see @SessionAttributes)
@ModelAttribute("formBean")
public FormBean createFormBean() {
return new FormBean();
}
@RequestMapping(method=RequestMethod.GET)
public void form() {
}
@RequestMapping(method=RequestMethod.POST)
public String processSubmit(@Valid FormBean formBean, BindingResult result,
@ModelAttribute("ajaxRequest") boolean ajaxRequest,
Model model, RedirectAttributes redirectAttrs) {
if (result.hasErrors()) {
return null;
}
// Typically you would save to a db and clear the "form" attribute from the session
// via SessionStatus.setCompleted(). For the demo we leave it in the session.
String message = "Form submitted successfully. Bound " + formBean;
// Success response handling
if (ajaxRequest) {
// prepare model for rendering success message in this request
model.addAttribute("message", message);
return null;
} else {
// store a success message for rendering on the next request after redirect
// redirect back to the form to render the success message along with newly bound values
redirectAttrs.addFlashAttribute("message", message);
return "redirect:/form";
}
}
}

package org.springframework.samples.mvc.form;

import javax.validation.Valid;

import org.springframework.mvc.extensions.ajax.AjaxUtils;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
@RequestMapping("/form")
@SessionAttributes("formBean")
public class FormController {

	// Invoked on every request

	@ModelAttribute
	public void ajaxAttribute(WebRequest request, Model model) {
		model.addAttribute("ajaxRequest", AjaxUtils.isAjaxRequest(request));
	}

	// Invoked initially to create the "form" attribute
	// Once created the "form" attribute comes from the HTTP session (see @SessionAttributes)

	@ModelAttribute("formBean")
	public FormBean createFormBean() {
		return new FormBean();
	}
	
	@RequestMapping(method=RequestMethod.GET)
	public void form() {
	}

	@RequestMapping(method=RequestMethod.POST)
	public String processSubmit(@Valid FormBean formBean, BindingResult result, 
								@ModelAttribute("ajaxRequest") boolean ajaxRequest, 
								Model model, RedirectAttributes redirectAttrs) {
		if (result.hasErrors()) {
			return null;
		}
		// Typically you would save to a db and clear the "form" attribute from the session 
		// via SessionStatus.setCompleted(). For the demo we leave it in the session.
		String message = "Form submitted successfully.  Bound " + formBean;
		// Success response handling
		if (ajaxRequest) {
			// prepare model for rendering success message in this request
			model.addAttribute("message", message);
			return null;
		} else {
			// store a success message for rendering on the next request after redirect
			// redirect back to the form to render the success message along with newly bound values
			redirectAttrs.addFlashAttribute("message", message);
			return "redirect:/form";			
		}
	}
	
}

FormController只有一个@RequestMapping，通过GET，POST来区分是访问表单页面（GET），还是提交表单（POST）。在这个类中有：

Java代码

@ModelAttribute("formBean")
public FormBean createFormBean() {
return new FormBean();
}

	@ModelAttribute("formBean")
	public FormBean createFormBean() {
		return new FormBean();
	}

它表示访问"http://localhost:8080/web/form/"时，就初始化一个叫formBean名字的属性放在Model中。在类的开头有：

Java代码

@SessionAttributes("formBean")

@SessionAttributes("formBean")

它表示Model中的这个formBean在session的范围内有效，想一下，session是跟浏览器窗口关联的，窗口关闭，session就失效，所以每次打开一个新的表单页面都会生成一个新的formBean，另外填写完表单内容以POST方式提交后，formBean会根据提交的参数自动设置FormBean的值。

Java代码

@ModelAttribute
public void ajaxAttribute(WebRequest request, Model model) {
model.addAttribute("ajaxRequest", AjaxUtils.isAjaxRequest(request));
}

	@ModelAttribute
	public void ajaxAttribute(WebRequest request, Model model) {
		model.addAttribute("ajaxRequest", AjaxUtils.isAjaxRequest(request));
	}

该配置会导致每次访问"http://localhost:8080/web/form/"，都会设置一个ajaxRequest值（因为没有象formBean一样设置ajaxRequest的范围，默认的范围为Request级，每次请求都执行）。之前说过填好表单后通过jQuery的Ajax提交表单，通过这个配置，就知道请求是否是Ajax请求。

