JavaBean
java代码:
public class Person { private String name = "aaa"; //getClass() private int age; private Date birthday; public Person() { super(); } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } }
jsp代码:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>jsp:usebean标签的使用</title> </head> <body> <!-- usebean标签的标签体只在usebean标签实例化bean时才执行 --> <jsp:useBean id="person" class="cn.itcast.domain.Person" scope="session"> bbbb </jsp:useBean> <%=person.getName()%> </body> </html>PS:第一次访问jsp页面,在session域中查询id为person的bean,没有找到,则在session域中实例化一个id为person的bean,所以实例化的时候输出标签体内容 bbbb,然后输出person的name属性aaa。 而第二次访问该jsp页面时,session域中有id为person的bean,所以不会实例化,也就不会输出标签体的内容,直接输出name属性。
jsp代码:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>jsp:setProperty标签</title> </head> <body> <jsp:useBean id="person" class="cn.itcast.domain.Person"></jsp:useBean> <!-- 手工为bean属性赋值 --> <jsp:setProperty name="person" property="name" value="xxxx"/> <%=person.getName() %><br/> <!-- 用请求参数给bean的属性赋值 http://localhost:8080/day09/2.jsp?name=yyyyyyyyyyyyyyyyyyyyyyyy--> <jsp:setProperty name="person" property="name" param="name"/> <!-- http://localhost:8080/day09/2.jsp?name=yyyyyyyyyyyyyyyyyyyyyyyy&age=12 --> <jsp:setProperty name="person" property="age" param="age"/> <!-- 支持8种基本数据类型的转换(把客户机提交的字符串,转成相应的8种基本类型,赋到bean的属性上) --> <!-- http://localhost:8080/day09/2.jsp?name=yyyyyyyyyyyyyyyyyyyyyyyy&age=12&birthday=1980-09-09 --> <%-- <jsp:setProperty name="person" property="birthday" value="<%=new Date() %>" /> --%> <%=person.getName() %><br/> <%=person.getAge() %><br/> <%=person.getBirthday() %><br/> <br/>====================================<br/> <!-- 用所有的请求参数为bean赋值 --> <jsp:setProperty name="person" property="*" /> <%=person.getName() %><br/> <%=person.getAge() %><br/> <!-- 因为jsp页面中最好不出现java代码,所以最好用以下代码输出 --> <jsp:getProperty name="person" property="name"/> <jsp:getProperty name="person" property="age"/> <jsp:getProperty name="person" property="birthday"/> </body> </html>