JSP & JSTL

View resolvers

InternalResourceViewResolver and the ResourceBundleViewResolver常用来解析视图，在web应用上下文里定义

<!-- the ResourceBundleViewResolver -->

<bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">

<property name="basename" value="views"/>

</bean>

# And a sample properties file is uses (views.properties in WEB-INF/classes):

welcome.(class)=org.springframework.web.servlet.view.JstlView

welcome.url=/WEB-INF/jsp/welcome.jsp

productList.(class)=org.springframework.web.servlet.view.JstlView

productList.url=/WEB-INF/jsp/productlist.jsp

ResourceBundleViewResolver需要properties文件定义view名字映射的class,url; ResourceBundleViewResolver可以使用不同类型视图只用同一个Resovler

<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">

<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>

<property name="prefix" value="/WEB-INF/jsp/"/>

<property name="suffix" value=".jsp"/>

</bean>

InternalResourceBundleViewResolver可以用来解析jsps，最好是使用带目录的/WEB-INF/jsp/指定，避免直接访问

Plain-old JSPs versus JSTL

TLD在常用的jar中用来获取绑定的数据

Using Spring’s form tag library

和其他的form和input标签不同，spring form tag是spring web mvc 完整提供的,访问命令对象和控制器处理的数据，使得jsps更方便

Configuration

The form tag library comes bundled in spring-webmvc.jar. The library descriptor is called spring-form.tld.

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>

The form tag

<form:form>

<table>

<tr>

<td>First Name:</td>

<td><form:input path="firstName" /></td>

</tr>

<tr>

<td>Last Name:</td>

<td><form:input path="lastName" /></td>

</tr>

<tr>

<td colspan="2">

<input type="submit" value="Save Changes" />

</td>

</tr>

</table>

</form:form>

firstName和lastName的值是由PageContext中的命令对象提供的

<form method="POST">

<table>

<tr>

<td>First Name:</td>

<td><input name="firstName" type="text" value="Harry"/></td>

</tr>

<tr>

<td>Last Name:</td>

<td><input name="lastName" type="text" value="Potter"/></td>

</tr>

<tr>

<td colspan="2">

<input type="submit" value="Save Changes" />

</td>

</tr>

</table>

</form>

其中form的变量名是返回对象的命令，如果要将form返回对象放入model在另一个名字下，你可以如下绑定名字

<form:form commandName="user">

<table>

<tr>

<td>First Name:</td>

<td><form:input path="firstName" /></td>

</tr>

<tr>

<td>Last Name:</td>

<td><form:input path="lastName" /></td>

</tr>

<tr>

<td colspan="2">

<input type="submit" value="Save Changes" />

</td>

</tr>

</table>

</form:form>

The input tag

The checkbox tag

将input tag 的 type =checkbox

Eg:user preferences类

public class Preferences {

private boolean receiveNewsletter;

private String[] interests;

private String favouriteWord;

public boolean isReceiveNewsletter() {

return receiveNewsletter;

}

public void setReceiveNewsletter(boolean receiveNewsletter) {

this.receiveNewsletter = receiveNewsletter;

}

public String[] getInterests() {

return interests;

}

public void setInterests(String[] interests) {

this.interests = interests;

}

public String getFavouriteWord() {

return favouriteWord;

}

public void setFavouriteWord(String favouriteWord) {

this.favouriteWord = favouriteWord;

}

}

Form.jsp  like:

<form:form>

<table>

<tr>

<td>Subscribe to newsletter?:</td>

<%-- Approach 1: Property is of type java.lang.Boolean --%>

<td><form:checkbox path="preferences.receiveNewsletter"/></td>

</tr>

<tr>

<td>Interests:</td>

<%-- Approach 2: Property is of an array or of type java.util.Collection --%>

<td>

Quidditch: <form:checkbox path="preferences.interests" value="Quidditch"/>

Herbology: <form:checkbox path="preferences.interests" value="Herbology"/>

Defence Against the Dark Arts: <form:checkbox path="preferences.interests" value="Defence Against the Dark Arts"/>

</td>

</tr>

<tr>

<td>Favourite Word:</td>

<%-- Approach 3: Property is of type java.lang.Object --%>

<td>

Magic: <form:checkbox path="preferences.favouriteWord" value="Magic"/>

</td>

</tr>

</table>

</form:form>

There are 3 approaches to the checkbox tag which should meet all your checkbox needs.

· Approach One - When the bound value is of type java.lang.Boolean, the input(checkbox) is marked as checked if the bound value is true. The value attribute corresponds to the resolved value of the setValue(Object) value property.

· Approach Two - When the bound value is of type array or java.util.Collection, the input(checkbox) is marked as checked if the configured setValue(Object) value is present in the bound Collection.

· Approach Three - For any other bound value type, the input(checkbox) is marked as checked if the configured setValue(Object) is equal to the bound value.

