JAVA servlet 上传文件(commons-fileupload, commons-io)

<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<FileItem> 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