The connection to adb is down, and a severe error has occured.

使用真机调试android程序的时候，有时候会报错：

1.* daemon not running. starting it now *
ADB server didn't ACK
* failed to start daemon *

2.The connection to adb is down, and a severe error has occured.
You must restart adb and Eclipse.
Please ensure that adb is correctly located at 'E:\Develop\adt-bundle-windows-x86\adt-bundle-windows-x86\sdk\platform-tools\adb.exe' and can be executed.

原因：

1.端口被占用；

2.adb没启用；

解决办法：
1.先把eclipse关闭.

2.杀死进程tadb.exe（腾讯手机管家）;

3.在管理器转到你的android SDK 的platform-tools下；

3.键入adb kill-server ,如果adb关闭了会提示 server not running *

4.再输入 adb start-server  如果不成功会提示 daemon not running. starting it now on port  ***的

而如果成功的话不提示任何语句的.

5.这时再重新打开eclipse，大功告成.