Spring3 MVC的最佳实践和理解（7）
个人学习参考所用，勿喷！
7.表单处理和多页表单向导
7.1）表单处理。
表单处理很常见。比如我们有下面的表单：
<form:form method="post" modelAttribute="reservation">
<form:errors path="*" cssClass="error" />
<table>
<tr>
<td>Court Name</td>
<td><form:input path="courtName" /></td>
<td><form:errors path="courtName" cssClass="error" /></td>
</tr>
<tr>
<td>Date</td>
<td><form:input path="date" /></td>
<td><form:errors path="date" cssClass="error" /></td>
</tr>
<tr>
<td>Hour</td>
<td><form:input path="hour" /></td>
<td><form:errors path="hour" cssClass="error" /></td>
</tr>
<tr>
<td>Player Name</td>
<td><form:input path="player.name" /></td>
<td><form:errors path="player.name" cssClass="error" /></td>
</tr>
<tr>
<td>Player Phone</td>
<td><form:input path="player.phone" /></td>
<td><form:errors path="player.phone" cssClass="error" /></td>
</tr>
<tr>
<td colspan="3"><input type="submit" /></td>
</tr>
</table>
</form:form>
这里使用的是spring的标签,HTML中需要<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>。 很多属性一看就知道含义。需要注意的是，modelAttribute属，这里联想下Struts2中的值栈就能够明白这里代表的是处理的返回结果。
编写后台的控制器类：
@Controller
// Bind controller to URL /reservationForm
// initial view will be resolved to the name returned in the default GET method
@RequestMapping("/reservationForm")
// Add Reservation object to session, since its created on setup and used after submission
@SessionAttributes("reservation") // Command name class was used in earlier Spring versions
public class ReservationFormController {
private ReservationService reservationService;
// Wire service in constructor, available in application context
@Autowired
public ReservationFormController(ReservationService reservationService) {
this.reservationService = reservationService;
}
// Create attribute for model
// Will be represented as drop box Sport Types in reservationForm
@ModelAttribute("sportTypes")
public List<SportType> populateSportTypes() {
return reservationService.getAllSportTypes();
}
// Controller will always look for a default GET method to call first, irrespective of name
// In this case, named setupForm to ease identification
@RequestMapping(method = RequestMethod.GET)
public String setupForm( @RequestParam(required = false, value = "username") String username,
Model model) {
Reservation reservation = new Reservation();
reservation.setPlayer(new Player(username, null));
model.addAttribute("reservation", reservation);
return "reservationForm";
}
// Controller will always look for a default POST method irrespective of name
// when a submission ocurrs on the URL (i.e.@RequestMapping(/reservationForm))
// In this case, named submitForm to ease identification
@RequestMapping(method = RequestMethod.POST)
// Model reservation object, BindingResult and SessionStatus as parameters
public String submitForm(@ModelAttribute("reservation") Reservation reservation,
BindingResult result, SessionStatus status) {
reservationService.make(reservation);
return "redirect:reservationSuccess";
}
}
需要注意的是@SessionAttributes("reservation")注解和submitForm(...)方法的返回值方式return "redirect:reservationSuccess"。
@SessionAttributes是的reservation对象唯一的存在于用户会话中，目的是为了保持用户每次提交的数据（用户提交可能会出错，所以不是一次提交就一定能够成功）。
"redirect:reservationSuccess"逻辑视图表明重定向到reservationSuccess逻辑视图，应用中设定是返回reservationSuccess.jsp，这样做的目的是为了防止提交成功后的刷新造成再次提交。这里应用了post/redirect/get设计模式来处理这个问题。
提供表单参考数据。例如这里的体育类型查考选择框：
<tr>
<td>Sport Type</td>
<td>
<form:select path="sportType" items="${sportTypes}"
itemValue="id" itemLabel="name" />
</td>
<td><form:errors path="sportType" cssClass="error" /></td>
</tr>
这里需要在控制器中添加一个@ModelAttribute("sportTypes") 标识的模式属性sportTypes（@ModelAttribute用于定义全局模式属性），在前面的submitForm(...)中也有@ModelAttribute("reservation") 用于应用session中的reservation对象。
@ModelAttribute("sportTypes")
public List<SportType> populateSportTypes() {
return reservationService.getAllSportTypes();
}
绑定自定义类型的属性。上述的SportType属性提交到处理程序是一个String id = "1" 的字符串类型，我们需要的是String sportType= "棒球" 这样字段。那么这里需要如同Struts2中的转换器相同功能的实现方式：
public class SportTypeEditor extends PropertyEditorSupport {
private ReservationService reservationService;
public SportTypeEditor(ReservationService reservationService) {
