使用java代码实现内容下载

package com.juneyaokc.bigdata.logcenter.ums.service.out.download.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
@RestController
@RequestMapping(value="/download/agent/java/V1.0")
public class DownloadAgentJava {
    //日志
    Logger logger = LoggerFactory.getLogger(DownloadAgentJava.class);


    //以流的方式下载
    @RequestMapping("/stream")
    public void download(HttpServletResponse response) {
        try {
            String path="E:\\ums-download\\TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96.jpg";
            // path是指欲下载的文件的路径。
            File file = new File(path);
            // 取得文件名。
            String filename = file.getName();
            // 取得文件的后缀名。
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();

            // 以流的形式下载文件。
            InputStream fis = new BufferedInputStream(new FileInputStream(path));
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();
            // 清空response
            response.reset();
            // 设置response的Header
            response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
            response.addHeader("Content-Length", "" + file.length());
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            toClient.write(buffer);
            toClient.flush();
            toClient.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
//        return null;
//        return response;
    }

    //下载本地文件
    @RequestMapping("/local")
    public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
        // 下载本地文件
        String fileName = "TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96-local.jpg".toString(); // 文件的默认保存名
        // 读到流中
        InputStream inStream = new FileInputStream("E:\\ums-download\\TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96.jpg");// 文件的存放路径
        // 设置输出的格式
        response.reset();
        response.setContentType("bin");
        response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
        // 循环取出流中的数据
        byte[] b = new byte[100];
        int len;
        try {
            while ((len = inStream.read(b)) > 0)
                response.getOutputStream().write(b, 0, len);
            inStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //下载网络文件
    @RequestMapping("/net")
    public void downloadNet(HttpServletResponse response) throws MalformedURLException {

//        String filePath="E:\\ums-download\\TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96.jpg";
        boolean isOnLine=false;

        // 下载网络文件
        int bytesum = 0;
        int byteread = 0;

        URL url = new URL("https://img.alicdn.com/tfs/TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96.jpg");
        String fileName=""+url.getFile();

        try {
            URLConnection conn = url.openConnection();
            InputStream inStream = conn.getInputStream();

            BufferedInputStream br = new BufferedInputStream(inStream);
            byte[] buf = new byte[1024];
            int len = 0;

            response.reset(); // 非常重要
            if (isOnLine) { // 在线打开方式
//                URL u = new URL("file:///" + filePath);
                response.setContentType(url.openConnection().getContentType());
                response.setHeader("Content-Disposition", "inline; filename=" + fileName);
                // 文件名应该编码成UTF-8
            } else { // 纯下载方式
                response.setContentType("application/x-msdownload");
                response.setHeader("Content-Disposition", "attachment; filename=" + fileName);
            }
            OutputStream out = response.getOutputStream();
            while ((len = br.read(buf)) > 0)
                out.write(buf, 0, len);

            inStream.close();
            br.close();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //支持在线文件打开
    @RequestMapping("/online")
    public void downLoad( HttpServletResponse response) throws Exception {
        String filePath="E:\\ums-download\\TB1slPFuBLoK1RjSZFuXXXn0XXa-1200-96.jpg";
        boolean isOnLine=true;
        File f = new File(filePath);
        if (!f.exists()) {
            response.sendError(404, "File not found!");
            return;
        }
        BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
        byte[] buf = new byte[1024];
        int len = 0;

        response.reset(); // 非常重要
        if (isOnLine) { // 在线打开方式
            URL u = new URL("file:///" + filePath);
            response.setContentType(u.openConnection().getContentType());
            response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
            // 文件名应该编码成UTF-8
        } else { // 纯下载方式
            response.setContentType("application/x-msdownload");
            response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
        }
        OutputStream out = response.getOutputStream();
        while ((len = br.read(buf)) > 0)
            out.write(buf, 0, len);
        br.close();
        out.close();
    }

    //下载文件系统中文件

    //下载对象存储文件

    //下载数据库中文件

}