Struts开发指南之工作流程

2016-02-19 13:11 2 1 收藏

下面图老师小编跟大家分享Struts开发指南之工作流程,一起来学习下过程究竟如何进行吧!喜欢就赶紧收藏起来哦~

【 tulaoshi.com - 编程语言 】

下图是Struts的工作流程,前边我们提到,所有的请求都提交给ActionServlet来处理。
  
  Struts开发指南之工作流程
点击查看大图

  
  ActionServlet是一个FrontController,它是一个标准的Servlet,它将request转发给RequestProcessor来处理,
  
  ActionMapping是ActionConfig的子类,实质上是对struts-config.XML的一个映射,从中可以取得所有的配置信息
  
  RequestProcessor根据提交过来的url,如*.do,从ActionMapping 中得到相应的ActionForn和Action。然后将request的参数对应到ActionForm中,进行form验证。假如验证通过则调用Action的execute()方法来执行Action,最终返回ActionFoward。
  
  ActionFoward是对mapping中一个foward的包装,对应于一个url
  
  ActionForm使用了ViewHelper模式,是对Html中form的一个封装。其中包含有validate方法,用于验证form数据的有效性。ActionForm是一个符合JavaBean规范的类,所有的属性都应满足get和set对应。对于一些复杂的系统,还可以采用DynaActionForm来构造动态的Form,即通过预制参数来生成Form。这样可以更灵活的扩展程序。
  
  ActionErrors是对错误信息的包装,一旦在执行action或者form.validate中出现异常,即可产生一个ActionError并最终加入到ActionErrors。在Form验证的过程中,假如有Error发生,则会将页面重新导向至输入页,并提示错误。
  
  Action是用于执行业务逻辑的RequsestHandler。每个Action都只建立一个instance。Action不是线程安全的,所以不应该在Action中访问特定资源。一般来说,应改使用 Business Delegate 模式来对Business tier进行访问以解除耦合。
  
  Struts提供了多种Action供选择使用。普通的Action只能通过调用execute执行一项任务,而DispatchAction可以根据配置参数执行,而不是仅进入execute()函数,这样可以执行多种任务。如insert,update等。LookupDispatchAction可以根据提交表单按钮的名称来执行函数。
  
  我们可以先回到刚才的例子,理解一下Struts的流程。
  
  下面我们看Struts自带的example实例:
  
  说明:实例二是Struts自带的example程序, 实现了登录,注册,修改功能。
  
  代码中大量应用了struts taglib,并且采用validator插件进行form的验证。
  
  但是代码树立了一个不好的榜样,即把大量的业务逻辑写在了action中。
  
  部分代码如下:
  
  登录:Logon.jsp
  
  <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  
  // 声明Taglib
  <%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
  <%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
  
  <html:html locale="true">
  <head>
   // bean是用来从ApplicationResource中读取i18n信息
   <title><bean:message key="Logon.title"/></title>
   <html:base/>
  </head>
  <body bgcolor="white">
  
  // 错误信息部分
  <html:errors/>
  
  // 登录form,action为logion.do
  <html:form action="/Logon" focus="username"
  onsubmit="return validateLogonForm(this);">
  <table border="0" width="100%">
  
   <tr>
  <th align="right">
   <bean:message key="prompt.username"/>:
  </th>
  <td align="left">
   <html:text property="username" size="16" maxlength="18"/>
  </td>
   </tr>
  
   <tr>
  <th align="right">
   <bean:message key="prompt.passWord" bundle="alternate"/>:
  </th>
  <td align="left">
   <html:password property="password" size="16" maxlength="18" redisplay="false"/>
  </td>
   </tr>
  
   <tr>
  <td align="right">
   <html:submit value="Submit"/>
  </td>
  <td align="left">
   <html:reset/>
  </td>
   </tr>
  
  </table>
  
  </html:form>
  
  // Validator插件,用于form验证
  <html:javascript formName="LogonForm" dynamicJavascript="true" staticJavascript="false"/>
  <script language="Javascript1.1" src="staticJavascript.jsp"></script>
  
  </body>
  </html:html>
  struts-config.xml配置
  
  <form-beans>
  
  <!-- Logon form bean -->
   <form-bean name="LogonForm" type="org.apache.struts.validator.DynaValidatorForm">
  <form-property name="username" type="java.lang.String"/>
  <form-property name="password" type="java.lang.String"/>
   </form-bean>
  
