Request 和 Response 原理

* Request 和 Response 原理:

Request 和 Response 原理
    * request对象和response对象由服务器创建,我们只需要在service方法中使用这两个对象即可
    
    * 继承体系结构:
        ServletRequest <--继承-- HttpServletRequest <--实现--- RequestFacade

* Response:封装响应消息,设置响应消息
    * 设置响应行:HTTP/1.1 200 ok
        * setStatus(int code):设置响应状态码
            * 演示重定向:302
                //简化版的重定向
                response.sendRedirect("http://192.168.1.66:8080/zxc/one");
                
                * 实现原理
                //1.设置响应状态码为 302
                response.setStatus(302);
                //2.设置响应头 location
                response.setHeader("location", "http://192.168.1.66:8080/zxc/one");
        
    * 设置响应头:
        * setHeader(String name,String value):
        * setDateHeader(String name, long date)
        * setIntHeader(String name, int value)

* 设置响应体:
        * getOutputStream():发送字节数据
            * 验证码:
                * 防止恶意注册
        
        * getWriter():发送字符数据
            * 发送中文数据时,需要在获取流之前设置编码方式,并且要告诉客户端浏览器,服务器使用的编码方式
                //简化版设置编码的方式
                response.setContentType("text/html;charset=utf-8");

 package Response;

 import java.io.IOException;
import java.io.PrintWriter; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class ResponseTest extends HttpServlet { private static final long serialVersionUID = -3007244764565301466L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* 设置响应消息体:
* getOutputStream():发送字节数据
* getWriter():发送字符数据
*/
/*
//设置流的编码方式
response.setCharacterEncoding("utf-8");
//告诉客户端,服务器使用的编码方式
response.setHeader("content-type", "text/html;charset=utf-8");
*/ //设置编码方式
response.setContentType("text/html;charset=utf-8");
//获取字符输出流
PrintWriter pw = response.getWriter();//默认编码是 iso-8859-1
//设置数据
pw.write("<h3>你好啊 ! response...</h3>");
//刷新
pw.flush();
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response); } }

* Request:封装请求消息,获取请求消息
    * 获取请求消息:
        * 获取请求行:GET /day08/req1?name=zs HTTP/1.1
            * getMethod():获取请求方式
            * getContextPath():获取虚拟目录
            
            * getRequestURI():获取URI(统一资源标识符)    /day07/one        /one
            * getRequestURL():获取URL(统一资源定位符)    http://localhost:8080/day07/one
            * getRemoteAddr():获取客户机的IP地址
            
            * getQueryString():get方式获取请求参数
        * 获取请求头:
            * String getHeader(String name)
            * long getDateHeader(String name)
            * int getIntHeader(String name)

 package Request;

 import java.io.IOException;

 import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class RequestTest2 extends HttpServlet { private static final long serialVersionUID = -5095708647887091449L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { //获取请求头
String agent = request.getHeader("user-agent");
System.out.println(agent); if(agent.contains("MSIE")){
System.out.println("IE 来了...");
}else if(agent.contains("Firefox")){
System.out.println("火狐 来了...");
}else if(agent.contains("Chrome")){
System.out.println("谷歌 来了...");
}else{
System.out.println("其他浏览器 来了...");
} System.err.println("..............................");
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response); } }

* 获取请求体:封装post请求参数数据
            * BufferedReader getReader():
            * ServletInputStream getInputStream():
        
        
            * 通用的获取请求参数的方式:
                * String getParameter(String name):根据键名获取值
                * String[] getParameterValues(String name):根据键名获取值的数组,一般用于复选框
                * Map<String,String[]> getParameterMap():获取所有参数的map集合
                * Enumeration getParameterNames():获取所有的键名枚举
        Request 和 Response 原理

 package Request;

 import java.io.IOException;

 import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class RequestTest extends HttpServlet { private static final long serialVersionUID = 4919849090529066482L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { //演示获取请求行数据 System.out.println(request.getMethod());//获取请求发式
System.out.println(request.getContextPath());//获取虚拟目录
System.out.println(request.getRequestURI());//获取URI
System.out.println(request.getRequestURL());//获取URL
System.out.println(request.getRemoteAddr());//获取ip
System.out.println(request.getQueryString());//获取请求参数
System.out.println(request.getProtocol());//获取协议 System.err.println("--------------------------"); response.sendRedirect(request.getContextPath()+"/index.jsp");
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response); } }

* 请求参数中文乱码问题:
                1.通用:
                    //1.解码  iso
                    byte[] bytes = username.getBytes("iso-8859-1");
                    //2.编码 utf-8
                    username = new String(bytes, "utf-8");
                2.post专用
                    //设置输入流的编码为 utf-8
                    request.setCharacterEncoding("utf-8");
    
    * 域对象:代表一次请求
    Request 和 Response 原理
    * 请求转发:
        * 转发特点:
            1.地址栏不发生变化
            2.一次请求,一次响应
            3.不能转发外部站点

 package Request;

 import java.io.IOException;

 import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class RequestTest7 extends HttpServlet { private static final long serialVersionUID = 3744695995118989884L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { System.out.println("req7 被访问了。。。"); //存储数据
request.setAttribute("msg", "hehehe..."); //转发至req
request.getRequestDispatcher("/req").forward(request, response);
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response); } }

* 重定向的特点:
            1.地址栏发生变化
            2.两次请求,两次响应
            3.可以访问外部的站点

 package Response;

 import java.io.IOException;

 import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class ResponseTest2 extends HttpServlet { /**
*
*/
private static final long serialVersionUID = -449184946348811489L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { System.out.println("resp2 被访问了。。。");
//演示重定向
//1.设置相应状态码 302
response.setStatus(302); //2.设置相应头 location
//注意: http:// 不可以少
//response.setHeader("location", "http://192.168.1.66:8080/zxc/resp"); //简化版的重定向
response.sendRedirect("http://192.168.1.66:8080/zxc/resp");
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response); } }
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