this.reservationService = reservationService;
}
public void setAsText(String text) throws IllegalArgumentException {
int sportTypeId = Integer.parseInt(text);
SportType sportType = reservationService.getSportType(sportTypeId);
setValue(sportType);
}
}
有了这个转换实现类，我们现在需要将其对应的控制器类联系起来，这里需要编写自己的WebBindingInitializer实现：
public class ReservationBindingInitializer implements WebBindingInitializer {
private ReservationService reservationService;
@Autowired
public ReservationBindingInitializer(ReservationService reservationService) {
this.reservationService = reservationService;
}
public void initBinder(WebDataBinder binder, WebRequest request) {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
dateFormat.setLenient(false);
binder.registerCustomEditor(Date.class, new CustomDateEditor(
dateFormat, true));
binder.registerCustomEditor(SportType.class, new SportTypeEditor(
reservationService));
}
}
还需要在应用上下文中进行配置注册：
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="webBindingInitializer"> <bean class="com.apress.springrecipes.court.web.ReservationBindingInitializer" /> </property> </bean>
表单的校验。表单成功提交前的校验在服务器端也需要做不仅是标准的做法，尤其在请求来自不支持JavaScript的wap终端时。这里可以编写如下的检验类：
@Component
public class ReservationValidator implements Validator {
public boolean supports(Class<?> clazz) {
return Reservation.class.isAssignableFrom(clazz);
}
public void validate(Object target, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "courtName",
"required.courtName", "Court name is required.");
ValidationUtils.rejectIfEmpty(errors, "date",
"required.date", "Date is required.");
ValidationUtils.rejectIfEmpty(errors, "hour",
"required.hour", "Hour is required.");
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "player.name",
"required.playerName", "Player name is required.");
ValidationUtils.rejectIfEmpty(errors, "sportType",
"required.sportType", "Sport type is required.");
Reservation reservation = (Reservation) target;
Date date = reservation.getDate();
int hour = reservation.getHour();
if (date != null) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
if (calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
if (hour < 8 || hour > 22) {
errors.reject("invalid.holidayHour", "Invalid holiday hour.");
}
} else {
if (hour < 9 || hour > 21) {
errors.reject("invalid.weekdayHour", "Invalid weekday hour.");
}
}
}
}
}
@Component注解告诉Spring实例化该类为与类名一样的Bean，这里为reservationValidator。这里需要像激活@Controller一样的激活改类所在的包。
然后在ReservationFormController控制器中添加添加使用刚刚定义的校验器：
@Controller
@RequestMapping("/reservationForm")
@SessionAttributes("reservation")
public class ReservationFormController {
private ReservationService reservationService;
private ReservationValidator validator;
@Autowired
public ReservationFormController(ReservationService reservationService,
ReservationValidator validator) {
this.reservationService = reservationService;
this.validator = validator;
}
@ModelAttribute("sportTypes")
public List<SportType> populateSportTypes() {
return reservationService.getAllSportTypes();
}
@RequestMapping(method = RequestMethod.GET)
public String setupForm(Model model) {
Reservation reservation = new Reservation();
reservation.setPlayer(new Player(username, null));
model.addAttribute("reservation", reservation);
return "reservationForm";
}
@RequestMapping(method = RequestMethod.POST)
public String submitForm(@ModelAttribute("reservation") Reservation reservation,
BindingResult result, SessionStatus status) {
validator.validate(reservation, result);
if (result.hasErrors()) {
return "reservationForm";
} else {
reservationService.make(reservation);
status.setComplete();
return "redirect:/reservationSuccess";
}
}
}
这里通过ReservationValidator的校验，如果有错误则返回错提示。一旦校验成功，完成提交后，需要通过status.setComplete()来释放@SessionAttributes("reservation")中的reservation对象，以此来处理到期的控制器的回话数据。
7.2）向导表单。
处理跨越多页的向导表单（Wizard forms），需要为向导控制器定义多个视图，一个控制器管理所有这些表单数据的状态。现在需要使用向导表单来完成预订球场功能，请求domain代码如下：
public class PeriodicReservation {
private String courtName;
private Date fromDate;
private Date toDate;
private int period;
private int hour;
private Player player;
//getter an setter
...
