Gson/Jackson/FastJson工具类

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

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
import com.google.gson.reflect.TypeToken;


public class GsonUtil {
    //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 GsonUtil() {
    }

    /**
     * 将对象转成json格式
     * 
     * @param object
     * @return String
     */
    public static String GsonString(Object object) {
        String gsonString = null;
        if (gson != null) {
            gsonString = gson.toJson(object);
        }
        return gsonString;
    }

    /**
     * 将json转成特定的cls的对象
     * 
     * @param gsonString
     * @param cls
     * @return
     */
    public static <T> T GsonToBean(String gsonString, Class<T> cls) {
        T t = null;
        if (gson != null) {
            //传入json对象和对象类型,将json转成对象
            t = gson.fromJson(gsonString, cls);
        }
        return t;
    }

    /**
     * json字符串转成list
     * 
     * @param gsonString
     * @param cls
     * @return
     */
    public static <T> List<T> GsonToList(String gsonString, Class<T> cls) {
        List<T> list = null;
        if (gson != null) {
            //根据泛型返回解析指定的类型,TypeToken<List<T>>{}.getType()获取返回类型
            list = gson.fromJson(gsonString, new TypeToken<List<T>>() {
            }.getType());
        }
        return list;
    }

    /**
     * json字符串转成list中有map的
     * 
     * @param gsonString
     * @return
     */
    public static <T> List<Map<String, T>> GsonToListMaps(String gsonString) {
        List<Map<String, T>> list = null;
        if (gson != null) {
            list = gson.fromJson(gsonString,
                    new TypeToken<List<Map<String, T>>>() {
                    }.getType());
        }
        return list;
    }

    /**
     * json字符串转成map的
     * 
     * @param gsonString
     * @return
     */
    public static <T> Map<String, T> GsonToMaps(String gsonString) {
        Map<String, T> map = null;
        if (gson != null) {
            map = gson.fromJson(gsonString, new TypeToken<Map<String, T>>() {
            }.getType());
        }
        return map;
    }
}

public class JacksonUtils {

    private final static ObjectMapper objectMapper = new ObjectMapper();

    private JacksonUtils() {

    }

    public static ObjectMapper getInstance() {
        return objectMapper;
    }

    /**
     * javaBean、列表数组转换为json字符串
     */
    public static String obj2json(Object obj) throws Exception {
        return objectMapper.writeValueAsString(obj);
    }

    /**
     * javaBean、列表数组转换为json字符串,忽略空值
     */
    public static String obj2jsonIgnoreNull(Object obj) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return mapper.writeValueAsString(obj);
    }

    /**
     * json 转JavaBean
     */

    public static <T> T json2pojo(String jsonString, Class<T> clazz) throws Exception {
        objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
        return objectMapper.readValue(jsonString, clazz);
    }

    /**
     * json字符串转换为map
     */
    public static <T> Map<String, Object> json2map(String jsonString) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return mapper.readValue(jsonString, Map.class);
    }

    /**
     * json字符串转换为map
     */
    public static <T> Map<String, T> json2map(String jsonString, Class<T> clazz) throws Exception {
        Map<String, Map<String, Object>> map = objectMapper.readValue(jsonString, new TypeReference<Map<String, T>>() {
        });
        Map<String, T> result = new HashMap<String, T>();
        for (Map.Entry<String, Map<String, Object>> entry : map.entrySet()) {
            result.put(entry.getKey(), map2pojo(entry.getValue(), clazz));
        }
        return result;
    }

    /**
     * 深度转换json成map
     *
     * @param json
     * @return
     */
    public static Map<String, Object> json2mapDeeply(String json) throws Exception {
        return json2MapRecursion(json, objectMapper);
    }

    /**
     * 把json解析成list，如果list内部的元素存在jsonString，继续解析
     *
     * @param json
     * @param mapper 解析工具
     * @return
     * @throws Exception
     */
    private static List<Object> json2ListRecursion(String json, ObjectMapper mapper) throws Exception {
        if (json == null) {
            return null;
        }

        List<Object> list = mapper.readValue(json, List.class);

        for (Object obj : list) {
            if (obj != null && obj instanceof String) {
                String str = (String) obj;
                if (str.startsWith("[")) {
                    obj = json2ListRecursion(str, mapper);
                } else if (obj.toString().startsWith("{")) {
                    obj = json2MapRecursion(str, mapper);
                }
            }
        }

        return list;
    }

    /**
     * 把json解析成map，如果map内部的value存在jsonString，继续解析
     *
     * @param json
     * @param mapper
     * @return
     * @throws Exception
     */
    private static Map<String, Object> json2MapRecursion(String json, ObjectMapper mapper) throws Exception {
        if (json == null) {
            return null;
        }

