Request对象及其相关方法

1.request对象是由服务器创建的.request对象是来获取请求消息

2.常用的方法

•   获取请求行数据

                1.获取请求方式:  *String getMethod()

                2.(重点)获取虚拟目录:  *String getContextPath()

                3.获取Servlet路径:  *String getServletPath()

                4.获取get方式请求参数: *String getQueryString()

                5.(重点)获取请求的URI:

                        *String getRequestURI() ;*URI:统一资源标识符:

                        *StringBuffer getRequestURL() ；*URL:统一资源定位符:

                        *标识符的范围比定位符的范围大

                6.获取协议以及版本号 *String getProtocol();

                7.获取客户机的IP地址 *String getRemoteAddr():

• 获取头数据

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

        *Enumeration<String> getHeaderNames():获取所有的请求头名称

• 获取体数据

        *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
        *步骤:
            1.获取流对象
                *BufferedReader getReader():获取字符输入流,只能操作字符数据
                *ServletInputStream():获取字节输入流,可以操作所有类型数据

            2.再从流对象中拿数据

•  其他方法:

                1.String getParameter(String name):根据参数名称获取参数值

                2.String[] getParameterValues(String name):根据参数名称获取参数值的数组                 3.Enumeration<String> getParameterNames():获取所有请求的参数名称                 4.Map<String,String[]> getParameterMap():获取所有参数的map集合

代码演示:

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("/servletDemo1")
public class servletDemo1 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req,resp);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     
        // 1.获取请求方式:  GET  *String getMethod()
        String method = req.getMethod();
        System.out.println(method);

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

        //3.获取Servlet路径: /demo1 *String getServletPath()
        String servletPath = req.getServletPath();
        System.out.println(servletPath);

        // 4.获取get方式请求参数: name=Zhangsan *String getQueryString()
        String queryString = req.getQueryString();
        System.out.println(queryString);

        //5.(重点)获取请求的URI: /day14/demo1
        // *String getRequestURI()  :/day14/demo
        //*StringBuffer getRequestURL()  :http://localhost/day14/demo1
        StringBuffer requestURL = req.getRequestURL();
        System.out.println(requestURL);
        String requestURI = req.getRequestURI();
        System.out.println(requestURI);

        //6.获取协议以及版本号 *String getProtocol();
        String protocol = req.getProtocol();
        System.out.println(protocol);

        //7.获取客户机的IP地址 *String getRemoteAddr():
        String remoteAddr = req.getRemoteAddr();
        System.out.println(remoteAddr);
    }
}