}
表单向导页依次分为如下三页：
reservationPlayerForm.jsp
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
<html>
<head>
<title>Reservation Court Form</title>
<style>
.error {
color: #ff0000;
font-weight: bold;
}
</style>
</head>
<body>
<form:form method="post" modelAttribute="reservation">
<table>
<tr>
<td>Court Name</td>
<td><form:input path="courtName" /></td>
<td><form:errors path="courtName" cssClass="error" /></td>
</tr>
<tr>
<td colspan="3">
<input type="hidden" value="0" name="_page"/>
<input type="submit" value="Next" name="_target1" />
<input type="submit" value="Cancel" name="_cancel" />
</td>
</tr>
</table>
</form:form>
</body>
</html>
reservationTimeForm.jsp
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
<html>
<head>
<title>Reservation Time Form</title>
<style>
.error {
color: #ff0000;
font-weight: bold;
}
</style>
</head>
<body>
<form:form method="post" modelAttribute="reservation">
<table>
<tr>
<td>From Date</td>
<td><form:input path="fromDate" /></td>
<td><form:errors path="fromDate" cssClass="error" /></td>
</tr>
<tr>
<td>To Date</td>
<td><form:input path="toDate" /></td>
<td><form:errors path="toDate" cssClass="error" /></td>
</tr>
<tr>
<td>Period</td>
<td><form:select path="period" items="${periods}" /></td>
<td><form:errors path="period" cssClass="error" /></td>
</tr>
<tr>
<td>Hour</td>
<td><form:input path="hour" /></td>
<td><form:errors path="hour" cssClass="error" /></td>
</tr>
<tr>
<td colspan="3">
<input type="hidden" value="1" name="_page"/>
<input type="submit" value="Previous" name="_target0" />
<input type="submit" value="Next" name="_target2" />
<input type="submit" value="Cancel" name="_cancel" />
</td>
</tr>
</table>
</form:form>
</body>
</html>
reservationPlayerForm.jsp
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!-- 添加页面编码设置来解决编码问题 -->
<%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
<html>
<head>
<title>Reservation Player Form</title>
<style>
.error {
color: #ff0000;
font-weight: bold;
}
</style>
</head>
<body>
<form:form method="post" modelAttribute="reservation">
<table>
<tr>
<td>Player Name</td>
<td><form:input path="player.name" /></td>
<td><form:errors path="player.name" cssClass="error" /></td>
</tr>
<tr>
<td>Player Phone</td>
<td><form:input path="player.phone" /></td>
<td><form:errors path="player.phone" cssClass="error" /></td>
</tr>
<tr>
<td colspan="3">
<input type="hidden" value="2" name="_page"/>
<input type="submit" value="Previous" name="_target1" />
<input type="submit" value="Finish" name="_finish" />
<input type="submit" value="Cancel" name="_cancel" />
</td>
</tr>
</table>
</form:form>
</body>
</html>
上面三个视图中包含了pre、next、submit和cancel按钮。控制器代码如下：
@Controller
@RequestMapping("/periodicReservationForm")
@SessionAttributes("reservation")
public class PeriodicReservationController {
private ReservationService reservationService;
@SuppressWarnings("unused")
private PeriodicReservationValidator validator;
@Autowired
public PeriodicReservationController(ReservationService reservationService,
PeriodicReservationValidator periodicReservationValidator) {
this.reservationService = reservationService;
this.validator = periodicReservationValidator;
}
@RequestMapping(method = RequestMethod.GET)
public String setupForm(Model model) {
PeriodicReservation reservation = new PeriodicReservation();