Java代码

@RequestMapping(method=RequestMethod.GET)
public void form() {
}

	@RequestMapping(method=RequestMethod.GET)
	public void form() {
	}

访问"http://localhost:8080/web/form/"，返回到"webapp/WEB-INF/views/form.jsp"。

Java代码

@RequestMapping(method=RequestMethod.POST)
public String processSubmit(@Valid FormBean formBean, BindingResult result,
@ModelAttribute("ajaxRequest") boolean ajaxRequest,
Model model, RedirectAttributes redirectAttrs) {
if (result.hasErrors()) {
return null;
}
// Typically you would save to a db and clear the "form" attribute from the session
// via SessionStatus.setCompleted(). For the demo we leave it in the session.
String message = "Form submitted successfully. Bound " + formBean;
// Success response handling
if (ajaxRequest) {
// prepare model for rendering success message in this request
model.addAttribute("message", message);
return null;
} else {
// store a success message for rendering on the next request after redirect
// redirect back to the form to render the success message along with newly bound values
redirectAttrs.addFlashAttribute("message", message);
return "redirect:/form";
}
}

	@RequestMapping(method=RequestMethod.POST)
	public String processSubmit(@Valid FormBean formBean, BindingResult result, 
								@ModelAttribute("ajaxRequest") boolean ajaxRequest, 
								Model model, RedirectAttributes redirectAttrs) {
		if (result.hasErrors()) {
			return null;
		}
		// Typically you would save to a db and clear the "form" attribute from the session 
		// via SessionStatus.setCompleted(). For the demo we leave it in the session.
		String message = "Form submitted successfully.  Bound " + formBean;
		// Success response handling
		if (ajaxRequest) {
			// prepare model for rendering success message in this request
			model.addAttribute("message", message);
			return null;
		} else {
			// store a success message for rendering on the next request after redirect
			// redirect back to the form to render the success message along with newly bound values
			redirectAttrs.addFlashAttribute("message", message);
			return "redirect:/form";			
		}
	}

processSubmit第一个参数formBean封装了页面提交的表单参数，注意到它前面有一个@Valid，因此有第二个参数BindingResult result，该参数可以知道表单是否验证通过。第三个参数获取Model中的属性值"ajaxRequest"，在方法体中，判断ajaxRequest，如果是，将返回"webapp/WEB-INF/views/form.jsp"，如果不是，将它重定向到一个jsp，当然，这个条件在本例子中没有使用到。

最后看看非常复杂的form.jsp，该jsp使用了大量的SpringMVC的标签：

Html代码

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://www.springframework.org/tags" prefix="s" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@ page session="false" %>
<c:if test="${!ajaxRequest}">
<html>
<head>
<title>forms | mvc-showcase</title>
<link href="<c:url value="/resources/form.css" />" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="<c:url value="/resources/jquery/1.6/jquery.js" />"></script>
</head>
<body>
</c:if>
<div id="formsContent">
<h2>Forms</h2>
<p>
See the <code>org.springframework.samples.mvc.form</code> package for the @Controller code
</p>
<form:form id="form" method="post" modelAttribute="formBean" cssClass="cleanform">
<div class="header">
<h2>Form</h2>
<c:if test="${not empty message}">
<div id="message" class="success">${message}</div>
</c:if>
<s:bind path="*">
<c:if test="${status.error}">
<div id="message" class="error">Form has errors</div>
</c:if>
</s:bind>
</div>
<fieldset>
<legend>Personal Info</legend>
<form:label path="name">
Name <form:errors path="name" cssClass="error" />
</form:label>
<form:input path="name" />
<form:label path="age">
Age <form:errors path="age" cssClass="error" />
</form:label>
<form:input path="age" />
<form:label path="birthDate">
Birth Date (in form yyyy-mm-dd) <form:errors path="birthDate" cssClass="error" />
</form:label>
<form:input path="birthDate" />
<form:label path="phone">
Phone (in form (###) ###-####) <form:errors path="phone" cssClass="error" />
</form:label>
<form:input path="phone" />
<form:label path="currency">
Currency (in form $#.##) <form:errors path="currency" cssClass="error" />
</form:label>
<form:input path="currency" />
<form:label path="percent">
Percentage (in form ##%) <form:errors path="percent" cssClass="error" />
</form:label>
<form:input path="percent" />
</fieldset>
<fieldset>
<legend>Inquiry</legend>
<form:label path="inquiry">
Type (select one)
</form:label>
<form:select path="inquiry">
<form:option value="comment">Comment</form:option>
<form:option value="feedback">Feedback</form:option>
<form:option value="suggestion">Suggestion</form:option>
</form:select>
<form:label path="inquiryDetails">
Details
</form:label>
<form:textarea path="inquiryDetails" />
</fieldset>
<fieldset class="checkbox">
<legend>Request Additional Info</legend>
<label><form:checkbox path="additionalInfo[mvc]" value="true" />on Spring MVC</label>
<label><form:checkbox path="additionalInfo[java]" value="true" />on Java (4-ever)</label>
</fieldset>
<fieldset class="radio">
<legend>Subscribe to Newsletter?</legend>
<label><form:radiobutton path="subscribeNewsletter" value="true" />Yes</label>
<label><form:radiobutton path="subscribeNewsletter" value="false" /> No</label>
</fieldset>
<p><button type="submit">Submit</button></p>
</form:form>
<script type="text/javascript">
$(document).ready(function() {
$("#form").submit(function() {
$.post($(this).attr("action"), $(this).serialize(), function(html) {
$("#formsContent").replaceWith(html);
$('html, body').animate({ scrollTop: $("#message").offset().top }, 500);
});
return false;
});
});
</script>
</div>
<c:if test="${!ajaxRequest}">
</body>
</html>
</c:if>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://www.springframework.org/tags" prefix="s" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@ page session="false" %>
<c:if test="${!ajaxRequest}">
<html>
<head>
	<title>forms | mvc-showcase</title>
	<link href="<c:url value="/resources/form.css" />" rel="stylesheet"  type="text/css" />		
	<script type="text/javascript" src="<c:url value="/resources/jquery/1.6/jquery.js" />"></script>
</head>
<body>
</c:if>
	<div id="formsContent">
		<h2>Forms</h2>
		<p>
			See the <code>org.springframework.samples.mvc.form</code> package for the @Controller code	
		</p>
		<form:form id="form" method="post" modelAttribute="formBean" cssClass="cleanform">
			<div class="header">
		  		<h2>Form</h2>
		  		<c:if test="${not empty message}">
					<div id="message" class="success">${message}</div>	
		  		</c:if>
		  		<s:bind path="*">
		  			<c:if test="${status.error}">
				  		<div id="message" class="error">Form has errors</div>
		  			</c:if>
		  		</s:bind>
			</div>
		  	<fieldset>
		  		<legend>Personal Info</legend>
		  		<form:label path="name">
		  			Name <form:errors path="name" cssClass="error" />
		 		</form:label>
		  		<form:input path="name" />
	
