ant 编译问题解决方案

在配置ant环境时，除了把ant路径写进环境变量，还需要关联sdk版本，才能正在编译成功。

android update project -p .

执行上述命令时，没关联sdk版本，会出现以下错误：

Error: The project either has no target set or the target is invalid.
Please provide a --target to the 'android update' command.

这个时候可执行 android list targets 来查看当前系统中的android模拟器

ljb@ljb-OptiPlex-3010:~/source/lib/K7Utils/K7Utils$ android list targets
Available Android targets:
----------
id: 1 or "android-17"
Name: Android 4.2.2
Type: Platform
API level: 17
Revision: 2
Skins: WVGA854, WSVGA, WXGA800-7in, WVGA800 (default), WQVGA432, HVGA, QVGA, WQVGA400, WXGA720, WXGA800
Tag/ABIs : no ABIs.
----------
id: 2 or "android-20"
Name: Android 4.4W
Type: Platform
API level: 20
Revision: 1
Skins: WVGA854, WSVGA, WXGA800-7in, WVGA800 (default), WQVGA432, HVGA, QVGA, WQVGA400, WXGA720, WXGA800
Tag/ABIs : no ABIs.
ljb@ljb-OptiPlex-3010:~/source/lib/K7Utils/K7Utils$

然后再执行命令，关联android 版本即可编译成功：

ljb@ljb-OptiPlex-3010:~/source/lib/K7Utils/K7Utils$ android update project -p . -t android-17 -s
Updated project.properties
Updated local.properties
Added file ./proguard-project.txt
ljb@ljb-OptiPlex-3010:~/source/lib/K7Utils/K7Utils$