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Servlet 3 HttpServletRequest HttpServletResponse 验证码图片 form表单

HttpServletRequest:
获得请求行和客户机信息
获得请求头中referer信息，防止盗链
获得form提交数据
请求重定向转发
RequestDispatcher.include包含
HttpServletResponse
生成状态码和头信息
从response/demo2.html 请求中获得用户名和密码判断是否正确
定时自动跳转网页
禁用浏览器缓存
生成HTML网页
生成XML
用Servlet程序生成一张验证码图片

工程目录:

获得请求行和客户机信息

package cn.itcast.servlet.request;

import java.io.IOException;

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

/**
 * 获得请求行 和 客户机信息
 * 
 * @author seawind
 * 
 */
public class RequestServlet1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获得请求方式
        System.out.println("请求方式：" + request.getMethod());
        // 获得协议
        System.out.println("协议：" + request.getProtocol());
        // 获得请求资源路径
        System.out.println("请求路径：" + request.getRequestURI());
        System.out.println("请求路径：" + request.getRequestURL());
        // 获得请求行中参数
        System.out.println("参数：" + request.getQueryString());
        // 打印客户机IP
        System.out.println("ip:" + request.getRemoteAddr());
        // 获得工程虚拟路径名称
        System.out.println("虚拟路径名称：" + request.getContextPath());
    }

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

}

获得请求头中referer信息，防止盗链

html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>正常访问页面，从这个页面访问 不属于盗链</h1>
<a href="/day6/request2" >访问重要资源</a>
</body>
</html>

Servlet

package cn.itcast.servlet.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;

/**
 * 获得请求头中referer信息，防止盗链
 * 
 * @author seawind
 * 
 */
public class RequestServlet2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 遍历所有请求头信息
        Enumeration<String> names = request.getHeaderNames();
        while (names.hasMoreElements()) {
            String name = names.nextElement();
            System.out.println(name + ":" + request.getHeader(name));
        }
        System.out.println("-----------------------------------------");

        System.out.println("您使用浏览器：" + request.getHeader("user-agent"));

        String referer = request.getHeader("referer");
        // 判断referer是否存在和有效
        if (referer != null && referer.startsWith("http://localhost/day6")) {
            // 不属于盗链
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().println("机密信息");
        } else {
            // 盗链
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().println("您的请求是盗链");
        }
    }

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

}

获得form提交数据

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>最复杂form表单</h1>
<form method="get" action="/day6/request3">
    用户名 <input type="text" name="username" /><br/>
    密码 <input type="password" name="password" /><br/>
    性别 <input type="radio" name="gender" value="男" /> 男 <input type="radio" name="gender" value="女" />女 <br/>
    爱好 <input type="checkbox" name="hobby" value="体育" />体育
    <input type="checkbox" name="hobby" value="音乐" />音乐
    <input type="checkbox" name="hobby" value="读书" />读书<br/>
    城市 <select name="city">
        <option value="北京">北京</option>
        <option value="上海">上海</option>
        <option value="广州">广州</option>
    </select> <br/>
    个人简介 <textarea rows="5" cols="60" name="introduce"></textarea><br/>
    <input type="submit" value="提交" />
</form>
</body>
</html>

Servlet

package cn.itcast.servlet.request;

import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;

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

/**
 * 获得form提交数据
 * 
 * @author seawind
 * 
 */
public class RequestServlet3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // POST提交 处理乱码
        // request.setCharacterEncoding("utf-8");

        String username = request.getParameter("username");
        // 校验username 有效
        if (username != null && username.length() > 0) {
            System.out.println("username 有效");
        }

        String password = request.getParameter("password");
        String gender = request.getParameter("gender");
        // 使用getParameter只能获得一个值
        // String hobby = request.getParameter("hobby");
        // 获得多个请求参数值
        String[] hobby = request.getParameterValues("hobby");

        String city = request.getParameter("city");
        String introduce = request.getParameter("introduce");

        // 对username 采用手动编解码 处理get乱码
        username = URLEncoder.encode(username, "ISO-8859-1");
        username = URLDecoder.decode(username, "utf-8");

        // 对gender用 另一个编解码方式
        gender = new String(gender.getBytes("ISO-8859-1"), "utf-8");

        System.out.println("姓名：" + username);
        System.out.println("密码：" + password);
        System.out.println("性别：" + gender);
        System.out.println("爱好：" + Arrays.toString(hobby));
        System.out.println("城市：" + city);
        System.out.println("个人介绍：" + introduce);

        // 使用parametermap 遍历所有请求参数
        Map<String, String[]> parameterMap = request.getParameterMap();
        Set<String> keySet = parameterMap.keySet();
        for (String parameterName : keySet) {
            System.out.println(parameterName + ": "
                    + Arrays.toString(parameterMap.get(parameterName)));
        }

