自动生成编码（java后台）

1.在数据库中建张表（最大值，字符前缀）

2.mapper中的dao层

根据字符前缀查询

3.mapper.xml文件SQL语句

注：红色圈（存在时更新，不存在是添加。具体访问：）：https://www.cnblogs.com/liaojie970/p/6824773.html

根据字符前缀查询的SQL

4.封装方法（参数拼接）

5.封装方法（字符拼接）

@Service
public class SysAssetsCodeService implements ISysAssetsCodeService {
private Lock lock = new ReentrantLock();
@Autowired
private SysAssetsCodeMapper codeMapper;
@Override
@Transactional
public String getCode(String preFixe,int numCode) {
try {
lock.lock();
int result = codeMapper.insertAssetsCode(preFixe);
SysAssetsCode sysAssetsCode = codeMapper.selectByPrefix(preFixe);
if(sysAssetsCode != null && result > 0 ){
return String.format("%s%"+numCode+"d", preFixe,sysAssetsCode.getMaxinx()).replace(" ", "0");
}else{
throw new RuntimeException("获取编码失败");
}
} finally {
lock.unlock();
}
}
}

6.Controller控制层

/**
* 根据资产编号获取详细信息
*/
@PreAuthorize("@ss.hasPermi('system:assets:query')")
@GetMapping(value ={"/", "/{id}"})
public AjaxResult getInfo(@PathVariable(value = "id", required = false) Long id)
{
AjaxResult ajax = AjaxResult.success();
SysAssets assets = null;
if(StringUtils.isNotNull(id)){
assets = assetsService.selectAssetsById(id);
}else{
assets = new SysAssets();
assets.setCodeId(codeService.getCode("YFCX",5));
}
ajax.put(AjaxResult.DATA_TAG,assets);
return ajax;
}