Java生成pdf 不是一个pdf文件或者已损坏

Question

首先，我通过HttpURLConnection去请求一个url。
通过postman解析出来的header是这样的

---

Connection →keep-alive
X-Powered-By →Undertow/1
Server →WildFly/10
Content-Type →text/plain;charset=UTF-8
Date →Wed, 13 Mar 2019 05:50:43 GMT
Vary →Accept-Encoding
Content-Encoding →gzip
Transfer-Encoding →chunked

---

body是个字节数组
我后台用inputstream in = con.getInputStream()去接的
我想用流直接把文件输出到指定目录
但是现在有个问题，我文件输出出来了，但一打开就报错 -不是一个pdf文件或者已损坏

Answer 1

private void copyFile(File oldFile, File newFile) throws Exception{
        FileInputStream in = new FileInputStream(oldFile);
        FileOutputStream out = new FileOutputStream(newFile);

        byte[] buffer = new byte[2097152];
        int readByte = 0;
        while((readByte = in.read(buffer)) != -1){
            out.write(buffer, 0, readByte);
        }

        in.close();
        out.close();
    }