zoukankan html css js c++ java

Request功能

1.获取请求消息数据

获取请求行数据
获取请求头数据
获取请求体数据

请求空行没必要获取

1.获取请求行数据

　　GET /虚拟目录 /servlet路径 ?请求参数 HTTP/1.1

　　GET/day14/demo1?username=zhangsan

　　方法：

1.获取请求方式：GET

　　String getMethod()

2.获取虚拟目录：/day14。常用

　　String getContextPath()

3.获取servlet路径：/demo1

　　String getServletPath()

4.获取get方式的请求参数：username=zhangsan

　　String getQueryString()

5.获取请求的uri：/day14/demo1。常用

　　String getRequestURI()：返回/day14/demo1

　　String getRequestURL()：返回http://localhoust/day14/demo1

6.获取协议和版本：HTTP/1.1

　　String getProtocol()从ServletRequest继承而来

7.获取客户机的IP地址

　　String getRemoteAddr()从ServletRequest继承而来

可以帮你继承HttpServlet复写两个方法

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-22 12:55
 * 演示
 */
@WebServlet("/requestServlet")
public class RequestServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
//http://localhost:8080/ji/requestServlet?name=zhang&age=12
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//          1.获取请求方式：GET
//        可以来判断请求方，根据请求方式不同，做出不同的代码逻辑处理
//        HttpServlet内部已经写好了
        String method = request.getMethod();
        System.out.println(method);

//        2.获取虚拟目录：/day14
        String contextPath = request.getContextPath();
        System.out.println(contextPath);

//        3.获取servlet请求路径：/requestServlet
        String servletPath = request.getServletPath();
        System.out.println(servletPath);

//        4.获取get方式的请求参数：name=zhang&age=12
//        有更高级的
        String queryString = request.getQueryString();
        System.out.println(queryString);

//        5.获取请求的uri：
        String requestURI = request.getRequestURI();
        StringBuffer requestURL = request.getRequestURL();
//        /ji/requestServlet
        System.out.println(requestURI);
//        http://localhost:8080/ji/requestServlet
        System.out.println(requestURL);

//        6.获取协议和版本：HTTP/1.1
        String protocol = request.getProtocol();
        System.out.println(protocol);
        
//        7.获取客户机的IP地址：0:0:0:0:0:0:0:1
        String remoteAddr = request.getRemoteAddr();
        System.out.println(remoteAddr);
    }
}

2.获取请求头数据常用

　　方法

　　　　String getHeader(String name)：通过请求头的名称获取请求头的值。常用

　　　　Enumeration<String> getHeaderNames()：获取所有请求头的名称

package cn.itcast.web.request;

import jdk.nashorn.internal.objects.annotations.Where;

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;

/**
 * @author 旗木五五开
 * @create 2020-02-22 14:04
 * 获取所有请求头数据
 */
@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        获取所有请求头名称
        Enumeration<String> headerNames = request.getHeaderNames();
//        遍历
        while (headerNames.hasMoreElements()) {
//              获取请求头名称
            String name = headerNames.nextElement();
//              获取请求头对应的值
            String value = request.getHeader(name);
            System.out.println(name+"："+value);
        }
    }
}

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-22 17:05
 * user-agent访问的浏览器版本信息
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        演示获取请求头数据user-agent
//        不区分大小写
        String agent = request.getHeader("user-agent");

//        判断浏览器版本，不同版本不同操作解决浏览器兼容问题
//        contains判断是否存在包含关系
        if(agent.contains("Chrome")){
//            谷歌
            System.out.println("谷歌");
        }else if(agent.contains("Firefox")){
//            火狐
            System.out.println("火狐");
        }
    }
}

referer请求从哪里来

没有从别的超链接，点链接来访问
直接从浏览器地址栏输入
        无法获取
因为我没有从哪里来，直接访问的referer
获取的是null

不能直接访问，用超链接来实现
返回：http://localhost:8080/ji/login.html

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-23 12:35
 * referer请求从哪里来
 */
@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        演示获取请求头数据：referer请求从哪里来
        String referer = request.getHeader("referer");
        System.out.println(referer);
        /*
        没有从别的超链接，点链接来访问
        直接从浏览器地址栏输入
        无法获取
        因为我没有从哪里来，直接访问的referer
        获取的是null

