新增病案查询接口，修改退费接口

src/main/java/com/guahao/common/util/XmlUtil.java

@@ -2219,7 +2219,18 @@ public class XmlUtil {
         str.append(vo.getPages());
         str.append("</Pages>");
         str.append("<ZFamount>");
-        str.append(vo.getAmount());
+        // 安全的数值减法运算，处理可能的空值和精度问题
+        BigDecimal amount = vo.getAmount();
+        BigDecimal selectAmount = vo.getSelectAmount();
+        BigDecimal result = BigDecimal.ZERO;
+        if (amount != null && selectAmount != null) {
+            result = amount.subtract(selectAmount);
+        } else if (amount != null) {
+            result = amount;
+        } else if (selectAmount != null) {
+            result = selectAmount.negate();
+        }
+        str.append(result);
         str.append("</ZFamount>");
         str.append("</request>");
         str.append("]]>");