        Map<String, Object> map = mapper.readValue(json, Map.class);

        for (Map.Entry<String, Object> entry : map.entrySet()) {
            Object obj = entry.getValue();
            if (obj != null && obj instanceof String) {
                String str = ((String) obj);

                if (str.startsWith("[")) {
                    List<?> list = json2ListRecursion(str, mapper);
                    map.put(entry.getKey(), list);
                } else if (str.startsWith("{")) {
                    Map<String, Object> mapRecursion = json2MapRecursion(str, mapper);
                    map.put(entry.getKey(), mapRecursion);
                }
            }
        }

        return map;
    }

    /**
     * 与javaBean json数组字符串转换为列表
     */
    public static <T> List<T> json2list(String jsonArrayStr, Class<T> clazz) throws Exception {

        JavaType javaType = getCollectionType(ArrayList.class, clazz);
        List<T> lst = (List<T>) objectMapper.readValue(jsonArrayStr, javaType);
        return lst;
    }


    /**
     * 获取泛型的Collection Type
     *
     * @param collectionClass 泛型的Collection
     * @param elementClasses  元素类
     * @return JavaType Java类型
     * @since 1.0
     */
    public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) {
        return objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses);
    }


    /**
     * map  转JavaBean
     */
    public static <T> T map2pojo(Map map, Class<T> clazz) {
        return objectMapper.convertValue(map, clazz);
    }

    /**
     * map 转json
     *
     * @param map
     * @return
     */
    public static String mapToJson(Map map) {
        try {
            return objectMapper.writeValueAsString(map);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    /**
     * map  转JavaBean
     */
    public static <T> T obj2pojo(Object obj, Class<T> clazz) {
        return objectMapper.convertValue(obj, clazz);
    }
}

/**
 * fastjson工具类
 * @version:1.0.0
 */
public class FastJsonUtils {
 
    private static final SerializeConfig config;
 
    static {
        config = new SerializeConfig();
        config.put(java.util.Date.class, new JSONLibDataFormatSerializer()); // 使用和json-lib兼容的日期输出格式
        config.put(java.sql.Date.class, new JSONLibDataFormatSerializer()); // 使用和json-lib兼容的日期输出格式
    }
 
    private static final SerializerFeature[] features = {SerializerFeature.WriteMapNullValue, // 输出空置字段
            SerializerFeature.WriteNullListAsEmpty, // list字段如果为null，输出为[]，而不是null
            SerializerFeature.WriteNullNumberAsZero, // 数值字段如果为null，输出为0，而不是null
            SerializerFeature.WriteNullBooleanAsFalse, // Boolean字段如果为null，输出为false，而不是null
            SerializerFeature.WriteNullStringAsEmpty // 字符类型字段如果为null，输出为""，而不是null
    };
    
 
    public static String toJSONString(Object object) {
        return JSON.toJSONString(object, config, features);
    }
    
    public static String toJSONNoFeatures(Object object) {
        return JSON.toJSONString(object, config);
    }
    
 
 
    public static Object toBean(String text) {
        return JSON.parse(text);
    }
 
    public static <T> T toBean(String text, Class<T> clazz) {
        return JSON.parseObject(text, clazz);
    }
 
    // 转换为数组
    public static <T> Object[] toArray(String text) {
        return toArray(text, null);
    }
 
    // 转换为数组
    public static <T> Object[] toArray(String text, Class<T> clazz) {
        return JSON.parseArray(text, clazz).toArray();
    }
 
    // 转换为List
    public static <T> List<T> toList(String text, Class<T> clazz) {
        return JSON.parseArray(text, clazz);
    }
 
    /**
     * 将javabean转化为序列化的json字符串
     * @param keyvalue
     * @return
     */
    public static Object beanToJson(KeyValue keyvalue) {
        String textJson = JSON.toJSONString(keyvalue);
        Object objectJson  = JSON.parse(textJson);
        return objectJson;
    }
    
    /**
     * 将string转化为序列化的json字符串
     * @param keyvalue
     * @return
     */
    public static Object textToJson(String text) {
        Object objectJson  = JSON.parse(text);
        return objectJson;
    }
    
    /**
     * json字符串转化为map
     * @param s
     * @return
     */
    public static Map stringToCollect(String s) {
        Map m = JSONObject.parseObject(s);
        return m;
    }
    
    /**
     * 将map转化为string
     * @param m
     * @return
     */
    public static String collectToString(Map m) {
        String s = JSONObject.toJSONString(m);
        return s;
    }
    
}