个人日常开发工具问题收集

Posted 2022-01-08 hi, wade~

一、SpringBoot try…catch回滚事务

1. 方法上添加注解

   @Transactional
   

2. 标记回滚开始节点

   Object savePoint = TransactionAspectSupport.currentTransactionStatus().createSavepoint();
   

3. 启动回滚

   TransactionAspectSupport.currentTransactionStatus().rollbackToSavepoint(savePoint);
   

二、MyBatis查询关联

1. mybatis一对多（ofType：关联表，column：外键）

   <resultMap id="resultMap" type="com.wade.www.entity.Entity1">
     <result property="id" column="id"/>
       <result property="name" column="name"/>
       <collection
          	property="entity2List"
            column="entity2Id=id"
            ofType="com.wade.www.entity.Entity2"
            javaType="ArrayList"
            select="com.wade.www.mapper.Entity2Mapper.queryById">
       </collection>
   </resultMap>
   

三、文件与String的相互转换

1. 文件转String

   private String fileToString(String pathStr) 
           File file = new File(pathStr);
           try 
               FileInputStream fis = new FileInputStream(file);
               ByteArrayOutputStream bos = new ByteArrayOutputStream(1000);
               byte[] b = new byte[1000];
               int n;
               while ((n = fis.read(b)) != -1) 
                   bos.write(b, 0, n);
               
               fis.close();
               byte[] data = bos.toByteArray();
               bos.close();
               return Base64.getEncoder().encodeToString(data);
            catch (Exception e) 
               e.printStackTrace();
           
           return null;
       
   

2. String转文件

    public static void StringToFile(String base64file, String filePath, String fileName) throws Exception 
           byte[] bytes = Base64.getDecoder().decode(base64file);
           BufferedOutputStream bos = null;
           FileOutputStream fos = null;
           File file;
           try 
               File dir = new File(filePath);
               if (!dir.exists() && !dir.isDirectory()) // 判断文件目录是否存在
                   dir.mkdirs();
               
               file = new File(filePath + "\\\\" + fileName);
               fos = new FileOutputStream(file);
               bos = new BufferedOutputStream(fos);
               bos.write(bytes);
            catch (Exception e) 
               throw new Exception("文件传输失败！");
            finally 
               if (bos != null) 
                   try 
                       bos.close();
                    catch (IOException e) 
                       e.printStackTrace();
                   
               
               if (fos != null) 
                   try 
                       fos.close();
                    catch (IOException e) 
                       e.printStackTrace();