Spring中的数据绑定

下面是一个SimpleFormController的实例，虽然有些地方显得吹毛求疵，但主要是为了表达一个完整的流程。

首先先看配置文件，web.xml就不说了，下面的是/WEB-INF/mvc-config.xml:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"     "http://www.springframework.org/dtd/spring-beans.dtd"> <beans>  <!--InternalResourceViewResolver-->  <bean id="viewResolver"   class="org.springframework.web.servlet.view.InternalResourceViewResolver">   <property name="prefix">    <value>/WEB-INF/jsp/</value>   </property>   <property name="suffix">    <value>.jsp</value>   </property>  </bean>    <!--SimpleUrlHandlerMapping-->  <bean id="urlHandlerMapping"   class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">   <property name="mappings">    <props>       <prop key="/user.htm">userController</prop>    </props>   </property>  </bean> </beans>

然后是/WEB-INF/controller-config.xml:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"     "http://www.springframework.org/dtd/spring-beans.dtd"> <beans>     <bean id="userValidator" class="com.yangsq.validator.UserValidator"/>    <bean id="userController"   class="com.yangsq.controller.UserController">   <property name="commandName">    <value>command</value>   </property>   <property name="commandClass">    <value>com.yangsq.domain.User</value>   </property>   <property name="validator">    <ref bean="userValidator" />   </property>   <property name="formView">    <value>user</value>   </property>   <property name="successView">    <value>hello</value>   </property>  </bean> </beans>

   这里需要对上面的配置文件进行说明。commandName属性的设置是为了可以在页面中使用Spring tag，对业务流程没有影响，如果不想使用Spring tag，则这个属性可以没有。commandClass指定了封装表单的类，注意，要指定完整的路径，不能只指定一个类名，也不能<ref .../>。validator的设定说明了要使用验证器。formView和successView这两个属性设定了转向的页面，它们是父类所具有的，所以不需要在你的controller中再注入了。

   下面是验证器：

import org.springframework.validation.Errors; import org.springframework.validation.Validator; import com.yangsq.domain.User; public class UserValidator implements Validator{    public boolean supports(Class clazz) {      return clazz.equals(User.class);  }    public void validate(Object obj, Errors err) {      User user = (User) obj;      if (user.getPhone().length() < 7) {       user.setCreateTime(null);       err.reject("phoneErr", "电话号码位数要大于7");      }else if (user.getAge() <= 0) {       user.setCreateTime(null);       err.reject("ageErr", "年龄要大于0");      }  } }

验证器实现了Validator借口，supports和validate这两个方法是必须实现的。验证器的主要任务是对表单类进行验证，这时请求的数据已经封装到表单类里了。

  下面是表单类:

public class User {  private String account;  private String phone;  private int age;  private String city;  private Date createTime;    public String getAccount() {   return account;  }  public void setAccount(String account) {   this.account = account;  }  public int getAge() {   return age;  }  public void setAge(int age) {   this.age = age;  }  public String getPhone() {   return phone;  }  public void setPhone(String phone) {   this.phone = phone;  }  public Date getCreateTime() {   return createTime;  }  public void setCreateTime(Date createTime) {   this.createTime = createTime;  }  public String getCity() {   return city;  }  public void setCity(String city) {   this.city = city;  } }

属性包括用户名称，电话，年龄，城市和创建日期。此外，为了表达一个完成的演示，还创建了一个city类：

public class City {  private String cityName;  private String cityNo;  public String getCityName() {   return cityName;  }  public void setCityName(String cityName) {   this.cityName = cityName;  }  public String getCityNo() {   return cityNo;  }  public void setCityNo(String cityNo) {   this.cityNo = cityNo;  } }

下面就是这个例子的主角，UserController：

public class UserController extends SimpleFormController {    protected Map referenceData(HttpServletRequest req) throws Exception {   Map map = new HashMap();      List cityList = new ArrayList();   City city1 = new City();   city1.setCityName("BeiJing");   city1.setCityNo("010");   cityList.add(city1);   City city2 = new City();   city2.setCityName("ShangHai");   city2.setCityNo("020");   cityList.add(city2);      map.put("cityList", cityList);   return map;  }  protected void onBind(HttpServletRequest req, Object obj) throws Exception {   User user = (User) obj;   //format the infor      user.setAccount(user.getAccount().trim());      user.setPhone(user.getPhone().trim());  }  protected void onBindAndValidate(HttpServletRequest req, Object obj, BindException err) throws Exception {   User user = (User) obj;   user.setCreateTime(new Date());  }  protected ModelAndView onSubmit(Object obj) throws Exception {   User user = (User) obj;   return new ModelAndView(this.getSuccessView(), "user", user);  } }

下面是使用到的页面 user.jsp的主要部分（表单）：

<FORM action="user.htm" method="post">  <TABLE>   <TBODY>    <TR>     <TD>      <spring:bind path="command.account">       用户名：<INPUT name="${status.expression}" type="text" value="${status.value}"/>      </spring:bind>     </TD>    </TR>    <TR>     <TD>      <spring:bind path="command.age">       年龄：<INPUT name="${status.expression}" type="text" value="${status.value}"/>      </spring:bind>     </TD>    </TR>    <TR>     <TD>      <spring:bind path="command.phone">       电话号码：<INPUT name="${status.expression}" type="text"  value="${status.value}"/>      </spring:bind>     </TD>    </TR>    <TR>     <TD>      <spring:bind path="command.city">       城市：       <SELECT name="${status.expression}">        <c:forEach items="${cityList}" var="city" varStatus="loopStep">         <OPTION value="${city.cityNo}" <c:if test="${city.cityNo == status.value}">selected</c:if>>          <c:out value="${city.cityName}"/>         </OPTION>        </c:forEach>       </SELECT>      </spring:bind>     </TD>    </TR>    <TR>     <TD>      <spring:bind path="command.*">       <c:out value="${status.errorMessage}"/>      </spring:bind>     </TD>    </TR>    <TR>     <TD align="center">      <INPUT type="submit" value="提交" />     </TD>    </TR>   </TBODY>  </TABLE> </FORM>

hello.jsp的主要部分：

<TABLE>     <TBODY>      <TR>       <TD>        User infor:       </TD>      </TR>      <TR>       <TD>        <c:out value="${user.account}" />       </TD>      </TR>      <TR>       <TD>        <c:out value="${user.age}" />       </TD>      </TR>      <TR>       <TD>        <c:out value="${user.phone}" />       </TD>      </TR>      <TR>       <TD>        <c:out value="${user.city}" />       </TD>      </TR>      <TR>       <TD>        <c:out value="${user.createTime}" />       </TD>      </TR>     </TBODY>  </TABLE>