request对象常用方法总结

た入场券 2021-06-24 15:58 604阅读 0赞

## JSP内置对象:request对象 ##

客户端的请求信息被封装在request对象中，通过它才能了解到客户的需求，然后做出响应。它是HttpServletRequest类的实例。request对象具有请求域,即完成客户端的请求之前,该对象一直有效。常用方法如下:

<table> 
 <thead> 
  <tr> 
   <th align="left">常用方法</th> 
   <th align="left">方法介绍</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left"><code>String getParameter(String name)</code></td> 
   <td align="left">返回name指定参数的参数值</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String[] getParameterValues(String name)</code></td> 
   <td align="left">返回包含参数name的所有值的数组</td> 
  </tr> 
  <tr> 
   <td align="left"><code>void setAttribute(String,Object)</code></td> 
   <td align="left">存储此请求中的属性</td> 
  </tr> 
  <tr> 
   <td align="left"><code>Object getAttribute(String name)</code></td> 
   <td align="left">返回指定属性的属性值</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getContentType()</code></td> 
   <td align="left">得到请求体的MIME类型</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getProtocol()</code></td> 
   <td align="left">返回请求用的协议类型及版本号</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getServerName()</code></td> 
   <td align="left">返回接受请求的服务器主机名</td> 
  </tr> 
  <tr> 
   <td align="left"><code>int getServerPort()</code></td> 
   <td align="left">返回服务器接受此请求所用的端口号</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getCharacterEncoding()</code></td> 
   <td align="left">返回字符编码方式</td> 
  </tr> 
  <tr> 
   <td align="left"><code>void setCharacterEncoding()</code></td> 
   <td align="left">设置请求的字符编码方式</td> 
  </tr> 
  <tr> 
   <td align="left"><code>int getContentLength()</code></td> 
   <td align="left">返回请求体的长度(以字节数)</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getRemoteAddr()</code></td> 
   <td align="left">返回发送此请求的客户端IP地址</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String getRealPath(String path)</code></td> 
   <td align="left">返回一虚拟路径的真实路径</td> 
  </tr> 
  <tr> 
   <td align="left"><code>String request.getContextPath()</code></td> 
   <td align="left">返回上下文路径</td> 
  </tr> 
 </tbody> 
</table>

## 测试代码: ##

*  reg.jsp
    
        <%@ page language="java" contentType="text/html; charset=utf-8"
        	pageEncoding="utf-8"%>
        <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
        <html>
        <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>Insert title here</title>
        </head>
        <body>
        	<h1>用户注册</h1>
        	<form name="regForm" action="request.jsp" method="get">
        		<table>
        			<tr>
        				<td>用户名:</td>
        				<td><input type="text" name="username" /></td>
        			</tr>
        			<tr>
        				<td>爱好:</td>
        				<td><input type="checkbox" name="favorite" value="read">读书
        				<input type="checkbox" name="favorite" value="music">音乐
        				<input type="checkbox" name="favorite" value="moive">电影
        				<input type="checkbox" name="favorite" value="internet">上网</td>
        			</tr>
        			<tr>
        				<td colspan="2"><input type="submit" value="提交" /></td>
        			</tr>
        		</table>
        	</form>
        	<br>
        	<br>
        	<a href="request.jsp?username=xxx">测试URL传参数</a>
        </body>
        </html>
 *  request.jsp
    
        <%@ page language="java" contentType="text/html; charset=utf-8"
        	pageEncoding="utf-8"%>
        <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
        <html>
        <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>Insert title here</title>
        </head>
        <body>
        	<h1>request内置对象</h1>
        	<%
        		request.setAttribute("password", "123456");
        	%>
        	用户名:<%=request.getParameter("username")%>
        	<br> 
        	爱好:
        	<%
        		if (request.getParameterValues("favorite") != null) {
        			String[] fav = request.getParameterValues("favorite");
        			for (int i = 0; i < fav.length; i++) {
        				out.println(fav[i] + "  ");
        			}
        		}
        	%>
        	<br> 
        	密码:<%=request.getAttribute("password")%><br> 
        	请求体的mime类型:<%=request.getContentType()%><br>
        	协议类型及版本号:<%=request.getProtocol()%><br> 
        	服务器主机名:<%=request.getServerName()%><br>
        	请求的端口号:<%=request.getServerPort()%><br> 
        	字符编码方式:<%=request.getCharacterEncoding()%><br>
        	请求体的长度:<%=request.getContentLength()%><br> 
        	返回发送请求的客户端IP地址:<%=request.getRemoteAddr()%><br>
        	返回虚拟路径的真实路径:<%=request.getRealPath("request.jsp")%><br> 
        	返回上下文路径:<%=request.getContextPath()%><br>
        
        </body>
        </html>

### 代码运行结果 ###

代码运行后浏览器中显示如下:  
![reg.jsp][]![request.jsp][]

--------------------

end.

[reg.jsp]: https://imgconvert.csdnimg.cn/aHR0cDovL2ltZy5ibG9nLmNzZG4ubmV0LzIwMTcxMjI3MjAzNzQ2MDA0?x-oss-process=image/format,png
[request.jsp]: /images/20210615/fcf506bdf32643d4b025fc7652c48ce1.png