HTTP文件的下载后台JAVA代码

1、使用org.apache.http.impl.client.CloseableHttpClient

先上代码：

    public String downloadFile(String src_file, String dest_file) throws Throwable {

        String fileName = getFileName(src_file);

        try (CloseableHttpClient httpclient = HttpClients.createDefault()) {

                    HttpGet httpget = new HttpGet(src_file);

                    httpget.setConfig(RequestConfig.custom() //

                            .setConnectionRequestTimeout(downloadTimeout) //

                            .setConnectTimeout(downloadTimeout) //

                            .setSocketTimeout(downloadTimeout) //

                            .build());

                    try (CloseableHttpResponse response = httpclient.execute(httpget)) {

                        org.apache.http.HttpEntity entity = response.getEntity();

                        File desc = new File(dest_file+File.separator+fileName);

                        File folder = desc.getParentFile();

                        folder.mkdirs();

                        try (InputStream is = entity.getContent(); //

                                OutputStream os = new FileOutputStream(desc)) {

                            StreamUtils.copy(is, os);

                        }

                    }catch(Throwable e){

                        throw new Throwable("文件下载失败......", e);

                    }

                }

            return dest_file+File.separator+fileName;

        }

另外：添加header代码如下：httpget.addHeader("X-Auth-Token",token);

2、使用curl:

windows系统中使用需要下载CURL,下载地址：https://curl.haxx.se/download.html 选择windows版；

使用命令行下载文件java代码：

package com.test.download;

import java.io.IOException;

public class TestDownload {

    public static void main(String[] args) {

        String curlPath = "D:\\curl\\I386\\CURL.EXE";

        String destPath = "D:\\2.jpg";

        String fileUrl = "http://i0.hdslb.com/bfs/archive/5a08e413f479508ab78bb562ac81f40ad28a4245.jpg";

        dowloadFile(curlPath,destPath,fileUrl);

    }

    private static void dowloadFile(String curlPath ,String filePath, String url) {

        long start = System.currentTimeMillis();

        String token = "12345678901234567890";

        System.out.println("执行命令==="+curlPath + " -o "+ filePath +" \"" + url +"\""

                + " -H \"X-Auth-Token:"+token+"\" -X GET");

        try {

            Runtime.getRuntime().exec(curlPath + " -o "+ filePath +" \"" + url +"\""

                    + " -H \"X-Auth-Token:"+token+"\" -X GET");

        } catch (IOException e) {

            e.printStackTrace();

        }

        System.out.println("下载成功，耗时(ms)："+(System.currentTimeMillis()-start));

    }

}

具体的CURL命令行使用可以看帮助：curl -h

3、Servlet文件下载：

public void downloadNet(HttpServletResponse response) throws MalformedURLException {

        int bytesum = 0;

        int byteread = 0;

        URL url = new URL("http://img.baidu.com/logo.gif");

        try {

            URLConnection conn = url.openConnection();

            InputStream inStream = conn.getInputStream();

            FileOutputStream fs = new FileOutputStream("c:/abc.gif");

            byte[] buffer = new byte[1204];

            int length;

            while ((byteread = inStream.read(buffer)) != -1) {

                bytesum += byteread;

                System.out.println(bytesum);

                fs.write(buffer, 0, byteread);

            }

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

    public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {

        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();

    }

download

4、添加两个文件复制的代码：

private static void nioTransferCopy(File source, File target) {

    FileChannel in = null;

    FileChannel out = null;

    FileInputStream inStream = null;

    FileOutputStream outStream = null;

    try {

        inStream = new FileInputStream(source);

        outStream = new FileOutputStream(target);

        in = inStream.getChannel();

        out = outStream.getChannel();

        in.transferTo(0, in.size(), out);

    } catch (IOException e) {

        e.printStackTrace();

    } finally {

        close(inStream);

        close(in);

        close(outStream);

        close(out);

    }

}  

private static void nioBufferCopy(File source, File target) {

    FileChannel in = null;

    FileChannel out = null;

    FileInputStream inStream = null;

    FileOutputStream outStream = null;

    try {

        inStream = new FileInputStream(source);

        outStream = new FileOutputStream(target);

        in = inStream.getChannel();

        out = outStream.getChannel();

        ByteBuffer buffer = ByteBuffer.allocate(4096);

        while (in.read(buffer) != -1) {

            buffer.flip();

            out.write(buffer);

            buffer.clear();

        }

    } catch (IOException e) {

        e.printStackTrace();

    } finally {

        close(inStream);

        close(in);

        close(outStream);

        close(out);

    }

}

添加一个文件下载的RestTemplate的实现：

public void downloadLittleFileToPath(String url, String target) {

        Instant now = Instant.now();

        RestTemplate template = new RestTemplate();

        ClientHttpRequestFactory clientFactory = new HttpComponentsClientHttpRequestFactory();

        template.setRequestFactory(clientFactory);

        HttpHeaders header = new HttpHeaders();

        List<MediaType> list = new ArrayList<MediaType>();

        // 指定下载文件类型

        list.add(MediaType.APPLICATION_OCTET_STREAM);

        header.setAccept(list);

        HttpEntity<byte[]> request = new HttpEntity<byte[]>(header);

        ResponseEntity<byte[]> rsp = template.exchange(url, HttpMethod.GET, request, byte[].class);

        logger.info("[下载文件] [状态码] code:{}", rsp.getStatusCode());

        try {

            Files.write(Paths.get(target), Objects.requireNonNull(rsp.getBody(), "未获取到下载文件"));

        } catch (IOException e) {

            logger.error("[下载文件] 写入失败:", e);

        }

        logger.info("[下载文件] 完成,耗时:{}", ChronoUnit.MILLIS.between(now, Instant.now()));

    }

     public void downloadBigFileToPath(String url, String target) {

            Instant now = Instant.now();

            try {

                RestTemplate template = new RestTemplate();

                ClientHttpRequestFactory clientFactory = new HttpComponentsClientHttpRequestFactory();

                template.setRequestFactory(clientFactory);

              //定义请求头的接收类型

              RequestCallback requestCallback = request -> request.getHeaders()

                      .setAccept(Arrays.asList(MediaType.APPLICATION_OCTET_STREAM, MediaType.ALL));

              // getForObject会将所有返回直接放到内存中,使用流来替代这个操作

              ResponseExtractor<Void> responseExtractor = response -> {

                // Here I write the response to a file but do what you like

                Files.copy(response.getBody(), Paths.get(target));

                return null;

              };

              template.execute(url, HttpMethod.GET, requestCallback, responseExtractor);

            } catch (Throwable e) {

                logger.error("[下载文件] 写入失败:", e);

            }

            logger.info("[下载文件] 完成,耗时:{}", ChronoUnit.MILLIS.between(now, Instant.now()));

          }

RestTemplate下载文件

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