Duplicatekeyexception是什么异常

1.异常代码

org.springframework.dao.DuplicateKeyException: 
### Error updating database.  Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry 'R12388' for key 'return_bill_code'
### The error may involve com.bjucloud.wms.bill.dao.ReturnBillDAO.save-Inline
### The error occurred while setting parameters
### SQL: insert into return_bill         (             `status`,             `return_bill_code`,             `return_bill_wave_id`,             `waybill_id`,             `waybill_code`,             `owner_id`,             `owner_code`,             `supplier_id`,             `supplier_code`,             `customer_id`,             `customer_code`,             `customer_name`,             `remark`,             `access_time`,             `operate_time`,             `inbound_time`,             `logistics_center_code`,             `warehouse_code`,             `dock_name`,             `acceptance_name`         )         values         (             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?,             ?         )

调用持久层进行保存或更新的时候，跟主键或唯一性约束（索引）冲突了，会抛出Duplicatekeyexception异常

2.解决办法

       调用持久层类的进行保存或更新前进行条件约束

       删除唯一性索引

       改唯一性索引为普通索引

       捕获异常处理