JSP（2）

xiaoxiao2023-09-26 172

本系列博客汇总在这里：JSP 汇总

JSP 中的 Java 代码块就是最常见的动态信息。它分为三种： ① <%…%>：java 代码片段代码片段会原模原样的出现在真身中，不会有变动。正常的 Java 代码都可以在代码片段中出现。 ② <%=…%>：表达式在页面上打印数据表达式会在“真身”中输出，例如：<%=a%>，对应真身中的 out.print(a)。只能出现常量、变量，以及有返回值的方法调用，而且不能出现分号！即在 out.println() 的合法参数都可以！

<%=a%> 对应 out.println(a)；<%=”a”%> 对应 out.println(“a”)；<%=fun()%> 对应 out.println(fun())；<%=a;%> 对应 out.println(a;)，所以出错；<%=System.out.println(“hello”)%> 对应out.println(System.out.println(“hello”))，所以出错。

③ <%!..%>：声明声明对应 “真身” 中的属性和方法！

以上操作完整源码

index

<%@ page language="java" import="java.util.*" pageEncoding="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 'index.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">  </head> <body> <form action="/jsp_demo1/index.jsp" method="post"> 行:<input type="text" name="row"><br> 列:<input type="text" name="col"><br> <br> <input type="submit" value="打印"> </form> <hr> <% String row = request.getParameter("row"); String col = request.getParameter("col"); Integer rowInt = 1; Integer colInt = 1; if(row != null){ rowInt = new Integer(row); } if(col != null){ colInt = new Integer(col); } %> <table border="1px;"> <% for(int i = 1; i <= rowInt; i++){ %> <tr> <% for(int j = 1; j <= colInt; j++){ %> <td> <% out.print(i*j); %> </td> <% } %> </tr> <% } %> </table> </body> </html>

index1

<%@ page language="java" import="java.util.*" pageEncoding="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 'index.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">  </head> <body> <form action="/jsp_demo1/index1.jsp" method="post"> row:<input type="text" name="row"><br> col:<input type="text" name="col"><br> <input type="submit" value="print"> </form> <hr> <% String row = request.getParameter("row"); String col = request.getParameter("col"); Integer rowInt = 1; Integer colInt = 1; if(row != null){ rowInt = new Integer(row); } if(col != null){ colInt = new Integer(col); } %> <table border="1px;"> <% for(int i = 1; i <= rowInt; i++){ %> <tr> <% for(int j = 1; j <= colInt; j++){ %> <td> <%=i*j %> </td> <% } %> </tr> <% } %> </table> </body> </html>

index2

<%@ page language="java" import="java.util.*" pageEncoding="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 'index.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">  </head> <body> <%! public static final String driver = "com.mysql.jdbc.Driver"; public int add(int i, int j){ return i*j; } %> <% String name = "weiyuxuan"; %> <%=driver %> <%=add(10, 10) %> <%=name %> </body> </html>

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如有错误，欢迎指正！

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JSP（2）

目录

JSP 的 scriptlet