使用servlet和“ setHeader”方法无法重定向请求

一尘不染

使用servlet和“ setHeader”方法无法重定向请求

tomcat

我是servlet开发的新手，正在阅读一本电子书，发现我可以使用重定向到另一个网页

setHeader("Location", "http://www.google.com")

但这不起作用，因为我将这段代码编写为：

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ModHelloWorld extends HttpServlet{
        public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException{
//              response.addHeader("Location", "http://www.google.com");
                response.setHeader("Location", "http://www.google.com");
                response.setContentType("text/html");
                PrintWriter pw = response.getWriter();
                pw.println("<html><head><title>Modified Hello World</title></head><body>");
                pw.println("<h1>");
                //getInitParameter function reads the contents ot init-param elements.
                pw.println(getInitParameter("message"));
                pw.println("</h1>");
                pw.println("</body></html>");
                pw.close();
        }
}

我已经使用程序检查了标头，以获取网页的标头，如下所示：

import java.net.*;
import java.io.*;
class getHeaders{
    public static void main(String args[]){
        URL url = null;
        URLConnection urc = null;
        try {
            url = new URL(args[0]);
            urc = url.openConnection();
            for(int i=0 ; ; i++) {
                String name = urc.getHeaderFieldKey(i);
                String value = urc.getHeaderField(i);
                if(name == null && value == null)//both null so end of header
                    break;
                else if(name == null){//first line of header{
                    System.out.println("Server HTTP version, Response code: ");
                    System.out.println(value);
                    System.out.println("ENd of first header field");
                } else {
                    System.out.println("name of header is: " + name + " and its value is : " + value);
                }
            }
        } catch(MalformedURLException e){
            System.out.println("Malformed URL " + e.getMessage());
        } catch(IOException e){
            e.printStackTrace();
        }
    }
}

我得到的输出为：

Server HTTP version, Response code: 
HTTP/1.1 200 OK
ENd of first header field
name of header is: Server and its value is : Apache-Coyote/1.1
name of header is: Location and its value is : http://www.google.com
name of header is: Content-Type and its value is : text/html
name of header is: Content-Length and its value is : 101
name of header is: Date and its value is : Sat, 05 Mar 2011 15:27:29 GMT

但是我没有从浏览器重定向到google的页面。

提前致谢：）

阅读 734

2020-06-16

共1个答案

一尘不染

如您所见，响应仍然是HTTP/1.1 200 OK。要指示重定向，您需要发送回302状态代码：

response.setStatus(HttpServletResponse.SC_FOUND); // SC_FOUND = 302

2020-06-16