| <?xml version="1.0"?> |
| <!-- |
| $Id$ |
| |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You under the Apache License, Version 2.0 |
| (the "License"); you may not use this file except in compliance with |
| the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| --> |
| <!-- |
| // ======================================================================== 78 |
| --> |
| <document> |
| |
| <properties> |
| <title>Welcome</title> |
| </properties> |
| |
| <body> |
| |
| <section name="Welcome to Struts 1"> |
| <a name="Welcome"/> |
| |
| <p> |
| Struts is a flexible control layer based on |
| <a href="userGuide/preface.html">standard technologies</a> |
| like Java |
| Servlets, JavaBeans, ResourceBundles, and XML, as well as |
| various |
| <a href="http://commons.apache.org/index.html">Apache |
| Commons</a> |
| packages, like BeanUtils and Chain of Responsibility. |
| The framework helps you create an extensible |
| development |
| environment for your application, |
| based on published standards and proven design patterns. |
| </p> |
| |
| <subsection name="Struts in a Nutshell"> |
| <a name="nutshell"/> |
| |
| <p> |
| The framework provides its own web |
| <strong>Controller</strong> |
| component and |
| integrates with other technologies to provide the Model |
| and the View. |
| For the |
| <strong>Model,</strong> |
| the framework can interact |
| with standard data access technologies, |
| like |
| <a href="http://java.sun.com/products/jdbc/">JDBC</a> |
| and |
| <a href="http://java.sun.com/products/ejb/">EJB,</a> |
| as well as most any third-party packages, |
| like |
| <a href="http://hibernate.org/">Hibernate,</a> |
| <a href="http://ibatis.apache.org/">iBATIS,</a> |
| or |
| <a href="http://db.apache.org/ojb/">Object Relational |
| Bridge.</a> |
| For the |
| <strong>View,</strong> |
| the framework works well with |
| <a href="http://java.sun.com/products/jsp/">JavaServer |
| Pages,</a> |
| including |
| <a href="struts-el/index.html">JSTL</a> and |
| <a href="struts-faces/index.html">JSF,</a> |
| as well as |
| <a href="http://velocity.apache.org/tools/struts/"> |
| Velocity Templates,</a> |
| <a href="http://stxx.sourceforge.net/">XSLT,</a> |
| and other presentation systems. |
| </p> |
| |
| <p> |
| The framework's Controller acts as a bridge between the |
| application's |
| Model and the web View. When a request is received, the |
| Controller invokes |
| an |
| <strong>Action</strong> |
| class. The Action class consults with the Model |
| (or, preferably, a |
| <strong>Facade</strong> |
| representing your Model) |
| to examine or update the application's state. |
| The framework provides an |
| <strong>ActionForm</strong> |
| class to help transfer |
| data between Model and View. |
| </p> |
| |
| <p> |
| Most often, the Model is represented as a set of |
| <strong>JavaBeans.</strong> |
| Typically, developers will use the Commons |
| <strong>BeanUtils</strong> |
| to |
| transfer data between ActionForms and the Model objects |
| (or a Facade). |
| Preferably, the Model will do the "heavy lifting", |
| and the Action will act as a "traffic cop" or adapter. |
| </p> |
| </subsection> |
| |
| <subsection name="Struts Config in a Nutshell"> |
| <a name="nutshell-config"/> |
| |
| <p> |
| A web application |
| uses a deployment descriptor to initialize resources |
| like |
| <a href="userGuide/preface.html#servlets">servlets</a> |
| and |
| <a href="userGuide/preface.html#jsp">taglibs.</a> |
| The deployment descriptor is formatted as a |
| <a href="userGuide/preface.html#xml">XML</a> |
| document |
| and named "web.xml". |
| Likewise, |
| the framework uses a configuration file to initialize its |
