Struts的简单登录应用 - hwoarangzk的博客

作者在 2007-12-21 10:17:37 发布以下内容

今天写个简单的登录应用。就是在没有用户登录进去时，主页显示Welcome world，当用户成功登录进去后，显示Welcome Username，同时出现一些只有登录用户才能看到的内容。与此同时还有一个Logout供已登录的用户登出。

需要的东西仍旧是我第一篇Struts例子里面的：jdk1.5, Tomcat 5.5, Eclipse3.2, Struts1.2包，common包.

LoginAction, LoginForm, LogoutAction,ApplicationResource都放在src下面，index.jsp, success.jsp, failure.jsp放在根目录下面，web.xml, struts-config.xml, validation.xml, validator-rules.xml放在WEB-INF下。

首先，我们配置web.xml文件。这个跟之前的例子差不多。

web.xml:

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

<!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>

<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>

<init-param>

<param-name>debug</param-name>

<param-value>0</param-value>

</init-param>

<init-param>

<param-name>detail</param-name>

<param-value>2</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>action</servlet-name>

<url-pattern>*.do</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

<taglib-uri>/tags/struts-html</taglib-uri>

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

</taglib>

<taglib-uri>/tags/struts-logic</taglib-uri>

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

</taglib>

<taglib-uri>/tags/struts-bean</taglib-uri>

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

</taglib>

</web-app>

这里又用到了struts的logic和bean标签。

然后是index.jsp文件，这个就跟之前的有很大不同了。

index.jsp:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ taglib uri="/tags/struts-html" prefix="html" %>

<%@ taglib uri="/tags/struts-bean" prefix="bean" %>

<%@ taglib uri="/tags/struts-logic" prefix="logic" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Index Page</title>

</head>

<body>

<logic:present name="User">

Welcome! <bean:write name="User" property="username" /><br/>

<a href="success.jsp">Go to success page</a><br/>

</logic:present>

<logic:notPresent name="User">

Welcome world!<br/>

<html:form. action="/login.do" method="post">

<table>

<tr>

<td>Username:<html:text property="username" /></td>

</tr>

<tr>

<td>Password:<html:password property="password" /></td>

<tr>

</tr>

</table>

</html:form>

</logic:notPresent>

<br/>

<logic:present name="User">

<html:link forward="logout">Logout</html:link>

</logic:present>

</center>

</body>

</html>

我们在这里用了<logic:present>标签。它的意思就是当它以name指定的bean出现时就显示里面的内容，如果没有出现就不显示。而<logic:notPresent>就刚好相反。不存在时显示，存在时不显示。

<bean:write>标签则是显示以name指定的bean的property内容。

<html:link forward>标签则提供了一个Logout的forward。

下面我们来看看struts-config.xml:

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

<!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>

<data-sources />

<form-beans>

<form-bean name="loginForm" type="src.LoginForm" />

</form-beans>

<global-exceptions />

<global-forwards>

</global-forwards>

<action-mappings>

<action path="/login"

name="loginForm"

input="/index.jsp"

validate="true"

type="src.LoginAction" >

</action>

<action path="/logout"

type="src.LogoutAction" >

</action>

</action-mappings>

<message-resources parameter="src.ApplicationResource" />

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">

<set-property property="pathnames" value="/WEB-INF/validation.xml,/WEB-INF/validator-rules.xml" />

</plug-in>

</struts-config>

这里，global-forwards里面多了一个logout，就是处理点击logout后要转向的action。然后在下面的action-mappings里面配置了由LogoutAction来处理这个请求。

我们还是使用了validator框架。需要将validator-rules.xml和validation.xml放在WEB-INF下面。可以参见前面的一篇Validator例子。

validation.xml:

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

<!DOCTYPE form-validation PUBLIC

"-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.1.3//EN"

"http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd">

<form-validation>

<form. name="loginForm">

</field>

<var>

<var-name>minlength</var-name>

<var-value>5</var-value>

</var>

</field>

</form>

</formset>

</form-validation>

ApplicationResource.properties:

prompt.username=User Name

prompt.password=User Password

errors.required={0} is required!

errors.minlength={0} can't be less than {1} characters!

然后是LoginForm.java。我们这里只用到了username和password两个属性，同时又使用了validator,所以不用编写validate()方法了。

LoginForm.java:

package src;

import org.apache.struts.validator.ValidatorForm;

public class LoginForm. extends ValidatorForm{

private String username;

private String password;

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

然后是LoginAction.java。在这里面，当输入的用户名和密码正确后(Jim, 1234567)，便会将一个名为User的bean放入session，说明用户已登录。

LoginAction.java:

package src;

import javax.servlet.http.*;

import org.apache.struts.action.*;

public class LoginAction extends Action{

public ActionForward execute(ActionMapping mapping,

ActionForm. form,

HttpServletRequest request,

HttpServletResponse response){

LoginForm. lf = (LoginForm)form;

HttpSession session = request.getSession();

String username = lf.getUsername();

String password = lf.getPassword();

ActionForward forward;

if(username.equals("Jim")&& password.equals("1234567")){

session.setAttribute("User", lf);

forward = mapping.findForward("success");

}else{

forward = mapping.findForward("failure");

}

return forward;

}

接着编写success.jsp，里面也用到了<logic:present>和<bean:write>标签：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ taglib uri="/tags/struts-html" prefix="html" %>

<%@ taglib uri="/tags/struts-bean" prefix="bean" %>

<%@ taglib uri="/tags/struts-logic" prefix="logic" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Success</title>

</head>

<body>

<logic:present name="User">

Welcome! <bean:write name="User" property="username" />

</logic:present>

<br/>

You can review your interested targets here!<br/>

<a href="index.jsp">Return to index page</a>

</center>

</body>

</html>

如果登录失败，要有一个失败的页面，即failure.jsp:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Failure</title>

</head>

<body>

<b>Login Failed!</b><br/>

<a href="index.jsp">Return to index page</a>

</center>

</body>

</html>

现在还差一个LogoutAction.java了：

package src;

import javax.servlet.http.*;

import org.apache.struts.action.*;

public class LogoutAction extends Action{

public ActionForward execute(ActionMapping mapping,

ActionForm. form,

HttpServletRequest request,

HttpServletResponse response){

ActionForward forward = new ActionForward();

HttpSession session = request.getSession();

session.invalidate();

//session.removeAttribute("User");

forward = mapping.findForward("logout");

return forward;

}

这里，我用了session.invalidate()方法，它的作用是消除一切session的内容。而removeAttribute()则只是将指定的bean移出线程。用后者的话，当登出返回登录页面时，以前的username和password还会在输入框里面。所以我用了invalidate()方法。这样的话登出后username和password输入框会被清空。

好了，现在可以运行看看效果了。这个例子比较简单，实现了最简单的登录登出功能。我们可以根据这个在以后的程序中添加更多的功能来丰富内容。