SpringBoot + WebService + CXF 返回值Json 字符串 实体类属性为null时，属性丢失？

最近在写 webService 接口，由于长时间没写过词类接口了 就把之前的知识忘掉了  结果可想而知  一顿操作猛如虎.......实际上是个小白鼠

上篇文章写到 SpingBoot 开发 webService 接口 SpringBoot 项目中开发 webService+CXF接口_丛林雪狼code的博客-CSDN博客项目架构：SpringBoot+Orcal前景： SpringBoot 项目中 对外公布接口，故采用 WebService ，在论坛上看了许多的代码示例，大体是分为以下几步： 1）引入jar包 ； 2）建立接口 interface ,并添加注解 @WebService 声明接口 以及 属性定义； 3）建立接口实现类，也要添加注解式声明 ； 4 ）建立配置类 随项目启动 ；经过自己实践，发现其实不需要那么繁琐，特总结如下，供己备用；首选一张图说明 webService...https://blog.csdn.net/qq_41639676/article/details/120954374?spm=1001.2014.3001.5502

今天在做数据监测时发现，返回值Json字符串 实体类属性值为null 时 会自动隐藏该属性；详情看下图：

原代码如下：

@WebMethod
public String getWjzJcNoDealtJcMsgs(){
    List list = new ArrayList<>();
    list =  jcTsxxMapper.selectAllNoCl();
    String json = JSONArray.toJSonString(list);
    return json ;
}

 JSON 在转字符串时 会默认忽略到属性为null 的属性，所以导致返回值 属性为null时 字段丢失；

解决办法：指定Json 转换格式 正确代码参考如下：

@WebMethod
public String getWjzJcNoDealtJcMsgs(){
    List list = new ArrayList<>();
    list =  jcTsxxMapper.selectAllNoCl();
    //使用日期格式化配置转换、允许值为null时以空字符串形式输出""
    String json = JSONArray.toJSonString(list, SerializerFeature.WriteDateUseDateFormat,SerializerFeature.WriteNullStringAsEmpty);
    return json ;
}

源码解析：toJSonString() 方法是可变参数方法 ，参数可以设置很多属性，具体根据业务所需进行；

源代码所示：

//toJsonString 方法 
public static String toJSonString(Object object, SerializerFeature... features) {
        return toJSonString(object, DEFAULT_GENERATE_FEATURE, features);
 }




public static int DEFAULT_GENERATE_FEATURE;
    static {
        int features = 0;
        features |= SerializerFeature.QuoteFieldNames.getMask();
        features |= SerializerFeature.SkipTransientField.getMask();
        features |= SerializerFeature.WriteEnumUsingName.getMask();
        features |= SerializerFeature.SortField.getMask();
        DEFAULT_GENERATE_FEATURE = features;
}




public enum SerializerFeature {
    QuoteFieldNames,
    
    UseSingleQuotes,
    
    WriteMapNullValue,
    
    WriteEnumUsingToString,
    
    WriteEnumUsingName,
    
    UseISO8601DateFormat,
    
    WriteNullListAsEmpty,
    
    WriteNullStringAsEmpty,
    
    WriteNullNumberAsZero,
    
    WriteNullBooleanAsFalse,
    
    SkipTransientField,
    
    SortField,
    
    @Deprecated
    WriteTabAsSpecial,
    
    PrettyFormat,
    
    WriteClassName,

    
    DisableCircularReferenceDetect, // 32768

    
    WriteSlashAsSpecial,

    
    BrowserCompatible,

    
    WriteDateUseDateFormat,

    
    NotWriteRootClassName,

    
    DisableCheckSpecialChar,

    
    BeanToArray,

    
    WriteNonStringKeyAsString,
    
    
    NotWriteDefaultValue,
    
    
    BrowserSecure,
    
    
    IgnoreNonFieldGetter,
    
    
    WriteNonStringValueAsString,
    
    
    IgnoreErrorGetter,

    
    WriteBigDecimalAsPlain
    ;

    SerializerFeature(){
        mask = (1 << ordinal());
    }

    public final int mask;

    public final int getMask() {
        return mask;
    }

    public static boolean isEnabled(int features, SerializerFeature feature) {
        return (features & feature.mask) != 0;
    }
    
    public static boolean isEnabled(int features, int fieaturesB, SerializerFeature feature) {
        int mask = feature.mask;
        
        return (features & mask) != 0 || (fieaturesB & mask) != 0;
    }

    public static int config(int features, SerializerFeature feature, boolean state) {
        if (state) {
            features |= feature.mask;
        } else {
            features &= ~feature.mask;
        }

        return features;
    }
    
    public static int of(SerializerFeature[] features) {
        if (features == null) {
            return 0;
        }
        
        int value = 0;
        
        for (SerializerFeature feature: features) {
            value |= feature.mask;
        }
        
        return value;
    }
    
    public final static SerializerFeature[] EMPTY = new SerializerFeature[0];

    public static final int WRITE_MAP_NULL_FEATURES
            = WriteMapNullValue.getMask()
            | WriteNullBooleanAsFalse.getMask()
            | WriteNullListAsEmpty.getMask()
            | WriteNullNumberAsZero.getMask()
            | WriteNullStringAsEmpty.getMask()
            ;
}

特此备注 留以后用。