var settings struct {
    serverMode bool
    sourceDir  string
    targetDir  string
}
func main() {
    // 然后是配置文件设置
    configFile, err := os.Open("config.json")
    if err != nil {
        printError("打开配置文件", err.Error())
    }
    jsonParser := json.NewDecoder(configFile)
    if err = jsonParser.Decode(&settings); err != nil {
        printError("解析配置文件", err.Error())
    }
    fmt.Printf("%v %s %s", settings.serverMode, settings.sourceDir, settings.targetDir)
    return
}

{
    "serverMode": true,
    "sourceDir": ".",
    "targetDir": "."
}

false
（false和两个空字符串）
我也尝试过使用`json.Unmarshal(..)`，但结果相同。
如何以填充结构体值的方式解析JSON？
<details>
<summary>英文:</summary>
I&#39;m trying to configure my Go program by creating a JSON file and parsing it into a struct:
    var settings struct {
        serverMode bool
        sourceDir  string
        targetDir  string
    }
    func main() {
        // then config file settings
        configFile, err := os.Open(&quot;config.json&quot;)
        if err != nil {
        	printError(&quot;opening config file&quot;, err.Error())
        }
        jsonParser := json.NewDecoder(configFile)
        if err = jsonParser.Decode(&amp;settings); err != nil {
        	printError(&quot;parsing config file&quot;, err.Error())
        }
        fmt.Printf(&quot;%v %s %s&quot;, settings.serverMode, settings.sourceDir, settings.targetDir)
        return
    }
The config.json file:
    {
        &quot;serverMode&quot;: true,
        &quot;sourceDir&quot;: &quot;.&quot;,
        &quot;targetDir&quot;: &quot;.&quot;
    }
The Program compiles and runs without any errors, but the print statement outputs:
    false  
(false and two empty strings)
I&#39;ve also tried with `json.Unmarshal(..)` but had the same result.
How do I parse the JSON in a way that fills the struct values?
</details>
# 答案1
**得分**: 53
你没有导出你的结构体元素。它们都以小写字母开头。
    var settings struct {
        ServerMode bool `json:"serverMode"`
        SourceDir  string `json:"sourceDir"`
        TargetDir  string `json:"targetDir"`
    }
将结构体元素的首字母改为大写以导出它们。JSON编码器/解码器不会使用未导出的结构体元素。
<details>
<summary>英文:</summary>
You&#39;re not exporting your struct elements.  They all begin with a lower case letter.
    var settings struct {
        ServerMode bool `json:&quot;serverMode&quot;`
        SourceDir  string `json:&quot;sourceDir&quot;`
        TargetDir  string `json:&quot;targetDir&quot;`
    }
Make the first letter of your stuct elements upper case to export them.  The JSON encoder/decoder wont use struct elements which are not exported.
</details>