        不能直接访问，用超链接来实现
        返回：http://localhost:8080/ji/login.html
         */

        //防盗链
        if (referer != null){
            if (referer.contains("ji")){
//                正常访问
                System.out.println("播放");
            }else{
//                盗链
                System.out.println("请访问优酷");
            }
        }
    }
}

创建另一个项目访问当前项目

http://localhost:8080/ji/requestDemo4
这个是直接访问referer的路径

这时候Tomcat默认部署（发布）的就是hehe项目

所以要新建一个Tomcat来部署（发布）servlet项目

不能有两个8080端口

启动hehe项目

启动servlet项目

从高清电影访问referer

在页面上显示

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-23 12:35
 * referer请求从哪里来
 */
@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        演示获取请求头数据：referer请求从哪里来
        String referer = request.getHeader("referer");
        System.out.println(referer);
        /*
        没有从别的超链接，点链接来访问
        直接从浏览器地址栏输入
        无法获取
        因为我没有从哪里来，直接访问的referer
        获取的是null

        不能直接访问，用超链接来实现
        http://localhost:8080/ji/login.html
         */

        //防盗链
        if (referer != null){
            if (referer.contains("ji")){
//                正常访问
                System.out.println("播放");

//                页面上显示
//                如果要写中文
                response.setContentType("text/html;charset=utf-8");
//                页面上显示的内容
                response.getWriter().write("播放");
            }else{
//                盗链
                System.out.println("请访问优酷");

//                页面上显示
//                如果要写中文
                response.setContentType("text/html;charset=utf-8");
//                页面上显示的内容
                response.getWriter().write("请访问优酷");
            }
        }
    }
}

hehe项目的高清电影访问

servlet上的login访问

3.获取请求体数据

只有POST请求方式才有请求体，在请求体post中封装了请求参数

request对象将请求体数据封装成流

步骤：

获取流对象
再从流东西中拿数据

获取流对象的方法：

字符流：BufferedReader getReader()：只能操作字符数据

字节流：ServletInputStream getInputStream()：可以操作所有类型数据，继承了InputStream，可以把它当做InputStream来用。

　　文件上传是写

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-24 12:14
 * getReader()案例
 */
@WebServlet("/requestDemo5")
public class RequestDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        1.获取请求消息体——请求参数
        BufferedReader br = request.getReader();
//        2.读取数据
        String line = null;
        while ((line = br.readLine())!=null){
            System.out.println(line);
        }
    }

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

    }
}

post参数的格式和get参数的格式是一样的，只不过存放的位置不一样。

常用的方法

获取虚拟目录：/day14。

　　String getContextPath()

获取请求的uri：/day14/demo1。

　　String getRequestURI()：返回/day14/demo1

　　String getRequestURL()：返回http://localhoust/day14/demo1

String getHeader(String name)：通过请求头的名称获取请求头的值。

2.其他功能：重要

基于第一类方法生成的，更方便使用request对象的方法

1.获取请求参数——通用方式（可以兼容get和post）常用

1.String getParameter(String name)：根据参数名称获取参数值。内部是通过流来获取的参数的值

　　　　　　　　　　　　　　　例如：username=zhang&password=123，传username返回zhang，传password返回123

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-24 14:33
 * 获取请求参数
 * 1.String getParameter(String name)：根据参数名称获取参数值
 */
@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        post获取请求参数
//        getParameter根据参数名称获取参数值
        String username = request.getParameter("username");
        System.out.println("post");
        System.out.println(username);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        get获取请求参数
//        String username = request.getParameter("username");
//        System.out.println("get");
//        System.out.println(username);
        this.doPost(request,response);
    }
}

2.String[] getParameterValues(String name)：根据参数名称获取参数值的数组。

　　　　　　　　　　　　　　　　　　　　例如hobby=xuexi&hobby=game，通过一个键可以获取两个值，把两个值封装成了一个数组。多用于复选框

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-24 14:33
 * 获取请求参数
 * 2.String[] getParameterValues(String name)：根据参数名称获取参数值的数组。
 */
@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        根据参数名称获取参数值的数组。
        String[] hobbies = request.getParameterValues("hobby");
        for (String hobby : hobbies) {
            System.out.println(hobby);
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

3.Enumeration<String> getParametNames()：获取请求参数的名称的枚举

方法是将发送请求页面中form表单里所有具有name属性的表单对象获取(包括button).返回一个Enumeration类型的枚举.

通过Enumeration的hasMoreElements()方法遍历.再由nextElement()方法获得枚举的值.此时的值是form表单中所有控件的name属性的值.