		  		<form:label path="age">
		  			Age <form:errors path="age" cssClass="error" />
		 		</form:label>
		  		<form:input path="age" />
		  		
		  		<form:label path="birthDate">
		  			Birth Date (in form yyyy-mm-dd) <form:errors path="birthDate" cssClass="error" />
		 		</form:label>
		  		<form:input path="birthDate" />
		  		 
		  		<form:label path="phone">
		  			Phone (in form (###) ###-####) <form:errors path="phone" cssClass="error" />
		  		</form:label>
		  		<form:input path="phone" />
	
		  		<form:label path="currency">
		  			Currency (in form $#.##) <form:errors path="currency" cssClass="error" />
		  		</form:label>
		  		<form:input path="currency" />
	
		  		<form:label path="percent">
		  			Percentage (in form ##%) <form:errors path="percent" cssClass="error" />
		  		</form:label>
		  		<form:input path="percent" />
	
		  	</fieldset>
	
			<fieldset>
				<legend>Inquiry</legend>
				<form:label path="inquiry">
					Type (select one)
				</form:label>
				<form:select path="inquiry">
					<form:option value="comment">Comment</form:option>
					<form:option value="feedback">Feedback</form:option>
					<form:option value="suggestion">Suggestion</form:option>
				</form:select>
				
		  		<form:label path="inquiryDetails">
		  			Details
		  		</form:label>
		  		<form:textarea path="inquiryDetails" />
		  	</fieldset>
	
			<fieldset class="checkbox">
				<legend>Request Additional Info</legend>
				<label><form:checkbox path="additionalInfo[mvc]" value="true" />on Spring MVC</label>
				<label><form:checkbox path="additionalInfo[java]" value="true" />on Java (4-ever)</label>				
			</fieldset>
		  		  	
			<fieldset class="radio">
				<legend>Subscribe to Newsletter?</legend>
				<label><form:radiobutton path="subscribeNewsletter" value="true" />Yes</label>
				<label><form:radiobutton path="subscribeNewsletter" value="false" /> No</label>
			</fieldset>
	
			<p><button type="submit">Submit</button></p>
		</form:form>
		<script type="text/javascript">
			$(document).ready(function() {
				$("#form").submit(function() {  
					$.post($(this).attr("action"), $(this).serialize(), function(html) {
						$("#formsContent").replaceWith(html);
						$('html, body').animate({ scrollTop: $("#message").offset().top }, 500);
					});
					return false;  
				});			
			});
		</script>
	</div>
<c:if test="${!ajaxRequest}">
</body>
</html>
</c:if>

基于Spring MVC的Web应用开发(10) - Views --Form

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