檔案上傳

SpringBoot的檔案上傳相對比較簡單，檔案資訊都包含在MultipartFile物件中，只要從中獲取檔案資訊即可
不煽情，直接上程式碼吧，這個部分出門右拐“百度一下”一大堆

/**
* 單檔案上傳
* 
* @param name 攜帶的其他文字表單(可以省略)
* @param file 檔案內容
* @return
*/
@RequestMapping(value = "/upload_single", method = RequestMethod.POST)
public @ResponseBody String handleFileUpload(@RequestParam
 
("name") String name,
            @RequestParam("file") MultipartFile file) {
    if (!file.isEmpty()) {
        BufferedOutputStream out = null;
        try {
            byte[] bytes = file.getBytes();
            out = new BufferedOutputStream(
                        new FileOutputStream(new File(BASE_PATH + "\\"
 
 + name + "-" + file.getOriginalFilename())));
            out.write(bytes);
            return "You successfully uploaded " + name + " into " + name + "-uploaded !";
        } catch (Exception e) {
            return "You failed to upload " + name + " => " + e.getMessage();
        } finally {
            if
 
 (null != out) {
                try {
                    out.close();
                } catch (IOException e) {
                        e.printStackTrace();
                }
            }
        }
    } else {
        return "You failed to upload " + name + " because the file was empty.";
    }
}

測試：

<p>單檔案上傳</p>
<form method="POST" enctype="multipart/form-data"  
      action="/upload_single">  
     File to upload: <input type="file" name="file"/><br /> 
     Name: <input type="text" name="name"/>
    <input type="submit"  value="單檔案上傳"/>
</form> 

多檔案上傳

多檔案上傳需要接收解析出MultipartHttpServletRequest物件中包含的檔案資訊

/**
* 多檔案上傳，主要是使用了MultipartHttpServletRequest和MultipartFile
* 
* @param name 攜帶的其他文字表單(可以省略)
* @param request
* @return
*/
@RequestMapping(value = "/upload", method = RequestMethod.POST)
public @ResponseBody String handleFileUpload(HttpServletRequest request,@RequestParam("name") String name) {
    List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");
    System.out.println("name==>"+name);
    MultipartFile file = null;
    BufferedOutputStream out = null;
    for (int i = 0; i < files.size(); ++i) {
        file = files.get(i);
        if (!file.isEmpty()) {
            try {
                byte[] bytes = file.getBytes();
                out = new BufferedOutputStream(new FileOutputStream(new File(BASE_PATH + "\\" + file.getOriginalFilename())));
                out.write(bytes);
            } catch (Exception e) {
                return "failed to upload " + i + " => " + e.getMessage();
            } finally {
                if (null != out) {
                    try {
                        out.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    out = null;
                }
            }
        } else {
            return "failed to upload " + i + " because the file was empty.";
        }
    }
    return "upload successful";
}

測試：

<p>多檔案上傳</p>
<form method="POST" enctype="multipart/form-data"
        action="/upload">
    Name: <input type="text" name="name"/>
    <p>檔案1：<input type="file" name="file" /></p>
    <p>檔案2：<input type="file" name="file" /></p>
    <p><input type="submit" value="多檔案上傳" /></p>
</form>

檔案下載（斷點續傳）

相對於上傳在檔案下載的處理上，需要自己處理HttpServletResponse中流的返回，這裡直接上一個有斷點續傳的程式碼：

@RequestMapping(value = "/download", method = RequestMethod.GET)
public void getDownload(String name, HttpServletRequest request, HttpServletResponse response) {
        // Get your file stream from wherever.
        String fullPath = "D:\\upload_test\\" + name;
        File downloadFile = new File(fullPath);

        ServletContext context = request.getServletContext();
        // get MIME type of the file
        String mimeType = context.getMimeType(fullPath);
        if (mimeType == null) {
            // set to binary type if MIME mapping not found
            mimeType = "application/octet-stream";
        }

        // set content attributes for the response
        response.setContentType(mimeType);
        // response.setContentLength((int) downloadFile.length());

