详解HTTP请求与响应基础及实例

GET /webDemo/Hellow HTTP/1.1  //请求行
Host: localhost:8080      //请求头
Connection: keep-alive
Accept: text/html
Accept-Encoding: gzip, deflate, sdch, br
Accept-Language: zh-CN,zh;q=0.8
                //空行
                //实体内容

HTTP/1.1 200 OK       //响应行
Server: Apache-Coyote/1.1  //相应头
Content-Length: 0
Date: Thu, 18 May 2017 13:21:23 GMT
              //空行
              //实体内容

//HttpServletRequest对象的常见方法
//请求行：
  request.getMethod(); //获取请求的提交方式
  request.getRequestURI(); //获取请求的URI
  request.getProtocol(); //获取请求的协议

//请求头：
  request.getHeader();  //获取请求头的强求值
  request.getHeaderName(); //获取请求头的所有名称

//实体内容：
  request.getInputStream(); //获取实体内容的输入流

package sun;

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

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

/**
 * Servlet implementation class Hellow
 */
@WebServlet("/Hellow")
public class GetRequestInfo extends HttpServlet {
  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //创建一个字符串来存储请求信息
    StringBuffer req = new StringBuffer();

    //获取请求行
    //获取请求方法，URI，HTTP版本 
    req.append(request.getMethod()+" "+request.getRequestURI()+" "+request.getProtocol()+"\n");

    //获取请求头
    //获取所有请求头
    Enumeration<?> headerName = request.getHeaderNames();
    while(headerName.hasMoreElements()){
      String header= (String)headerName.nextElement();
      req.append(header+": ");

      //获取指定请求头的值
      Enumeration<?> headerValue = request.getHeaders(header);
      while(headerValue.hasMoreElements()){
        req.append((String)headerValue.nextElement()+";");
      }
      req.append("\n");
    }

    req.append("\n");
    //获取实体内容
    InputStream input = request.getInputStream();
    byte[] buffer = new byte[1024];
    int len = 0;
    while((len=input.read(buffer))!=-1){
      String str = new String(buffer,0,len);
      req.append(str);
    }
    //输出请求信息
    System.out.println(req);
  }

}

package sun;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Response
 */
@WebServlet("/Response")
public class ModifyResponseInfo extends HttpServlet {


  /**
   * Description:
   * 通过HttpServletResponse对象，改变响应信息
   * */
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    //1、修改响应行
    resp.setStatus(404);
    //resp.sendError(404);

    //2、修改响应头
    resp.setHeader("Server","JBoss");

    //3、修改实体内容
    //发送字符类型的实体内容
    resp.getWriter().write("response");
    //发送字节类型的实体内容
    resp.getOutputStream().write("response".getBytes());


    //4、通过修改响应头，来请求重定向
    //发送要给302状态码，location的响应头
    /*
    当浏览器认识到302状态码的时候，会再次自动向服务器发出一个请求，请求的地址就是location的value值 
    请求重定向，一共向服务器发出2次请求
     */
    resp.setStatus(302);
    resp.setHeader("location","/webDemo/index.html");

    //也可以直接调用sendRedirect方法直接重定向
    //resp.sendRedirect("/webDemo/adv.html");

    //5、通过修改响应头，来实现定时刷新页面
    //一秒后刷新页面
    resp.setHeader("refresh","1");

    //也可以定时重定向页面
    //resp.setHeader("refresh","1;url=/webDemo/index.html");

    //6、通过修改响应头，来修改服务端和客户端的传输的数据类型
    //resp.setHeader("content-type","text/html")

    //也可以直接调用setContentType方法直接设置
    //在web.xml文件中找到对应的数据类型写法
    resp.setContentType("text/html");

  }

}

//获取GET方式参数：
request.getQueryString();

//获取POST方式参数：
request.getInputStream();

  //根据指定名字来获取参数值
    request.getParameter("name");
    request.getParameter("password");

    //获取所有参数名字
    Enumeration<String> params = request.getParameterNames();
    while(params.hasMoreElements()){
      String param = params.nextElement();
      String value = request.getParameter(param);
    }

name = new String(name.getBytes("iso-8859-1"),"utf-8");

<!-- A "Connector" represents an endpoint by which requests are received
     and responses are returned. Documentation at :
     Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
     Java AJP Connector: /docs/config/ajp.html
     APR (HTTP/AJP) Connector: /docs/apr.html
     Define a non-SSL/TLS HTTP/1.1 Connector on port 8080
  -->
  <!--在这里，加上属性URIEncoding，及指定编码值-->
  <Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443" URIEncoding="utf-8"/>