shangrila-xiu

112
文章
101
分类
33
标签

jsp_neizhiduixiang

jsp的内置对象

jsp的常用的内置对象有：out、request、response、session、application、Page、pageContext、

jsp的常用的内置对象有：out、request、response、session、application、Page、pageContext、exception 、config

1、out对象

(1)打印一首诗

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'out.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
    <h1>out内置对象：out对象是JSPWriter类的实例，是像客户端输出内容常用的对象。</h1>
    <h4>常用的方法如下：</h4>
    1、void println()向客户端打印字符串<br>
    2、void clear()清除缓冲区内容，如果在flush之后调用会抛出异常<br>
    3、void clearBuffer();清除缓冲区的内容，如果在flush之后调用不会抛出异常与上面的一个相似<br>
    <hr>
    
    <%
    	out.println("<h2>静夜思</h2>");
    	out.println("床前明月光<br>");
    	out.println("疑是地上霜<br>");
    	out.flush();
    	//out.clear();//这里会抛出异常，就不会再执行了
    	//out.clearBuffer();//不会抛出异常，后面的程序仍然执行
    	out.println("举头望明月<br>");
    	out.println("低头思故乡<br>");
     %>
     <hr>
     缓冲区大小；<%=out.getBufferSize() %>byte<br>
     缓冲区剩余大小：<%=out.getRemaining() %>byte<br>
     是否自动清空缓冲区：<%=out.isAutoFlush() %><br>
     
     <hr>
     
  </body>
</html>

(2)打印九九乘法表

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'Nine-nine.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  <!-- 定义函数 -->
  	<%!
  	//返回九九乘法表对应的HTML代码，通过表达式来调用，在页面上显示
  	String printMultiTable()
  	{
  		String s="";
  		for(int i=1;i<=9;i++){
  		for(int j=1;j<=i;j++){
  			s+=i+"*"+j+"="+(i*j)+"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
  		}
  			s+="<br>";//追加换行标签
  		}
  		return s;
  	}
  	
  	
  	//jsp内置out对象，使用脚本方式，打印九九乘法表
  	void printMultiTable2(JspWriter out) 
  	throws Exception//对两个out.println抛出异常
  	{
  		for(int i=1;i<=9;i++){
  		for(int j=1;j<=i;j++){
  			out.println(i+"*"+j+"="+(i*j)+"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
  		}
  			out.println("<br>");//追加换行标签
  		}
  	}
  	 %>
    <h1>打印九九乘法表</h1> <br>
    <hr>
    <%=printMultiTable() %><hr>
    <%printMultiTable2(out); %>
</body>
</html>

2、request对象（上）

request常用对象

常用的两个，也比较容易弄混的两个request.getParameter(String args[])、request.getParameterValues(String args[])

例：

主页面req.jsp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'reg.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  
     <h2>用户注册</h2>
    <hr>
    <form name="regForm" action="request.jsp" method="post">
    <table>
    <tr><td>用户名：<input type="text" name="username" /></td></tr>
     <tr>
	     <td>爱好：
	     <td><input type="checkbox" name="favo" value="read" >读书</td>
	     <td><input type="checkbox" name="favo" value="swim" >游泳</td>
	     <td><input type="checkbox" name="favo" value="ball" >打球</td>
     </tr>
     <tr><td colspan="2"><input type="submit" value="提交"></td></tr>
   </table>
   </form>
     <br>
    <br>
    <a href="request.jsp?username=秀儿">URL传参数</a>
  </body>
</html>

跳转到request.jsp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'request.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  <h1>request内置对象</h1>
  <%
  		request.setCharacterEncoding("utf-8");//解决中文乱码问题,无法解决url乱码 。如果要解决url问题，在Tomcat下的server.xml里找到Connector,并在后面配置URIEncoding="utf-8"
   %>
   用户名：<%=request.getParameter("username") %><br>
   爱好：<%
      if(request.getParameterValues("favo")!=null)
      {
	   		String[] fav=request.getParameterValues("favo");
	   		for(int i=0;i<fav.length;i++){
	   		out.println(fav[i]+"&nbsp;"+"&nbsp;");
	   		 }
   		}
    %>
   
    
  </body>
</html>

3、request与response

request与response