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Tapestry入门及进阶一

林星阑
2023-12-01
要Tapestry开发一个Web Application,对一个新手来说有点困难的,Tapestry由于不同于

以前的Web Presentation Framework,所以不可讳言,学习曲线比较长这是事实。

我先讲讲一个Web Application的大体结构:
以JBuider9为开发工具,你要先建立一个工程,例如是名称是TapestryExmaple,它的

workspace是F:/myproject/TapestryExmaple.它下面的子目录和文件有
bak--   这是Jbuider自建的backup目录。
build--  我的ant的工作目录,我的ant会利用这个目录编译打包。
classes-- JBuilder编译时放class的目录
configs-- 我的一些配置文件放置的地方
lib--      我的要用到的库文件放置的目录
context-- 我的Web application的context目录
 doc-- 我的文档目录
src--     我的java source的目录
build.properties--ant工作的属性设置文件
build.xml--ant工作的定义文件

你建立好这个工程以后,你好需要建立Web Application, 点击File-->New-->Web-->Web
Application,因为我们需要在JBuilder里利用Tomcat4.1调试,用Jboss3.x也可以,不过你
要去下载一个插件叫 EntWizard_JBoss3x_JB9_v3-1-5.zip 的插件,JBuiderx提供对JB
oss的支持,不过Jbuiderx经常有些莫名其妙的怪毛病,而且比较慢,我是不用的。

你建立Web Application的时候你要输入Name和Directory两项值,Name比如是
patientrecord,注意你在这里输入的name,会在你将来测试时的URL里出现:
你的URL就可能像这样: http://localhost:8080/patientrecord/app
后面那个app是在web.xml里配置的,下面再说。
你的Web Application的Directory值要跟我们上面预定的一致,就是那个context目录,

在这里就是F:/myproject/TapestryExmaple/context,这个context目录是web applicatio
n
的核心目录,下面要详细的讲讲。

例如像我的context目录下面有这三个目录
home  -- 我的web applicattion的子模块home的context
     下面有子目录  css--放置本子模块用到的css文件
            images--放置本子模块用到的image(图标)
        文件: Home.html,Register.xml ...
                        这些是我字模块中的页面对应的HTML template(模版)   
  
patientrecord--我的web applicattion的子模块patientrecord的context
        目录结构跟home子模块相同

WEB-INF--最核心的目录
     下面的子目录和文件有
           classes--你的java classes会在这里有一份拷贝
      lib--你的工程引用的lib在这里用一份拷贝
      patientrecord.application--你的Tapestry核心配置文件
      web.xml--web application的核心配置文件

下面我们来研究一下patientrecord.application和web.xml这两个文件,我的范例文
件如下:
web.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" " http://java.sun.com/dtd/web-app_2_3.dtd>
<web-app>
  <display-name>Patient Record System</display-name>
  <filter>
    <filter-name>redirect</filter-name>
    <filter-class>org.apache.tapestry.RedirectFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>redirect</filter-name>
    <url-pattern>/</url-pattern>
  </filter-mapping>
  <servlet>
    <servlet-name>patientrecord</servlet-name>
    <servlet-class>com.ht.web.PatientRecordServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>patientrecord</servlet-name>
    <url-pattern>/app</url-pattern>
  </servlet-mapping>
  <session-config>
    <session-timeout>15</session-timeout>
  </session-config>
</web-app>  
          
这个里面属性有
display-name --不重要,只是显示名称
filter和filter-mapping配置--不要动,使用默认配置,
servlet配置--这个是很重要的,我的servle name是patientrecord, 对应的class为
com.ht.web.PatientRecordServlet,这是我自己开发的一个类:
这个类看上去很简单:

package com.ht.web;

import org.apache.tapestry.ApplicationServlet;

/**
*  @version $Id: SimpleServlet.java,v 1.9 2002/05/04 12:43:31 hship Exp $
*  @author Howard Lewis Ship
*
*/
public class PatientRecordServlet extends ApplicationServlet
{
}

你一般就是定义一个类extends org.apache.tapestry.ApplicationServlet就行了
当然,如果你还有什么特别要求,你可对这个类进行强化。
我再来谈谈这个核心类的作用:这其实是个Dispatcher(分发者),它接受外界传来的
http request请求,然后把请求处理后派发给Tapestry Engine处理.

