<1>获取二进制文件流并输出

　　　　 InputStream inputStream = request.getInputStream();        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));        String s;        while ((s = reader.readLine()) != null) {            System.out.println(s);        }

<2>借用服务器提供的架包(commons-fileupload, commons-io)

package servlet_file_upload;import java.io.File;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;@WebServlet("/FileUploadServlet")public class FileUploadServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    public FileUploadServlet() {        super();    }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // 设置跨域访问        response.addHeader("Access-Control-Allow-Origin", "*");        // 设置请求和返回编码为 UTF-8, 如非必要,不要设置,不然会影响文件扩展名的获取        //response.setCharacterEncoding("UTF-8");    　　//request.setCharacterEncoding("UTF-8");        // 获取项目根目录绝对路径        String path = getServletContext().getRealPath("");        // 设置存放返回路径的变量        StringBuilder returnPath = new StringBuilder(200);                try {            // 实例化本地磁盘工厂            DiskFileItemFactory factory = new DiskFileItemFactory();            // 设置文件上传启用的缓存的值,每 2M 写入一次临时文件            factory.setSizeThreshold(2 * 1024 * 1024);            // 设置缓存文件的临时存放目录            factory.setRepository(new File(path + "Upload"));            // 实例化文件上传类            ServletFileUpload upload = new ServletFileUpload(factory);            // 设置全部文件上传的最大值            //upload.setSizeMax(Integer.valueOf(100) * 1024 * 1024);            // 获取前端上传的文件列表            List
     
       items = upload.parseRequest(request);            // 循环所有上传的字段或文字            for (FileItem item : items) {                if (item.isFormField()) {                    // 获取字段名                    String name = item.getFieldName();                    // 获取字段值 括号内的参数不可少否则乱码                    String value = item.getString("UTF-8");                    // 打印不是文件的字段                    System.out.println(name + ".." + value);                } else {                    // 获取文件名                    String name = item.getName();                    // 确定文件存放的相对路径                     String filePath = "Upload/" + System.currentTimeMillis() + "." + name.split("\\.")[1];                    // 将文件写入指定的路径                    item.write(new File(path + filePath));                    // 删除缓存文件, 如果没有设置, 大部分时候临时文件也会被删除                    item.delete();                    // 将相对路径赋值给返回值                    returnPath.append(filePath);                    // 路径之间用逗号隔开                    returnPath.append(",");                }            }            response.getWriter().write(returnPath.substring(0, returnPath.length()- 1));        } catch (Exception e) {            response.getWriter().write("上传失败");        }    }}
     

 

注:  前端代码请参考   http://www.cnblogs.com/lovling/p/6685634.html