reservation.setPlayer(new Player());
model.addAttribute("reservation", reservation);
return "reservationCourtForm";
}
@SuppressWarnings({ "rawtypes", "unchecked" })
@RequestMapping(method = RequestMethod.POST)
public String submitForm(
HttpServletRequest request, HttpServletResponse response,
@ModelAttribute("reservation") PeriodicReservation reservation,
BindingResult result, SessionStatus status,
@RequestParam("_page") int currentPage, Model model) {
Map pageForms = new HashMap();
pageForms.put(0,"reservationCourtForm");// Mapped to /WEB-INF/jsp/reservationCourtForm.jsp
pageForms.put(1,"reservationTimeForm");// Mapped to /WEB-INF/jsp/reservationTimeForm.jsp
pageForms.put(2,"reservationPlayerForm");// Mapped to /WEB-INF/jsp/reservationPlayerForm.jsp
if (request.getParameter("_cancel") != null) {
return (String)pageForms.get(currentPage);
} else if (request.getParameter("_finish") != null) {
new PeriodicReservationValidator().validate(reservation, result);
if (!result.hasErrors()) {
reservationService.makePeriodic(reservation);
status.setComplete();
return "redirect:reservationSuccess";
} else {
return (String)pageForms.get(currentPage);
}
} else {
int targetPage = WebUtils.getTargetPage(request, "_target", currentPage);
if (targetPage < currentPage) {
return (String)pageForms.get(targetPage);
}
switch (currentPage) {
case 0:
new PeriodicReservationValidator().validateCourt(reservation, result); break;
case 1:
new PeriodicReservationValidator().validateTime(reservation, result); break;
case 2:
new PeriodicReservationValidator().validatePlayer(reservation, result); break;
}
if (!result.hasErrors()) {
return (String)pageForms.get(targetPage);
} else {
return (String)pageForms.get(currentPage);
}
}
}
@ModelAttribute("periods")
public Map<Integer, String> periods() {
Map<Integer, String> periods = new HashMap<Integer, String>();
periods.put(1, "Daily");
periods.put(7, "Weekly");
return periods;
}
}
这里还是用HTTP GET方法来初始化空表单，用一个HTTP POST处理方法来处理前进、后退、提交和退出等事件。不同页面中的数据都用@SessionAttributes("reservation")的唯一的会话对象中。在这里还添加对数据的校验功能，而且需要特别注意上面对每次next步骤中的数据校验，可以看到校验器代码如下：
@Component
public class PeriodicReservationValidator implements Validator {
public boolean supports(Class<?> clazz) {
return PeriodicReservation.class.isAssignableFrom(clazz);
}
public void validate(Object target, Errors errors) {
validateCourt(target, errors);
validateTime(target, errors);
validatePlayer(target, errors);
}
public void validateCourt(Object target, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "courtName",
"required.courtName", "Court name is required.");
}
public void validateTime(Object target, Errors errors) {
ValidationUtils.rejectIfEmpty(errors, "fromDate",
"required.fromDate", "From date is required.");
ValidationUtils.rejectIfEmpty(errors, "toDate", "required.toDate",
"To date is required.");
ValidationUtils.rejectIfEmpty(errors, "period",
"required.period", "Period is required.");
ValidationUtils.rejectIfEmpty(errors, "hour", "required.hour",
"Hour is required.");
}
public void validatePlayer(Object target, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "player.name",
"required.playerName", "Player name is required.");
}
}
这种更加细粒度的校验实现对分页表单相当来说是最好的检验方式。
参考：
juyon的blog:《spring3 MVC国际化支持之中文乱码》
Gary Mark等的书籍：《Spring Recipes》2ed