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  • 关于超过js的number类型最大值(9007199254740992),的解决办法

    bug经过:点击修改无法展示信息(修改时调用queryOne,以id(long)为值,页面传过去的id=1480042498255640-00 ,在数据库中该id=148004249825564012,即错误的id)

    根本原因:

    js的number类型有个最大值(安全值)。即2的53次方,为9007199254740992。如果超过这个值,那么js会出现不精确的问题。这个值为16位。

    using System;
    using System.ComponentModel;
    using System.Linq;
    using Newtonsoft.Json;

    namespace Holder.Framework.Common
    {
    /// <inheritdoc />
    /// <summary>
    /// 大数据json序列化重写
    /// </summary>
    public sealed class NumberConverter : JsonConverter
    {
    /// <summary>
    /// 转换成字符串的类型
    /// </summary>
    private readonly NumberConverterShip _ship;

    /// <summary>
    /// 大数据json序列化重写实例化
    /// </summary>
    public NumberConverter()
    {
    _ship = (NumberConverterShip)0xFF;
    }

    /// <summary>
    /// 大数据json序列化重写实例化
    /// </summary>
    /// <param name="ship">转换成字符串的类型</param>
    public NumberConverter(NumberConverterShip ship)
    {
    _ship = ship;
    }

    /// <inheritdoc />
    /// <summary>
    /// 确定此实例是否可以转换指定的对象类型。
    /// </summary>
    /// <param name="objectType">对象的类型。</param>
    /// <returns>如果此实例可以转换指定的对象类型,则为:<c>true</c>,否则为:<c>false</c></returns>
    public override bool CanConvert(Type objectType)
    {
    var typecode = Type.GetTypeCode(objectType.Name.Equals("Nullable`1") ? objectType.GetGenericArguments().First() : objectType);
    switch (typecode)
    {
    case TypeCode.Decimal:
    return (_ship & NumberConverterShip.Decimal) == NumberConverterShip.Decimal;
    case TypeCode.Double:
    return (_ship & NumberConverterShip.Double) == NumberConverterShip.Double;
    case TypeCode.Int64:
    return (_ship & NumberConverterShip.Int64) == NumberConverterShip.Int64;
    case TypeCode.UInt64:
    return (_ship & NumberConverterShip.UInt64) == NumberConverterShip.UInt64;
    case TypeCode.Single:
    return (_ship & NumberConverterShip.Single) == NumberConverterShip.Single;
    default: return false;
    }
    }

    /// <inheritdoc />
    /// <summary>
    /// 读取对象的JSON表示。
    /// </summary>
    /// <param name="reader">从 <see cref="T:Newtonsoft.Json.JsonReader" /> 中读取。</param>
    /// <param name="objectType">对象的类型。</param>
    /// <param name="existingValue">正在读取的对象的现有值。</param>
    /// <param name="serializer">调用的序列化器实例。</param>
    /// <returns>对象值。</returns>
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
    return AsType(reader.Value.ToString(), objectType);
    }

    /// <summary>
    /// 字符串格式数据转其他类型数据
    /// </summary>
    /// <param name="input">输入的字符串</param>
    /// <param name="destinationType">目标格式</param>
    /// <returns>转换结果</returns>
    public static object AsType(string input, Type destinationType)
    {
    try
    {
    var converter = TypeDescriptor.GetConverter(destinationType);
    if (converter.CanConvertFrom(typeof(string)))
    {
    return converter.ConvertFrom(null, null, input);
    }

    converter = TypeDescriptor.GetConverter(typeof(string));
    if (converter.CanConvertTo(destinationType))
    {
    return converter.ConvertTo(null, null, input, destinationType);
    }
    }
    catch
    {
    return null;
    }
    return null;
    }

    /// <inheritdoc />
    /// <summary>
    /// 写入对象的JSON表示形式。
    /// </summary>
    /// <param name="writer">要写入的 <see cref="T:Newtonsoft.Json.JsonWriter" /> 。</param>
    /// <param name="value">要写入对象值</param>
    /// <param name="serializer">调用的序列化器实例。</param>
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
    if (value == null)
    {
    writer.WriteNull();
    }
    else
    {
    var objectType = value.GetType();
    var typeCode = Type.GetTypeCode(objectType.Name.Equals("Nullable`1") ? objectType.GetGenericArguments().First() : objectType);
    switch (typeCode)
    {
    case TypeCode.Decimal:
    writer.WriteValue(((decimal)value).ToString("f6"));
    break;
    case TypeCode.Double:
    writer.WriteValue(((double)value).ToString("f4"));
    break;
    case TypeCode.Single:
    writer.WriteValue(((float)value).ToString("f2"));
    break;
    default:
    writer.WriteValue(value.ToString());
    break;
    }
    }
    }
    }

    /// <summary>
    /// 转换成字符串的类型
    /// </summary>
    [Flags]
    public enum NumberConverterShip
    {
    /// <summary>
    /// 长整数
    /// </summary>
    Int64 = 1,

    /// <summary>
    /// 无符号长整数
    /// </summary>
    UInt64 = 2,

    /// <summary>
    /// 浮点数
    /// </summary>
    Single = 4,

    /// <summary>
    /// 双精度浮点数
    /// </summary>
    Double = 8,

    /// <summary>
    /// 大数字
    /// </summary>
    Decimal = 16
    }
    }

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  • 原文地址:https://www.cnblogs.com/chinasoft/p/14804809.html
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