Servlet中的Request的一些实现细节和应用
Servlet中，response是向浏览器发出请求，而request就是获得浏览器向服务器发出的请求了，下面首先演示request的常用方法
package com.bird.request;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @use Request的常用方法
* @author Bird
*
*/
public class RequestDemo1 extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// System.out.println("request" + request.getRequestURI());
// System.out.println("request" + request.getRequestURL());
// System.out.println(request.getQueryString());//得到查询窜
// System.out.println(request.getRemoteAddr());//得到访问的IP地址
// System.out.println(request.getRemotePort());//得到访问端口
System.out.println(request.getMethod());//得到请求方式
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
}
获取求情头的信息和数据
package com.bird.request;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @use 获取请求头信息和数据
* @author Bird
*
*/
public class RequestDemo2 extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// String username = request.getParameter("username");
// System.out.println(username);
}
//获取头相关的方法
private void test1(HttpServletRequest request) {
String headValue = request.getHeader("Accept-Encoding");
System.out.println(headValue);
System.out.println("-----------------------------");
Enumeration en = request.getHeaders("Accept-Encoding");
while(en.hasMoreElements()){
String value = (String) en.nextElement();
System.out.println(value);
}
System.out.println("++++++++++++++++++++++++++");
en = request.getHeaderNames();
while(en.hasMoreElements()){
String value = (String) en.nextElement();
System.out.println(value);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
System.out.println(username);
}
}
控制浏览器的定时刷新
package com.bird.ServletResponse;
import java.io.IOException;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ResponseDemo3 extends HttpServlet {
/**
* @use 控制浏览器定时刷新
* @author Bird
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//实用的自动跳转技术
String message = "<meta http-equiv='refresh' content='3;url=/ServletDemo/index.jsp'>恭喜你登录成功，本浏览器将在3s后跳转,如果没有跳转，请点击<a href =''>连接</a>";
this.getServletContext().setAttribute("message", message);
this.getServletContext().getRequestDispatcher("/message.jsp").forward(request, response);
}
//控制登录完毕后几秒内跳转
private void test2(HttpServletResponse response) throws IOException {
//假设这个是一个处理登录的Servlet，用户到此就算是登录成功了
//浏览器需要在登录成功后自动跳转
response.setCharacterEncoding("UTF-8");//设置当前码表
response.setContentType("text/html;charset=UTF-8");
response.setHeader("refresh", "3;url='/ServletDemo/index.jsp'");
response.getWriter().write("恭喜你登录成功，本浏览器将在3s后跳转,如果没有跳转，请点击<a href =''>连接</a>");
}
//控制浏览器定时刷新
private void test1(HttpServletResponse response) throws IOException {
response.setHeader("refresh", "3");//控制浏览器每隔3秒访问一次服务器也就是刷新
String date = new Date().toString();
response.getOutputStream().write(date.getBytes());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
}
Expries头控制缓存
package com.bird.ServletResponse;
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 ResponseDemo4 extends HttpServlet {
/**
* @use 使用Expries头控制缓存
* @author Bird
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//一定要弄当前时间加上你所需要的时间才行
response.setDateHeader("expires", System.currentTimeMillis()+1000*3600);
String date = "aaaaaaa";
response.getWriter().write(date);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
}
重定向的特点
package com.bird.ServletResponse;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 重定向的特点
* 1.浏览器会向服务器发送两次，意味着有两个response
* 2.用重定向，浏览器地址栏会发生变化
* 3.必须使用购物车才可以
* 4.同时调用getoutputstream和getwriter会抛出这个已经使用的异常，特别是重定向的时候
*/
public class ResponseDemo5 extends HttpServlet {
/**
* @use 使用response实现请求的重定向
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// response.setStatus(302);//设置重定向状态码
// response.setHeader("location", "/ServletDemo/index.jsp");
response.sendRedirect("/ServletDemo/index.jsp");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
}