MyBatis-Plus：代码增强-抽取公共字段、Lambda获取字段名

转x33g5p2x  于2022-06-27 转载在 其他  
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1. 增强

1.1 抽取公共字段（Model）

  1. @Getter
  2. @Setter
  3. @ToString
  4. @Accessors(chain = true)
  5. public class BaseDB<T extends BaseDB<?>> extends Model<T> {
  7.     private static final long serialVersionUID = 3253505422347170166L;
  9.     /** 主键 - 记录插入自动填充主键处理{@path application.yml} */
  10.     @TableId
  11.     private String id;
  13.     @TableField(fill = FieldFill.INSERT)
  14.     private String createTime;
  16.     @TableField(fill = FieldFill.INSERT_UPDATE)
  17.     private String updateTime;
  19.     /** 记录是否被逻辑删除：0未删除 1逻辑删除 - 逻辑处理值定义{@path application.yml}*/
  20.     @TableField
  21.     @TableLogic
  22.     private Integer isDel;
  24.     @TableField("is_del")
  25.     private IsDelEnum isDelEnum;
  27.     /**
  28.      * 乐观锁(记录的被修改数)
  29.      *
  30.      * 很鸡肋，需要通过代码查出记录然后手动取此对象的version给准备update的对象，或者直接在查出记录上进行update
  31.      */
  32.     @TableField
  33.     @Version
  34.     private Integer version;
  36. }

1.2 物理删除、逻辑删除同时支持（BaseMapper增强）

MyBatisPlusConfig.java

  1. @Configuration
  2. public class MyBatisPlusConfig {
  4.     /**
  5.      * SQL注入器
  6.      * @return
  7.      */
  8.     @Bean
  9.     public ISqlInjector enhanceISqlInjector() {
  10.         return new DefaultSqlInjector() {
  11.             @Override
  12.             public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
  13.                 List<AbstractMethod> methodList = super.getMethodList(mapperClass, tableInfo);
  15.                 methodList.add(new DeleteByIdPhysical());
  16.                 methodList.add(new DeleteByIdLogic());
  18.                 return methodList;
  19.             }
  20.         };
  21.     }
  23. }

DeleteByIdLogic.java

  1. /**
  2.  * 作用：逻辑删除
  3.  *  照抄官方{@link DeleteById}
  4.  * @author LinRuChang
  5.  * @version 1.0
  6.  * @date 2022/06/14
  7.  * @since 1.8
  8.  **/
  9. public class DeleteByIdLogic extends AbstractMethod {
  10.     @Override
  11.     public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
  13.         boolean withLogicDelete = tableInfo.isWithLogicDelete();
  15.         //当前表支持逻辑删除，不支持则不注入
  16.         if(withLogicDelete) {
  17.             String sql;
  18.             SqlMethod sqlMethod = SqlMethod.LOGIC_DELETE_BY_ID;
  19.             List<TableFieldInfo> fieldInfos = tableInfo.getFieldList().stream()
  20.                     .filter(TableFieldInfo::isWithUpdateFill)
  21.                     .filter(f -> !f.isLogicDelete())
  22.                     .collect(toList());
  23.             if (CollectionUtils.isNotEmpty(fieldInfos)) {
  24.                 String sqlSet = "SET " + SqlScriptUtils.convertIf(fieldInfos.stream()
  25.                         .map(i -> i.getSqlSet(EMPTY)).collect(joining(EMPTY)), "!@org.apache.ibatis.type.SimpleTypeRegistry@isSimpleType(_parameter.getClass())", true)
  26.                         + tableInfo.getLogicDeleteSql(false, false);
  27.                 sql = String.format(sqlMethod.getSql(), tableInfo.getTableName(), sqlSet, tableInfo.getKeyColumn(),
  28.                         tableInfo.getKeyProperty(), tableInfo.getLogicDeleteSql(true, true));
  29.             } else {
  30.                 sql = String.format(sqlMethod.getSql(), tableInfo.getTableName(), sqlLogicSet(tableInfo),
  31.                         tableInfo.getKeyColumn(), tableInfo.getKeyProperty(),
  32.                         tableInfo.getLogicDeleteSql(true, true));
  33.             }
  34.             SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, Object.class);
  35.             //return addUpdateMappedStatement(mapperClass, modelClass, getMethod(sqlMethod), sqlSource);
  36.             return addUpdateMappedStatement(mapperClass, modelClass, "deleteByIdLogic", sqlSource);
  37.         }
  39.         //无逻辑删除字段，则不注入上述SQL,当调用work.linruchang.mybatisplussamplestest.dao.MyBaseMapper.deleteByIdLogic(java.io.Serializable)会报异常
  40.         return null;
  41.     }
  42. }

