首先须要下载3个包，下载地址在Github FasterXML，这三个核心模块各自是：
Streaming ("jackson-core") defines low-level streaming API, and includes JSON-specific implementations
Annotations ("jackson-annotations") contains standard Jackson annotations
Databind ("jackson-databind") implements data-binding (and object serialization) support on streaming package;
it depends both on streaming and annotations packages。
json文件：
POJO类：
解析json文件的类：