概述

request相关的API

代码一

@WebServlet("/servlet/RequestDemo1")
public class RequestDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /*
        * 	getRequestURL方法 -- 返回客户端发出请求完整URL
			getRequestURI方法 -- 返回请求行中的资源名部分
			getQueryString方法 -- 返回请求行中的参数部分
			getRemoteAddr方法 -- 返回发出请求的客户机的IP地址
			getMethod -- 得到客户机请求方式
			!!getContextPath -- 获得当前web应用虚拟目录名称 --
			* 在写路径时不要将web应用的虚拟路径的名称写死,
			* 应该在需要写web应用的名称的地方通过getContextPath方法动态获取
        * */
        StringBuffer url = request.getRequestURL();
        System.out.println("url:"+url);
        String uri = request.getRequestURI();
        System.out.println("uri:"+uri);
        String paramters = request.getQueryString();
        System.out.println("paramters:"+paramters);
        String ip = request.getRemoteAddr();
        System.out.println("ip:"+ip);
        String method = request.getMethod();
        System.out.println("method:"+method);
        String contextPath = request.getContextPath();
        System.out.println("contextPath:"+contextPath);

    }

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

代码二

@WebServlet("/servlet/RequestDemo2")
public class RequestDemo2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /*
        * 	getHeader(name)方法 --- String
			getHeaders(String name)方法 --- Enumeration<String>
            getHeaderNames方法 --- Enumeration<String>
        * */
        //根据指定的请求头名称来获取对应的值
        String host = request.getHeader("host");
        System.out.println("host1:"+host);
        //根据请求头的名称来获取一组值放在迭代器中
        Enumeration<String> hosts = request.getHeaders("host");
        //遍历迭代器
        System.out.println("打印host列表");
        while (hosts.hasMoreElements()){
            String value = hosts.nextElement();
            System.out.println("host:"+value);
        }
        //获取全部请求头的名称
        System.out.println("获取全部请求头的名称");
        Enumeration<String> heads = request.getHeaderNames();
        while (heads.hasMoreElements()){
            String headname = heads.nextElement();
            System.out.println(headname);
        }

    }

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

代码三

@WebServlet("/servlet/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        /*
        *
        * 	getParameter(String name) --- String 通过name获得值
			getParameterValues(String name)  --- String[ ] 通过name获得多值 checkbox
			getParameterMap()  --- Map<String,String[ ]> key :name value: 多值  将查询的参数保存在一个Map中
            getParameterNames()  --- Enumeration<String> 获得所有name
        *
        * */

        //指定服务器解码的码表
        request.setCharacterEncoding("utf8");

        //根据参数名来获取参数值
        System.out.println("根据参数名来获取参数值:");
        String username = request.getParameter("username");
        System.out.println("username:"+username);
        //根据参数名来获取多值
        String[] likes = request.getParameterValues("like");
        for(String l:likes){
            System.out.println("like:"+l);
        }

        //把参数名当作键，参数多值数组当做值存放在一个map中
        System.out.println("把参数名当作键，参数多值数组当做值存放在一个map中");
        Map<String, String[]> map = request.getParameterMap();
        for(Map.Entry<String,String[]> m:map.entrySet()){
            System.out.println(m.getKey()+":"+ Arrays.toString(m.getValue()));
        }

        //
        System.out.println("获得所有name:");
        Enumeration<String> names = request.getParameterNames();
        while (names.hasMoreElements()){
            String name = names.nextElement();
            System.out.println(name);
        }
    }

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

代码四【请求转发forward】

@WebServlet("/servlet/RequestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //创建调度器(指定资源跳转的位置)
        RequestDispatcher rd = request.getRequestDispatcher("/servlet/RequestDemo5");
       /* //
        response.getWriter().write("demo4");
        response.flushBuffer();//强制冲刷响应缓冲区*/
        System.out.println("begin...");
        //请求转发
        rd.forward(request,response);
        System.out.println("end...");
    }

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

@WebServlet("/servlet/RequestDemo5")
public class RequestDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("start...");
        //请求转发
        request.getRequestDispatcher("/servlet/RequestDemo6").forward(request,response);
        System.out.println("stop...");
    }

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

@WebServlet("/servlet/RequestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().write("demo6");
    }

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

代码五【域属性】

@WebServlet("/servlet/RequestDemo7")
public class RequestDemo7 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置域属性
        request.setAttribute("name", "小朴朴");
        //请求转发
        request.getRequestDispatcher("/servlet/RequestDemo8").forward(request, response);
    }

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

@WebServlet("/servlet/RequestDemo7")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取域属性值
        Object name = request.getAttribute("name");
        //
        System.out.println(name);
    }

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

代码六【servlet和jsp之间共享数据】

@WebServlet("/servlet/RequestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置域属性
        request.setAttribute("name","小朴朴");
        request.setAttribute("age","35");
        request.setAttribute("addr","北京");
        request.setAttribute("gender","男");
        //
        request.getRequestDispatcher("/index.jsp").forward(request,response);
    }

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

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
    <h3>获取RequestDemo9的域属性值</h3>
    姓名:<%=request.getAttribute("name")%><br/>
    年龄:<%=request.getAttribute("age")%><br/>
    地址:<%=request.getAttribute("addr")%><br/>
    性别:<%=request.getAttribute("gender")%><br/>
  </body>
</html>

代码七【请求包含include】

@WebServlet("/servlet/RequestDemo10")
public class RequestDemo10 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //创建调度器
        RequestDispatcher rd = request.getRequestDispatcher("/servlet/RequestDemo11");
        response.getWriter().write("demo10");
        //调用方法做请求包含
        rd.include(request,response);
    }

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

@WebServlet("/servlet/RequestDemo11")
public class RequestDemo11 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().write("demo11");
    }

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