JSP JavaBeans

Javabean的设计原则

公有类
无参公有构造方法
私有属性
getter和setter方法

在Jsp页面中如何使用Javabeans?

　　像使用普通Java类一样，创建JavaBeans实例。

　　在JSP页面中通常使用JSP动作标签使用JavaBeans。

　　　　useBeans动作

　　　　setProperty动作

　　　　getProperty动作

示例代码：

package com.po;


/**
 * 用户类
 */
public class Users {
    private String username;
    private String password;

    public Users(){

    }

    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;
    }
}

JavaBeans

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Login Demo</title>
</head>
<body>
    <h1>系统登录</h1>
    <hr>
    <form name="loginForm" action="do_login.jsp?myPass=888888&myUser=Vincent" method="post">
        <table>
            <tr>
                <td>Username:</td>
                <td><input type="text" name="username" value="" placeholder="username" /></td>
            </tr>
            <tr>
                <td>Password:</td>
                <td><input type="password" name="password" value="" placeholder="password" /></td>
            </tr>
            <tr>
                <td colspan="2" align="center"><input type="submit" value="Login"/></td>
            </tr>
        </table>
    </form>
</body>
</html>

HTML-Login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>DoLogin Demo</title>
</head>
<body>
    <jsp:useBean id="myUsers" class="com.po.Users" scope="page" />
    <h1>setProperty动作元素</h1>
    <hr>
    <!-- 根据表单自动匹配所有的属性 -->
    <jsp:setProperty name="myUsers" property="*" />
    Username: <%=myUsers.getUsername()%><br>
    Password: <%=myUsers.getPassword()%><br>

    <!-- 根据表单匹配所有部分的属性 -->
    <jsp:setProperty name="myUsers" property="username" />
    <jsp:setProperty name="myUsers" property="password" />
    Username: <%=myUsers.getUsername()%><br>
    Password: <%=myUsers.getPassword()%><br>

    <!-- 跟表单无关，通过手工赋值给属性 -->
    <jsp:setProperty name="myUsers" property="username" value="Menroe" />
    <jsp:setProperty name="myUsers" property="password" value="123456" />
    Username: <%=myUsers.getUsername()%><br>
    Password: <%=myUsers.getPassword()%><br>

    <!-- 通过Request获取参数属性 -->
    <jsp:setProperty name="myUsers" property="username" param="myUser" />
    <jsp:setProperty name="myUsers" property="password" param="myPass" />
    Username: <%=myUsers.getUsername()%><br>
    Password: <%=myUsers.getPassword()%><br>
</body>
</html>

HTML-doLogin.jsp