    }

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

}

请求重定向转发

package cn.itcast.servlet.request;

import java.io.IOException;

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

/**
 * 执行 Servlet4后执行Servlet5
 * 
 * @author seawind
 * 
 */
public class RequestServlet4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().println("servlet4");
        System.out.println("request servlet 4 ...");
        // 重定向
        // response.sendRedirect("/day6/request5");

        // 转发
        // 转发操作过程中，可以通过request传递数据
        request.setAttribute("name", "传智播客");// 保存request对象
        RequestDispatcher dispatcher = request
                .getRequestDispatcher("/request5");// 服务器内部行为
        dispatcher.forward(request, response);
    }

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

}

package cn.itcast.servlet.request;

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 RequestServlet5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().println("servlet5");
        System.out.println("request servlet 5 ...");
        // 取出保存request中数据
        String name = (String) request.getAttribute("name");
        System.out.println("取出name : " + name);
    }

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

}

RequestDispatcher.include包含

package cn.itcast.servlet.request;

import java.io.IOException;

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

/**
 * 生成一个网页，将logo.html 、menu.html、footer.html 都包含进行
 * 
 * @author seawind
 * 
 */
public class RequestServlet6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获得Dispatcher转发器
        RequestDispatcher dispatcher1 = request
                .getRequestDispatcher("/request/demo6/logo.html");
        dispatcher1.include(request, response);

        RequestDispatcher dispatcher2 = request
                .getRequestDispatcher("/request/demo6/menu.html");
        dispatcher2.include(request, response);

        // 输出正文信息，引用三个页面默认采用response.getOutputStream输出的
        response.getOutputStream().println("<h1>Content</h1>");

        RequestDispatcher dispatcher3 = request
                .getRequestDispatcher("/request/demo6/footer.html");
        dispatcher3.include(request, response);
    }

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

}

HttpServletResponse
生成状态码和头信息

package cn.itcast.servlet.response;

import java.io.IOException;

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

/**
 * 生成状态码和头信息
 * 
 * @author seawind
 * 
 */
public class ResponseServlet1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 生成状态码
        // response.setStatus(500); // 设置不同状态码

        // 结合302状态码和 Location头信息 ，完成请求重定向
        response.setStatus(302);
        response.setHeader("Location", "/day6/hello.html");// location值重定向后资源路径
    }

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

}

从response/demo2.html 请求中获得用户名和密码判断是否正确

html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>登陆页面，密码错误完成重定向</h1>
<form action="/day6/response2" method="post">
    用户名 <input type="text" name="username" /><br/>
    密码 <input type="password" name="password" /><br/>
    <input type="submit" value="登陆" />
</form>
</body>
</html>

package cn.itcast.servlet.response;

import java.io.IOException;

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

/**
 * 从response/demo2.html 请求中 获得用户名和密码 判断是否正确
 * 
 * @author seawind
 * 
 */
public class ResponseServlet2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获得请求中 用户名和密码
        String username = request.getParameter("username");
        // 字符串要为form表单对象name属性
        String password = request.getParameter("password");

        // 假设admin/admin 就是用户名和密码
        if (username.equals("admin") && password.equals("admin")) {
            // 登陆成功
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().println("登陆成功！");
        } else {
            // 用户名或者密码错误 ---- 重定向 登陆页面
            // response.setStatus(302);
            // response.setHeader("Location", "/day6/response/demo2.html");
            response.sendRedirect("/day6/response/demo2.html");
        }
    }

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

}

定时自动跳转网页

package cn.itcast.servlet.response;

import java.io.IOException;

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

/**
 * 定时自动刷新网页
 * 
 * @author seawind
 * 
 */
public class ResponseServlet3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setHeader("refresh", "5;url=/day6/hello.html");

        response.setContentType("text/html;charset=utf-8");
        response.getWriter().println("页面会在5秒后 自动跳转hello.html");

    }

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

}

html中meta标签可以实现和HTTP响应头信息设置相同效果

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<!-- meta标签 可以实现和HTTP响应头信息设置相同效果 -->
<meta http-equiv="refresh" content="5;url=/day6/hello.html" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
    var i = 5;
    function init(){
        document.getElementById("mytimes").innerHTML = i;
        // 每隔1秒重复调用 init方法 i-- 
        i--;
        // 通过window 内置对象 setTimeOut 完成每隔1秒重复调用
        window.setTimeout("init();", 1000);
    }
</script>
</head>
<!-- 在页面加载完成后 执行init 方法 -->
<body onload="init();">
<h1>HTML中通过Meta实现<span id="mytimes"></span>秒后自动跳转hello.html</h1>
</body>
</html>

