文件上传首先要引入两个核心包
commons-fileupload-1.2.1.jar
commons-io-1.4.jar
下面是对文件上传和下载的一些代码做的一个简单封装，可以方便以后直接使用【使用时将封装好的jar包直接导入工程中即可使用】
上传文件核心代码
1 package com.lizhou.fileload; 2 3 import java.io.File; 4 import java.io.FileOutputStream; 5 import java.io.IOException; 6 import java.io.InputStream; 7 import java.io.OutputStream; 8 import java.util.ArrayList; 9 import java.util.List; 10 import java.util.UUID; 11 12 import javax.servlet.http.HttpServletRequest; 13 14 import org.apache.commons.fileupload.FileItem; 15 import org.apache.commons.fileupload.FileUploadException; 16 import org.apache.commons.fileupload.disk.DiskFileItemFactory; 17 import org.apache.commons.fileupload.servlet.ServletFileUpload; 18 19 import com.lizhou.exception.FileFormatException; 20 import com.lizhou.exception.NullFileException; 21 import com.lizhou.exception.ProtocolException; 22 import com.lizhou.exception.SizeException; 23 24 /** 25 * 上传文件 26 * @author bojiangzhou 27 * 28 */ 29 public class FileUpload { 30 /** 31 * 上传文件用的临时目录 32 */ 33 private String tempPath = null; 34 /** 35 * 上传文件用的文件目录 36 */ 37 private String filePath = null; 38 /** 39 * 内存中缓存区的大小,默认100k 40 */ 41 private int bufferSize = 100; 42 /** 43 * 上传文件的最大大小,默认1M 44 */ 45 private int fileSize = 1000; 46 /** 47 * 上传文件使用的编码方式,默认UTF-8 48 */ 49 private String encoding = "UTF-8"; 50 /** 51 * 上传文件的格式,默认无格式限制 52 */ 53 private List fileFormat = new ArrayList (); 54 /** 55 * HttpServletRequest 56 */ 57 private HttpServletRequest request; 58 //私有化无参构造 59 private FileUpload(){} 60 61 public FileUpload(HttpServletRequest request){ 62 this.request = request; 63 } 64 65 public FileUpload(String tempPath, String filePath, HttpServletRequest request){ 66 this.request = request; 67 this.tempPath = tempPath; 68 this.filePath = filePath; 69 makeDirectory(tempPath); 70 makeDirectory(filePath); 71 } 72 73 /** 74 * 上传文件 75 * @return 上传成功返回true 76 * @throws ProtocolException 77 * @throws FileUploadException 78 * @throws NullFileException 79 * @throws SizeException 80 * @throws FileFormatException 81 * @throws IOException 82 */ 83 public boolean uploadFile() 84 throws ProtocolException, NullFileException, SizeException, FileFormatException, IOException, FileUploadException{ 85 boolean b = true; 86 ServletFileUpload upload = getUpload(); 87 //解析request中的字段，每个字段(上传字段和普通字段)都会自动包装到FileItem中 88 List fileItems = upload.parseRequest(this.request); 89 for(FileItem item : fileItems){ 90 //如果为普通字段 91 if(item.isFormField()){ 92 continue; 93 } 94 //获取文件名 95 String fileName = item.getName(); 96 //因为IE6得到的是文件的全路径，所以进一步处理 97 fileName = fileName.substring(fileName.lastIndexOf("\\")+1); 98 //判断上传的文件是否为空 99 if(item.getSize() <= 0){100 b = false;101 throw new NullFileException();102 }103 //判断文件是否超过限制的大小104 if(item.getSize() > fileSize*1000){105 b = false;106 throw new SizeException();107 }108 //判断上传文件的格式是否正确109 if( !isFormat(fileName.substring(fileName.lastIndexOf(".")