java - 在 FormBean 中设置属性之前如何抛出异常或设置 ActionError

Question

我有以下 formbean:

public class EmployeeForm extends org.apache.struts.action.ActionForm {

private int empid,age;

public int getEmpid() {
    return empid;
}

public void setEmpid(int empid) {
    this.empid = empid;
}

public int getAge() {
    return age;
}

public void setAge(int age) {
    if(age>20)
    this.age = age;

}

public String getEmpname() {
    return empname;
}

public void setEmpname(String empname) {
    this.empname = empname;
}

public String getPosition() {
    return position;
}

public void setPosition(String position) {
    this.position = position;
}
private String empname,position;

public EmployeeForm() {
    super();
    // TODO Auto-generated constructor stub
}

/**
 * This is the action called from the Struts framework.
 *
 * @param mapping The ActionMapping used to select this instance.
 * @param request The HTTP Request we are processing.
 * @return
 */
public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {
    ActionErrors errors = new ActionErrors();
    if (getEmpname() == null || getEmpname().length() < 1) {
        errors.add("name", new ActionMessage("error.name.required"));
        // TODO: add 'error.name.required' key to your resources
    }
    return errors;
}
}

现在，我想在用户输入小于 20 岁的年龄时显示错误。怎么做？ bean 本身是否有可能抛出错误？

以下是指向 ActionObject 的 View :

<html:errors/>
    <html:form action="EmployeeAction" >

        <table>
            <tr><td>Enter employee Id</td>
                <td><html:text name="EmployeeForm" property="empid" /></td>
            </tr>

            <tr><td>Enter employee Name</td>
                <td><html:text name="EmployeeForm" property="empname" /></td>
            </tr>
            <tr><td>Enter employee Age</td>
                <td><html:text name="EmployeeForm" property="age" /></td>
            </tr>
            <tr><td>Enter employee position</td>
                <td><html:text name="EmployeeForm" property="position" /></td>
            </tr>


            <tr><td align="right"><html:submit value="Add" property="method" /></td>
                <td> <html:submit property="method" value="Delete" />

            <html:submit property="method">Update</html:submit></td>
        </tr>


            </table>
    </html:form>

Answer 1

定义获取消息资源的辅助方法

public static MessageResources getResources(HttpServletRequest request) {
  return ((MessageResources) request.getAttribute(Globals.MESSAGES_KEY));
}

然后使用资源

public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {
  try {
    MessageResources resources = getResources(request);
    ActionErrors errors = super.validate(mapping, request);
    if (getEmpname() == null || getEmpname().length() < 1) {
        errors.add("name", new ActionMessage("error.name.required"));
        throw new Exception(getResources(request).getMessage("error.name.required"));
    }
    return errors;
  } catch (Exception ex) {
    request.setAttribute(Globals.EXCEPTION_KEY, ex);
    return null;
  }
}

检查请求处理器中的异常键

// Check out if exception occurred
Exception exception = (Exception)request.getAttribute(Globals.EXCEPTION_KEY);
if (exception != null){
  ActionForward forward = processException(request, response, exception, form, mapping);
  processForwardConfig(request, response, forward);
  return;
}