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网站蜘蛛记录器 v1.2,wordpress en,视频网页制作教程,uc浏览器访问网站一、概述 1、Request与Response Request 对象 和 Response 对象是由服务器（Tomcat）创建的Request 对象是来获取请求消息Response 对象是来设置响应消息 2、Request 体系结构 3、Servlet 体系结构 二、HttpServletRequest HttpServletRequest对象代表客户…

一、概述

1、Request与Response

  • Request 对象 和 Response 对象是由服务器（Tomcat）创建的
  • Request 对象是来获取请求消息
  • Response 对象是来设置响应消息

2、Request 体系结构

在这里插入图片描述

3、Servlet 体系结构

在这里插入图片描述

二、HttpServletRequest

        HttpServletRequest对象代表客户端的请求，当客户端通过HTTP协议访问服务器时，HTTP请求头中的所有信息都封装在这个对象中，通过这个对象提供的方法，可以获得客户端请求的所有信息

三、request 获取请求行的数据

先写一个 input.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>文本输入框</title>
</head>
<body>
<form action="servletRequestDemo01" method="get"><input type="text" name="username" value="name"><br><input type="text" name="password" value="password"><br><input type="submit" value="get 提交">
</form><br>
<form action="servletRequestDemo01" method="post"><input type="text" name="username" value="name"><br><input type="text" name="password" value="password"><br><input type="submit" value="post 提交">
</form><br>
</body>
</html>

再写一个 Servlet 类 ，类名为：ServletRequestDemo01.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/servletRequestDemo01")
public class ServletRequestDemo01 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");//解决请求乱码response.setCharacterEncoding("utf-8");//解决响应乱码doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求方式：GetString method = request.getMethod();System.out.println("获取的请求方式为：" + method);//获取虚拟目录String contextPath = request.getContextPath();System.out.println("获取的虚拟目录为：" + contextPath);//获取请求的路径String servletPath = request.getServletPath();System.out.println("获取请求的路径为：" + servletPath);//获取Get方式的请求参数String queryString = request.getQueryString();System.out.println("获取Get方式的请求参数为：" + queryString);//获取URI相对服务器路径 及 URL全路径String requestURI = request.getRequestURI();System.out.println("获取URI相对服务器路径为：" + requestURI);StringBuffer requestURL = request.getRequestURL();System.out.println("获取URL全路径为：" + requestURL);//获取HTTP协议及版本号String protocol = request.getProtocol();System.out.println("获取HTTP协议及版本号：" + protocol);//获取客户机的IP地址String remoteAddr = request.getRemoteAddr();System.out.println("获取客户机的IP地址：" + remoteAddr);}
}

控制台显示：

 总结：

  • String method = request.getMethod();获取请求方式：Get
  • String contextPath = request.getContextPath();获取虚拟目录
  • String servletPath = request.getServletPath();获取请求的路径
  • String queryString = request.getQueryString();获取Get方式的请求参数
  • String requestURI = request.getRequestURI();获取URI相对服务器路径
  • StringBuffer requestURL = request.getRequestURL();获取URL全路径
  • String protocol = request.getProtocol();获取HTTP协议及版本号
  • String remoteAddr = request.getRemoteAddr();获取客户机的IP地址
  • String remoteHost = request.getRemoteHost();
  • int remotePort = request.getRemotePort();
  • String remoteUser = request.getRemoteUser();
  • String pathInfo = request.getPathInfo();
  • String localAddr = request.getLocalAddr();获取WEB服务器的IP地址
  • String localName = request.getLocalName();获取WEB服务器的主机名

四、request 获取请求头的数据

1、获取请求头的方法：

  • String getHeader(String name):通过请求头的名称获取请求头的值
  • Enumeration<String> getHeaderNames():获取所有的请求头名称

2、实例：新建文件 ServletRequestDemo03.java 执行 service 方法

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;@WebServlet("/ServletRequestDemo03")
public class ServletRequestDemo03 extends HttpServlet {@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取所有请求头数据Enumeration<String> headerNames = req.getHeaderNames();//遍历while (headerNames.hasMoreElements()){String name = headerNames.nextElement();String value = req.getHeader(name);//根据 neme 获取请求头的 valueSystem.out.println("请求头名为：" + name + "---------对应请求头的值为：" + value);}}
}

查看控制台：

在这里插入图片描述

 3、实例
查看客户端是谷歌浏览器还是火狐浏览器

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo04")
public class ServletRequestDemo04 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求头数据 user_agentString agent = request.getHeader("user-agent");//判断浏览器的 agent 版本if (agent.contains("Chrome")){System.out.println("客户端使用的是谷歌浏览器");}else if (agent.contains("Firefox")){System.out.println("客户端使用的是火狐浏览器");}}
}

4、实例
防盗链

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo05")
public class ServletRequestDemo05 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求头的数据 refererString referer = request.getHeader("referer");System.out.println(referer);//防盗链if (referer != null){if (referer.contains("ServletRequestDemo04")){response.setContentType("text/html;charset=utf-8");response.getWriter().write("播放电影");}else {//盗链response.setContentType("text/html;charset=utf-8");response.getWriter().write("想看电影来快播.....");}}}
}

