JsonUtils & json转换

发布时间：2020-12-16 19:05:02 所属栏目：百科来源：网络整理

导读：package com.ynet.ci.utils; import java.io.IOException; import java.io.StringWriter; import java.lang.reflect.Type; import java.math.BigDecimal; import java.math.BigInteger; import java.text.ParseException; import java.text.SimpleDateFormat

package com.ynet.ci.utils;

import java.io.IOException;
import java.io.StringWriter;
import java.lang.reflect.Type;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Pattern;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.helpers.FormattingTuple;
import org.slf4j.helpers.MessageFormatter;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.type.TypeFactory;

/**
* JSON 转换相关的工具类注意,Map的Key只能为简单类型,不可采用复杂类型.
* @author moping
*/

@SuppressWarnings(“unchecked”)
public final class JsonUtils {

private static final TypeFactory TYPE_FACTORY = TypeFactory.defaultInstance();
private static final long LONG_JS_MAX_VLAUE = 1L << 53;
private static final Pattern NUMBER_PATTERN = Pattern.compile("^d*$");
private static final Pattern DATE_1_PATTERN = Pattern.compile("^19d{12}$");
private static final Pattern DATE_2_PATTERN = Pattern.compile("^20d{12}$");
private static final Pattern DATE_3_PATTERN = Pattern.compile("^d{4}[-]d{2}$");
private static final Pattern DATE_4_PATTERN = Pattern.compile("^d{4}[-]d{2}[-]d{2}$");
private static final Pattern DATE_5_PATTERN = Pattern.compile("^d{4}[-]d{2}[-]d{2} d{2}[:]d{2}[:]d{2}$");
private static final Pattern DATE_6_PATTERN = Pattern.compile("^d{4}[-]d{2}[-]d{2} d{2}[:]d{2}[:]d{2}[.]d{3}$");

private static final ObjectMapper MAPPER;

static {
    MAPPER = new ObjectMapper();
    MAPPER.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
    MAPPER.enable(SerializationFeature.WRITE_DATE_KEYS_AS_TIMESTAMPS);
    MAPPER.enable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
    // Long
    SimpleModule module = new SimpleModule();
    JsonSerializer<Long> longSerializer = new JsonSerializer<Long>() {
        public void serialize(Long value,JsonGenerator jgen,SerializerProvider provider) throws IOException,JsonProcessingException {
            if (value >= LONG_JS_MAX_VLAUE) {
                jgen.writeString(value.toString());
            } else {
                jgen.writeNumber(value);
            }
        }

    };
    JsonDeserializer<? extends Long> longDeserializer = new JsonDeserializer<Long>() {
        public Long deserialize(JsonParser jp,DeserializationContext ctxt) throws IOException,JsonProcessingException {
            return Long.valueOf(jp.getValueAsString());
        }
    };
    // BIGINTEGER
    JsonSerializer<BigInteger> bigIntSerializer = new JsonSerializer<BigInteger>() {
        public void serialize(BigInteger value,SerializerProvider provider)
                throws IOException,JsonProcessingException {
            if (value.longValue() >= LONG_JS_MAX_VLAUE) {
                jgen.writeString(value.toString());
            } else {
                jgen.writeNumber(value);
            }
        }
    };
    // BIGDECIMAL
    JsonSerializer<BigDecimal> bigDecSerializer = new JsonSerializer<BigDecimal>() {
        public void serialize(BigDecimal value,JsonProcessingException {
            jgen.writeString(String.valueOf(value));
        }
    };
    // DATE
    JsonDeserializer<Date> dateDeserializer = new JsonDeserializer<Date>() {
        public Date deserialize(JsonParser jp,JsonProcessingException {
            String text = jp.getValueAsString();
            if (StringUtils.isEmpty(text)) {
                return null;
            } 
            if(NUMBER_PATTERN.matcher(text).matches()) {
                if(DATE_2_PATTERN.matcher(text).matches() || DATE_1_PATTERN.matcher(text).matches()) {
                    return string2Date(text,"yyyyMMddHHmmss");
                }
                // MS
                return new Date(Long.valueOf(text));
            }
            if(DATE_3_PATTERN.matcher(text).matches()) {
                return string2Date(text,"yyyy-MM");
            }
            if(DATE_4_PATTERN.matcher(text).matches()) {
                return string2Date(text,"yyyy-MM-dd");
            }
            if(DATE_5_PATTERN.matcher(text).matches()) {
                return string2Date(text,"yyyy-MM-dd HH:mm:ss");
            }
            if(DATE_6_PATTERN.matcher(text).matches()) {
                return string2Date(text,"yyyy-MM-dd HH:mm:ss.SSS");
            }
            throw new RuntimeException("日期数据格式不符 - " + text);
        }
    };
    module.addSerializer(long.class,longSerializer);
    module.addSerializer(Long.class,longSerializer);
    module.addSerializer(BigInteger.class,bigIntSerializer);
    module.addSerializer(BigDecimal.class,bigDecSerializer);

