1、HttpServletRequest概述:
我们在创建Servlet时,会重写service()方法、doGet()、doPost()方法,这些方法都有两个参数request(请求)和response(响应),service中的request是ServletRequset,而
doGet()和doPost()方法中的是:HttpServletRequest,HttpServletRequest是ServletRequest的子接口。
2、request的运行流程:
3、通过request获得请求行
(1)获得客户端的请求方式:
String method=request。getMethod()
(2)获得请求资源:
String URI=request。getRequestURI();
String URL=request.getRequestURL();
(3)获得WEB应用的名称
String webname=request.getContextPath();
(4)get提交url地址后的参数字符串
String queryString=request.getQueryString();
(5)获得访问的客户端IP地址
String ip=request.getRemoteAddr();
4.通过request获得请求头
(1)获取请求头
String agent=request.getHeader("User-Agent");
(2)
获取所有请求头名称
Enumeration<String> headerNames=request.getHeaderNames();
while(headerNames.hasMoreElements()){
//获取每个请求头名称
String headerName=headerNames.nextElement();
//跟距请求头获取请求值
String value=request.getHeader(headerName);
System.out.println(headerName);
System.out.println(value);
referer头的作用:执行该此访问的的来源
做防盗链跳转
package servlet; 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 ReferServlet extends HttpServlet { //防盗链 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取请求头中的referer String referer=request.getHeader("referer"); //不是以"http://localhosr:8080"开头的不能访问 if(referer!=null&&referer.startsWith("http://localhosr:8080")){ //认为可以正常访问 //结觉中文乱码 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("啊啊啊啊啊啊啊啊"); }else{ response.setContentType("text/html;charset=utf-8"); response.getWriter().write("不不不不不不不不不不不不不不不不不不不不不不不不"); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
5.通过request获得请求体解决中文乱码等问题
获取表单元素的值:String username=request.getParameter("username");
获取表单所有元素的值:Map<String,String[]> map=request.getParameterMap();
package servlet; import java.io.IOException; import java.util.Map; import java.util.Set; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class BodyServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //post方式解决中文乱码 request.setCharacterEncoding("utf-8"); //获取表单元素的值、 //get方式结觉中文乱码问题 String username=request.getParameter("username"); //username=new String //(username.getBytes("iso8859-1"),"utf-8"); String password=request.getParameter("password"); System.out.println(username+"..."+password); //获取表单所有元素的值 Map<String,String[]> map=request.getParameterMap(); Set<String> set=map.keySet(); for(String s:set){ String key=s; String[] value=map.get(s); //遍历数组 for(String s1:value){ System.out.println(s+":"+s1); } } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
6、request是一个域对象
request对象也是一个存储数据的区域对象,所以也具有如下方法:
setAttribute(xxxx, xxxxxxxxxxx)
getAttribute(String name)
removeAttribute(String name)
注意:request域的作用范围:一次请求中
7、request完成请求转发
获得请求转发器----path是转发的地址
RequestDispatcher getRequestDispatcher(String path)
通过转发器对象转发
requestDispathcer.forward(ServletRequest request, ServletResponse response)
转发:
package servlet; 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 Servlet01 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //向request中内放值 request.setAttribute("name","小红帽"); //请求转发 request.getRequestDispatcher("/Servlet02").forward(request, response); response.getWriter().write("servlet01"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package servlet; 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 Servlet02 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name=(String) request.getAttribute("name"); //解决中文乱码 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("servlet02"+name); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }