servlet之cookie实现

三个servlet的实现:

package app02c;

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

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

/**
 * Cookies的实现(设置cookie)
 */
@WebServlet( name = "PreferenceServlet", urlPatterns = "/preference")
public class PreferenceServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    // 主菜单
    public static final String MENU =
            "<div style='background:#e8e8e8;"
            + "padding:15px'>"
            + "<a href='cookieClass'>Cookie Class</a>&nbsp;&nbsp;"
            + "<a href='cookieInfo'>Cookie Info</a>&nbsp;&nbsp;"
            + "<a href='preference'>Preference</a>" + "</div>";   
    /**
     * @see HttpServlet#HttpServlet()
     */
    public PreferenceServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * 主页的选择
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         response.setContentType("text/html");
            PrintWriter writer = response.getWriter();
            writer.print("<html><head>" + "<title>Preference</title>"
                    + "<style>table {" + "font-size:small;"
                    + "background:NavajoWhite }</style>"
                    + "</head><body>"
                    + MENU
                    + "Please select the values below:"
                    + "<form method='post'>"
                    + "<table>"
                    + "<tr><td>Title Font Size: </td>"
                    + "<td><select name='titleFontSize'>"
                    + "<option>large</option>"
                    + "<option>x-large</option>"
                    + "<option>xx-large</option>"
                    + "</select></td>"
                    + "</tr>"
                    + "<tr><td>Title Style & Weight: </td>"
                    +"<td><select name='titleStyleAndWeight' multiple>"
                    + "<option>italic</option>"
                    + "<option>bold</option>"
                    + "</select></td>"
                    + "</tr>"
                    + "<tr><td>Max. Records in Table: </td>"
                    + "<td><select name='maxRecords'>"
                    + "<option>5</option>"
                    + "<option>10</option>"
                    + "</select></td>"
                    + "</tr>"
                    + "<tr><td rowspan='2'>"
                    + "<input type='submit' value='Set'/></td>"
                    + "</tr>"
                    + "</table>" + "</form>" + "</body></html>");
    }

    /**
     * 设置cookie
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String maxRecords = request.getParameter("maxRecords");
        // 下拉列表multiple属性的获取方式
        String[] titleStyleAndWeight = request
                .getParameterValues("titleStyleAndWeight");
        String titleFontSize =
                request.getParameter("titleFontSize");
        // 设置cookie
        response.addCookie(new Cookie("maxRecords", maxRecords));
        response.addCookie(new Cookie("titleFontSize",
                titleFontSize));

        // delete titleFontWeight and titleFontStyle cookies first
        // Delete cookie by adding a cookie with the maxAge = 0;
        
        Cookie cookie = new Cookie("titleFontWeight", "");
        cookie.setMaxAge(0);
        response.addCookie(cookie);

        cookie = new Cookie("titleFontStyle", "");
        cookie.setMaxAge(0);
        response.addCookie(cookie);

        if (titleStyleAndWeight != null) {
            for (String style : titleStyleAndWeight) {
                if (style.equals("bold")) {
                    // 添加cookie
                    response.addCookie(new
                            Cookie("titleFontWeight", "bold"));
                } else if (style.equals("italic")) {
                    response.addCookie(new Cookie("titleFontStyle",
                            "italic"));
                }
            }
        }

        response.setContentType("text/html");
        PrintWriter writer = response.getWriter();
        writer.println("<html><head>" + "<title>Preference</title>"
                + "</head><body>" + MENU
                + "Your preference has been set."
                + "<br/><br/>Max. Records in Table: " + maxRecords
                + "<br/>Title Font Size: " + titleFontSize
                + "<br/>Title Font Style & Weight: ");

        // titleStyleAndWeight will be null if none of the options
        // was selected
        if (titleStyleAndWeight != null) {
            writer.println("<ul>");
            for (String style : titleStyleAndWeight) {
                writer.print("<li>" + style + "</li>");
            }
            writer.println("</ul>");
        }
        writer.println("</body></html>");
    }

}

package app02c;

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

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

/**
 * 显示数据,根据接受的cookie来选择输出数量
 */
@WebServlet( name = "CookieClassServlet", urlPatterns = "/cookieClass")
public class CookieClassServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    // 设置显示的数据
    private String[] methods = {
            "clone", "getComment", "getDomain",
            "getMaxAge", "getName", "getPath",
            "getSecure", "getValue", "getVersion",
            "isHttpOnly", "setComment", "setDomain",
            "setHttpOnly", "setMaxAge", "setPath",
            "setSecure", "setValue", "setVersion"
    };
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CookieClassServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取cookie
        Cookie[] cookies = request.getCookies();
        Cookie maxRecordsCookie = null;
        if (cookies != null) {
            // 遍历cookie
            for (Cookie cookie : cookies) {
                if (cookie.getName().equals("maxRecords")) {
                    maxRecordsCookie = cookie;
                    break;
                }
            }
        }
        
        int maxRecords = 5; // default
        if (maxRecordsCookie != null) {
            try {
                maxRecords = Integer.parseInt(
                        maxRecordsCookie.getValue());
            } catch (NumberFormatException e) {
                // do nothing, use maxRecords default value
            }
        }
        
        response.setContentType("text/html");
        PrintWriter writer = response.getWriter();
        writer.print("<html><head>" + "<title>Cookie Class</title>"
                + "</head><body>"
                + PreferenceServlet.MENU
                + "<div>Here are some of the methods in " +
                        "javax.servlet.http.Cookie");
        writer.print("<ul>");
        
        for (int i = 0; i < maxRecords; i++) {
            writer.print("<li>" + methods[i] + "</li>");
        }
        writer.print("</ul>");
        writer.print("</div></body></html>");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

package app02c;

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

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

/**
 * 根据接受到cookie来显示详细信息
 */
@WebServlet(name = "CookieInfoServlet", urlPatterns = "/cookieInfo")
public class CookieInfoServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CookieInfoServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie[] cookies = request.getCookies();
        StringBuilder styles = new StringBuilder();
        // 设置修饰
        styles.append(".title {");
        if (cookies != null) {
            // 根据设置的cookie显示
            for (Cookie cookie : cookies) {
                String name = cookie.getName();
                String value = cookie.getValue();
                if (name.equals("titleFontSize")) {
                    styles.append("font-size:" + value + ";");
                } else if (name.equals("titleFontWeight")) {
                    styles.append("font-weight:" + value + ";");
                } else if (name.equals("titleFontStyle")) {
                    styles.append("font-style:" + value + ";");
                }
            }
        }
        styles.append("}");
        response.setContentType("text/html");
        PrintWriter writer = response.getWriter();
        writer.print("<html><head>" + "<title>Cookie Info</title>"
                + "<style>" + styles.toString() + "</style>"
                + "</head><body>" + PreferenceServlet.MENU
                + "<div class='title'>"
                + "Session Management with Cookies:</div>");
        writer.print("<div>");

        // cookies will be null if there's no cookie
        if (cookies == null) {
            writer.print("No cookie in this HTTP response.");
        } else {
            writer.println("<br/>Cookies in this HTTP response:");
            // 显示cookie
            for (Cookie cookie : cookies) {
                writer.println("<br/>" + cookie.getName() + ":"
                        + cookie.getValue());
            }
        }
        writer.print("</div>");
        writer.print("</body></html>");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}