        // set headers for the response
        String headerKey = "Content-Disposition";
        String headerValue = String.format("attachment; filename=\"%s\"", downloadFile.getName());
        response.setHeader(headerKey, headerValue);
        // 解析斷點續傳相關資訊
        response.setHeader("Accept-Ranges", "bytes");
        long downloadSize = downloadFile.length();
        long fromPos = 0, toPos = 0;
        if (request.getHeader("Range") == null) {
            response.setHeader("Content-Length", downloadSize + "");
        } else {
            // 若客戶端傳來Range，說明之前下載了一部分，設定206狀態(SC_PARTIAL_CONTENT)
            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
            String range = request.getHeader("Range");
            String bytes = range.replaceAll("bytes=", "");
            String[] ary = bytes.split("-");
            fromPos = Long.parseLong(ary[0]);
            if (ary.length == 2) {
                toPos = Long.parseLong(ary[1]);
            }
            int size;
            if (toPos > fromPos) {
                size = (int) (toPos - fromPos);
            } else {
                size = (int) (downloadSize - fromPos);
            }
            response.setHeader("Content-Length", size + "");
            downloadSize = size;
        }
        // Copy the stream to the response's output stream.
        RandomAccessFile in = null;
        OutputStream out = null;
        try {
            in = new RandomAccessFile(downloadFile, "rw");
            // 設定下載起始位置
            if (fromPos > 0) {
                in.seek(fromPos);
            }
            // 緩衝區大小
            int bufLen = (int) (downloadSize < 2048 ? downloadSize : 2048);
            byte[] buffer = new byte[bufLen];
            int num;
            int count = 0; // 當前寫到客戶端的大小
            out = response.getOutputStream();
            while ((num = in.read(buffer)) != -1) {
                out.write(buffer, 0, num);
                count += num;
                //處理最後一段，計算不滿緩衝區的大小
                if (downloadSize - count < bufLen) {
                    bufLen = (int) (downloadSize-count);
                    if(bufLen==0){
                        break;
                    }
                    buffer = new byte[bufLen];
                }
            }
            response.flushBuffer();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (null != out) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != in) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
}

該部分本人直接在Android客戶端上測試：
下載程式碼：

public static boolean downLoadFile(String url, int from, int to,String savePath) {
    try {
        URL link = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) link.openConnection();
        // 設定斷點續傳的開始位置
        if (to != 0) {
                conn.setRequestProperty("Range", "bytes=" + from + "-" + to);
        }else{
            conn.setRequestProperty("Range", "bytes=" + from + "-");
        }
        Log.e("m_tag", "code:" + conn.getResponseCode());
        if (conn.getResponseCode() == 206) {
            RandomAccessFile file = new RandomAccessFile(savePath, "rw");
            file.seek(from);
            InputStream in = conn.getInputStream();
            byte[] buffer = new byte[1024];
            int num;
            while ((num = in.read(buffer)) > 0) {
                file.write(buffer, 0, num);
            }
            file.close();
            in.close();
            return true;
        }
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return false;
}

Activity中運用：

class MyTask extends AsyncTask<Object, Integer, Object> {

        @Override
        protected Object doInBackground(Object... params) {
                String uri = (String) params[0];
                int from = (Integer) params[1];
                int to = (Integer) params[2];
                String savePath = (String) params[3];
                return HttpUtil.downLoadFile(uri, from, to, savePath);
        }

        @Override
        protected void onPostExecute(Object result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            tvRes.setText(result.toString());
        }

}

//這裡用兩個按鈕點選模擬分段，第一個按鈕下載0-50B，第二個從50B下載到末尾
...省略其他部分...
case R.id.btn_part_01:
    new MyTask().execute("http://192.168.2.183:8080/download?name=11.jpg",0, 50, "/mnt/sdcard/pic_123.jpg");
break;
case R.id.btn_part_02:
    new MyTask().execute("http://192.168.2.183:8080/download?name=11.jpg",50, 0, "/mnt/sdcard/pic_123.jpg");
break;
...省略其他部分...

[附]

檔案上傳時相對路徑配置

以上的上傳檔案可以儲存到伺服器端的D:\upload_test但是對於這個路徑，客戶端如果想要使用一個相對路徑來訪問的話，需要做以下配置：

1、在application.properties中宣告一個變數描述該地址

#圖片上傳儲存路徑
imagesPath=file:/D:/upload_test/

2、定義一個配置檔案可以將該絕對路徑對映到一個/images的相對路徑上

package com.example.demo.config;

import org.apache.log4j.spi.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class FileConfig extends WebMvcConfigurerAdapter {

    @Value("${imagesPath}") 
    private String mImagesPath;

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        if (mImagesPath.equals("") || mImagesPath.equals("${imagesPath}")) {
            String imagesPath = FileConfig.class.getClassLoader().getResource("").getPath();
            if (imagesPath.indexOf(".jar") > 0) {
                imagesPath = imagesPath.substring(0, imagesPath.indexOf(".jar"));
            } else if (imagesPath.indexOf("classes") > 0) {
                imagesPath = "file:" + imagesPath.substring(0, imagesPath.indexOf("classes"));
            }
            imagesPath = imagesPath.substring(0, imagesPath.lastIndexOf("/")) + "/images/";
            mImagesPath = imagesPath;
        }
        System.out.println("imagesPath=" + mImagesPath);
        registry.addResourceHandler("/images/**").addResourceLocations(mImagesPath);
        super.addResourceHandlers(registry);
    }
}

這樣之後對於伺服器上D:\upload_test\1.jpg這個圖片可以在客戶端直接使用http://127.0.0.1:8080/images/1.jpg這個路徑就可以訪問了