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MapperUtils
为使用Jackson类包进行序列化、反序列化操作的同学开发方便，我们抽象出了一些通用的方法：
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Jackson 工具类
*
* @author liuxiaojun
* @date 2019-03-02 21:09
* ------------------- History -------------------
* <date> <author> <desc>
* 2019-03-02 liuxiaojun 初始创建
* -----------------------------------------------
*/
public class MapperUtils {
private final static ObjectMapper objectMapper = new ObjectMapper();
public static ObjectMapper getInstance() {
return objectMapper;
}
/**
* 转换为 JSON 字符串
*
* @param obj
* @return
* @throws Exception
*/
public static String obj2json(Object obj) throws Exception {
return objectMapper.writeValueAsString(obj);
}
/**
* 转换为 JSON 字符串，忽略空值
*
* @param obj
* @return
* @throws Exception
*/
public static String obj2jsonIgnoreNull(Object obj) throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
return mapper.writeValueAsString(obj);
}
/**
* 转换为 JavaBean
*
* @param jsonString
* @param clazz
* @return
* @throws Exception
*/
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);
}
/**
* 字符串转换为 Map<String, Object>
*
* @param jsonString
* @return
* @throws Exception
*/
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);
}
/**
* 字符串转换为 Map<String, T>
*/
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;
}
/**
* 将 JSON 数组转换为集合
*
* @param jsonArrayStr
* @param clazz
* @return
* @throws Exception
*/
public static <T> List<T> json2list(String jsonArrayStr, Class<T> clazz) throws Exception {
JavaType javaType = getCollectionType(ArrayList.class, clazz);
List<T> list = (List<T>) objectMapper.readValue(jsonArrayStr, javaType);
return list;
}
/**
* 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);
}
/**
* 将 Map 转换为 JavaBean
*
* @param map
* @param clazz
* @return
*/
public static <T> T map2pojo(Map map, Class<T> clazz) {
return objectMapper.convertValue(map, clazz);
}
/**
* 将 Map 转换为 JSON
*
* @param map
* @return
*/
public static String mapToJson(Map map) {
try {
return objectMapper.writeValueAsString(map);
} catch (Exception e) {
e.printStackTrace();
}
return "";
}
/**
* 将 JSON 对象转换为 JavaBean
*
* @param obj
* @param clazz
* @return
*/
public static <T> T obj2pojo(Object obj, Class<T> clazz) {
return objectMapper.convertValue(obj, clazz);
}
/**
* 将对象转换为字符串数组
*
* @param obj
* @return
*/
public static String[] obj2ArrayString(Object obj) {
Object[] objs = objectMapper.convertValue(obj, Object[].class);
String[] arr = new String[objs.length];
for (int i = 0; i < objs.length; i++) {
arr[i] = objs[i].toString();
}
return arr;
}
/**
* 将对象转换为字符串数组
*
* @param obj
* @return
*/
public static int[] obj2ArrayInt(Object obj) {
Object[] objs = objectMapper.convertValue(obj, Object[].class);
int[] arr = new int[objs.length];
for (int i = 0; i < objs.length; i++) {
arr[i] = Integer.parseInt(objs[i].toString());
}
return arr;
}
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