gson工具类

gson工具类：

import com.google.gson.*;
import lombok.extern.slf4j.Slf4j;

import java.util.ArrayList;
import java.util.List;

@Slf4j
public class GsonUtils {

	//log日志
	//private static final Logger LOGGER = LoggerFactory.getLogger(GsonUtils.class);

	//不用创建对象,直接使用Gson.就可以调用方法
	private static Gson gson = null;

	//判断gson对象是否存在了,不存在则创建对象
	static {
		if (gson == null) {
			//gson = new Gson();
			//当使用GsonBuilder方式时属性为空的时候输出来的json字符串是有键值key的,显示形式是"key":null，而直接new出来的就没有"key":null的
			gson= new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
		}
	}

	//无参的私有构造方法
	private GsonUtils() {

	}

	/**
	 * 将对象转成json格式
	 * @param object
	 * @return String
	 */
	public static String beanToString(Object object) {
		String gsonString = null;
		try {
			if (gson != null) {
				gsonString = gson.toJson(object);
			}
		} catch (Exception e) {
			log.error("对象转换json异常",e);
		}
		return gsonString;
	}

	/**
	 * 将json转成特定的cls的对象
	 * @param gsonString
	 * @param cls
	 * @return
	 */
	public static <T> T stringToBean(String gsonString, Class<T> cls) {
		T t = null;
		try {
			if (gson != null) {
				//传入json对象和对象类型,将json转成对象
				t = gson.fromJson(gsonString, cls);
			}
		} catch (JsonSyntaxException e) {
			log.error("非法json字符串",e);
		}
		return t;
	}

	/**
	 * json字符串转成list
	 * 解决泛型问题
	 * 备注：
	 * List<T> list=gson.fromJson(gsonString, new TypeToken<List<T>>() {}.getType());
	 * 该方法会报泛型类型擦除问题
	 * @param gsonString
	 * @param cls
	 * @param <T>
	 * @return
	 */
	public static <T> List<T> stringToList(String gsonString, Class<T> cls) {
		List<T> list = new ArrayList<T>();
		try {
			if(gson!=null){
				JsonArray array = new JsonParser().parse(gsonString).getAsJsonArray();
				for(final JsonElement elem : array){
					list.add(gson.fromJson(elem, cls));
				}
			}
		} catch (JsonSyntaxException e) {
			log.error("非法json字符串",e);
		}
		return list;
	}

}

测试方法：

@Test
	public void testListToString(){
		List<String> list=new ArrayList<>(Arrays.asList("11","12","13"));
		System.out.println("list集合："+list);

		//将[11,12,13]转换为字符串"11,12,13"
		String collection=list.stream().collect(Collectors.joining(","));
		System.out.println("collection str:"+collection);
	}

	@Test
	public void  testBeanToString(){
		CustomMarket market=new CustomMarket();
		market.setMarketId(7);
		market.setInclude(Arrays.asList("11","12","13"));
		market.setExclude(Arrays.asList("21","22","23"));
		String gsonStr = GsonUtils.beanToString(market);
		System.out.println("gsonStr:"+gsonStr);
		//gsonStr:{"marketId":7,"include":["11","12","13"],"exclude":["21","22","23"]}
	}

	@Test
	public void testStringToBean(){
		String gsonStr="{\"include\":[{\"audienceId\":103731,\"userAudienceId\":190021,\"mediaAudienceIds\":[]}]," 
				+ "\"exclude\":[{\"audienceId\":104540,\"userAudienceId\":104550,\"mediaAudienceIds\":[]}]}";
		Audience audience = GsonUtils.stringToBean(gsonStr, Audience.class);
		List<AudienceUserSelected> include = audience.getInclude();
		List<AudienceUserSelected> exclude =audience.getExclude();
		System.out.println("include audienceId:"+include.get(0).getAudienceId());
		System.out.println("exclude audienceId:"+exclude.get(0).getAudienceId());
		//include audienceId:103731
		//exclude audienceId:104540
		
	}

	@Test
	public void testStringToList(){
		String gsonStr="[{\"iden\":1,\"times\":[0]},{\"iden\":2,\"times\":[0]},{\"iden\":3,\"times\":[0]},{\"iden\":4," 
				+ "\"times\":[0]},{\"iden\":5,\"times\":[0]},{\"iden\":6,\"times\":[0]},{\"iden\":0,\"times\":[0]}]";
		//方法一：用gson解析json对象数组
//		List<TimeSlot> timeSlots = new Gson()
//				.fromJson(gsonStr, new TypeToken<List<TimeSlot>>() {
//				}.getType());

		//方法二：
		List<TimeSlot> timeSlots = GsonUtils.stringToList(gsonStr, TimeSlot.class);
		for (TimeSlot timeSlot : timeSlots) {
			Integer iden=timeSlot.getIden();
			List<Integer> times = timeSlot.getTimes();
			System.out.println("iden:"+iden);
			System.out.println("times:"+times.toString());
		}
	}

测试类：

CustomMarket ：

@Data
public class CustomMarket implements Serializable {

	private static final long serialVersionUID = 5449480257660129769L;

	/**
	 * 交易市场id
	 */
	private Integer marketId;

	/**
	 * 包含
	 */
	private List<String> include;

	/**
	 * 排除
	 */
	private List<String> exclude;

}

@Data
public class Audience implements Serializable {

	private static final long serialVersionUID = 2949364089756452317L;

	/**
	 * 包含
	 */
	private List<AudienceUserSelected> include;

	/**
	 * 排除
	 */
	private List<AudienceUserSelected> exclude;
}

@Data
public class AudienceUserSelected implements Serializable {

	private static final long serialVersionUID = -3775367505215832758L;

	/**
	 * 人群包ID
	 */
	private Long audienceId;

	/**
	 * 商户人群包ID
	 */
	private Long userAudienceId;

	/**
	 * 媒体侧人群ID集合
	 */
	private List<Integer> mediaAudienceIds;
}

@Data
public class TimeSlot implements Serializable {

	private static final long serialVersionUID = 4913373453802986540L;

	/**
	 * 投放星期 0-6
	 */
	private Integer iden;

	/**
	 * 投放小时 0-23
	 */
	private List<Integer> times;
}