+1)) ){110 b = false;111 throw new FileFormatException();112 }113 String uuidFileName = getUuidFileName(fileName);114 //获取文件的输入流115 InputStream is = item.getInputStream();116 //创建输出流117 OutputStream os = new FileOutputStream(this.filePath+"/"+uuidFileName);118 //输出119 output(is, os);120 //将上传文件时产生的临时文件删除121 item.delete();122 }123 return b;124 }125 126 /**127 * 获取文件上传的输入流128 * @return129 * @throws ProtocolException130 * @throws NullFileException131 * @throws SizeException132 * @throws FileFormatException133 * @throws IOException134 * @throws FileUploadException135 */136 public InputStream getUploadInputStream() 137 throws ProtocolException, NullFileException, SizeException, FileFormatException, IOException, FileUploadException{138 ServletFileUpload upload = getUpload();139 //解析request中的字段，每个字段(上传字段和普通字段)都会自动包装到FileItem中140 List fileItems = upload.parseRequest(this.request);141 for(FileItem item : fileItems){142 //如果为普通字段143 if(item.isFormField()){144 continue;145 }146 //获取文件名147 String fileName = item.getName();148 //因为IE6得到的是文件的全路径，所以进一步处理149 fileName = fileName.substring(fileName.lastIndexOf("\\")+1);150 //判断上传的文件是否为空151 if(item.getSize() <= 0){152 throw new NullFileException();153 }154 //判断文件是否超过限制的大小155 if(item.getSize() > fileSize*1000){156 throw new SizeException();157 }158 //判断上传文件的格式是否正确159 if( !isFormat(fileName.substring(fileName.lastIndexOf(".")+1)) ){160 throw new FileFormatException();161 }162 //获取文件的输入流163 InputStream is = item.getInputStream();164 165 return is;166 }167 return null;168 }169 170 /**171 * 获取上传文件的核心172 * @return ServletFileUpload173 * @throws ProtocolException 174 */175 public ServletFileUpload getUpload() throws ProtocolException{176 //创建上传文件工厂177 DiskFileItemFactory factory = new DiskFileItemFactory();178 //设置内存中缓存区的大小179 factory.setSizeThreshold(bufferSize);180 //如果用户未设置上传文件目录，则设置默认目录181 if(filePath == null){182 setDefaultFilePath();183 }184 //如果用户未设置临时存放目录，则设置默认目录185 if(tempPath == null){186 setDefaultTempPath();187 }188 //设置上传文件的的临时存放目录189 factory.setRepository(new File(this.tempPath));190 //创建上传文件对象[核心]191 ServletFileUpload upload = new ServletFileUpload(factory);192 //设置上传文件的编码方式193 upload.setHeaderEncoding(this.encoding);194 /*195 * 判断客户端上传文件是否使用MIME协议196 * 只有当以MIME协议上传文件时，upload才能解析request中的字段197 */198 if(!upload.isMultipartContent(this.request)){199 throw new ProtocolException();200 }201 return upload;202 }203 204 /**205 * 输出206 * @param is207 * @param os208 * @throws IOException209 */210 public void output(InputStream is, OutputStream os) throws IOException{211 byte[] by = new byte[1024];212 int len = 0;213 while( (len = is.read(by)) > 0 ){214 os.write(by, 0, len);215 }216 is.close();217 os.close();218 }219 220 /**221 * 判断上传文件的格式是否正确222 * @param format 文件格式223 * @return boolean224 */225 private boolean isFormat(String format){226 if(fileFormat.size() == 0){227 return true;228 }229 for(String f : fileFormat){230 if(f.equalsIgnoreCase(format)){231 return true;232 }233 }234 return false;235 }236 237 /**238 * 返回文件的UUID名,防止文件名重复239 * @param fileName 文件名240 * @return uuid名241 */242 public String getUuidFileName(String fileName){243 return UUID.randomUUID().toString()+"#"+fileName;244 }245 246 /**247 * 设置默认临时目录248 */249 private void setDefaultTempPath(){250 tempPath = filePath+"/temp";251 252 makeDirectory(tempPath);253 }254 255 /**256 * 设置默认文件目录257 * 默认在D盘258 */259 private void setDefaultFilePath(){260 filePath = "D:/uploadFile";261 262 makeDirectory(filePath);263 }264 265 /**266 * 根据给定的文件目录创建目录267 * @param filePath268 */269 private void makeDirectory(String filePath){270 File file = new File(filePath);271 if(!file.exists()){272 