| own resources. |
| These resources include |
| <a href="userGuide/building_controller.html#action_form_classes"> |
| ActionForms</a> |
| to collect input from users, |
| <a href="http://struts.apache.org/userGuide/building_controller.html#actionmapping"> |
| ActionMappings</a> |
| to direct input to server-side |
| <a href="http://struts.apache.org/userGuide/building_controller.html#action_classes"> |
| Actions,</a> |
| and ActionForwards to select output pages. |
| </p> |
| |
| <p> |
| Here's a simple configuration (struts-config.xml) for a |
| login workflow: |
| </p> |
| |
| <pre> |
| <code><![CDATA[ |
| <?xml version="1.0" encoding="ISO-8859-1" ?> |
| <!DOCTYPE struts-config PUBLIC |
| "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" |
| "http://struts.apache.org/dtds/struts-config_1_3.dtd"> |
| <struts-config> |
| <form-beans> |
| <form-bean |
| name="logonForm" |
| type="app.LogonForm"/> |
| </form-beans> |
| <action-mappings> |
| <action |
| path="/Welcome" |
| forward="/pages/Welcome.jsp"/> |
| <action |
| path="/Logon" |
| forward="/pages/Logon.jsp"/> |
| <action |
| path="/LogonSubmit" |
| type="app.LogonAction" |
| name="logonForm" |
| scope="request" |
| validate="true" |
| input="/pages/Logon.jsp"> |
| <forward |
| name="success" |
| path="/pages/Welcome.jsp"/> |
| <forward |
| name="failure" |
| path="/pages/Logon.jsp"/> |
| </action> |
| <action |
| path="/Logoff" |
| type="app.LogoffAction"> |
| <forward |
| name="success" |
| path="/pages/Logoff.jsp"/> |
| </action> |
| </action-mappings> |
| <message-resources parameter="resources.application"/> |
| </struts-config> |
| ]]></code> |
| </pre> |
| |
| <p> |
| There are several other resources you can specify in the |
| framework's |
| configuration file. |
| You can specify validations for the ActionForms in an XML |
| descriptor, |
| using the |
| <a href="faqs/validator.html"> |
| Struts Validator</a>. A standard extension, |
| <a href="http://struts.apache.org/struts-tiles/dev_tiles.html"> |
| Tiles</a>, helps you build pages from smaller fragments. |
| </p> |
| |
| <p> |
| Struts is extensible. |
| Every class deployed by the framework can be replaced by |
| your own default class. |
| The properties of your default class can be set using the |
| <a href="http://commons.apache.org/digester/"> |
| Digester's</a> |
| <code>set-property</code> |
| feature. |
| This is one reason why there are so many |
| <a href="learning.html#resources"> |
| contributor |
| extensions.</a> |
| We provide the base framework, but you can still write |
| <b>your</b> |
| application |
| <b>your</b> |
| way. |
| </p> |
| |
| <p> |
| For more about the framework and its underlying |
| technologies, see the |
| <a href="userGuide/index.html">User Guide.</a> |
| </p> |
| |
| </subsection> |
| |
| <subsection |
| name="Is Struts the best choice for every project?"> |
| |
| <p> |
| No. If you need to write a very simple application, with a |
| handful of |
| pages, |
| then you might consider a "Model 1" solution that uses |
| only server |
| pages. |
| </p> |
| |
| <p> |
| But, if you are writing a more complicated application, |
| with dozens of pages, |
| that need to be maintained over time, then Struts |
| can help. |
| For more about whether Model 1 or MVC/Model 2 is right for |
| you, see |
| <a href="http://www.javaworld.com/javaworld/jw-12-1999/jw-12-ssj-jspmvc.html"> |
| Understanding JavaServer Pages Model 2 |
| architecture.</a> |
| </p> |
| |
| </subsection> |
| </section> |
| |
| <section> |
| <p class="right"> |
| Next: |
| <a href="learning.html">Learning about Struts</a> |
| </p> |
| </section> |
| |
| </body> |
| </document> |
