Hamcrest is a library of matchers, which can be combined in to create flexible expressions of intent in tests.Hamcrest 是一个为了测试为目的，且能组合成灵活表达式的匹配器类库。Alternatively, if you don't care:hamcrest-all.jar -- Includes all of the above.一般，在项目中导入hamcrest-core.jar， hamcrest-library.jar就能满足使用。