   <!-- Subscription form bean -->
   <form-bean name="subscriptionForm"type="org.apache.struts.webapp.example.SubscriptionForm"/>
  
   </form-beans>
   <action-mappings>
  
   <!-- Edit mail subscription -->
   <action path="/editSubscription"
  type="org.apache.struts.webapp.example.EditSubscriptionAction"
  attribute="subscriptionForm"
  scope="request"
  validate="false">
  <forward name="failure" path="/mainMenu.jsp"/>
  <forward name="sUCcess" path="/subscription.jsp"/>
   </action>
  ...
  subscriptionForm 是一个标准的ActionForm,其中reset方法用于清除form的值,validate方法用于验证
  
  public final class SubscriptionForm extends ActionForm {
  // The maintenance action we are performing (Create or Edit).
  private String action = "Create";
  // Should we auto-connect at startup time?
  private boolean autoConnect = false;
  // The host name.
  private String host = null;
  private String password = null;
  private String type = null;
  private String username = null;
  
  public String getAction() { return (this.action); }
  public void setAction(String action) { this.action = action; }
  
  public boolean getAutoConnect() { return (this.autoConnect); }
  public void setAutoConnect(boolean autoConnect) { this.autoConnect = autoConnect; }
  
  public String getHost() { return (this.host); }
  public void setHost(String host) { this.host = host; }
  
  public String getPassword() { return (this.password); }
  public void setPassword(String password) { this.password = password; }
  
  public String getType() { return (this.type); }
  public void setType(String type) { this.type = type; }
  
  public String getUsername() { return (this.username); }
  public void setUsername(String username) { this.username = username; }
  
  /**
  * Reset all properties to their default values.
  *
  * @param mapping The mapping used to select this instance
  * @param request The servlet request we are processing
  */
  public void reset(ActionMapping mapping, HttpServletRequest request) {
  
   this.action = "Create";
   this.autoConnect = false;
   this.host = null;
   this.password = null;
   this.type = null;
   this.username = null;
  
  }
  
  
  /**
  * Validate the properties that have been set from this HTTP request,
  * and return an <code>ActionErrors</code> object that encapsulates any
  * validation errors that have been found. If no errors are found, return
  * <code>null</code> or an <code>ActionErrors</code> object with no
  * recorded error messages.
  *
  * @param mapping The mapping used to select this instance
  * @param request The servlet request we are processing
  */
  public ActionErrors validate(ActionMapping mapping,
  HttpServletRequest request) {
  
   ActionErrors errors = new ActionErrors();
  
   if ((host == null) (host.length() < 1))
  errors.add("host",
  new ActionError("error.host.required"));
   if ((username == null) (username.length() < 1))
  errors.add("username",
  new ActionError("error.username.required"));
   if ((password == null) (password.length() < 1))
  errors.add("password",
  new ActionError("error.password.required"));
   if ((type == null) (type.length() < 1))
  errors.add("type",
  new ActionError("error.type.required"));
   else if (!"imap".equals(type) && !"pop3".equals(type))
  errors.add("type",new ActionError("error.type.invalid", type));
   return (errors);
   }
  }
  
  LogonAction
  
  public final class LogonAction extends Action {
  /**
  * Process the specified HTTP request, and create the corresponding HTTP
  * response (or forward to another web component that will create it).
  * Return an <code>ActionForward</code> instance describing where and how
  * control should be forwarded, or <code>null</code> if the response has
  * already been completed.
  *
  * @param mapping The ActionMapping used to select this instance
  * @param form The optional ActionForm bean for this request (if any)
  * @param request The HTTP request we are processing
  * @param response The HTTP response we are creating
  *
  * @exception Exception if business logic throws an exception
  */
  public ActionForward execute(ActionMapping mapping,
  ActionForm form,
  HttpServletRequest request,
  HttpServletResponse response)
  throws Exception {
  
   // Extract attributes we will need
   Locale locale = getLocale(request);
   MessageResources messages = getResources(request);
   User user = null;
  