DeleteByIdPhysical.java

  1. /**
  2.  * 作用：物理删除
  3.  *  照抄{@link DeleteById}
  4.  * @author LinRuChang
  5.  * @version 1.0
  6.  * @date 2022/06/14
  7.  * @since 1.8
  8.  **/
  9. public class DeleteByIdPhysical extends AbstractMethod {
  10.     @Override
  11.     public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
  12.         String sql;
  13.         SqlMethod sqlMethod  = SqlMethod.DELETE_BY_ID;
  14.         sql = String.format(sqlMethod.getSql(), tableInfo.getTableName(), tableInfo.getKeyColumn(),
  15.                 tableInfo.getKeyProperty());
  16.         SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, Object.class);
  17.         //return this.addDeleteMappedStatement(mapperClass, getMethod(sqlMethod), sqlSource);
  18.         return this.addDeleteMappedStatement(mapperClass, "deleteByIdPhysical", sqlSource);
  19.     }
  20. }

 
MyBaseMapper.java

  1. public interface MyBaseMapper<T> extends BaseMapper<T> {
  3.     /**
  4.      * 物理删除
  5.      * @param id
  6.      * @return
  7.      */
  8.     int deleteByIdPhysical(Serializable id);
  10.     /**
  11.      * 物理删除
  12.      * @param entity
  13.      * @return
  14.      */
  15.     int deleteByIdPhysical(T entity);
  17.     /**
  18.      * 逻辑删除
  19.      *
  20.      * 打算调这个方法，如果发现实体没有@TableLogic就会报异常出来提示用户
  21.      * @param id
  22.      * @return
  23.      */
  24.     int deleteByIdLogic(Serializable id);
  26.     /**
  27.      * 逻辑删除
  28.      * @param entity
  29.      * @return
  30.      */
  31.     int deleteByIdLogic(T entity);
  33.     /**
  34.      * 删除
  35.      * @param id 主键ID
  36.      * @param logicDeleteFlag null老逻辑  true逻辑删除 false物理删除
  37.      * @return
  38.      */
  39.     default int deleteById(Serializable id, Boolean logicDeleteFlag) {
  41.         //无指定则根据实体是否有@TableLogic进行评判（原逻辑）
  42.         if(logicDeleteFlag == null) {return deleteById(id);}
  44.         //指定逻辑删除、物理删除
  45.         if(BooleanUtil.isTrue(logicDeleteFlag)) {
  46.             Class currentMapperClazz = (Class) ReflectUtil.getFieldValue(ReflectUtil.getFieldValue(AopUtils.getTargetObject(this),"h"),"mapperInterface");
  47.             Type typeArgument = TypeUtil.getTypeArgument(currentMapperClazz, 0);
  48.             TableInfo tableInfo = TableInfoHelper.getTableInfo((Class<?>) typeArgument);
  49.             if(tableInfo.isWithLogicDelete()) {
  50.                 return deleteByIdLogic(id);
  51.             }
  52.             throw new RuntimeException(StrUtil.format("当前表【{}】：不支持逻辑删除，请检查是否有配置逻辑删除字段", tableInfo.getTableName()));
  53.         }else {
  54.             return deleteByIdPhysical(id);
  55.         }
  56.     }
  58. }

SysUserDao.java

  1. @Mapper
  2. public interface SysUserDao extends MyBaseMapper<SysUser> {
  3. }

SysUserServiceTest.java

  1. @SpringBootTest
  2. class SysUserServiceTest {
  4.     @Autowired
  5.     SysUserDao sysUserDao;
  7.     /**
  8.      * 物理删除支持
  9.      */
  10.     @Test
  11.     public void test9() {
  12.         int insertFlag = sysUserDao.deleteById("dde66e90c44bcc535cce872541dd8b36", false);
  13.         Console.log("删除情况：{}",insertFlag);
  14.     }
  16.     /**
  17.      * 逻辑删除
  18.      */
  19.     @Test
  20.     public void test10() {
  21.         int insertFlag = sysUserDao.deleteById("dde66e90c44bcc535cce872541dd8b36", true);
  22.         Console.log("逻辑删除情况：{}",insertFlag);
  23.     }
  24. }