图例:
http://bbs1.nju.edu.cn/file/high-level-component-request.p

servlet-mapping--这是URL映射的设置,一般设为app

<session-config>
    <session-timeout>15</session-timeout>
</session-config>
这段是对HTTP Session的timeout的配置,这里是15分钟。

下面再来研究一下patientrecord.application文件,这也是一个XML文件:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE application PUBLIC
  "-//Apache Software Foundation//Tapestry Specification 3.0//EN"
  " http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd>

<application name="Patient Record System" engine-class="com.ht.web.PatientRecordEngine">
  <property name="org.apache.tapestry.visit-class" value="com.ht.web.VisitorState"/>

  <property name="com.ht.home-page" value="home:Home"/>

  <!--<property name="com.ht.exception-page" value="home:PaitentRecordException"/>--> 
  <property name="com.ht.security-exception-page" value="home:SecurityExceptionPage"/>

  <!--Overrided the Home Service to let us to decide which page will be the home page-->
  <service name="home" class="com.ht.web.HomeService"/>
 
  <library id="home" specification-path="/com/ht/home/Home.library"/>
  <library id="patientrecord" specification-path="/com/ht/patientrecord/PatientRecord.library"/>
</application>

由这个文档我们可以看出
我的application name="Patient Record System"
我的engine-class为com.ht.web.PatientRecordEngine
我的org.apache.tapestry.visit-class为com.ht.web.VisitorState
以上两项是override Tapestry的默认实现

<property name="com.ht.home-page" value="home:Home"/>
这是我配置我的home-page页指向我的web application的子模块home里Home页

<!--<property name="com.ht.exception-page" value="home:PaitentRecordException"/>--> 
  <property name="com.ht.security-exception-page" value="home:SecurityExceptionPage"/>

这两项是我设定出错处理页
其中的com.ht.exception-page是处理普通的org.apache.tapestry.ApplicationException,
现在被注释掉,因为目前在开发阶段,我要察看详细的出错情况,不需处理。
com.ht.security-exception-page是处理java.lang.SecurityException,
因为对于一个需要登录的网站,一个为登录的用户是不可以访问大多数资源,
如果他访问了不可访问的资源,我就抛出SecurityException交给engine处理。

  <!--Overrided the Home Service to let us to decide which page will be the home page-->
  <service name="home" class="com.ht.web.HomeService"/>
Tapestry engine 可以定义一些service提供服务,我在这里定义一个home service就是
要我自己决定我的home page页,而不是Tapestry的默认配置页。

<library id="home" specification-path="/com/ht/home/Home.library"/>
  <library id="patientrecord" specification-path="/com/ht/patientrecord/PatientRecord.library"/>

这两项是说明我的application包含两个library,这其实是一个Web application切分
子模块的手段,比如/com/ht/home/Home.library"/ 对应着我的home子模块,
而/com/ht/patientrecord/PatientRecord.library则对应着我的patientrecord子模块

下面说说Tapestry engine,例如我的engine实现如下:

package com.ht.web;

import java.io.*;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.tapestry.*;
import org.apache.tapestry.engine.BaseEngine;
import org.apache.tapestry.engine.IPropertySource;
import org.apache.tapestry.request.ResponseOutputStream;
import org.apache.commons.lang.StringUtils;

/**
* @author Hery Tang
*
* Creation Date 2003-9-18
* Version 1.0
*/
public class PatientRecordEngine extends BaseEngine {
 
        public static final String HOME_PAGE_NAME = "com.ht.home-page";
        public static final String EXCEPTION_PAGE_NAME= "com.ht.exception-page";
        public static final String SECURITY_EXCEPTION_PAGE_NAME = "com.ht.security-exception-page";

        private transient boolean killSession;
       
        protected void cleanupAfterRequest(IRequestCycle cycle)
        {
                super.cleanupAfterRequest(cycle);
                if (killSession)
                {
                        try
                        {
                                HttpSession session = cycle.getRequestContext().getSession();