禁用浏览器缓存

package cn.itcast.servlet.response;

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;

/**
 * 禁用浏览器缓存
 * 
 * @author seawind
 * 
 */
public class ResponseServlet4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 设置response 的三个头信息
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        // Expires 要求格式 日期格式
        // 通过setDateHeader设置一个毫秒信息，自动转换日期格式
        response.setDateHeader("Expires", -1);

        response.getWriter().println("AAAAA" + new Date().toLocaleString());
    }

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

}

生成HTML网页

package cn.itcast.servlet.response;

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

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

/**
 * 生成HTML网页
 * 
 * @author seawind
 * 
 */
public class ResponseServlet5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 设置字符集
        // response.setCharacterEncoding("utf-8");

        // 设置文件类型，通知浏览器查看编码方式
        response.setContentType("text/html;charset=gbk");

        // 获得响应字符输出流
        PrintWriter out = response.getWriter();

        out.println("<html>");
        out.println("<body>");
        out.println("Servlet生成网页");
        out.println("</body>");
        out.println("</html>");

        // 响应输出流 会自动关闭 （由tomcat服务器关闭 ）

    }

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

}

生成XML

package cn.itcast.servlet.response;

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

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

/**
 * 生成XML
 * 
 * @author seawind
 * 
 */
public class ResponseServlet6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 设置文件类型和字符集
        response.setContentType("text/xml;charset=utf-8");
        // 获得响应输出流
        PrintWriter out = response.getWriter();

        // 打印XML内容
        out.println("<book>");
        out.println("<name>java编程思想</name>");
        out.println("<price>80</price>");
        out.println("</book>");
    }

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

}

用Servlet程序生成一张验证码图片

html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
    // 点击切换验证码原理 ，重新载入图片
    function change(){
        // 获得id为myimg对象 ，重新加载Servlet程序
        document.getElementById("myimg").src= "/day6/response7?"+new Date().getTime();
    }
</script>
</head>
<body>
<!-- 引用一张图片，显示网页上 -->
<img src="/day6/response7" onclick="change();" id="myimg" style="cursor: pointer;"/>
</body>
</html>

Servlet

package cn.itcast.servlet.response;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 用Servlet程序生成一张验证码图片
 * 
 * @author seawind
 * 
 */
public class ResponseServlet7 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 禁止浏览器缓存 验证码图片
        // response.setHeader("cache-control", "no-cache");
        // response.setHeader("pragma", "no-cache");
        // response.setDateHeader("expires", -1);

        // 生成图片。使用Java图形界面技术awt、swing 包
        // 1 创建内存中图片
        int width = 120;
        int height = 30;
        BufferedImage bufferedImage = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 2 绘制图片背景色
        Graphics2D graphics2d = (Graphics2D) bufferedImage.getGraphics();
        // 指定颜色
        graphics2d.setColor(Color.GRAY);
        graphics2d.fillRect(0, 0, width, height);

        // 3、绘制边框
        graphics2d.setColor(Color.yellow);
        graphics2d.drawRect(0, 0, width - 1, height - 1);

        // 4、向图片中生成验证码内容
        graphics2d.setColor(Color.BLUE);
        graphics2d.setFont(new Font("新宋体", Font.BOLD, 18));
        // String word =
        // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
        // 如果使用汉字，字体必须要支持汉字
        String word = "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";
        Random random = new Random();
        int x = 5;
        for (int i = 0; i < 4; i++) {
            // 加入字体旋转 角度-30 --- 30之间
            int jiaodu = random.nextInt(60) - 30;
            // 转换角度为弧度
            double theta = jiaodu * Math.PI / 180;

            int randomIndex = random.nextInt(word.length());// 生成下标
            char c = word.charAt(randomIndex);
            // 将字符写入图片
            graphics2d.rotate(theta, x, 20);
            graphics2d.drawString(c + "", x, 20);
            graphics2d.rotate(-theta, x, 20);
            x += 30;
        }

        // 5 绘制干扰线
        graphics2d.setColor(Color.LIGHT_GRAY);
        int x1;
        int x2;
        int y1;
        int y2;
        for (int i = 0; i < 10; i++) {
            x1 = random.nextInt(width);
            x2 = random.nextInt(width);
            y1 = random.nextInt(height);
            y2 = random.nextInt(height);

            graphics2d.drawLine(x1, y1, x2, y2);
        }
        // 释放内存中资源
        graphics2d.dispose();

        // 生成图片到浏览器
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
    }

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

    public static void main(String[] args) {
        System.out.println('u9fa5');
        System.out.println('u9fa4');
        System.out.println('u9fa3');
    }

}

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原文地址：https://www.cnblogs.com/vaer/p/3925206.html