2. 工具类

2.1 Lambda获取字段名

代码
  1. /**
  2.  * 作用：mybatisPlus工具类
  3.  *
  4.  * @author LinRuChang
  5.  * @version 1.0
  6.  * @date 2021/03/09
  7.  * @since 1.8
  8.  **/
  9. public class MyBatisPlusUtil {
  11.     /**
  12.      * Collection<SFunction> 转成 Array<SFunction>
  13.      * 容器类型转换
  14.      * @param beanFields
  15.      * @param <T>
  16.      * @return
  17.      */
  18.     public static <T> SFunction<T,?>[] sFunctionCollsToArray(Collection<SFunction<T, ?>> beanFields) {
  19.         return Optional.ofNullable(beanFields)
  20.                 .map(bfs -> {
  21.                     SFunction<T,?>[] result = new SFunction[beanFields.size()];
  22.                     return bfs.toArray(result);
  23.                 })
  24.                 .orElse(new SFunction[0]);
  25.     }
  27.     /**
  28.      * Bean字段转select的数据库列名【即Bean变量名【驼峰变量名】转成下划线形式】
  29.      *      过程：sfunction =》Bean变量名 =》驼峰转下划线字符串
  30.      *      注意：仅仅只是基于getxx进行解析，对于@TableFiled上的真正的注解列名不生效
  31.      * @param beanFields
  32.      * @param <T>
  33.      * @return 同一个表的多个表列名
  34.      */
  35.     public static <T> Set<String> sFunctionConvertToDataBaseFields(SFunction<T, ?>... beanFields) {
  36.         return sFunctionConvertToDataBaseFields(beanFields == null ? Collections.emptySet():Arrays.asList(beanFields));
  37.     }
  39.     /**
  40.      * Bean字段转select的数据库列名【即Bean变量名【驼峰变量名】转成下划线形式】
  41.      *      过程：sfunction =》Bean变量名 =》驼峰转下划线字符串
  42.      *      注意：仅仅只是基于getxx进行解析，对于@TableFiled上的真正的注解列名不生效
  43.      * @param beanFields 多个属性Bean变量
  44.      * @param <T>
  45.      * @return 同一个表的多个表列名
  46.      */
  47.     public static <T> Set<String> sFunctionConvertToDataBaseFields(Collection<SFunction<T, ?>> beanFields) {
  48.         return Optional.ofNullable(beanFields).map(columnNames -> {
  49.             return beanFields.stream()
  50.                     .map(MyBatisPlusUtil::sFunctionConverToDataBaseFieldFieldName)
  51.                     .collect(Collectors.toSet());
  52.         }).orElse(Collections.emptySet());
  53.     }
  55.     /**
  56.      * 将Bean变量名转成数据库列名【约定俗成的形式】 == 驼峰转下划线
  57.      * 注意：仅仅只是基于getxx进行解析，对于@TableFiled上的真正的注解列名不生效
  58.      * @param beanFileldName 属性Bean变量
  59.      * @param <T>
  60.      * @return 数据库列名【下划线】
  61.      */
  62.     public static <T> String sFunctionConverToDataBaseFieldFieldName(SFunction<T, ?> beanFileldName) {
  63.         return Optional.ofNullable(sFunctionConverToBeanFieldName(beanFileldName))
  64.                 .map(com.baomidou.mybatisplus.core.toolkit.StringUtils::camelToUnderline)
  65.                 .orElse(null);
  66.     }
  68.     /**
  69.      * 获取Bean的变量名 == 一般都是驼峰变量名
  70.      * 注意：仅仅只是基于getxx进行解析，对于@TableFiled上的真正的注解列名不生效
  71.      * @param beanFileldName 属性Bean变量
  72.      * @param <T>
  73.      * @return Bean属性名
  74.      */
  75.     public static <T> String sFunctionConverToBeanFieldName(SFunction<T, ?> beanFileldName) {
  76.         return Optional.ofNullable(beanFileldName).map(bfe -> {
  77.             SerializedLambda resolve = LambdaUtils.resolve(bfe);
  78.             return PropertyNamer.methodToProperty(resolve.getImplMethodName());
  79.         }).orElse(null);
  80.     }
  82. }
使用
  1. @Service
  2. @Slf4j
  3. public class RoleService extends ServiceImpl<RoleDao, Role> {    
  4.     public List<Role> getList(SFunction<Role, ?>... fieldName) {
  5.         return this.getBaseMapper().getList(MyBatisPlusUtil.sFunctionConvertToDataBaseFields(fieldName));
  6.     }
  7. }
  9. @Mapper
  10. public interface RoleDao extends BaseMapper<Role> {
  11.     public List<Role> getList(@Param("selectTableColumnNames") Set<String> selectTableColumnNames);
  12. }
  1. <!--注意列名拼接必须使用${变量}，使用#{变量}的话，最后语句变成  select '列名1', '列名2' from 表名 这句是错的，应该变成 select 列名1, 列名2 from 表名 -->
  2.     <select id="getList" resultType="top.linruchang.springdemo.db.Role">
  3.         SELECT
  4.             <choose>
  5.                 <when test="selectTableColumnNames != null and selectTableColumnNames.size() > 0">
  6.                     <foreach collection="selectTableColumnNames" separator="," item="columnName">
  7.                         ${columnName}
  8.                     </foreach>
  9.                 </when>
  10.                 <otherwise>*</otherwise>
  11.             </choose>
  12.         FROM role
  13.     </select>

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原文链接 : https://blog.csdn.net/weixin_39651356/article/details/125328483

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