servlet(二)--session管理---cookie

最新推荐文章于 2024-10-24 21:50:28 发布

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最新推荐文章于 2024-10-24 21:50:28 发布

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分类专栏： Servlet 文章标签： servlet cookies

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本文介绍了一种利用Servlet和Cookie来实现用户偏好设置的方法。通过PreferenceServlet接收用户的设置选项并将其保存到Cookie中，然后在CookieClassServlet及CookieInfoServlet中读取这些设置，并应用于页面样式和内容展示。

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servlet--cookie

package com.cdc.test;

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;

/****在PreferenceServlet类里面,doGet()方法发送了一个表单,当提交表单时,将doGet()里面的几个输入域里面的值添加到cookie里面,并在浏览器里面显示出来。***/

@WebServlet(name = "PreferenceServlet", urlPatterns = { "/preference" })
public class PreferenceServlet extends HttpServlet {
	private static final long serialVersionUID = 888L;

	public static final String MENU = "<div>"
			+ "<a href='cookieClass'>Cookie Class</a>  "
			+ "<a href='cookieInfo'>Cookie Info</a>  "
			+ "<a href='preference'>Preference</a>" + "</div>";

	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		response.setCharacterEncoding("utf-8");
		PrintWriter writer = response.getWriter();
		writer.print("<html><head>" + "<title>Preference</title>" + "<table>"
				+ "</head><body>"
				+ MENU
				+ "请选择下面的值:"
				+ "<form method='post'>"
				+ "<table>"
				+ "<tr><td>标题字的尺寸: </td>"
				+ "<td><select name='titleFontSize'>"
				+ "<option>large</option>"
				+ "<option>x-large</option>"
				+ "<option>xx-large</option>"
				+ "</select></td>"
				+ "</tr>"
				+ "<tr><td>字体样式和尺寸: </td>"
				+ "<td><select name='titleStyleAndWeight' multiple='multiple'>"
				+ "<option>italic</option>"
				+ "<option>bold</option>"
				+ "</select></td>"
				+ "</tr>"
				+ "<tr><td>表里的最大记录: </td>"
				+ "<td><select name='maxRecords'>"
				+ "<option>5</option>"
				+ "<option>10</option>"
				+ "</select></td>"
				+ "</tr>"
				+ "<tr><td rowspan='2'>"
				+ "<input type='submit' value='设置'/></td>"
				+ "</tr>"
				+ "</table>" + "</form>" + "</body></html>");

	}

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

		String maxRecords = request.getParameter("maxRecords");
		String[] titleStyleAndWeight = request
				.getParameterValues("titleStyleAndWeight");
		String titleFontSize = request.getParameter("titleFontSize");
		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;

		/**
		 * 删除一个cookie时,需要创建一个同名的cookie,将它的maxAge属性设置为0,
		 * 并在HttpServletResponse中添加一个新的cookie. 如下所示:
		 **/
		// 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")) {
					response.addCookie(new Cookie("titleFontWeight", "bold"));
				} else if (style.equals("italic")) {
					response.addCookie(new Cookie("titleFontStyle", "italic"));
				}
			}
		}

		response.setContentType("text/html;charset=utf-8");
		PrintWriter writer = response.getWriter();
		writer.println("<html><head>" + "<title>Preference</title>"
				+ "</head><body>" + MENU + "你已经设置了." + "<br/><br/>表里最大的记录: "
				+ maxRecords + "<br/>标题字的尺寸: " + titleFontSize
				+ "<br/>字体的样式和尺寸: ");

		// 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>");

	}
}

在PreferenceServlet里面设置的cookie,可以在CookieClassServlet以及在下面的CookieInfoServlet里面获取并且显示。

package com.cdc.test;

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;

@WebServlet(name = "CookieClassServlet", urlPatterns = { "/cookieClass" })
public class CookieClassServlet extends HttpServlet {
	private static final long serialVersionUID = 837369L;

	private String[] methods = { "clone", "getComment", "getDomain",
			"getMaxAge", "getName", "getPath", "getSecure", "getValue",
			"getVersion", "isHttpOnly", "setComment", "setDomain",
			"setHttpOnly", "setMaxAge", "setPath", "setSecure", "setValue",
			"setVersion" };

	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		Cookie[] cookies = request.getCookies();
		Cookie maxRecordsCookie = null;
		if (cookies != null) {
			for (Cookie cookie : cookies) {
				if (cookie.getName().equals("maxRecords")) {
					maxRecordsCookie = cookie;
					break;
				}
			}
		}

		int maxRecords = 2; // default
		if (maxRecordsCookie != null) {
			try {
				maxRecords = Integer.parseInt(maxRecordsCookie.getValue());
			} catch (NumberFormatException e) {
				// do nothing, use maxRecords default value
			}
		}

		response.setContentType("text/html;charset=utf-8");
		PrintWriter writer = response.getWriter();
		writer.print("<html><head>" + "<title>Cookie Class</title>"
				+ "</head><body>" + PreferenceServlet.MENU + "<div>一些"
				+ "javax.servlet.http.Cookie里面的一些方法 ");
		writer.print("<ul>");
		if (maxRecords >= 5) {
			writer.print("<p>从cookie里面获得的值是:" + maxRecords + "</p>");
		}
		for (int i = 0; i < maxRecords; i++) {
			writer.print("<li>" + methods[i] + "</li>");
		}
		writer.print("</ul>");
		writer.print("</div></body></html>");
	}
}

package com.cdc.test;

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;

@WebServlet(name = "CookieInfoServlet", urlPatterns = { "/cookieInfo" })
public class CookieInfoServlet extends HttpServlet {
    private static final long serialVersionUID = 3829L;

    @Override
    public void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException,
            IOException {

        Cookie[] cookies = request.getCookies();
      //拼成这样的字符串,控制.title {font-weight:bold;font-size:large;}----Session Management with Cookies:这一内容的样式,大小,字体等.
        StringBuilder styles = new StringBuilder();
        styles.append(".title {");
        if (cookies != null) {
            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:");
            for (Cookie cookie : cookies) {
                writer.println("<br/>" + cookie.getName() + ":"
                        + cookie.getValue());
            }
        }
        writer.print("</div>");
        writer.print("<p>"+styles.toString()+"</p>");
        writer.print("</body></html>");
    }
}