需要jar包：
json.jar
jackson-core.jar
jacson-mapper.jar
一、ArrayList转json和hashmap转json代码一样
/**
* 把map转换成json对象
* @param map
* @return 返回一个json
*/
@SuppressWarnings("finally")
public static <T> String mapToJson(T obj){
String json=null;
ObjectMapper mapper=null;
try{
mapper = new ObjectMapper();
json=mapper.writeValueAsString(obj);//把map或者是list转换成
}catch(Exception e){
e.printStackTrace();
}finally{
mapper=null;
return json;
}
}
二、json转成hashmap
/**
* 把json转成HashMap对象
* @param jsonStr json值
* @return 返回一个HashMap对象
*/
@SuppressWarnings("finally")
public static HashMap<String,Object> jsonToMap(String jsonStr){
HashMap<String,Object> hashMap=null;
ObjectMapper mapper=null;
try{
mapper = new ObjectMapper();
hashMap = mapper.readValue(jsonStr, new TypeReference<Map<String,Object>>() { });//把json转成HashMap
}catch(Exception e){
e.printStackTrace();
}finally{
mapper=null;
return hashMap;
}
}
public class JsonUtil {
private static ObjectMapper objectMapper = new ObjectMapper();
private static ObjectMapper objectMapperDateFormatLong = new ObjectMapper();
static {
objectMapper
.configure(
DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,
false);
objectMapperDateFormatLong
.configure(
DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,
false);
}
private static final String JSON_RESPONSE_FIELD = "jsonResponse";
private static final String STATUS_CODE_FIELD = "statusCode";
private static final String RESPONSE_FIELD = "response";
private static final String RESPONSE_INFO = "additionalInfo";
/**
* Deserialize a JSON string into a Java Object
*
* @param value
* The JSON string to be deserialized
* @param type
* The Java Object class type
* @return
* @throws IOException
*/
public static <U> U fromString(String value, Class<U> type)
throws IOException {
return objectMapper.readValue(value, type);
}
/**
* Extract the entity from a JsonResponse string. If status code is not 0,
* throw Exception
*
* @param <U>
* @param value
* The JsonResponse string to be extracted
* @param type
* The entity type to be extracted
* @return
* @throws IOException
* @throws RemoteApiCallException
*/
public static <U> U convertJsonResponseObject(String value, Class<U> type)
throws IOException, RemoteApiCallException {
JsonNode jsonResponse = null;
JsonNode rootResponse = null;
JsonNode responseInfo = null;
U responseObj = null;
try {
jsonResponse = (JsonNode) objectMapper.readTree(value).get(
JSON_RESPONSE_FIELD);
responseInfo = jsonResponse.get(RESPONSE_INFO);
rootResponse = jsonResponse.get(RESPONSE_FIELD);
responseObj = objectMapper.readValue(rootResponse.toString(), type);
} catch (IOException ex) {
if (rootResponse != null) {
throw new RemoteApiCallException(responseInfo.getValueAsText(),
jsonResponse.get(STATUS_CODE_FIELD).getIntValue(),
responseInfo.toString());
} else if (jsonResponse != null) {
throw new RemoteApiCallException(jsonResponse.get(
RESPONSE_FIELD).getValueAsText(), jsonResponse.get(
STATUS_CODE_FIELD).getIntValue(), jsonResponse);
} else {
throw ex;
}
}
if (jsonResponse.get(STATUS_CODE_FIELD).getIntValue() != 0) {
throw new RemoteApiCallException(responseInfo.getValueAsText(),
jsonResponse.get(STATUS_CODE_FIELD).getIntValue(),
responseObj);
}
return responseObj;
}
/**
* Extract the entity list from a JsonResponse string. If status code is not
* 0, throw Exception
*
* @param <U>
* @param value
* The JsonResponse string to be extracted
* @param type
* The entity type to be extracted
* @return The entity list
* @throws IOException
* @throws RemoteApiCallException
*/
public static <U> List<U> convertJsonResponseObjectCollection(String value,
Class<U> type) throws IOException, RemoteApiCallException {
JsonNode jsonResponse = null;
JsonNode rootResponse = null;
JsonNode responseInfo = null;
List<U> responseCollection = new ArrayList<U>();
try {
jsonResponse = (JsonNode) objectMapper.readTree(value).get(
JSON_RESPONSE_FIELD);
responseInfo = jsonResponse.get(RESPONSE_INFO);
rootResponse = jsonResponse.get(RESPONSE_FIELD);
Iterator<JsonNode> iterator = rootResponse.getElements();
while (iterator.hasNext()) {
String content = iterator.next().toString();
responseCollection.add(objectMapper.readValue(content, type));
}
} catch (IOException ex) {
ex.printStackTrace();
if (jsonResponse != null) {
if (responseInfo != null) {
throw new RemoteApiCallException(responseInfo
.getValueAsText(), jsonResponse.get(
STATUS_CODE_FIELD).getIntValue(), jsonResponse);
} else {
throw new RemoteApiCallException(jsonResponse.get(
RESPONSE_FIELD).getValueAsText(), jsonResponse.get(
STATUS_CODE_FIELD).getIntValue(), jsonResponse);
}
} else {
throw ex;
}
}
if (jsonResponse.get(STATUS_CODE_FIELD).getIntValue() != 0) {
throw new RemoteApiCallException(responseInfo.getValueAsText(),
jsonResponse.get(STATUS_CODE_FIELD).getIntValue(),
responseCollection);
}
return responseCollection;
}
/**
* Serialize an entity into JSON string
*
* @param value
* @return
* @throws IOException
*/
public static String toString(Object value) throws IOException {
DateFormat dateFormat = new SimpleDateFormat(
ICodeConstants.DATETIME_FORMAT);
dateFormat.setTimeZone(TimeZone.getTimeZone("PST"));
objectMapper.getSerializationConfig().setDateFormat(dateFormat);
return objectMapper.writeValueAsString(value);
}
public static String toString(Object value, boolean isDateFormat)
throws IOException {
if (isDateFormat) {
return toString(value);
} else {
return objectMapperDateFormatLong.writeValueAsString(value);
}
}
public static Integer getJsonResponseStatusCode(String value) {
JsonNode jsonResponse = null;
Integer result = -1;
try {
jsonResponse = (JsonNode) objectMapper.readTree(value).get(
JSON_RESPONSE_FIELD);
} catch (JsonProcessingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
if (jsonResponse != null) {
result = jsonResponse.get(STATUS_CODE_FIELD).getIntValue();
}
return result;
}
}