                                if (session != null)
                                {
                                        session.invalidate();
                                }
                        }
                        catch (IllegalStateException ex)
                        {
                                // Ignore.
                        }
                }
        }

        public void logout()
        {
                VisitorState visit = (VisitorState) getVisit();

                if (visit != null)
                {
                        visit.setUser(null);
                        visit = null;
                }

                killSession = true;
        }

        /**
         * This methods read the home page name which defined by the user by using
         * propetry com.ht.home-page in application specification
         *
         * @return The name of home page.
         */
        public String getHomePageName() {
                return getPropertySource().getPropertyValue(HOME_PAGE_NAME);
        }

        /**
         * Return the security exception page name. If user does not defined this
         * page name, the normal exception page will be return.
         * @return The name of the security exception page.
         */
        public String getSecurityExceptionPageName() {
                String result =
                        getPropertySource().getPropertyValue(
                                SECURITY_EXCEPTION_PAGE_NAME);

                if (StringUtils.isEmpty(result)) {
                        result = getExceptionPageName();
                }

                return result;
        }

        /**
         * Return the exception page name. If user does not defined this page name,
         * the default exception page will be return.
         * @return The name of the normal exception page.
         */
        public String getExceptionPageName() {
       
                String result =
                        getPropertySource().getPropertyValue(EXCEPTION_PAGE_NAME);

                if (StringUtils.isEmpty(result)) {
                        result = super.getExceptionPageName();
                }

                return result;
        }

        /**
         * Overide the method to support security Exception.
         */
        protected void activateExceptionPage(
                IRequestCycle cycle,
                ResponseOutputStream output,
                Throwable cause)
                throws ServletException {
                //Print it to console first
                printExceptions(cause);

                try {
                        String exceptionPageName;

                        Throwable throwable = cause;
                        Throwable securityException = null;
                        boolean isSecurityException = false;

                        if (throwable
                                instanceof org.apache.tapestry.ApplicationRuntimeException) {
                                ApplicationRuntimeException exception =
                                        (ApplicationRuntimeException) throwable;
                                if (exception.getRootCause() instanceof SecurityException) {
                                        securityException = exception.getCause();
                                        isSecurityException = true;
                                }
                        }

                        if (isSecurityException) {
                                exceptionPageName = getSecurityExceptionPageName();
                        } else {
                                exceptionPageName = getExceptionPageName();
                        }

                        IPage exceptionPage = cycle.getPage(exceptionPageName);
                        if (securityException == null) {
                                exceptionPage.setProperty("exception", cause);
                        } else {
                                exceptionPage.setProperty("exception", securityException);
                        }

                        cycle.activate(exceptionPage);

                        renderResponse(cycle, output);
                } catch (Throwable ex) {
                        // Worst case scenario.  The exception page itself is broken, leaving
                        // us with no option but to write the cause to the output.
                        reportException(
                                Tapestry.getMessage(
                                        "AbstractEngine.unable-to-process-client-request"),
                                cause);

                        // Also, write the exception thrown when redendering the exception
                        // page, so that can get fixed as well.
                        reportException(
                                Tapestry.getMessage(
                                        "AbstractEngine.unable-to-present-exception-page"),
                                ex);

                        // And throw the exception.
                        throw new ServletException(ex.getMessage(), ex);
                }
        }

        private void printExceptions(Throwable throwable) {
                if (throwable == null) {
                        return;
                }

                throwable.printStackTrace();
                printExceptions(throwable.getCause());
        }

       
}

 public void logout() 说明
   一个用户登出,则将一个代表用户状态的VisitorState对象里的状态清空,同时置
   killSession标志量为true

  protected void cleanupAfterRequest(IRequestCycle cycle)
    overrride父类BaseEngine实现,先调用父类实现然后再察看killSession标志量,如果为true,则invalidate session.

  public String getHomePageName()
  public String getSecurityExceptionPageName()
  public String getExceptionPageName()
都是为了取出我在在patientrecord.application的配置。

protected void activateExceptionPage(
                IRequestCycle cycle,
                ResponseOutputStream output,
                Throwable cause)
override AbstractEngine的是实现,用我自己的方式处理各种Exception.

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