   // Validate the request parameters specified by the user
   ActionErrors errors = new ActionErrors();
   String username = (String)
   PropertyUtils.getSimpleProperty(form, "username");
   String password = (String)
   PropertyUtils.getSimpleProperty(form, "password");
   UserDatabase database = (UserDatabase)
   servlet.getServletContext().getAttribute(Constants.DATABASE_KEY);
   if (database == null)
  errors.add(ActionErrors.GLOBAL_ERROR,
  new ActionError("error.database.missing"));
   else {
  user = getUser(database, username);
  if ((user != null) && !user.getPassword().equals(password))
   user = null;
  if (user == null)
   errors.add(ActionErrors.GLOBAL_ERROR,
   new ActionError("error.password.mismatch"));
   }
  
  // Report any errors we have discovered back to the original form
  if (!errors.isEmpty()) {
   saveErrors(request, errors);
   return (mapping.getInputForward());
  }
  
  // Save our logged-in user in the session
  HttpSession session = request.getSession();
  session.setAttribute(Constants.USER_KEY, user);
  if (log.isDebugEnabled()) {
   log.debug("LogonAction: User '" + user.getUsername() +
  "' logged on in session " + session.getId());
  }
  
  // Remove the obsolete form bean
  if (mapping.getAttribute() != null) {
   if ("request".equals(mapping.getScope()))
  request.removeAttribute(mapping.getAttribute());
   else
  session.removeAttribute(mapping.getAttribute());
  }
  
  // Forward control to the specified success URI
  return (mapping.findForward("success"));
  
  }
  
  /**
  * Look up the user, throwing an exception to simulate business logic
  * rule exceptions.
  *
  * @param database Database in which to look up the user
  * @param username Username specified on the Logon form
  *
  * @exception ModuleException if a business logic rule is violated
  */
  public User getUser(UserDatabase database, String username)
  throws ModuleException {
  
  // Force an ArithmeticException which can be handled eXPlicitly
  if ("arithmetic".equals(username)) {
   throw new ArithmeticException();
  }
  
  // Force an application-specific exception which can be handled
  if ("expired".equals(username)) {
   throw new ExpiredPasswordException(username);
  }
  
  // Look up and return the specified user
  return ((User) database.findUser(username));
  
  }
  }

来源:https://www.tulaoshi.com/n/20160219/1603238.html

延伸阅读
标签: Web开发
//C# public class Index : System.Web.UI.Page{ private void Page_Load(object sender, EventArgs e){ Ajax.Utility.RegisterTypeForAjax(typeof(Index)); //... } //... } 对RegisterTypeForAjax方法的调用在页面产生如下的javascript代码(另外一种选择,你也可以人工在页面上添加如下的javascript代码) <scrip...
标签: Web开发
AJAX依靠服务器作为中介来分发和处理请求。为了完成这项工作,.net封装类依赖于客户端的请求对象,而xmlHttpRequest对象被大部分的浏览器支持,因此使用这个对象是一个不错的解决方案。因为封装的目的是隐藏xmlHttpRequest的实现,故我们不讨论他的实现细节。 封装类是通过在.net的方法上增加AJAX属性标记来实现的,一旦被标记,AJAX创建...
标签: Web开发
[Ajax.AjaxMethod] public string Test1(string name, string email, string comment){ string html = ""; html += "Hello " + name + "<br>"; html += "Thank you for your comment <b>"; html += System.Web.HttpUtility.HtmlEncode(comment); html += "</b>."; return html; } SessionState 在服务端函数,你可能需要接受...
标签: Web开发
private void Page_Load(object sender, EventArgs e){ Utility.RegisterTypeForAjax(typeof(User)); } 在客户端我们可以通过这样的方式调用GetUser函数: <script language="javascript"> function getUser(userId){ User.GetUser(GetUser_callback); } function GetUser_callback(response){ if (response != null && resp...
标签: 电脑入门
在Word2010文档中,利用自选图形库提供的丰富的流程图形状和连接符可以制作各种用途的流程图,制作步骤如下所述: 第1步:打开Word2010文档窗口,切换到插入功能区。在插图分组中单击形状按钮,并在打开的菜单中选择新建绘图画布命令,如图1所示。 图1 选择新建绘图画布命令 小提示:也可以不使用画布,而只直接在Word2010文档页面中直接...

经验教程

524

收藏

59
微博分享 QQ分享 QQ空间 手机页面 收藏网站 回到头部