对于Web工程下URL地址,有两种写法: ① 绝对路径(“以’/ '开头的路径”) ② 相对路径(”不以’/ '开头的路径“)
对于绝对路径的URL(“以’/ '开头的路径”)需要根据这个URL是给服务器用的,还是客户端浏览器用的。
- ① 如果是给服务器用的,则"/"代表当前应用(如这里的RequestAndResponse或者是你的web项目路径WebContent、WebRoot);
- ② 如果是给客户端浏览器用的,则"/"代表当前站点(如这里的
http://localhost:8080/
或者是tomcat下的> webapps);
例子:
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
//1.转发类型:(给服务器用的地址)
//request.getRequestDispatcher("/page/test1.jsp").forward(request, response);//正确
//request.getRequestDispatcher("page/test1.jsp").forward(request, response);//相对于当前web项目 正确
//request.getRequestDispatcher("/RequestAndResponse/page/test1.jsp").forward(request, response); //HTTP Status 404 - /RequestAndResponse/RequestAndResponse/page/test1.jsp
//2.重定向类型:(给浏览器用的地址)
//response.sendRedirect("/page/test1.jsp");//error: http://localhost:8080/page/test1.jsp
//response.sendRedirect("page/test1.jsp");//正确
//response.sendRedirect("/RequestAndResponse/page/test1.jsp");//正确
//3.获取资源真实路径:(给服务器用的)
response.setHeader("Content-Type", "text/html;charset=utf-8");
OutputStream out = response.getOutputStream();
String path = this.getServletContext().getRealPath("/page/test1.jsp");//(1)正确:
String path = this.getServletContext().getRealPath("page/test1.jsp"); //(2)正确:
String path = this.getServletContext().getRealPath("/RequestAndResponse/page/test1.jsp");//(3)错误地址得到的是:E:\workspace\jsp\.metadata\.me_tcat\webapps\RequestAndResponse\RequestAndResponse\page\test1.jsp
//4.获取资源文件输入流对象:(给服务器用的)
InputStream in = this.getServletContext().getResourceAsStream("/page/test1.jsp");//正确:正确输出test1.jsp页面
InputStream in = this.getServletContext().getResourceAsStream("page/test1.jsp");//正确:正确输出test1.jsp页面
InputStream in = this.getServletContext().getResourceAsStream("/RequestAndResponse/page/test1.jsp");//错误java.lang.NullPointerException;
}
<%@ 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 'test2.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>
5. 给客户端浏览器用的地址-form action="">类型<br>
表单1:
<form action="/page/test1.jsp">
<input type="text" name="username" value="中国">
<input type="submit" value="提交" name="button">
(action="/page/test1.jsp" 地址错误=localhost:8080/page/test1.jsp)
</form>
<br>
表单2:
<form action="page/test1.jsp">
<input type="text" name="username" value="中国">
<input type="submit" value="提交" name="button">
(action="page/test1.jsp" 地址正确)
</form>
<br>
表单3:
<form action="/RequestAndResponse/page/test1.jsp">
<input type="text" name="username" value="中国">
<input type="submit" value="提交" name="button">
(action="/RequestAndResponse/page/test1.jsp" 地址正确)
</form>
<br>
表单4:
<form action="../page/test1.jsp">
<input type="text" name="username" value="中国">
<input type="submit" value="提交" name="button">
(action="../page/test1.jsp" 地址错误,跳转至http://localhost:8080/page/test1.jsp)
</form>
<br>
6. 给客户端浏览器用的地址 a标签
<a href="/page/test1.jsp">连接1(href="/page/test1.jsp" 地址错误)</a><p>
<a href="page/test1.jsp">连接2(href="page/test1.jsp" 地址正确)</a><p>
<a href="/RequestAndResponse/page/test1.jsp">连接3(href="/RequestAndResponse/page/test1.jsp" 地址正确)</a> <p>
<a href="../page/test1.jsp">连接4(href="../page/test1.jsp" 地址错误,跳转至http://localhost:8080/page/test1.jsp)</a><p>
</body>
</html>
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