}
四：文件上传示例：
JSP代码：
<form action="${pageContext.request.contextPath}/servlet/UploadServlet" method="post" enctype="multipart/form-data">
用户名:<input type="text" name="username"/><br/>
文件1:<input type="file" name="f1"/><br/>
文件2:<input type="file" name="f2"/><br/>
<input type="submit" value="保存"/>
</form>servlet后台代码：
public class UploadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter pout = response.getWriter();
try {
// 得到存放上传文件的真实路径
String storePath = getServletContext()
.getRealPath("/WEB-INF/files");
// 设置环境
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setRepository(new File(getServletContext().getRealPath("/temp")));//设置临时存放目录
// 判断一下form是否是enctype=multipart/form-data类型的
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (!isMultipart) {
System.out.println("大傻鸟");
return;
}
// ServletFileUpload核心类
ServletFileUpload upload = new ServletFileUpload(factory);
// upload.setProgressListener(new ProgressListener() {
// //pBytesRead：当前以读取到的字节数
// //pContentLength：文件的长度
// //pItems:第几项
// public void update(long pBytesRead, long pContentLength,
// int pItems) {
// System.out.println("已读取："+pBytesRead+",文件大小："+pContentLength+",第几项："+pItems);
// }
//
// });
upload.setFileSizeMax(4 * 1024 * 1024);// 设置单个上传文件的大小
upload.setSizeMax(6 * 1024 * 1024);// 设置总文件大小
// 解析
List<FileItem> items = upload.parseRequest(request);
for (FileItem item : items) {
if (item.isFormField()) {
// 普通字段
String fieldName = item.getFieldName();
String fieldValue = item.getString("UTF-8");
System.out.println(fieldName + "=" + fieldValue);
} else {
// 得到MIME类型
String mimeType = item.getContentType();
// 只允许上传图片
if(mimeType.startsWith("image")){
// 上传字段
InputStream in = item.getInputStream();
// 上传的文件名
String fileName = item.getName();// C:\Documents and
if(fileName==null||"".equals(fileName.trim())){
continue;
}
// Settings\wzhting\妗岄潰\a.txt
// a.txt
fileName = fileName
.substring(fileName.lastIndexOf("\\") + 1);// a.txt
fileName = UUID.randomUUID() + "_" + fileName;
System.out.println(request.getRemoteAddr()+"=============="+fileName);
// 构建输出流
// 打散存储目录
String newStorePath = makeStorePath(storePath, fileName);// 根据
// /WEB-INF/files和文件名，创建一个新的存储路径
// /WEB-INF/files/1/12
String storeFile = newStorePath + "\\" + fileName;// WEB-INF/files/1/2/sldfdslf.txt
OutputStream out = new FileOutputStream(storeFile);
byte b[] = new byte[1024];
int len = -1;
while ((len = in.read(b)) != -1) {
out.write(b, 0, len);
}
out.close();
in.close();
item.delete();//删除临时文件
}
}
}
} catch (org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException e) {
// 单个文件超出大小时的异常
pout.write("单个文件大小不能超出4M");
} catch (org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e) {
// 总文件超出大小时的异常
pout.write("总文件大小不能超出6M");
} catch (Exception e) {
e.printStackTrace();
}
}
// 根据 /WEB-INF/files和文件名，创建一个新的存储路径 /WEB-INF/files/1/12
private String makeStorePath(String storePath, String fileName) {
int hashCode = fileName.hashCode();
int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个
int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个
String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
File file = new File(path);
if (!file.exists())
file.mkdirs();
return path;
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
五：文件下载
1.显示上述存储所有的照片信息:
//显示所有上传的文件，封装到域对象中，交给jsp去显示
public class ShowAllFilesServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Map<String, String> map = new HashMap<String, String>();//key：UUID文件名；value：老文件名
//得到存储文件的根目录
String storePath = getServletContext().getRealPath("/WEB-INF/files");
//递归遍历其中文件
File file = new File(storePath);
treeWalk(file,map);
//交给JSP去显示：如何封装数据.用Map封装。key：UUID文件名；value：老文件名
request.setAttribute("map", map);
request.getRequestDispatcher("/listFiles.jsp").forward(request, response);
}
//遍历/WEB-INF/files所有文件，把文件名放到map中
private void treeWalk(File file, Map<String, String> map) {
if(file.isFile()){
//是文件
String uuidName = file.getName();// UUID_a_a.txt//真实文件名
String oldName = uuidName.substring(uuidName.indexOf("_")+1);
map.put(uuidName, oldName);
}else{
//是一个目录
File[] fs = file.listFiles();
for(File f:fs){
treeWalk(f,map);
}
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}2.显示所有文件listFiles.jsp页面中的内容：<body>
<h1>本站有以下好图片</h1>
<c:forEach items="${map}" var="me">
<c:url value="/servlet/DownloadServlet" var="url">
<c:param name="filename" value="${me.key}"></c:param>
</c:url>
${me.value} <a href="${url}">下载</a><br/>
</c:forEach>
</body>3.文件下载DownloadServlet：
public class DownloadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
OutputStream out = response.getOutputStream();
String filename = request.getParameter("filename");//get请求方式
filename = new String(filename.getBytes("ISO-8859-1"),"UTF-8");//中文编码
//截取老文件名
String oldFileName = filename.split("_")[1];
//得到存储路径
String storePath = getServletContext().getRealPath("/WEB-INF/files");
//得到文件的全部路径
String filePath = makeStorePath(storePath, filename)+"\\"+filename;
//判断文件是否存在
File file = new File(filePath);
if(!file.exists()){
out.write("对比起！你要下载的文件可能已经不存在了".getBytes("UTF-8"));
return;
}
InputStream in = new FileInputStream(file);
//通知客户端以下载的方式打开
response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(oldFileName, "UTF-8"));
byte[] b = new byte[1024];
int len = -1;
while((len=in.read(b))!=-1){
out.write(b, 0, len);
}
in.close();
out.write("下载成功".getBytes("UTF-8"));
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
private String makeStorePath(String storePath, String fileName) {
int hashCode = fileName.hashCode();
int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个
int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个
String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
File file = new File(path);
if (!file.exists())
file.mkdirs();
return path;
}
}
原文地址：http://blog.csdn.net/ankeyuan/article/details/35595255
