import java.io.IOException;  
    import java.util.Iterator;  
    import com.fasterxml.jackson.core.JsonParseException;  
    import com.fasterxml.jackson.databind.JsonMappingException;  
    import com.fasterxml.jackson.databind.JsonNode;  
    import com.fasterxml.jackson.databind.ObjectMapper;  

    public class JacksonTest {  

        public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {  
            String json = "{\"username\":\"zhangsan\",\"性别\":\"男\",\"company\":{\"companyName\":\"中华\",\"address\":\"北京\"},\"cars\":[\"奔驰\",\"宝马\"]}";  
            ObjectMapper mapper = new ObjectMapper();  
            //JSON ----> JsonNode  
            JsonNode rootNode = mapper.readTree(json);    
            Iterator<String> keys = rootNode.fieldNames();     
            while(keys.hasNext()){    
                String fieldName = keys.next();    
                System.out.println(fieldName + ": " + rootNode.path(fieldName).toString());    
            }  
            //JsonNode ----> JSON  
            System.out.println(mapper.writeValueAsString(rootNode));  
        }  

    }