我现在在转换为json字符串与转出出现了BigDecimal属性变为BigInteger，该怎么办

你可以自定义一个ObjectWriter实现，就是单独一个ObjectWriterProvider，不影响全局。比如：

static final ObjectWriterProvider provider = new ObjectWriterProvider();

@BeforeEach
void setup() {
    provider.register(BigDecimal.class, new ObjectWriter<BigDecimal>() {
        @Override
        public void write(JSONWriter jsonWriter, Object object, Object fieldName, Type fieldType, long features) {
            BigDecimal decimal = (BigDecimal) object;
            if (decimal.scale() == 0) {
                decimal = decimal.setScale(1);
            }
            jsonWriter.writeDecimal(decimal);
        }
    });
}

@Test
public void test() throws Exception {
    BigDecimal decimal = BigDecimal.valueOf(Long.MAX_VALUE).add(BigDecimal.ONE);
    JSONWriter.Context context = JSONFactory.createWriteContext(provider);
    String str = JSON.toJSONString(decimal, context);
    assertEquals("9223372036854775808.0", str);
    BigDecimal decimal1 = (BigDecimal) JSON.parse(str);
    assertEquals(decimal, decimal1.stripTrailingZeros());
}

原回答者GitHub用户wenshao