首先，我使用的是 Struts 2 和 Java。我正在尝试让我的
LoginUserUserBean当
LoginUserfullNameuserBean<s:property>但是，当我单击
More Infosuccess.jspfullName<s:property>null success.jsp 也是null我的问题：
为什么 Bean 没有像预期那样保留信息？
技术说明：我正在使用 Eclipse IDE 作为 Maven 项目进行开发，并且仅使用 Apache Tomcat 7 来测试/部署。
LoginUserpackage test.Home1;
@SuppressWarnings("unused")
public class LoginUser {
private String username = "";
private String password = "";
private String userOK = "admin";
private String passOK = "admin";
// Password getters/setters
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
// Username getters/setters
public void setUsername(String username) {
this.username = username;
}
public void setPassword(String password) {
this.password = password;
}
// Bean is instantiated here
private UserBean userBean = new UserBean();
// userBean getters/setters
public void setUserBean(UserBean userBean) {
this.userBean = userBean;
}
public UserBean getUserBean() {
return userBean;
}
// Execute the following action when this class is called via struts action
public String execute() {
if (this.username.equalsIgnoreCase(userOK) && this.password.equals(passOK)) {
userBean.setAccessLevel("full");
userBean.setFullName("Administrator");
userBean.setUserName(username);
return "SUCCESS";
}
else {
return "FAIL";
}
}
}
UserBeanpackage Test.Home1;
public class UserBean {
private String userName;
private String password;
private String fullName;
private String accessLevel;
private boolean LoggedIn = false;
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;
}
public String getFullName() {
return fullName;
}
public void setFullName(String fullName) {
this.fullName = fullName;
}
public String getAccessLevel() {
return accessLevel;
}
public void setAccessLevel(String accessLevel) {
this.accessLevel = accessLevel;
}
public boolean isLoggedIn() {
return LoggedIn;
}
public void setLoggedIn(boolean loggedIn) {
LoggedIn = loggedIn;
}
}
login.jsp<%@ page contentType="text/html; charset=UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
<title>
Hello World at Home (Struts 2 Tutorial)
</title>
</head>
<body style="font-family: Arial;">
<h1>Please Log in</h1>
<s:form action="LoginUser" autocomplete="off">
<s:textfield name="username" label="Username"/>
<s:password name="password" label="Password"/>
<s:submit/>
</s:form>
</body>
</html>
success.jsp<%@ page contentType="text/html; charset=UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
<title>
Hello World at Home (Struts 2 Tutorial) - LOGGED IN
</title>
</head>
<body style="font-family: Arial;">
<h1>Struts 2 Hello World Example</h1>
<h4>Hello <s:property value="userBean.fullName" />
</h4>
<br><br>
<s:a value="Info">More Info</s:a>
</body>
</html>
moreInfo.jsp<%@ page contentType="text/html; charset=UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
<title>
Hello World at Home (Struts 2 Tutorial) - LOGGED IN
</title>
</head>
<body style="font-family: Arial;">
<h1>Are you still there <s:property value="userBean.fullName" />?</h1>
<h4>Can you still see your name above?</h4>
<br><br>
<s:a value="Home">Home</s:a>
</body>
</html>
操作 bean 仅在同一个请求期间存在，但如果您按下链接，它会调用另一个请求，其中
userBeannull当 OGNL 尝试从包含参数名称的表达式填充 bean 时，其默认行为是
createIfNull==true如果您添加一些参数，如这段代码
<s:a action="ShowUser"><s:param name="userBean.fullName" value="Administrator"/> More Info</s:a>
然后它将创建一个
userBeanfullNameexecute()参考资料：