JavaWeb15.3【response：案例-服务器输出字符数据到浏览器(中文乱码问题)、服务器输出字节数据到浏览器、验证码生成并输出到浏览器】

 

 

 

 

 

 

package com.haifei.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * Response对象案例-服务器输出字符数据到浏览器
 */
@WebServlet("/responseDemo4")
public class ResponseDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        /*//1 获取字符输出流
        PrintWriter pw = response.getWriter();
        //response在一次响应完成后会被自动销毁，同时它获取的流getWriter()也会被自动关闭
        //之前学流的时候：.write()后需要flush()才能写入；close()自带flush效果
        //所以此处不需要在pw.write()手动对pw进行flush()

        //2 输出数据
        pw.write("<h1>hello response</h1>");  //即为页面上的响应体*/



       /* //获取流对象之前，流的默认编码为ISO-8859-1，手动设置为utf-8
         response.setCharacterEncoding("utf-8");
        //告诉浏览器，服务器发送的消息体数据的编码。建议浏览器使用该编码解码
        response.setHeader("content-type","text/html;charset=utf-8"); //content-type是一种常见的响应头*/
        //简单的形式：设置编码并告诉浏览器，防止中文乱码
        response.setContentType("text/html;charset=utf-8");

        PrintWriter pw = response.getWriter();
        pw.write("<h1>你好啊 response</h1>");
    }

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

 

package com.haifei.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Response对象案例-服务器输出字节数据到浏览器
 */
@WebServlet("/responseDemo5")
public class ResponseDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8"); //设置编码
        //1 获取字节输出流
        ServletOutputStream sos = response.getOutputStream();
        //2 输出数据
        sos.write("你好啊hello".getBytes("utf-8"));
    }

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

 

package com.haifei.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * Response对象案例-验证码
 */
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 100;
        int height = 50;

        //1 创建对象，再内存中画图（验证码图片对象）
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //2 美化图片
        //2.1 填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);//设置画笔颜色
        g.fillRect(0,0,width,height);
        //2.2画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width - 1,height - 1);
        //2.3画验证码
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        Random ran = new Random();
        for (int i = 1; i <= 4; i++) {
            //生成随机下标
            int index = ran.nextInt(str.length());
            //获取随机字符
            char ch = str.charAt(index);
            //写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }
        //2.4画干扰线
        g.setColor(Color.GREEN);
        for (int i = 0; i < 10; i++) { //随机生成坐标点
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);
            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }

        //3 将图片输出到页面展示
        ImageIO.write(image, "jpg", response.getOutputStream());
    }

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

 

 

 

 

 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        /*
           分析：
               点击超链接或者图片，需要换一张
               1.给超链接和图片绑定单击事件
               2.重新设置图片的src属性值
        */
        window.onload = function () {
            //获取图片对象
            var img = document.getElementById("checkCode");
            //绑定单击事件
            img.onclick = function () {
                // img.src = "/day15/checkCodeServlet"; //因为浏览器缓存而访问原路径时达不到效果

                //+时间戳
                var data = new Date().getTime();
                img.src = "/day15/checkCodeServlet?" + data;
            };

            var a = document.getElementById("change");
            a.onclick = function () {
                var data = new Date().getTime();
                img.src = "/day15/checkCodeServlet?" + data;
                // alert("/day15/checkCodeServlet?" + data);
            };
        }
    </script>
</head>
<body>
    <img id="checkCode" src="/day15/checkCodeServlet" />
    <a id="change" href="">看不清换一张？</a>
</body>
</html>