SpringBoot实现文件下载的四种方式

/**
* @param path 想要下载的文件的路径
* @param response
* @功能描述 下载文件:
*/
@RequestMapping("/download")
public void download(String path, HttpServletResponse response) {
try {
// path是指想要下载的文件的路径
File file = new File(path);
log.info(file.getPath());
// 获取文件名
String filename = file.getName();
// 获取文件后缀名
String ext = filename.substring(filename.lastIndexOf(".") + 1).toLowerCase();
log.info("文件后缀名：" + ext);
 
// 将文件写入输入流
FileInputStream fileInputStream = new FileInputStream(file);
InputStream fis = new BufferedInputStream(fileInputStream);
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
 
// 清空response
response.reset();
// 设置response的Header
response.setCharacterEncoding("UTF-8");
//Content-Disposition的作用：告知浏览器以何种方式显示响应返回的文件，用浏览器打开还是以附件的形式下载到本地保存
//attachment表示以附件方式下载 inline表示在线打开 "Content-Disposition: inline; filename=文件名.mp3"
// filename表示文件的默认名称，因为网络传输只支持URL编码的相关支付，因此需要将文件名URL编码后进行传输,前端收到后需要反编码才能获取到真正的名称
response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
// 告知浏览器文件的大小
response.addHeader("Content-Length", "" + file.length());
OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
outputStream.write(buffer);
outputStream.flush();
} catch (IOException ex) {
ex.printStackTrace();
	}
} 

@RequestMapping("getFile")
@ResponseBody
public void getFile(HttpServletResponse response) throws Exception{
    File readFile = new File("/home/ssx/Music/CloudMusic/夜曲-周杰伦.flac");
    //字节流-用于读文件  这里只是demo用的非缓冲流。实际项目可以用BufferedInputStream。 此功能是读取图片，所以用的字节流。如果是文本的话可以用字符流效率高，具体类看下面注释
	//        BufferedReader bufferedReader = new BufferedReader(new FileReader(readFile));//字符流
    FileInputStream fileInputStream = new FileInputStream(readFile);//字节流
    //设置文件下载方式
    response.setHeader("content-disposition","attachment;filename="+ URLEncoder.encode("夜曲-周杰伦.flac","utf-8"));
    //获取servlet响应输出字节流
	//        PrintWriter writer = response.getWriter();//字符流
    ServletOutputStream outputStream = response.getOutputStream(); //字节流

    //流数据交换，每次交换10k数据大小 （1024k = 1m）
    byte[] bytes = new byte[1024*10];
    int read;
    do {
        read = fileInputStream.read(bytes);
        outputStream.write(bytes,0,read);
    }while (-1 != read);

    //关闭资源
    IOUtils.closeQuietly(fileInputStream);
    IOUtils.closeQuietly(outputStream);
}

/**
* @param path 指想要下载的文件的路径
* @param response
* @功能描述 下载文件:将输入流中的数据循环写入到响应输出流中，而不是一次性读取到内存
*/
@RequestMapping("/downloadLocal")
public void downloadLocal(String path, HttpServletResponse response) throws IOException {
// 读到流中
InputStream inputStream = new FileInputStream(path);// 文件的存放路径
response.reset();
response.setContentType("application/octet-stream");
String filename = new File(path).getName();
response.addHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
ServletOutputStream outputStream = response.getOutputStream();
byte[] b = new byte[1024];
int len;
//从输入流中读取一定数量的字节，并将其存储在缓冲区字节数组中，读到末尾返回-1
while ((len = inputStream.read(b)) > 0) {
outputStream.write(b, 0, len);
}
inputStream.close();
} 

/**
* @param path 下载后的文件路径和名称
* @param netAddress 文件所在网络地址
* @功能描述 网络文件下载到服务器本地
*/
@RequestMapping("/netDownloadLocal")
public void downloadNet(String netAddress, String path) throws IOException {
URL url = new URL(netAddress);
URLConnection conn = url.openConnection();
InputStream inputStream = conn.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(path);
 
int bytesum = 0;
int byteread;
byte[] buffer = new byte[1024];
while ((byteread = inputStream.read(buffer)) != -1) {
bytesum += byteread;
System.out.println(bytesum);
fileOutputStream.write(buffer, 0, byteread);
}
fileOutputStream.close();
} 

/**
* @param netAddress
* @param filename
* @param isOnLine
* @param response
* @功能描述 网络文件获取到服务器后，经服务器处理后响应给前端
*/
@RequestMapping("/netDownLoadNet")
public void netDownLoadNet(String netAddress, String filename, boolean isOnLine, HttpServletResponse response) throws Exception {
 
URL url = new URL(netAddress);
URLConnection conn = url.openConnection();
InputStream inputStream = conn.getInputStream();
 
response.reset();
response.setContentType(conn.getContentType());
if (isOnLine) {
// 在线打开方式 文件名应该编码成UTF-8
response.setHeader("Content-Disposition", "inline; filename=" + URLEncoder.encode(filename, "UTF-8"));
} else {
//纯下载方式 文件名应该编码成UTF-8
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
}
 
byte[] buffer = new byte[1024];
int len;
OutputStream outputStream = response.getOutputStream();
while ((len = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, len);
}
inputStream.close();
}