JSON put方法对比

org.json.JSONObject

/**
     * Maps {@code name} to {@code value}, clobbering any existing name/value
     * mapping with the same name. If the value is {@code null}, any existing
     * mapping for {@code name} is removed.
     *
     * @param value a {@link JSONObject}, {@link JSONArray}, String, Boolean,
     *     Integer, Long, Double, {@link #NULL}, or {@code null}. May not be
     *     {@link Double#isNaN() NaNs} or {@link Double#isInfinite()
     *     infinities}.
     * @return this object.
     */
    public JSONObject put(String name, Object value) throws JSONException {
        if (value == null) {
            nameValuePairs.remove(name);
            return this;
        }
        if (value instanceof Number) {
            // deviate from the original by checking all Numbers, not just floats & doubles
            JSON.checkDouble(((Number) value).doubleValue());
        }
        nameValuePairs.put(checkName(name), value);
        return this;
    }

put方法如果value为空，则会把这个key值移除掉，相当于没有put这个字段。

image.png

fastJson的put方法其实是放到了map里，所以不会有这个问题。