//獲取文件名
String filename=request.getParameter("file");
//解決文件名亂碼問題
filename=new String(filename.getBytes("ISO-8859-1"),"UTF-8");
//獲取User-Agent獲取客戶端瀏覽器到底是哪個瀏覽器
String agent=request.getHeader("User-Agent");
String filenameEncoder="";
if (agent.contains("MSIE")) {
// IE瀏覽器
filenameEncoder= URLEncoder.encode(filename, "utf-8");
filenameEncoder= filenameEncoder.replace("+", " ");
} else if (agent.contains("Firefox")) {
// 火狐瀏覽器
BASE64Encoder base64Encoder = new BASE64Encoder();
filenameEncoder= "=?utf-8?B?"
+ base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
} else {
// 其它瀏覽器
filenameEncoder= URLEncoder.encode(filename, "utf-8");
}
//告知瀏覽器文件的類型
response.setContentType(getServletContext().getMimeType(filename));
//告知瀏覽器以附件的方式下載而不是解析
response.setHeader("Content-Disposition", "attachment;filename="+ filenameEncoder);
//獲取字節輸出流
ServletOutputStream sos=response.getOutputStream();
//獲取數據源絕對路徑
String realpath=getServletContext().getRealPath("download/"+filename);
//獲取字節輸入流
FileInputStream fis=new FileInputStream(realpath);
//開始賦值
byte[] bytes=new byte[1024];
int len=0;
while((len=fis.read(bytes))!=-1){
sos.write(bytes,0,len);
}
//釋放資源
fis.close();
驗證碼
這段驗證碼可查網上
package com.oracle.demo02;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
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;
/**
* 驗證碼生成程序
*
*
*
*/
public class CheckImgServlet extends HttpServlet {
// 集合中保存所有成語
private List<String> words = new ArrayList<String>();
@Override
public void init() throws ServletException {
// 初始化階段，讀取new_words.txt
// web工程中讀取 文件，必須使用絕對磁盤路徑
String path = getServletContext().getRealPath("/WEB-INF/new_words.txt");
try {
BufferedReader reader = new BufferedReader(new FileReader(path));
String line;
while ((line = reader.readLine()) != null) {
words.add(line);
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 禁止緩存
// response.setHeader("Cache-Control", "no-cache");
// response.setHeader("Pragma", "no-cache");
// response.setDateHeader("Expires", -1);
int width = 120;
int height = 30;
// 步驟一 繪制一張內存中圖片
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 步驟二 圖片繪制背景顏色 ---通過繪圖對象
Graphics graphics = bufferedImage.getGraphics();// 得到畫圖對象 --- 畫筆
// 繪制任何圖形之前 都必須指定一個顏色
graphics.setColor(getRandColor(200, 250));
graphics.fillRect(0, 0, width, height);
// 步驟三 繪制邊框
graphics.setColor(Color.WHITE);
graphics.drawRect(0, 0, width - 1, height - 1);
// 步驟四 四個隨機數字
Graphics2D graphics2d = (Graphics2D) graphics;
// 設置輸出字體
graphics2d.setFont(new Font("宋體", Font.BOLD, 18));
Random random = new Random();// 生成隨機數
int index = random.nextInt(words.size());
String word = words.get(index);// 獲得成語
// 定義x坐標
int x = 10;
for (int i = 0; i < word.length(); i++) {
// 隨機顏色
graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
// 旋轉 -30 --- 30度
int jiaodu = random.nextInt(60) - 30;
// 換算弧度
double theta = jiaodu * Math.PI / 180;
// 獲得字母數字
char c = word.charAt(i);
// 將c 輸出到圖片
graphics2d.rotate(theta, x, 20);
graphics2d.drawString(String.valueOf(c), x, 20);
graphics2d.rotate(-theta, x, 20);
x += 30;
}
// 將驗證碼內容保存session
request.getSession().setAttribute("checkcode_session", word);
// 步驟五 繪制干擾線
graphics.setColor(getRandColor(160, 200));
int x1;
int x2;
int y1;
int y2;
for (int i = 0; i < 30; i++) {
x1 = random.nextInt(width);
x2 = random.nextInt(12);
y1 = random.nextInt(height);
y2 = random.nextInt(12);
graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
}
// 將上面圖片輸出到瀏覽器 ImageIO
graphics.dispose();// 釋放資源
//將圖片寫到response.getOutputStream()中
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* 取其某一范圍的color
*
* @param fc
* int 范圍參數1
* @param bc
* int 范圍參數2
* @return Color
*/
private Color getRandColor(int fc, int bc) {
// 取其隨機顏色
Random random = new Random();
if (fc > 255) {
fc = 255;
}
if (bc > 255) {
bc = 255;
}
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
在導入驗證碼servlet后要去web.xml去更新一下servlet里面的內容，更新一下地址
<!--隨機驗證碼 -->
<servlet>
<description></description>
<display-name>CheckImgServlet</display-name>
<servlet-name>CheckImgServlet</servlet-name>
<servlet-class>com.oracle.demo02.CheckImgServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CheckImgServlet</servlet-name>
<url-pattern>/CheckImgServlet</url-pattern>
</servlet-mapping>
在建立一個jsp
<script type="text/javascript">
function code(node){
//要注意每次傳入的參數要不同，才可以實時更新數據
node.src="/WEB05/CheckImgServlet?time="+new Date().getTime();
}
</script>
</head>
<body>
<img src="/WEB05/CheckImgServlet" onclick="code(this)">