Servlet-ServletRequest
Servlet-Service参数
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
}
ServletRequest：封装了请求信息，可以从中获取到任何的请求信息
ServletResponse：封装了响应信息，如果想给用户什么响应，具体可以使用该接口的方法实现。
这两个接口的实现类是服务器给予实现的，并在服务器调用service方法时传入。
1、Servlet-ServletRequest
1）获取请求参数：
> String getParameter(String name):根据请求参数的名字，返回参数值
若请求参数有多个值(例如：checkbox)，该方法只能获取到第一个提交的值
>String getParameterValues(String name):根据请求参数的名字，返回请求参数对应的字符串数组
>Enumeration getParameterNames():返回参数名对应的Enumeration对象，类似于ServletConfig(或ServletContext)的getInitParameterNames()方法
>Map getParameterMap():返回请求参数的键值对： key：参数名，value：参数值，String数组类型
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
System.out.println("请求来了。。。");
String user = servletRequest.getParameter("username");
System.out.println(user);
String interesting = servletRequest.getParameter("interesting");
System.out.println("__"+interesting);
String[] param = servletRequest.getParameterValues("interesting");
/* atguigu
__111*/
for (String interes:param
) {
System.out.println("<>"+interes);
}
/* <>111
<>222*/
Enumeration<String> names = servletRequest.getParameterNames();
while (names.hasMoreElements()){
String name = names.nextElement();
String value = servletRequest.getParameter(name);
System.out.println("- _ -"+name +" "+value);
}
/* - _ -username atguigu
- _ -password 123
- _ -interesting 111*/
Map<String,String[]> map = servletRequest.getParameterMap();
for (Map.Entry<String,String[]> m:map.entrySet()
) {
System.out.println(" _ " + m.getKey()+ ":" + Arrays.asList( m.getValue()));
}
/* _ username:[atguigu]
_ password:[123]
_ interesting:[111, 222]*/
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
String requestURI = httpServletRequest.getRequestURI();
System.out.println(requestURI);
String method = httpServletRequest.getMethod();
System.out.println(method);
String queryString = httpServletRequest.getQueryString();
System.out.println(queryString);
String servletPath = httpServletRequest.getServletPath();
System.out.println(servletPath);
/* /loginServlet
POST
null
/loginServlet*/
/loginServlet
GET
username=atguigu&password=123&interesting=111&interesting=222
/loginServlet
}
获取请求方式：
HttpServletRequest：是ServletRequest的子接口，针对于HTTP请求所定义，里面包含了大量获取HTTP请求相关的方法
2.Servlet-ServletResponse
1）getWriter()：返回PrintWriter对象，调用该对象的print()方法，将把print()中的参数直接打印到客户的浏览器上
PrintWriter printWriter = servletResponse.getWriter();
2）设置响应的内容类型
servletResponse.setContentType("application/msword");
3）void sendRedirect(String location):请求的重定向（此方法为HttpServletResponse中定义）