Cookie注意事项

浏览器里;分割的就是一个cookie,cookie是一个键值对

getCookies()获取到的就是所有的cookie,浏览器里以;分割

Cookie.setValue()里的值不能放入特殊字符如

[ ] ( ) = , " / ? @ : ;

利用cookie实现简单的商品浏览历史记录

package top.freeme.web.servlet;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.Arrays;
import java.util.stream.Stream;

@WebServlet(name = "RecordServlet", value = "/record")
public class RecordServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html;charset-utf8");
         //1.获取到浏览的历史
        String record = request.getParameter("record");

        String value = null;
        Cookie cookie = null;
        //3. 处理第二次访问时，需要从客户端获取到上一次存放的cookie值
        Cookie[] cookies = request.getCookies();
        if(cookies.length> 1){
            for (Cookie ck : cookies) {
                if("record".equals(ck.getName())){
                    value = ck.getValue();
                    value = record+"-"+value;
                    StringBuilder sb = new StringBuilder();
                    if (value!=null){

                        String[] split = value.split("-");

                        for (int i = 0; i < split.length; i++) {
                            for (int j = i+1; j < split.length ; j++) {
                                if (split[i].equals(split[j])){
                                    split[j] = "";
                                }
                            }

                        }
                        for (String s : split) {
                            if (!s.equals("")){
                                sb.append(s+"-");
                            }
                        }
                        value=sb.toString();
                    }
                    //-- 设置value
                    ck.setValue(value);
                    cookie = ck;
                }
            }
        }else {
            cookie = new Cookie("record", record);
        }

        response.addCookie(cookie);
        response.getWriter().write(value);

    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

前端操作cookie

JS操作cookie比较麻烦