json 工具类
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.bcht.bigdata.dsjmh.api.utils;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONException;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.*;
/**
* json utils
*/
public class JSONUtils {
private static final Logger logger = LoggerFactory.getLogger(JSONUtils.class);
/**
* can use static singleton, inject: just make sure to reuse!
*/
private static final ObjectMapper objectMapper = new ObjectMapper();
/**
* init
*/
private static final JSONUtils instance = new JSONUtils();
private JSONUtils() {
//Feature that determines whether encountering of unknown properties, false means not analyzer unknown properties
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false).setTimeZone(TimeZone.getDefault());
}
/**
* json representation of object
* @param object
* @return object to json string
*/
public static String toJson(Object object) {
try{
return JSONObject.toJSONString(object,false);
} catch (Exception e) {
logger.error("object to json exception!",e);
}
return null;
}
/**
*
* This method deserializes the specified Json into an object of the specified class. It is not
* suitable to use if the specified class is a generic type since it will not have the generic
* type information because of the Type Erasure feature of Java. Therefore, this method should not
* be used if the desired type is a generic type. Note that this method works fine if the any of
* the fields of the specified object are generics, just the object itself should not be a
* generic type.
*
* @param json the string from which the object is to be deserialized
* @param clazz the class of T
* @return an object of type T from the string
* classOfT
*/
public static <T> T parseObject(String json, Class<T> clazz) {
if (StringUtils.isEmpty(json)) {
return null;
}
try {
return JSONObject.parseObject(json, clazz);
} catch (Exception e) {
logger.error("parse object exception!",e);
}
return null;
}
/**
* json to list
*
* @param json
* @param clazz c
* @param <T>
* @return
*/
public static <T> List<T> toList(String json, Class<T> clazz) {
if (StringUtils.isEmpty(json)) {
return new ArrayList<>();
}
try {
return JSONArray.parseArray(json, clazz);
} catch (Exception e) {
logger.error("JSONArray.parseArray exception!",e);
}
return new ArrayList<>();
}
/**
* check json object valid
*
* @param json
* @return
*/
public static boolean checkJsonVaild(String json) {
if (StringUtils.isEmpty(json)) {
return false;
}
try {
objectMapper.readTree(json);
return true;
} catch (IOException e) {
logger.error("check json object valid exception!",e);
}
return false;
}
/**
* Method for finding a JSON Object field with specified name in this
* node or its child nodes, and returning value it has.
* If no matching field is found in this node or its descendants, returns null.
*
* @param fieldName Name of field to look for
*
* @return Value of first matching node found, if any; null if none
*/
public static String findValue(JsonNode jsonNode, String fieldName) {
JsonNode node = jsonNode.findValue(fieldName);
if (node == null) {
return null;
}
return node.toString();
}
/**
* json to map
*
* {@link #toMap(String, Class, Class)}
*
* @param json
* @return
*/
public static Map<String, String> toMap(String json) {
if (StringUtils.isEmpty(json)) {
return null;
}
try {
return JSONObject.parseObject(json, new TypeReference<HashMap<String, String>>(){});
} catch (Exception e) {
logger.error("json to map exception!",e);
}
return null;
}
/**
*
* json to map
*
* <pre>
* String jsonStr = "{\"id\":\"1001\",\"name\":\"Jobs\"}";
* Map<String,String> models = JSONUtils.toMap(jsonStr, String.class,String.class);
* </pre>
* @param json
* @param classK
* @param classV
* @param <K>
* @param <V>
* @return
*/
public static <K, V> Map<K, V> toMap(String json, Class<K> classK, Class<V> classV) {
if (StringUtils.isEmpty(json)) {
return null;
}
try {
return JSONObject.parseObject(json, new TypeReference<HashMap<K, V>>() {});
} catch (Exception e) {
logger.error("json to map exception!",e);
}
return null;
}
/**
* 对象装json字符串 <p>
*
* @return json string
*/
public static String toJsonString(Object object) {
try{
return JSONObject.toJSONString(object,false);
} catch (Exception e) {
throw new RuntimeException("Json deserialization exception.", e);
}
}
/**
* json serializer
*/
public static class JsonDataSerializer extends JsonSerializer<String> {
@Override
public void serialize(String value, JsonGenerator gen, SerializerProvider provider) throws IOException {
gen.writeRawValue(value);
}
}
/**
* json data deserializer
*/
public static class JsonDataDeserializer extends JsonDeserializer<String> {
@Override
public String deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
JsonNode node = p.getCodec().readTree(p);
return node.toString();
}
}
public static String resultSetToJson(ResultSet rs) throws SQLException, JSONException
{
// json数组
JSONArray array = new JSONArray();
// 获取列数
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
// 遍历ResultSet中的每条数据
while (rs.next()) {
JSONObject jsonObj = new JSONObject();
// 遍历每一列
for (int i = 1; i <= columnCount; i++) {
String columnName =metaData.getColumnLabel(i);
String value = rs.getString(columnName);
jsonObj.put(columnName, value);
}
array.add(jsonObj);
}
return array.toString();
}
}