· <tr>

·     <td>Interests:</td>

·     <td>

·         Quidditch: <input name="preferences.interests" type="checkbox" value="Quidditch"/>

·         <input type="hidden" value="1" name="_preferences.interests"/>

·         Herbology: <input name="preferences.interests" type="checkbox" value="Herbology"/>

·         <input type="hidden" value="1" name="_preferences.interests"/>

·         Defence Against the Dark Arts: <input name="preferences.interests" type="checkbox" value="Defence Against the Dark Arts"/>

·         <input type="hidden" value="1" name="_preferences.interests"/>

·     </td>

· </tr>

· What you might not expect to see is the additional hidden field after each checkbox. When a checkbox in an HTML page is not checked, its value will not be sent to the server as part of the HTTP request parameters once the form is submitted, so we need a workaround for this quirk in HTML in order for Spring form data binding to work. The checkbox tag follows the existing Spring convention of including a hidden parameter prefixed by an underscore ("_") for each checkbox. By doing this, you are effectively telling Spring that "the checkbox was visible in the form and I want my object to which the form data will be bound to reflect the state of the checkbox no matter what".

The checkboxes tag

不会全显示，只有在运行时返回值在集合中array,list,map

<form:form>

<table>

<tr>

<td>Interests:</td>

<td>

<%-- Property is of an array or of type java.util.Collection --%>

<form:checkboxes path="preferences.interests" items="${interestList}"/>

</td>

</tr>

</table>

</form:form>

The radiobutton tag

<tr>

<td>Sex:</td>

<td>

Male: <form:radiobutton path="sex" value="M"/> <br/>

Female: <form:radiobutton path="sex" value="F"/>

</td>

</tr>

The radiobuttons tag

运行时显示，In the case where you use a Map, the map entry key will be used as the value and the map entry’s value will be used as the label to be displayed.

<tr>

<td>Sex:</td>

<td><form:radiobuttons path="sex" items="${sexOptions}"/></td>

</tr>

The select tag

The option tag

The options tag

The textarea tag

The hidden tag

The errors tag

public class UserValidator implements Validator {

public boolean supports(Class candidate) {

return User.class.isAssignableFrom(candidate);

}

public void validate(Object obj, Errors errors) {

ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", "required", "Field is required.");

ValidationUtils.rejectIfEmptyOrWhitespace(errors, "lastName", "required", "Field is required.");

}

}

The form.jsp would look like:

<form:form>

<table>

<tr>

<td>First Name:</td>

<td><form:input path="firstName" /></td>

<%-- Show errors for firstName field --%>

<td><form:errors path="firstName" /></td>

</tr>

<tr>

<td>Last Name:</td>

<td><form:input path="lastName" /></td>

<%-- Show errors for lastName field --%>

<td><form:errors path="lastName" /></td>

</tr>

<tr>

<td colspan="3">

<input type="submit" value="Save Changes" />

</td>

</tr>

</table>

</form:form>

· path="*" - displays all errors

· path="lastName" - displays all errors associated with the lastName field

· if path is omitted - object errors only are displayed

显示一系列错误在网页的上面，显示具体的错误在field旁边

<form:form>

<form:errors path="*" cssClass="errorBox" />

<table>

<tr>

<td>First Name:</td>

<td><form:input path="firstName" /></td>

<td><form:errors path="firstName" /></td>

</tr>

<tr>

<td>Last Name:</td>

<td><form:input path="lastName" /></td>

<td><form:errors path="lastName" /></td>

</tr>

<tr>

<td colspan="3">

<input type="submit" value="Save Changes" />

</td>

</tr>

</table>

</form:form>

HTTP Method Conversion http方法转变

Rest的重要原则是使用统一接口，意味着所有的资源都能被这四种方法操作（get,put,post,delete）,对于每一个方法，http规格定义了明确的语义，例如，get必须是安全的操作，没有其他影响，,PUT和delete行为是idempotent，你可以一次又一次重复这些操作，但最终结果是一样的，http定义这四种方式时，html只支持两种，get和post.幸运的是有两种变通方案：你可以用javascript使用put和delete,后者简单使用post方法作为参数（在html form中作为隐藏区），之后这是Spring’s HiddenHttpMethodFilter做的，是基本的servlet过滤器，可以和任何web framework工作，简单将filter加入web.xml,隐藏参数的方法将被转换为相关的http方法请求

<form:form method="delete">

<p><input type="submit" value="Delete Pet"/></p>

</form:form>

是一个http post,实际是一个delete方法隐藏在一个请求参数中，将会被HiddenHttpMethodFilter：

<filter>

<filter-name>httpMethodFilter</filter-name>

<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>httpMethodFilter</filter-name>

<servlet-name>petclinic</servlet-name>

</filter-mapping>

相应的@C otroller方法如下

@RequestMapping(method = RequestMethod.DELETE)

public String deletePet(@PathVariable int ownerId, @PathVariable int petId) {

this.clinic.deletePet(petId);

return "redirect:/owners/" + ownerId;

}

HTML5 Tags

Velocity & FreeMarker

ur web application will need to include velocity-1.x.x.jar or freemarker-2.x.jar