Android模拟器（simulator）把它自己作为了localhost,也就是说，代码中使用localhost或者127.0.0.1来访问，都是访问模拟器自己！这是不行的！
如果你想在模拟器simulator上面访问你的电脑，那么就使用android内置的IP 10.0.2.2 吧，10.0.2.2 是模拟器设置的特定ip，是你的电脑的别名alias
记住，在模拟器上用10.0.2.2访问你的电脑本机。
详细请参考Android文档android-sdk-windows\docs\guide\developing\devices\emulator.html下的Emulator Networking
| Network Address |
Description |
| 10.0.2.1 |
Router/gateway address |
| 10.0.2.2 |
Special alias to your host loopback interface (i.e., 127.0.0.1 on your development machine) |
| 10.0.2.3 |
First DNS server |
| 10.0.2.4 / 10.0.2.5 / 10.0.2.6 |
Optional second, third and fourth DNS server (if any) |
| 10.0.2.15 |
The emulated device's own network/ethernet interface |
| 127.0.0.1 |
The emulated device's own loopback interface |