最后通过request.getParameter()方法获取表单控件的value值.

package cn.itcast.web.request;

import javax.naming.Name;
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;

/**
 * @author 旗木五五开
 * @create 2020-02-24 14:33
 * 获取请求参数
 * 3.Enumeration<String> getParametNames()：获取请求参数的名称的枚举
 */
@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Enumeration<String> parameterNames = request.getParameterNames();
        while (parameterNames.hasMoreElements()){
            String name = parameterNames.nextElement();
            System.out.println(name);
            String value = request.getParameter(name);
            System.out.println(value);
            System.out.println("-------------");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

没有获取到学习

4.Map<String,String[]> getParameterMap()：获取所有参数的map集合。常用

　　　　键是字符串，值是字符串数组。是为了防止上面那种情况，复选框只能获取一个值

package cn.itcast.web.request;

import javax.naming.Name;
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;
import java.util.Map;
import java.util.Set;

/**
 * @author 旗木五五开
 * @create 2020-02-24 14:33
 * 获取请求参数
 * 4.Map<String,String[]> getParameterMap()：获取所有参数的map集合
 */
@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        获取所有参数的map集合
        Map<String, String[]> parameterMap = request.getParameterMap();
//        遍历
        Set<String> keyset = parameterMap.keySet();
        for (String name : keyset) {
//            根据键获取值
            String[] values = parameterMap.get(name);
            System.out.println(name);
            for (String value : values) {
                System.out.println(value);
            }
            System.out.println("--------------");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

解决请求参数中文乱码

get方式：Tomcat8已经将乱码问题解决了

post方式：会乱码

解决方式：设置流的编码。

　　以后页面多的时候无论get还是post在获取请求参数的时候就写上这个代码
request.setCharacterEncoding("utf-8");

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-27 11:08
 */
@WebServlet("/requestDemo7")
public class RequestDemo7 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        1.设置流的编码
        request.setCharacterEncoding("utf-8");
//        获取请求参数username
        String username = request.getParameter("username");
        System.out.println(username);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

utf-8从哪里来的？

2.请求转发：一种在服务器内部的资源跳转方式

程序设计要求：功能单一，细化。不要把很多代码写到一个类里，方法里。不利于后期维护，不利于分工协作

请求转发就是为了这个，A做完，丢给B

步骤：

　　1.通过request对象，获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)

　　2.使用RequestDispatcher 对象转发：forward(ServletRequest request, ServletResponse response)

package cn.itcast.web.request;

import javax.servlet.RequestDispatcher;
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;

/**
 * @author 旗木五五开
 * @create 2020-02-27 13:47
 */
@WebServlet("/requestDemo8")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("8被访问了");
//        转发到demo9资源
        /*
        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");
        requestDispatcher.forward(request,response);
        不要这样写，把代码合成一行。
        因为requestDispatcher只用一次，只调用一次forward。这样写要单独创建变量不合算
        */
        request.getRequestDispatcher("/requestDemo9").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

特点：

　　1.浏览器地址栏不发生变化

　　2.只能转发到服务器的内部资源中

　　3.转发是一次请求

3.共享数据

A做完丢给B的时候，需要告诉B干到哪了，之间需要数据通信的

转发的时候才使用

步骤：

　　1.存储数据到request域中

　　2.转发

　　3.获取

package cn.itcast.web.request;

import javax.servlet.RequestDispatcher;
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;

/**
 * @author 旗木五五开
 * @create 2020-02-27 13:47
 */
@WebServlet("/requestDemo8")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("8被访问了");
//        1.存储数据到request域中
        request.setAttribute("msg","hello");
//        2.转发
        request.getRequestDispatcher("/requestDemo9").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

package cn.itcast.web.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;

/**
 * @author 旗木五五开
 * @create 2020-02-27 13:47
 */
@WebServlet("/requestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("9被访问了");
//        获取数据
        Object msg = request.getAttribute("msg");
        System.out.println(msg);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

4.获取ServletContext

ServletContext getServletContext()

package cn.itcast.web.request;

import javax.servlet.ServletContext;
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;

/**
 * @author 旗木五五开
 * @create 2020-02-27 14:31
 */
@WebServlet("/requestDemo10")
public class RequestDemo10 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = request.getServletContext();
        System.out.println(servletContext);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

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原文地址：https://www.cnblogs.com/rijiyuelei/p/12404637.html