action中请求参数获取的两种方式
1.属性驱动? a.直接在 action 类中提供与请求参数匹配属性，提供 get/set 方法? b.在 action 类中创始一个 javaBean,对其提供 get/set ，在请求时页面上要进行修改，? 例如 user.username user.password ,要使用 ognl 表达式? 以上两种方式的优缺点:? 第一种比较简单，在实际操作我们需要将 action 的属性在赋值给模型(javaBean)去操作? 第二种:不需要在直接将值给 javaBean过程，因为直接将数据封装到了 javaBean? 中。它要 求在页面上必须使用 ognl 表达式，就存在页面不通用问题。2.模型驱动? 步骤:? 1.让 Action 类要实现一个指定接口 ModelDriven? 2.实例化模型对象(就是要 new 出来 javaBean)? 3.重写 getModel 方法将实例化的模型返回
public class Login3Action extends ActionSupport implements ModelDriven<User> {
private User user = new User();
public User getModel() {
return user;
}
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优点:解决了属性驱动存在的问题
缺点:一次只能封装一个model对象.
以下为三个案例的struts.xml文件的内容：
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd"> ? <struts> <!-- 开启开发模式 --> <constant name="struts.devMode" value="true" /> <package name="p1" extends="struts-default"> <!-- 配置一个动作 --> <action name="sayHello" class="com.itheima.action.HelloAction" method="sayHello"> <!-- 配置结果视图 --> <result name="success">/success.jsp</result> </action> </package> ? <package name="default" namespace="/" extends="struts-default"> <action name="login" class="cn.itcast.action.LoginAction"> <result name="failer">/login.jsp</result> <result type="redirect">/success.jsp</result> </action> ? <action name="login1" class="cn.itcast.action.Login1Action"> <result name="failer">/login1.jsp</result> <result type="redirect">/success.jsp</result> </action> ? <action name="login2" class="cn.itcast.action.Login2Action"> <result name="failer">/login2.jsp</result> <result type="redirect">/success.jsp</result> </action> <action name="login3" class="cn.itcast.action.Login3Action"> <result name="failer">/login3.jsp</result> <result type="redirect">/success.jsp</result> </action> </package> </struts>
方式一案例：
Login1Action.Java文件：
package cn.itcast.action;
?
import javax.servlet.http.HttpServletRequest;
?
import org.apache.struts2.ServletActionContext;
?
import com.opensymphony.xwork2.ActionSupport;
?
//获取请求参数 属性驱动 第一种，直接将action做为model
public class Login1Action extends ActionSupport {
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;
}
?
@Override
public String execute() throws Exception {
HttpServletRequest request = ServletActionContext.getRequest();
// 2.判断用户名与密码是否正确
if ("tom".equals(username) && "123".equals(password)) {
request.getSession().setAttribute("username", username);
return SUCCESS;
} else {
request.setAttribute("login.message", "用户名或密码错误");
return "failer";
}
}
}
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP ‘index.jsp‘ starting page</title>
</head>
<body>
${requestScope["login.message"] }<br>
<form action="${pageContext.request.contextPath}/login1" method="post">
username:<input type="text" name="username"><br>
password:<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
方式二案例：
Login2Action.java文件
package cn.itcast.action;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
import cn.itcast.domain.User;
import com.opensymphony.xwork2.ActionSupport;
//获取请求参数 属性驱动 第二种，直接在action声明一个model
public class Login2Action extends ActionSupport {
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Override
public String execute() throws Exception {
HttpServletRequest request = ServletActionContext.getRequest();
// 2.判断用户名与密码是否正确
if ("tom".equals(user.getUsername()) && "123".equals(user.getPassword())) {
request.getSession().setAttribute("username", user.getUsername());
return SUCCESS;
} else {
request.setAttribute("login.message", "用户名或密码错误");
return "failer";
}
}
}
User.java文件：
package cn.itcast.domain;
public class User {
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;
}
@Override
public String toString() {
return "User [username=" + username + ", password=" + password + "]";
}
}
login2.jsp文件：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP ‘index.jsp‘ starting page</title>
</head>
<body>
${requestScope["login.message"] }<br>
<form action="${pageContext.request.contextPath}/login2" method="post">
username:<input type="text" name="user.username"><br>
password:<input type="password" name="user.password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
方式三案例： Login3Action.java文件：
package cn.itcast.action;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
import cn.itcast.domain.User;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
//获取请求参数 模型驱动
public class Login3Action extends ActionSupport implements ModelDriven<User> {
private User user = new User();
public User getModel() {
return user;
}
@Override
public String execute() throws Exception {
HttpServletRequest request = ServletActionContext.getRequest();
// 2.判断用户名与密码是否正确
if ("tom".equals(user.getUsername())
&& "123".equals(user.getPassword())) {
request.getSession().setAttribute("username", user.getUsername());
return SUCCESS;
} else {
request.setAttribute("login.message", "用户名或密码错误");
return "failer";
}
}
}
login3.jsp文件：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP ‘index.jsp‘ starting page</title>
</head>
<body>
${requestScope["login.message"] }<br>
<form action="${pageContext.request.contextPath}/login3" method="post">
username:<input type="text" name="username"><br>
password:<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
时间： 2024-10-07 06:29:59