创建JavaBean实例：

<jsp:useBean id=”name” class=”” scope=”page/session/request/application”/>

id为类的另一个名字，class指定具体的类，scope表示范围，在scope的范围内查找是否有指定的属性存在

赋值

指定参数和值
<jsp:setProperty name="user" property="password" value="123" />
将指定参数的值赋值给JavaBean的属性
<jsp:setProperty name="user" param="pwd" property="password" />
通过自省机制自动匹配
<jsp:setProperty name="user" property="*" />

使用jsp:useBean的目的是减少Script的使用
一个典型的javabean: JavaBean.java

java">package Bean;
import java.io.Serializable;
public class JavaBean implements Serializable {
    private String name ;
    private String password;


    public JavaBean(String name, String password) {
        super();
        this.name = name;
        this.password = password;
    }
    public JavaBean() {
        super();
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    } 
    public boolean isValid(){
        if(name.equals("tom") && password.equals("123")){
            return true;
        }
        return false;
    }
}

使用jsp:Bean标签

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<jsp:useBean id="user" class="Bean.JavaBean" scope="page" />
<jsp:setProperty name="user" property="*" />

<html>
  <body>
  <font color='red'>
    <jsp:getProperty property="name" name="user"/>
    </font>
  </body>
</html>

web容器翻译后的Java代码

      Bean.JavaBean user = null;
      user = (Bean.JavaBean) _jspx_page_context.getAttribute("user", javax.servlet.jsp.PageContext.PAGE_SCOPE);
      if (user == null){
        user = new Bean.JavaBean();
        _jspx_page_context.setAttribute("user", user, javax.servlet.jsp.PageContext.PAGE_SCOPE);
      }

采用传统方式的做法：

<%@ page language="java" import="java.util.*,Bean.JavaBean" pageEncoding="UTF-8"%>
<html>
  <body>
    <%
    JavaBean user = (JavaBean)request.getAttribute("user");
    if(user == null){
        user = new JavaBean();
    }
    user.setName(request.getParameter("name"));
    user.setPassword(request.getParameter("pwd"));
    if(user.isValid()){
        out.println("登录成功");
    }else{
        out.println("登录失败");
    }
    %>
  </body>
</html