Json 意想不到的角色 

Question

我正在使用下面的代码使用 PowerShell 重新生成我的 Json，但是它会在 json { 标记开始之前创建意外字符。

<#$data = Get-Content -Raw -Path myfile.json | ConvertFrom-Json#>

$data = @"
{
  "stations": [
    {
      "code": "1",
      "name": "United force"
    },
    {
      "code": "2",
      "name": "Toowoon Bay Service Station"
    }
],

 "prices": [
    {
      "stationcode": "1",
      "fueltype": "DL",
      "price": 126.97
    },
    {
      "stationcode": "1",
      "fueltype": "E10",
      "price": 118.92
    },
    {
      "stationcode": "2",
      "fueltype": "E10",
      "price": 112.90
    },
    {
      "stationcode": "2",
      "fueltype": "P95",
      "price": 125.90
    },
    {
      "stationcode": "2",
      "fueltype": "P98",
      "price": 155.90
    },
    {
      "stationcode": "2",
      "fueltype": "U91",
      "price": 115.20
    }
 ]
}
"@ | ConvertFrom-Json


foreach ($price in $data.prices) {
    $data.stations | 
    Where-Object { $_.code -eq $price.stationcode } |
    Add-Member -MemberType NoteProperty -Name $price.fueltype -Value $price.price
}

$data | Select-Object -Property stations | ConvertTo-Json | Set-Content "testJson.json" -Encoding UTF8

上传后调用此文件时，由于该意外字符，我无法读取 json 文件。

希望有人可以在 PowerShell 代码中提供帮助，以确保没有这样的字符，我可能正在做一些简单的事情，但不确定如何。

我正在读取PowerShell到Flutter之后生成的json文件，抛出如下所示的错误

谢谢，

Answer 1

您需要找到一种方法让 Flutter 处理 UTF-8 字节顺序标记 (0xEF 0xBB 0xBF)，或者将文件写入不带 BOM 的 UTF8。

如果您使用的是 PowerShell 6 或更高版本，则可以使用

Set-Content "testJson.json" -Encoding utf8NoBOM

对于低于版本 6 的 PowerShell，这是不可用的，因此您可以使用

$json = $data | Select-Object -Property stations | ConvertTo-Json

# [System.IO.File]::WriteAllText() defaults to UTF8 without BOM
# use an absolute path here
[System.IO.File]::WriteAllText("D:\Test\testJson.json", $json)

Answer 2

Windows PowerShell 和 PowerShell Core 都具有用于 Get-Content 和 Set-Content 的 -Encoding 参数。

PS C:\> $PSVersionTable.PSVersion.ToString()
5.1.19041.1

ASCII:  Uses the encoding for the ASCII (7-bit) character set.
BigEndianUnicode:  Encodes in UTF-16 format using the big-endian byte order.
Byte:   Encodes a set of characters into a sequence of bytes.
String:  Uses the encoding type for a string.
Unicode:  Encodes in UTF-16 format using the little-endian byte order.
UTF7:   Encodes in UTF-7 format.
UTF8:  Encodes in UTF-8 format.
Unknown:  The encoding type is unknown or invalid. The data can be treated as binary.

PS C:\> $PSVersionTable.PSVersion.ToString()
7.1.0-preview.3

`ascii`: Uses the encoding for the ASCII (7-bit) character set.
`bigendianunicode`: Encodes in UTF-16 format using the big-endian byte order.
`oem`: Uses the default encoding for MS-DOS and console programs.
`unicode`: Encodes in UTF-16 format using the little-endian byte order.
`utf7`: Encodes in UTF-7 format.
`utf8`: Encodes in UTF-8 format.
`utf8BOM`: Encodes in UTF-8 format with Byte Order Mark (BOM)
`utf8NoBOM`: Encodes in UTF-8 format without Byte Order Mark (BOM)
`utf32`: Encodes in UTF-32 format.