Java Web基础小结之Jsp JavaBean

Java Web基础小结

In computing, Java Web Start (also known as JavaWS, javaws or JAWS) is a framework developed by Sun Microsystems (now Oracle) that allows users to start application software for the Java Platform directly from the Internet using a web browser. Some key benefits of this technology include seamless version updating for globally distributed applications and greater control of memory allocation to the Java virtual machine.

Jsp

执行原理

脚本

<%
    //java代码
    String username="admin";
%>

表达式

<%=username%>

指令元素

page指令

<%@ page language="java" contentType="text/html;charset=utf-8" %>

include指令

<%@ include file="login.jsp" %>

taglib指令

<%@ taglib uri="标签库URI" prefix="标签前缀" %>

动作元素

include

<jsp:include page="login.jsp" flush="true">
    <jsp:param name="username" value="admin" />
</jsp:include>

forward

<jsp:forward page="success.jsp">
    <jsp:param name="username" value="admin" />
</jsp:forward>

useBean

<jsp:useBean id="user" class="org.info.User" scope="page"/>

scope包括page,request,session,application

setProperty

<jsp:setProperty name="user" property="username" value="admin"/>
或者
<jsp:setProperty name="user" property="username" param="username"/>

getProperty

<jsp:getProperty name="user" property="username" />

得到String类型的值

内置对象

request

response

| ————————————- | —————————– |
| void setContentType(String name) | 设置响应内容的类型和字符编码 |
| void sendRedirect(String url) | 重定向到指定的URL资源 |

方法	作用
void setContentType(String name)	设置响应内容的类型和字符编码
void sendRedirect(String url)	重定向到指定的URL资源

out

session

application

方法	作用
void setAttribute(String name,Object value)	以键值对的方式存储application域属性
Object getAttribute(String name)	根据属性名获取属性值
void removeAttribute(String name)	根据属性名从application域移除属性

pageContext

page

<%=this.getServletInfo()%>

config

exception

<% exception.printStackTrace(response.getWriter()); %>

JavaBean

设计原则

Jsp使用JavaBean

<jsp:useBean>
<jsp:setProperty>
<jsp:getProperty>