五、request 获取请求体的数据

1、提醒：

请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数获取流对象，再从流对象中拿数据。

2、方法：

  • BufferedReader getReader()：获取字符输入流，只能操作字符数据
  • ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据

3、实例
先写一个 input.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>文本输入框</title>
</head>
<body>
<form action="ServletRequestDemo06" method="post"><!--只能使用POST方式才能获取请求体--><input type="text" name="username" value="请输入姓名"><br><input type="text" name="password" value="请输入密码"><br><input type="submit" value="提交">
</form>
</body>
</html>

再写一个 Java 类 ：ServleRequestDemo06.java 获取提交数据

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;@WebServlet("/ServletRequestDemo06")
public class ServletRequestDemo06 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求体消息，请求参数BufferedReader bufferedReader = request.getReader();//获取字符流String line = null;while ((line = bufferedReader.readLine()) != null){//读取一行数据System.out.println(line);}}
}

六、获取请求的通用方式

不论get请求方式还是post请求方式都可以使用下列方法来获取请求参数

  • String getParameter(String name):根据参数名称获取参数值
  • String[] getParameterValues(String name)：根据参数名称获取参数值的数组，如：hobby=xx&hobby=game
  • Enumeration<String> getParameterNames():获取所有请求的参数名称
  • Map<String,String[]> getParameterMap():获取所有参数的map集合

案例：
先写一个 regist.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>注册页面</title>
</head>
<body>
<form action="/project/ServletRequestDemo07" method="post"><input type="text" placeholder="请输入用户名" name="username"><br><input type="text" placeholder="请输入密码" name="password"><br><input type="checkbox" name="hobby" value="game">游戏<input type="checkbox" name="hobby" value="study">学习<br><input type="submit" value="注册">
</form>
</body>
</html>

再写一个测试类 ServletRequstDemo07.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.Map;@WebServlet("/ServletRequestDemo07")
public class ServletRequestDemo07 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");//根据参数名称获取参数值System.out.println(username);String[] hobby = request.getParameterValues("hobby");//根据参数名称获取参数数组System.out.println(Arrays.toString(hobby));//只能得到一个参数String hobby2 = request.getParameter("hobby");System.out.println(hobby2);System.out.println("--------------");//得到所有的参数名Enumeration<String> names = request.getParameterNames();while (names.hasMoreElements()) {String name = names.nextElement();String value = request.getParameter(name);System.out.println(name + ":\t" + value);}System.out.println("-----------");//得到所有的参数的Map形式Map<String, String[]> parameterMap =  request.getParameterMap();for (String key : parameterMap.keySet()) {System.out.println(key + Arrays.toString(parameterMap.get(key)));}}
}

七、中文乱码的解决

  1. get方式：tomcat 8 已经将get方式乱码问题解决了
  2. post方式：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

案例：
新建 input02.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>登录</title>
</head>
<body>
<form action="/project/ServletRequestDemo08" method="post"><input type="text" name="username" value="请输入用户名"><br><input type="text" name="password" value="请输入密码"><br><input type="submit" value="提交">
</form>
</body>
</html>

再建一个 ServletRequestDemo08.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo08")
public class ServletRequestDemo08 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置编码格式request.setCharacterEncoding("utf-8");//获取参数usernameString username = request.getParameter("username");System.out.println(username);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

八、请求转发

一种在服务器内部的资源跳转方式

通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)
使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response)

特点：

浏览器地址栏路径不发生变化，只能转发到当前服务器内部资源中，转发是一次请求。

案例：
新建一个ServletRequestDemo09.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo09")
public class ServletRequestDemo09 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//请求转发，转发路径不需要加虚拟目录，重定向需要加虚拟目录request.getRequestDispatcher("/ServletRequestDemo10").forward(request,response);}
}

新建一个ServletRequestDemo10.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo10")
public class ServletRequestDemo10 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.getWriter().print("ServletRequestDemo10 被访问了，通过 ServletRequestDemo9 请求转发过来的");}
}

当访问ServletRequestDemo09.java 时，它直接跳到ServletRequestDemo10.java

九、共享数据

域对象：一个有作用范围的对象，可以在范围内共享数据
request域：代表一次请求的范围，一般用于请求转发的多个资源中共享数据

方法：

  • void setAttribute(String name,Object obj):存储数据
  • Object getAttitude(String name):通过键获取值
  • void removeAttribute(String name):通过键移除键值对

案例：
新建一个ServletRequestDemo09.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo09")
public class ServletRequestDemo09 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//在request作用域存储数据request.setAttribute("name1","存入数据的Object01");request.setAttribute("name2","存入数据的Object02");request.setAttribute("name3","存入数据的Object03");request.setAttribute("name4","存入数据的Object04");//请求转发，转发路径不需要加虚拟目录，重定向需要加虚拟目录request.getRequestDispatcher("/ServletRequestDemo10").forward(request,response);}
}

新建一个ServletRequestDemo10.java

package cn.lemon.request;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/ServletRequestDemo10")
public class ServletRequestDemo10 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {Object obj = request.getAttribute("name1");//取出数据response.getWriter().print(obj);//打印数据response.getWriter().print("ServletRequestDemo10 被访问了，通过 ServletRequestDemo9 请求转发过来的");}
}

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