如何解决springmvc文件下载,内容损坏的问题

public String inputStream2String(InputStream in) throws IOException {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int len = 0;
        byte[] b = new byte[1024];	
        while ((len = in.read(b, 0, b.length)) != -1) {                     
            baos.write(b, 0, len);
        }
        byte[] buffer =  baos.toByteArray();
        //base64加密
        return Base64.encodeBase64String(buffer);
	}

Map<String, Object> reMap = gitCodeViewService.gitCodeView(Id, path, version);
String content = (String) reMap.get("content");
			
//用base64进行解码
byte[] decodeByte = Base64.decodeBase64(content);
//将解码的二进制文件转换为inputStream
InputStream is = new ByteArrayInputStream(decodeByte);

String content = (String) codeViewMap.get("content");
			
//用base64进行解码
byte[] decodeByte = Base64.decodeBase64(content);
//将解码的二进制文件转换为inputStream
InputStream is = new ByteArrayInputStream(decodeByte);
			
String userAgent = request.getHeader("User-Agent");
if (userAgent.contains("MSIE") || userAgent.contains("Trident")) {  
    //IE浏览器处理
    fileName = java.net.URLEncoder.encode(fileName, "UTF-8");  
    } else {  
    // 非IE浏览器的处理：  
    fileName = new String(fileName.getBytes("UTF-8"), "ISO-8859-1");  
   } 
			
// 设置文件头：最后一个参数是设置下载文件名
response.setHeader("Content-Disposition", "attachment;fileName="+fileName);
// 设置文件ContentType类型，这样设置，会自动判断下载文件类型  
response.setContentType("application/octet-stream");
OutputStream os = response.getOutputStream();
// 输入流输出流对拷
int len = 0;
byte[] b = new byte[1024];
while ((len = is.read(b)) > 0) {
	os.write(b, 0, len);
}
os.close();
is.close();

InputStream in = new FileInputStream(path);

response.getOutputStream()

response.setContentType("application/force-download");
response.setHeader("content-disposition","attachment;filename="+filename);

int len = 0;
byte[] b = new byte[1024];
while((len=in.read(b))!=-1){
    out.write(b,0,len);
}