import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;

import java.util.List;

public class JsonUtils {

    // 定义jackson对象
    private static final ObjectMapper MAPPER = new ObjectMapper();

    /**
     * 将对象转换成json字符串。
     * <p>Title: pojoToJson</p>
     * <p>Description: </p>
     * @param data
     * @return
     */
    public static String objectToJson(Object data) {
        try {
            String string = MAPPER.writeValueAsString(data);
            return string;
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**
     * 将json结果集转化为对象
     * 
     * @param jsonData json数据
     * @param clazz 对象中的object类型
     * @return
     */
    public static <T> T jsonToPojo(String jsonData,Class<T> beanType) {
        
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,false);
        mapper.setPropertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERscoreS);
        
        try {
            T t = mapper.readValue(jsonData,beanType);
            return t;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**
     * 将json数据转换成pojo对象list
     * <p>Title: jsonToList</p>
     * <p>Description: </p>
     * @param jsonData
     * @param beanType
     * @return
     */
    public static <T>List<T> jsonToList(String jsonData,Class<T> beanType) {
        JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class,beanType);
        try {
            List<T> list = MAPPER.readValue(jsonData,javaType);
            return list;
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return null;
    }
    
    /**
     * 获取泛型的Collection Type
     * @description 获取泛型的Collection Type ，如List<User>
     * @param collectionClass    ArrayList.class
     * @param elementClasses    User.class
     * @return
     * @author 刘育
     * @version 1.0
     * @date:2016年12月20日下午3:43:27
     */
    public static JavaType getCollectionType(Class<?> collectionClass,Class<?>... elementClasses) {
        ObjectMapper mapper = new ObjectMapper();
        return mapper.getTypeFactory().constructParametricType(collectionClass,elementClasses);   
    }
    
    
    
    public static <T> T  jsonToObject(String content,Class<T> t){
        try {
            ObjectMapper om=new ObjectMapper();
            return om.readValue(content,t);
        } catch (Exception e) {
            return null;
        }
    }
    
}