Hello World（struts）

最新推荐文章于 2024-09-01 13:52:27 发布

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最新推荐文章于 2024-09-01 13:52:27 发布

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分类专栏： STRUTS 文章标签： struts html string action bean resources

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从Eclipse里建个web project,然后加入Struts 标签.这样就可以做我的东西了.

1.建个hello.jsp页面,这个页面也就是所说的视图页面,使用的是Struts标签.

<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>

<html:html locale="true">
<head>
<title><bean:message key="hello.jsp.title"/></title>
<html:base/>
</head>

<body bgcolor="white"><p>
    <h2><bean:message key="hello.jsp.page.heading"/></h2><p>
   <html:errors/><p>
    <logic:present name="personbean" scope="request">
       <h2>
         <bean:message key="hello.jsp.page.hello"/>
         <bean:write name="personbean" property="userName" />!<p>
       </h2>
    </logic:present>

    <html:form action="/HelloWorld.do" focus="userName" >
      <bean:message key="hello.jsp.prompt.person"/>
      <html:text property="userName" size="16" maxlength="16"/><br>
      <html:submit property="submit" value="Submit"/>
      <html:reset/>
    </html:form><br>

<html:img page="/struts-power.gif" alt="Powered by Struts"/>
</body>
</html:html>

2.创建消息资源文件application.properties ,这个文件是用来定义一些常量的文本信息.把信息放到资源文件中,使用起来相对方便.

#Application Resources for the "Hello" sample application
#Application Resources that are specific to the hello.jsp file

hello.jsp.title=Hello - A first Struts program
hello.jsp.page.heading=Hello World! A first Struts application
hello.jsp.prompt.person=Please enter a UserName to say hello to :
hello.jsp.page.hello=Hello

#Validation and error messages for HelloForm.java and HelloAction.java

hello.dont.talk.to.monster=We don't want to say hello to Monster!!!
hello.no.username.error=Please enter a <i>UserName</i> to say hello to!

3.再来创建一个表单文件HelloForm.java,这个表单是与hello.jsp中表单字段一一对应的,主要是set,get方法.

package com.boyang.co;

import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;

public class HelloForm extends ActionForm {
private String userName = null;

public String getUserName() {
   return this.userName;
}

public void setUserName(String userName) {
   this.userName = userName;
}

public void reset(ActionMapping mapping,
    HttpServletRequest request) {
   this.userName = null;
}

public ActionErrors validate(ActionMapping mapping,
    HttpServletRequest request) {
   ActionErrors errors = new ActionErrors();

   if ((userName == null) || (userName.length() < 1))
    errors.add("username", new ActionError("hello.no.username.error"));
   return errors;
}
}

其中,包含了一个validate()方法,用来进行表单验证的,如果验证错误,Struts框架会把ActionErrors对象保存到request范围中,然后把请求转发到hello.jsp视图文件中,视图文件通过<html:error>标签把request范围内的ActionErrors对象中包含的错误信息显示出来.

4.接下来,我们创建控制器组件HelloAction.java. 组件:ActionServlet类和Action类.ActionServlet是Struts框架的控制枢纽,Action是用来处理特定的HTTP请求.

package com.boyang.co;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.util.MessageResources;

public final class HelloAction extends Action {
    public ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 HttpServletRequest request,
                                 HttpServletResponse response)
    throws Exception {

// These "messages" come from the ApplicationResources.properties file

// 用来读取资源文件.
MessageResources messages = getResources(request);

ActionErrors errors = new ActionErrors();
String userName = (String)((HelloForm) form).getUserName();

String badUserName = "Monster";

// 用<html:errors/>标签来显示错误消息.

        if (userName.equalsIgnoreCase(badUserName)) {
           errors.add("username", new ActionError("hello.dont.talk.to.monster", badUserName));
           saveErrors(request, errors);
           return (new ActionForward(mapping.getInput()));
        }

PersonBean pb = new PersonBean();
pb.setUserName(userName);

// 持久化的消息处理.
pb.saveToPersistentStore();

request.setAttribute( Constants.PERSON_KEY, pb);

// Remove the Form Bean - don't need to carry values forward
request.removeAttribute(mapping.getAttribute());

        // Forward control to the specified success URI
        return (mapping.findForward("SayHello"));
    }
}

5.模型组件PersonBean.java

模型组件把业务逻辑的实现和其它的应用分开,提高了灵活性,重用性,可扩展性.可用来保存持久化的数据系统中.

package com.boyang.co;

public class PersonBean {

private String userName = null;

public String getUserName() {
return this.userName;
}

public void setUserName(String userName) {
this.userName = userName;
}

// 持久化的消息处理.
public void saveToPersistentStore() {
//
}
}

6.创建常量文件Constants.java

package com.boyang.co;

public final class Constants {
public static final String PERSON_KEY = "personbean";
}

7.创建WEB应用配置文件web.xml,应该对ActionServlet类进行配置,此外还应该包含标签库:Struts Bean,Struts HTML,Struts Logic标签库.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>
<display-name>HelloApp Struts Application</display-name>


<servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
     <load-on-startup>2</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>


<welcome-file-list>
    <welcome-file>hello.jsp</welcome-file>
</welcome-file-list>

<taglib>
<taglib-uri>/WEB-INF/struts-bean.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-bean.tld</taglib-location>
</taglib>

<taglib>
<taglib-uri>/WEB-INF/struts-html.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-html.tld</taglib-location>
</taglib>

<taglib>
<taglib-uri>/WEB-INF/struts-logic.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-logic.tld</taglib-location>
</taglib>

</web-app>

8.创建Struts框架的配置文件struts-config.xml

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE struts-config PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 1.1//EN"
"http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">

<struts-config>

    
    <form-beans>
        <form-bean name="HelloForm" type="com.boyang.co.HelloForm"/>
    </form-beans>

<action-mappings>
    
    <action    path      = "/HelloWorld"
               type      = "com.boyang.co.HelloAction"
               name      = "HelloForm"
               scope     = "request"
               validate = "true"
               input     = "/hello.jsp"
     >
        <forward name="SayHello" path="/hello.jsp" />
    </action>
</action-mappings>