获取请求头信息

获取请求头信息
req.getHeader(“headerKey”)
根据请求头中的key获取对应的value。
String headerValue=req.getHeader(“headerKey”);

req.getHeaderNames()
获取请求头中所有的key，该方法返回枚举类型。
Enumeration headerNames = req.getHeaderNames();

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
public class GetRequestHeaderServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //根据指定的key获取请求头信息
        String headerInfo = req.getHeader("Cookie");
        //获取请求头中所有数据
        Enumeration<String> headerNames = req.getHeaderNames();
        PrintWriter printWriter = resp.getWriter();
        printWriter.println(headerInfo);
        while (headerNames.hasMoreElements()){
            String key = headerNames.nextElement();
            String value = req.getHeader(key);
            printWriter.println(key+":"+value);
        }
        printWriter.flush();
        printWriter.close();
    }
}