Http 416错误解决方案

今天写多线程下载时老报Http416的错误，正常的话应该返回code
206，但是这次却不正常，后来研究了一下，发现如下问题：

以下是错误log：

Server returned HTTP response code: 416 for URL: http://localhost:8080/QQ.exe
at
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)

at
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown
Source)

at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown
Source)

at
java.lang.reflect.Constructor.newInstance(Unknown Source)

at
sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown
Source)

at
sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown
Source)

at
java.security.AccessController.doPrivileged(Native Method)

at
sun.net.www.protocol.http.HttpURLConnection.getChainedException(Unknown
Source)

at
sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown
Source)

at
com.lyc.download.Demo$DownloadThread.run(Demo.java:97)

HTTP response code:
416是由于读取文件时设置的Range有误造成的，具体的说就是下面这行代码有误：

connection.setRequestProperty("Range",
"bytes=:"+startIndex+"-"+endIndex);

中间的冒号：就是罪魁祸首，敲代码的时候不小心多敲了个冒号造成的；