Jackson工具类（各种转换）

来源：互联网发布：java计算器程序编辑：程序博客网时间：2024/05/22 09:02
首先要在项目中引入jackson的jar包（在此不做说明）
下面直接上代码
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);    }}
导入相应的包就可以使用，个人觉得还是挺方便的
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