request（获取请求信息、用户提交的数据）
request对象封装的是请求的数据，由服务器创建，作为实参传递给Servlet的方法，一个请求对应一个request对象，request对象可以获得请求数据。
1、获取请求行信息
（1）get提交
<body bgcolor="#f5f5dc"> <center> <h3>登录</h3> <form action="http://localhost:8080/MyServlet_war_exploded/abc" method="get"> 用户名：<input type="text" name="myname" size="12"><br> 密 码：<input type="password" name="mypassword" size="6" ><br><br> <input type="reset" value="取消"> <input type="submit" value="登录"> </form> </center> </body>
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ServletOutputStream out=response.getOutputStream(); String method= request.getMethod(); System.out.println(method); String URI=request.getRequestURI(); System.out.println(URI); StringBuffer URL=request.getRequestURL(); System.out.println(URL); String path=request.getContextPath(); System.out.println(path); }
运行结果：
getMethod()：获取提交方式
getRequestURI（）：URI
getRequestURL():URL
getContextPath():项目名称
（2）post提交
2、获取请求头信息
（1）获取请求头的一条信息：
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String header=request.getHeader("Host"); System.out.println(header); }
（2）获取请求头的所有信息：
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Enumeration<String> headerNames=request.getHeaderNames();//获取键的名字 while(headerNames.hasMoreElements()){ String headerName= headerNames.nextElement(); String headerValue=request.getHeader(headerName); System.out.println(headerName+":"+headerValue); } }
3、获取用户信息
（1）get提交：
<center>
<h3>登录</h3>
<form action="http://localhost:8080/MyServlet_war_exploded/abc" method="get">
用户名：<input type="text" name="userName" size="12"><br>
密 码：<input type="password" name="password" size="6" ><br><br>
<input type="reset" value="取消">
<input type="submit" value="登录">
</form>
</center>
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name=request.getParameter("userName"); String password=request.getParameter("password"); System.out.println(name+":"+password); }
（2）post提交：
post提交与get提交的运行结果相同。
4、对用户提交的数据的同键不同值的处理
（1）获取提交数据的值：
<form action="http://localhost:8080/MyServlet_war_exploded/abc" method="post"> <input type="checkbox" name="book" value="xiangzi">《骆驼祥子》<br> <input type="checkbox" name="book" value="xiyou">《西游记》<br> <input type="checkbox" name="book" value="shuihu">《水浒传》<br> <input type="checkbox" name="book" value="hongloumemg">《红楼梦》<br> <input type="checkbox" name="book" value="sanguo">《三国演义》<br> <input type="reset" value="取消"> <input type="submit" value="确定"> </form>
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String[] books= request.getParameterValues("book"); if(books!=null){ for(String shu:books){ System.out.println(shu); } } }
（2）获取名字：
<center>
<h3>您喜欢的书有哪些：</h3>
<form action="http://localhost:8080/MyServlet_war_exploded/abc" method="post">
<input type="checkbox" name="book1" value="xiangzi">《骆驼祥子》<br>
<input type="checkbox" name="book2" value="xiyou">《西游记》<br>
<input type="checkbox" name="book3" value="shuihu">《水浒传》<br>
<input type="checkbox" name="book4" value="hongloumemg">《红楼梦》<br>
<input type="checkbox" name="book5" value="sanguo">《三国演义》<br>
<input type="reset" value="取消">
<input type="submit" value="确定">
</form>
</center>
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Enumeration<String> names=request.getParameterNames(); while(names.hasMoreElements()){ System.out.println(names.nextElement()); } }
（3） 获取键和值:
public class MyServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Map<String,String[]> map=request.getParameterMap(); for(Map.Entry<String,String[]> entry:map.entrySet()){ System.out.println(entry.getKey()); for(String str:entry.getValue()){ System.out.println(str); } } }