file.mkdir();273 }274 }275 276 277 278 /**279 * 获取临时目录280 * @return281 */282 public String getTempPath() {283 return tempPath;284 }285 /**286 * 设置临时目录287 * @param tempPath288 */289 public void setTempPath(String tempPath) {290 this.tempPath = tempPath;291 makeDirectory(tempPath);292 }293 /**294 * 获取文件路径295 * @return296 */297 public String getFilePath() {298 return filePath;299 }300 /**301 * 返回文件路径302 * @param filePath303 */304 public void setFilePath(String filePath) {305 this.filePath = filePath;306 makeDirectory(filePath);307 }308 /**309 * 获取内存中缓存区大小310 * @return311 */312 public int getBufferSize() {313 return bufferSize;314 }315 /**316 * 设置内存中缓存区大小 317 * 默认100k318 * @param bufferSize319 */320 public void setBufferSize(int bufferSize) {321 this.bufferSize = bufferSize;322 }323 /**324 * 获取上传文件的最大大小325 * @return326 */327 public int getFileSize() {328 return fileSize;329 }330 /**331 * 限制上传文件的最大大小,单位为k332 * 默认1000k333 * @param fileSize334 */335 public void setFileSize(int fileSize) {336 this.fileSize = fileSize;337 }338 /**339 * 返回上传文件的编码方式340 * @return341 */342 public String getEncoding() {343 return encoding;344 }345 /**346 * 设置上传文件的编码方式347 * 默认UTF-8格式348 * @param encoding349 */350 public void setEncoding(String encoding) {351 this.encoding = encoding;352 }353 /**354 * 获取允许上传文件的格式355 * @return356 */357 public String getFileFormat() {358 if(fileFormat.size() == 0){359 return "*";360 }361 String format = "";362 for(String s:fileFormat){363 format += ","+s;364 }365 format = format.substring(format.indexOf(",")+1);366 return format;367 }368 /**369 * 设置上传文件的格式,多个文件格式则多次调用该方法进行设置370 * @param fileFormat371 */372 public void setFileFormat(String format) {373 this.fileFormat.add(format);374 }375 376 public HttpServletRequest getRequest() {377 return request;378 }379 380 public void setRequest(HttpServletRequest request) {381 this.request = request;382 }383 384 }
下载文件核心代码
1 package com.lizhou.fileload; 2 3 import java.io.File; 4 import java.io.FileInputStream; 5 import java.io.FileNotFoundException; 6 import java.io.IOException; 7 import java.io.InputStream; 8 import java.io.OutputStream; 9 import java.io.UnsupportedEncodingException; 10 import java.net.URLEncoder; 11 import java.util.ArrayList; 12 import java.util.List; 13 14 import javax.servlet.http.HttpServletRequest; 15 import javax.servlet.http.HttpServletResponse; 16 17 import com.lizhou.domain.DownloadFile; 18 import com.lizhou.exception.FileNotExistsException; 19 20 /** 21 * 下载文件 22 * @author bojiangzhou 23 * 24 */ 25 public class FileDownload { 26 /** 27 * 下载时的默认文件目录 28 */ 29 private String filePath = null; 30 /** 31 * 要下载文件的格式 32 */ 33 private List fileFormat = new ArrayList (); 34 /** 35 * HttpServletRequest 36 */ 37 private HttpServletRequest request; 38 39 public FileDownload(HttpServletRequest request){ 40 this.request = request; 41 } 42 43 public FileDownload(String filePath, HttpServletRequest request){ 44 this.request = request; 45 this.filePath = filePath; 46 } 47 48 /** 49 * 将下载列表绑定到域中 50 * 默认session 51 * @param var 域对象变量名 52 * @throws FileNotExistsException 53 */ 54 public void bindDownloadFilesToScope(String var) throws FileNotExistsException{ 55 if(filePath == null){ 56 filePath = "D:/uploadFile"; 57 } 58 if(!isFileExists(this.filePath)){ 59 throw new FileNotExistsException(); 60 } 61 List list = new ArrayList (); 62 getDownloadFiles(filePath, list); 63 request.getSession().setAttribute(var, list); 64 } 65 66 /** 67 * 获得下载目录下的所有文件 68 * @param filePath 69 * @param list 70 */ 71 private void getDownloadFiles(String filePath, List list){ 72 File file = new File(filePath); 73 if(file.isFile()){ 74 String uuidFileName = file.getName(); 75 if(isFormat(uuidFileName.substring(uuidFileName.lastIndexOf(".")