    module.addDeserializer(long.class,longDeserializer);
    module.addDeserializer(Long.class,longDeserializer);
    module.addDeserializer(Date.class,dateDeserializer);
    MAPPER.registerModule(module);
}

private JsonUtils() {
    throw new IllegalAccessError("该类不允许实例化");
}

/**
 * 将对象转换为 JSON 的字符串格式
 * @param obj 被转换的对象
 * @return 当参数为空时会返回null

public static String object2String(Object obj) {
    if (obj == null) {
        return null;
    }
    StringWriter writer = new StringWriter();
    try {
        MAPPER.writeValue(writer,obj);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将对象[{}]转换为JSON字符串时发生异常",obj,e);
        throw new RuntimeException(message.getMessage(),e);
    }
    return writer.toString();
}

/**
 * 将 JSON 格式的字符串转换为 map
 * @param json JSON，允许为空
 * @return json为null时会返回空的Map实例
 */

public static Map<String,Object> string2Map(String json) {
    try {
        if (StringUtils.isBlank(json)) {
            return HashMap.class.newInstance();
        }
        JavaType type = TYPE_FACTORY.constructMapType(HashMap.class,String.class,Object.class);
        return MAPPER.readValue(json,type);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为Map时出现异常",json);
        throw new RuntimeException(message.getMessage(),e);
    }
}

/**
 * 将 JSON 格式的字符串转换为数组
 * @param <T>
 * @param json 字符串
 * @param clz 数组类型
 * @return json为null时会返回null
 */

public static <T> T[] string2Array(String json,Class<T> clz) {
    try {
        if (StringUtils.isBlank(json)) {
            return null;
        }
        JavaType type = TYPE_FACTORY.constructArrayType(clz);
        return (T[]) MAPPER.readValue(json,type);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为数组时出现异常",json,e);
    }
}

/**
 * 将 JSON 格式的字符串转换为对象
 * @param <T>
 * @param json 字符串
 * @param clz 对象类型
 * @return json为null时会返回null

public static <T> T string2Obj(String json,Class<T> clz) {
    try {
        if (StringUtils.isBlank(json)) {
            return null;
        }
        JavaType type = TYPE_FACTORY.constructType(clz);
        return (T) MAPPER.readValue(json,type);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为对象[{}]时出现异常",new Object[] { json,clz.getSimpleName(),e });
        throw new RuntimeException(message.getMessage(),e);
    }
}

/**
 * 将 JSON 格式的字符串转换为对象
 * @param <T>
 * @param json 字符串
 * @param type 对象类型
 * @return json为null时会返回null
 */

public static <T> T string2Obj(String json,Type type) {
    try {
        if (StringUtils.isBlank(json)) {
            return null;
        }
        JavaType t = TYPE_FACTORY.constructType(type);
        return (T) MAPPER.readValue(json,t);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为对象[{}]时出现异常",type,e);
    }
}

/***
 * json 泛型转换
 * @param tr 示例 new TypeReference<List<Long>>(){}
 **/

public static <T> T string2GenericObject(String json,TypeReference<T> tr) {
    if (StringUtils.isBlank(json)) {
        return null;
    } else {
        try {
            return (T) MAPPER.readValue(json,tr);
        } catch (Exception e) {
            FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为[{}]时出现异常",tr });
            throw new RuntimeException(message.getMessage(),e);
        }
    }
}

