文件下载

1、HttpServletResponse response返回文件

//包装流

BufferedInputStream bfs = new BufferedInputStream(ips);
OutputStream os = response.getOutputStream();
byte[] a = new byte[1024];
int len;
while((len = bfs.read(a)) != -1){
   os.write(a, 0, len);
}
os.flush();
ips.close();
bfs.close();

// 配置文件下载

response.setHeader("content-type", "application/octet-stream");

response.setContentType("application/octet-stream");

// 下载文件能正常显示中文

response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));

2、springboot文件下载，（文件读取字节数组转为base64格式的字符串，再转化为流）

@RequestMapping("/download")
	public ResponseEntity<InputStreamResource> download(String params, HttpServletResponse response){
		RestTemplate restTemplate = new RestTemplate();
		String url = "";
		
		  
	    
	    //MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
	 
	    //HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
		
		ResponseEntity<String> rs = restTemplate.postForEntity(url, null, String.class);
		try {
			JSONObject jo = JSONObject.fromObject(rs.getBody());
			if("true".equals(jo.getString("isend"))){
				byte[] bytes = Base64.getDecoder().decode(jo.getString("content"));
				
				String fileName = jo.getString("name");
				Long fileSize = jo.getLong("size");
				ByteArrayInputStream ips = new ByteArrayInputStream(bytes);
				/*BufferedInputStream bfs = new BufferedInputStream(ips);
				OutputStream os = response.getOutputStream();
				byte[] a = new byte[1024];
				int len;
				while((len = bfs.read(a)) != -1){
					os.write(a, 0, len);
				}
				os.flush();
				ips.close();
				bfs.close();*/
				HttpHeaders headers = new HttpHeaders();
			    headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
			    headers.add("Cache-Control", "no-cache, no-store, must-revalidate");  
		        headers.add("Content-Disposition", "attachment;filename="+URLEncoder.encode(fileName, "UTF-8"));  
		        headers.add("Pragma", "no-cache");  
		        headers.add("Expires", "0");
				return ResponseEntity  
		                .ok()  
		                .headers(headers)  
		                .contentLength(fileSize)  
		                .contentType(MediaType.parseMediaType("application/octet-stream"))  
		                .body(new InputStreamResource(ips));
			} else {
				int slice = jo.getInt("slice");
				if(slice > 1){
					for(int i = 2; i < slice; i++){
						String urlsi = url + "?slice=" + i;
						ResponseEntity<String> re = restTemplate.postForEntity(urlsi, null, String.class);
						JSONObject jb = JSONObject.fromObject(re.getBody());
						byte[] bt = Base64.getDecoder().decode(jb.getString("content"));
						
					}
				}
			}
		} catch (JSONException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		return null;
	}