+1))){ 76 DownloadFile df = new DownloadFile(); 77 df.setFileName(uuidFileName.substring(uuidFileName.indexOf("#")+1)); 78 df.setUuidFileName(uuidFileName); 79 df.setFilePath(file.getPath()); 80 list.add(df); 81 } 82 } else{ 83 File[] childFiles = file.listFiles(); 84 for(File cf : childFiles){ 85 getDownloadFiles(cf.getPath(), list); 86 } 87 } 88 } 89 90 /** 91 * 下载文件 92 * @param var 下载列表的域变量名 93 * @param uuidFileName 客户端传来的文件的uuid名 94 * @param response 95 * @throws IOException 96 */ 97 public void downloadFile(String var, String uuidFileName, HttpServletResponse response) throws IOException{ 98 byte[] by = uuidFileName.getBytes("ISO-8859-1"); 99 uuidFileName = new String(by, "UTF-8");100 List files = (List ) this.request.getSession().getAttribute(var);101 for(DownloadFile file : files){102 if(file.getUuidFileName().equals(uuidFileName)){103 InputStream is = new FileInputStream(file.getFilePath());104 OutputStream os = response.getOutputStream();105 response.setHeader("Content-Disposition", "attachment; filename="+URLEncoder.encode(file.getFileName(), "UTF-8"));106 output(is, os);107 break;108 }109 }110 }111 112 public void output(InputStream is, OutputStream os) throws IOException{113 byte[] by = new byte[1024];114 int len = 0;115 while( (len = is.read(by)) > 0 ){116 os.write(by, 0, len);117 }118 is.close();119 os.close();120 }121 122 /**123 * 判断文件的格式是否正确124 * @param format 文件格式125 * @return boolean126 */127 private boolean isFormat(String format){128 if(fileFormat.size() == 0){129 return true;130 }131 for(String f : fileFormat){132 if(f.equalsIgnoreCase(format)){133 return true;134 }135 }136 return false;137 }138 139 /**140 * 判断文件目录是否存在141 * @param filePath 文件目录142 * @return boolean143 */144 private boolean isFileExists(String filePath){145 boolean b = true;146 File file = new File(filePath);147 if(!file.exists()){148 b = false;149 }150 return b;151 }152 153 public String getFilePath() {154 return filePath;155 }156 157 /**158 * 设置下载路径159 * @param filePath160 * @throws FileNotExistsException161 */162 public void setFilePath(String filePath) {163 this.filePath = filePath;164 }165 166 /**167 * 获取允许上传文件的格式168 * @return169 */170 public String getFileFormat() {171 if(fileFormat.size() == 0){172 return "*";173 }174 String format = "";175 for(String s:fileFormat){176 format += ","+s;177 }178 format = format.substring(format.indexOf(",")+1);179 return format;180 }181 /**182 * 设置上传文件的格式,多个文件格式则多次调用该方法进行设置183 * @param fileFormat184 */185 public void setFileFormat(String format) {186 this.fileFormat.add(format);187 }188 189 public HttpServletRequest getRequest() {190 return request;191 }192 193 public void setRequest(HttpServletRequest request) {194 this.request = request;195 }196 197 }
注：上传文件时，前台form表单一定要有如下属性：enctype="multipart/form-data"
附上源码+导出的jar包+使用demo：