/**
 * 将 JSON 格式的字符串转换为对象
 * @param <T>
 * @param json 字符串
 * @param type 对象类型
 * @return json为null时会返回null
 */

public static <T> T bytes2Object(byte[] json,Type type) {
    try {
        if (json == null || json.length == 0) {
            return null;
        }
        JavaType t = TYPE_FACTORY.constructType(type);
        return (T) MAPPER.readValue(json,e);
    }
}

/***
 * json数组泛型转换
 * @param tr 示例 new TypeReference<List<Long>>(){}
 **/

public static <T> T bytes2GenericObject(byte[] json,TypeReference<T> tr) {
    if (json == null || json.length == 0) {
        return null;
    } else {
        try {
            return (T) MAPPER.readValue(json,e);
        }
    }
}

/**
 * 将 JSON 格式的字符串转换为集合
 * @param <T>
 * @param json 字符串
 * @param collectionType 集合类型
 * @param elementType 元素类型
 * @return json为null时会返回空的集合实例
 */

public static <C extends Collection<E>,E> C string2Collection(String json,Class<C> collectionType,Class<E> elementType) {
    try {
        if (StringUtils.isBlank(json)) {
            return collectionType.newInstance();
        }
        JavaType type = TYPE_FACTORY.constructCollectionType(collectionType,elementType);
        return MAPPER.readValue(json,type);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将字符串[{}]转换为集合[{}]时出现异常",collectionType.getSimpleName(),e);
    }
}

/**
 * 将字符串转换为{@link HashMap}对象实例
 * @param json 被转换的字符串
 * @param keyType 键类型
 * @param valueType 值类型
 * @return json为null时会返回空的HashMap实例
 */

public static <K,V> Map<K,V> string2Map(String json,Class<K> keyType,Class<V> valueType) {
    try {
        if (StringUtils.isBlank(json)) {
            return HashMap.class.newInstance();
        }
        JavaType type = TYPE_FACTORY.constructMapType(HashMap.class,keyType,valueType);
        return (Map<K,V>) MAPPER.readValue(json,e);
    }
}

/**
 * 将字符串转换为特定的{@link Map}对象实例
 * @param json 被转换的字符串
 * @param keyType 键类型
 * @param valueType 值类型
 * @param mapType 指定的{@link Map}类型
 * @return json为空时会返回空的Map实例
 */

public static <M extends Map<K,V>,K,V> M string2Map(String json,Class<V> valueType,Class<M> mapType) {
    try {
        if (StringUtils.isBlank(json)) {
            return mapType.newInstance();
        }
        JavaType type = TYPE_FACTORY.constructMapType(mapType,valueType);
        return MAPPER.readValue(json,e);
    }
}

/**
 * 将 JSON 对象类型转换
 * @param <T>
 * @param value 字符串
 * @param type 对象类型
 * @return json为null时会返回null
 */

public static <T> T convertObject(Object value,TypeReference<T> type) {
    try {
        if (value == null) {
            return null;
        }
        JavaType t = TYPE_FACTORY.constructType(type);
        return (T) MAPPER.convertValue(value,t);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将对象[{}]转换为类型[{}]时出现异常",new Object[] { value,e);
    }
}

/**
 * java map 转换对象
 * @param mapData 原始数据
 * @param tr 转换类型
 */

public static <T> T map2Object(Map<?,?> mapData,TypeReference<T> tr) {
    try {
        JsonNode node = MAPPER.valueToTree(mapData);
        return MAPPER.readValue(node.traverse(),tr);
    } catch (Exception e) {
        FormattingTuple message = MessageFormatter.format("将MAP[{}]转换为[{}]时出现异常",new Object[] { mapData,tr });
        throw new RuntimeException(message.getMessage(),e);
    }
}

private static Date string2Date(String string,String pattern){
    try {
        SimpleDateFormat format = new SimpleDateFormat(pattern);
        Date date = format.parse(string);
        return date;
    } catch (ParseException e) {
        throw new IllegalArgumentException("无法将字符串："+string+"转成日期");
    }
}

}

（编辑：李大同）

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