java cookie 的使用_java cookie-优快云博客

本文链接：https://blog.youkuaiyun.com/spftay/article/details/21634643

一新建一个html 页面把需要保存的数据传送过去

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>index.html</title>

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">



</head>
<form action="/CookieTest/servlet/SetCookie">
<body>
<table border="1px">
<tr>
<td colspan="2">
<h1>
请输入用户名保存cookie
</h1>
</td>
</tr>
<tr>
<td>
用户名
</td>
<td>
<input type="text" name="username" />
</td>
</tr>
<tr>
<td>
<input type="reset" value="重置" />
</td>
<td>
<input type="submit" value="提交" />
</td>
</tr>

</table>
</body>
</form>
</html>

二：新建一个servlet进行保存

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SetCookie extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter writer = response.getWriter();
String value = request.getParameter("username");
if (value == null || "".equals(value)) {
writer.write("输入不正确:<a href = " + request.getContextPath()
+ "/index.html" + ">重新输入<a/>");

} else {
Cookie cookie = new Cookie("username", value);
cookie.setMaxAge(60 * 60 * 24 * 30);
cookie.setPath("/");
response.addCookie(cookie);

writer.write("保存成功：<a href = " + request.getContextPath()
+ "/servlet/GetCookie" + ">查看<a/>");
writer.close();
}
}
}

三通过request得到cookie

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class GetCookie extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter writer = response.getWriter();
Cookie[] cookies = request.getCookies();
for (int i = 0; i < cookies.length; i++) {
if (cookies[i].getName().equals("username")) {
writer.write("username:" + cookies[i].getValue());
}
}
writer.close();
}
}

删除一个cookie

Cookie cookie = new Cookie(Cookiename, null); 
cookie.setMaxAge(-1);
response.addCookie(cookie); 

setMaxAge方法设置cookie经过多长秒后被删除。如果参数是0，就说明立即删除。如果是负数就表明当浏览器关闭时自动删除。
如果没有设定cookie的age可以用getMaxAge方法来查看cookie的默认存活时间。