可以使用 HttpServletRequest 的 getHeaderNames() 方法來讀取 HTTP 頭信息。該方法返回了一個(gè)枚舉，包含與當(dāng)前的 HTTP 請求相關(guān)的頭信息。
通過遍歷枚舉的方式可以獲取所有頭字段及相關(guān)值信息。
使用 hasMoreElements() 方法來確定何時(shí)停止循環(huán)，使用 nextElement() 方法來獲取每個(gè)參數(shù)的名稱。
具體測試代碼如下：

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Httphead extends HttpServlet {

    /**
         * Constructor of the object.
         */
    public Httphead() {
        super();
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        Enumeration headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()){
            String name = (String) headerNames.nextElement();
            String value = request.getHeader(name);
            out.println("head信息如下：");
            out.println("===========================");
            out.println("zi duan ming:"+name+" "+"zhi "+value);
            System.out.println("zi duan ming:"+name+" "+"zhi "+value);
        }
        
    }

    /**
        *獲取客戶端http頭信息測試代碼
         */
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html");
        
    }

}

運(yùn)行結(jié)果