HttpServletResponse

import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

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

public class ServletDemo3 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//通过路径得到一个输入流
String path = this.getServletContext().getRealPath("/WEB-INF/classes/美女.jpg");
FileInputStream fis = new FileInputStream(path);
//创建字节输出流
ServletOutputStream sos = response.getOutputStream();

//得到要下载的文件名
String filename = path.substring(path.lastIndexOf("\\")+1);

//设置文件名的编码
filename = URLEncoder.encode(filename, "UTF-8");//将不安全的文件名改为UTF-8格式

//告知客户端要下载文件
response.setHeader("content-disposition", "attachment;filename="+filename);
response.setHeader("content-type", "image/jpeg");

//执行输出操作
int len = 1;
byte[] b = new byte[1024];
while((len=fis.read(b))!=-1){
sos.write(b,0,len);
}

sos.close();
fis.close();
}

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

}

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

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

public class ServletDemo2 extends HttpServlet {

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

response.setContentType("text/html;charset=UTF-8");

ServletOutputStream sos = response.getOutputStream();
sos.write("你好123".getBytes("UTF-8"));//getBytes默认编码为本地编码（即：gbk）
}

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

}

import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

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

public class ServletDemo3 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//通过路径得到一个输入流
String path = this.getServletContext().getRealPath("/WEB-INF/classes/美女.jpg");
FileInputStream fis = new FileInputStream(path);
//创建字节输出流
ServletOutputStream sos = response.getOutputStream();

//得到要下载的文件名
String filename = path.substring(path.lastIndexOf("\\")+1);

//设置文件名的编码
filename = URLEncoder.encode(filename, "UTF-8");//将不安全的文件名改为UTF-8格式

//告知客户端要下载文件
response.setHeader("content-disposition", "attachment;filename="+filename);
response.setHeader("content-type", "image/jpeg");

//执行输出操作
int len = 1;
byte[] b = new byte[1024];
while((len=fis.read(b))!=-1){
sos.write(b,0,len);
}

sos.close();
fis.close();
}

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

}  

package com.itheima.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
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;

import cn.dsna.util.images.ValidateCode;

public class ServletDemo4 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//告诉客户端不使用缓存
response.setHeader("pragma", "no-cache");
response.setHeader("cache-control", "no-cache");
response.setIntHeader("expires", 0);

ValidateCode vc = new ValidateCode(110, 25, 4, 9);
String code = vc.getCode();//得到生成的字符
vc.write(response.getOutputStream());

}

private void test1(HttpServletResponse response) throws IOException {
int width = 110;
int height = 25;
//在内存中创建一个图像对象
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

//创建一个画笔
Graphics g = img.getGraphics();

//给图片添加背景色
g.setColor(Color.PINK);//设置一个颜色
g.fillRect(1, 1, width-2, height-2);//填充颜色

//给边框一个色
g.setColor(Color.RED);
g.drawRect(0, 0, width-1, height-1);//设置边框的显示坐标

//设置文本样式
g.setColor(Color.BLUE);
g.setFont(new Font("宋体", Font.BOLD|Font.ITALIC, 15));

//给图片添加文本
Random rand = new Random();
int position = 20;
for (int i = 0; i < 4; i++) {
g.drawString(rand.nextInt(10)+"", position, 20);//给图片填充文本
position+=20;
}

//添加9条干扰线
for (int i = 0; i < 9; i++) {
g.drawLine(rand.nextInt(width), rand.nextInt(height), rand.nextInt(width), rand.nextInt(height));
}
//将图片对象以流的方式输出的客户端
ImageIO.write(img, "jpg", response.getOutputStream());
}

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

}

package com.itheima.servlet;

import java.io.IOException;
import java.util.Random;

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

public class ServletDemo5 extends HttpServlet {

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

response.setContentType("text/html;charset=UTF-8");
/*response.setIntHeader("refresh", 1);//设置1秒钟刷新一次

Random r = new Random();

response.getWriter().write(r.nextInt()+"");*/

response.getWriter().write("注册成功！3秒钟跳到主页");
//设置3秒钟跳转
response.setHeader("refresh", "3;url=/day09_00_HttpServletResponse/servlet/demo6");
}

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

}