工具---文件上传工具的使用
1 、jsp
<%-- 表单中有文件上传输入项时,表单的enctype属性必须设置为multipart/form-data --%>
<form action="${pageContext.request.contextPath}/upload.do" method="post" enctype="multipart/form-data">
<input type="text" name="user"> <br>
<input type="file" name="file1"> <br>
<input type="file" name="file2"> <br>
<input type="submit" > <input type="reset"> <br>
</form>
表单中有文件上传输入项时,表单的enctype属性必须设置为multipart/form-data
2 、依赖包
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.3</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
</dependency>
3 、servlet
文件上传必须使用post方法
public class FileServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//判断是普通表单还是文件表单
if (!ServletFileUpload.isMultipartContent(req)) {
return; //如果是普通文件,终止方法运行,直接返回
}
//创建上传文件的保存路径,建议在web-inf下,安全,用户无法直接访问上传的文件
String uploadPath = this.getServletContext().getRealPath("/WEB-INF/upload");
File uploadFile = new File(uploadPath);
if (!uploadFile.exists()) {
uploadFile.mkdir(); //创建目录
}
//缓存临时文件,临时路径(文件超过设定大小,就放在临时文件夹中,过几天自动删除或提醒用户转存为永久)
String tempPath = this.getServletContext().getRealPath("/WEB-INF/temp");
File tempFile = new File(tempPath);
if (!tempFile.exists()) {
tempFile.mkdir(); //创建目录
}
//处理上传的文件,一般要通过流的方式来获取,可以使用req.getInputStream(),但比较麻烦
//建议使用文件上传组件实现,common-fileupload,需要依赖于commons-io组件
try {
// 1 创建DiskFileItemFactory对象,处理文件上传路径、大小限制
DiskFileItemFactory factory = getDiskFileItemFactory(tempFile);
// 2 获取ServletFileUpload
ServletFileUpload upload = getServletFileUpload(factory);
// 3 处理上传文件
String msg = uploadParseRequest(upload, req, uploadPath);
req.setAttribute("msg", msg);
req.getRequestDispatcher("info.jsp").forward(req,resp);
} catch (FileUploadException e) {
e.printStackTrace();
}
}
public static DiskFileItemFactory getDiskFileItemFactory(File file) {
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024 * 1024); //缓存区大小
factory.setRepository(file); //临时文件保存的路径
return factory;
}
public static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) {
ServletFileUpload upload = new ServletFileUpload(factory);
//监听文件上传进度
upload.setProgressListener(new ProgressListener() {
@Override
public void update(long l, long l1, int i) {
System.out.println("总大小: " + l1 + " 已上传: " + l);
}
});
upload.setHeaderEncoding("utf-8");
upload.setFileSizeMax(1024 * 1024 * 10); //单个文件大小 10M
return upload;
}
public static String uploadParseRequest(ServletFileUpload upload, HttpServletRequest request, String uploadPath) throws IOException, FileUploadException {
String msg = "";
//把前端的请求解析,封装成fileItem对象(需要从获取ServletFileUpload对象获取)
List<FileItem> fileItems = upload.parseRequest(request);
for (FileItem fileItem : fileItems) {
//判断表单是否是带文件的表单
if (fileItem.isFormField()) { //不是文件表单
String uploadFieldName = fileItem.getFieldName();
String value = fileItem.getString("utf-8");
System.out.println(uploadFieldName + ":" + value);
} else { //是文件表单
//########################### 处理文件 ########################################//
String uploadFieldName = fileItem.getName();
if (uploadFieldName == null || uploadFieldName.trim().equals("")) { //文件名不合法
continue;
}
//获得上传的文件名
String fileName = uploadFieldName.substring(uploadFieldName.lastIndexOf("/") + 1);
//获得上传的文件的后缀名
String fileEnd = uploadFieldName.substring(uploadFieldName.lastIndexOf(".") + 1);
System.out.println("文件名" + fileName + "文件类型" + fileEnd);
String uuidPath = UUID.randomUUID().toString();
//########################### 存放地址 ########################################//
String realPath = uploadPath + "/" + uuidPath;
File file = new File(realPath);
if (!file.exists()) {
file.mkdir();
}
//########################### 文件传输 ########################################//
InputStream inputStream = fileItem.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(realPath + "/" + fileName);
byte[] buffer = new byte[1024 * 1024];
int len = 0;
while ((len = inputStream.read(buffer)) > 0) {
fileOutputStream.write(buffer, 0, len);
}
fileOutputStream.close();
inputStream.close();
msg = "文件上传成功";
fileItem.delete(); //上传成功,清除临时文件
}
}
return msg;
}
}
记得在web.xml中注册servlet
3 、上传位置
maven项目会上传到tomcat–>webapps–>ROOT–>WEB-INF
空项目会上传到输出文件夹中