javaweb实现文件上传下载

最新推荐文章于 2024-07-24 16:04:04 发布

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最新推荐文章于 2024-07-24 16:04:04 发布

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文章标签： java web class

本文链接：https://blog.youkuaiyun.com/qq_22546951/article/details/70738494

本文介绍了如何在JavaWeb环境中实现文件的上传和下载功能。针对下载，展示了一个`DownloadServlet`的简单实现，而文件上传部分则通过`Upload` servlet进行演示，包括设置请求编码和使用`Part`接口处理上传的文件。

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文件下载：

@WebServlet(“/download”)
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public DownloadServlet() {
    super();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //乱码问题
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;charset=utf-8");
    response.setCharacterEncoding("UTF-8");

//获取下载文件名称

      String filename=request.getParameter("name");

//乱码问题
     // filename=new String(filename.getBytes("iso8859-1"),"utf-8");

        ServletContext context = this.getServletContext();

//文件下载

        //1.设置文件类型

        String mimeType = context.getMimeType(filename);
        response.setContentType(mimeType);
        //String _filename=DownLoadUtils.getName(request.getHeader("user-agent"), filename);
        //response.setHeader("content-disposition", "attachment;filename="+_filename);

    //2.    设置文件下载的头信息

        //这里gbk和uft-8好像没什么差别
        response.setHeader("content-disposition", "attachment;filename="+new String(filename.getBytes("gbk"),"iso8859-1"));
   //3.  对拷流   输入输出
        InputStream is = context.getResourceAsStream("/download/"+filename);

        //获取输出流
        ServletOutputStream os = response.getOutputStream();

        IOUtils.copy(is, os);

        os.close();
        is.close();

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
}

}

文件上传：
/**
*
*/
package crose.com.upload;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

import org.apache.commons.io.IOUtils;

@WebServlet(“/upload”)

@MultipartConfig  //注意  一定要实现这个注解

public class Upload extends HttpServlet {

static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//0.设置编码
req.setCharacterEncoding(“utf-8”);

            //1.获取普通的上传组件  username
            String username = req.getParameter("username");
            System.out.println(username);

            //2.获取文件上传组件
            Part part = req.getPart("f");
            //2.1获取文件的名称
            String sss = part.getHeader("content-disposition");
            String realName=sss.substring(sss.indexOf("filename=")+10, sss.length()-1);

            System.out.println("文件的名称:"+realName);

            //2.2 获取随机名称
            String uuidName = UploadUtils.getUUIDName(realName);

            System.out.println("文件随机名称:"+uuidName);


            //2.3 获取文件存放的目录
            String dir = UploadUtils.getDir(uuidName);

            String realPath = this.getServletContext().getRealPath("/upload"+dir);
            File file = new File(realPath);
            if(!file.exists()){
                file.mkdirs();
            }

            System.out.println("文件的目录:"+realPath);

            //3.对拷流
            InputStream is = part.getInputStream();
            FileOutputStream os = new FileOutputStream(new File(file,uuidName));
            IOUtils.copy(is, os);
            os.close();
            is.close();

            //4.删除临时文件
            part.delete();

}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    doGet(req,resp);
}

}

注意用对拷流需要导入 io包