一、前言程式猿為什麼如此執著於造輪子？MyBatis-Plus如此強大的工具流行這麼多年了，我為啥還在重覆造這樣的輪子？ 1、公司的技術規範不允許使用MyBatis-Plus，咱也不知道什麼原因； 3、以前使用SpringDataJpa慣了，今年第一次用MyBatis，必須把它打造成我想要的樣子； ...

一、前言

程式猿為什麼如此執著於造輪子？MyBatis-Plus如此強大的工具流行這麼多年了，我為啥還在重覆造這樣的輪子？

1、公司的技術規範不允許使用MyBatis-Plus，咱也不知道什麼原因；

3、以前使用SpringDataJpa慣了，今年第一次用MyBatis，必須把它打造成我想要的樣子；

6、MyBatis-Plus好像不支持聯合主鍵；

7、還有一些其它的需求，比如對字典欄位自動翻譯：字典可能來自枚舉、字典表、Redis......

10、通用數據許可權控制；

11、如果不造此輪子，就沒有這篇文章。

以上12點原因，便是造這個輪子的理由。實際上，輪子不重要，重要的是掌握輪子的原理，取其精華，去其糟粕。也歡迎大家拍磚，請輕拍，數學能力被誰拍壞了誰來陪。

二、需求

通用Mapper起碼應該包含以下功能：

1、增

2、刪

3、改

4、批量增

5、批量刪

6、只更新指定欄位

7、分頁查詢查當前頁

8、分頁查詢查總數

9、字典欄位翻譯

10、數據許可權控制

大概長下麵這個樣子：

public interface BaseMapper<T,K> {

    int insert(T t);

    int batchInsert(List<T> entity);
    
    int deleteById(K id);
    
    int deleteBatchIds(Collection<K> ids);
    
    int updateById(T entity);
    
    int updateSelectiveById(T entity);
    
    T selectById(K id);
    
    List<T> selectBatchIds(Collection<K> ids);
    
    List<T> selectAll();
    
    List<T> selectPage(PageRequest<T> pageRequest);
    
    Long selectCount(T entity);

}

三、實現原理

1、基於MyBatis3提供的SqlProvider構建動態Sql

例如如下代碼：

@SelectProvider(type = UserSqlBuilder.class, method = "buildGetUsersByName")
List<User> getUsersByName(String name);

class UserSqlBuilder {
  public static String buildGetUsersByName(final String name) {
    return new SQL(){{
      SELECT("*");
      FROM("users");
      if (name != null) {
        WHERE("name like #{value} || '%'");
      }
      ORDER_BY("id");
    }}.toString();
  }
}

2、基於自定義註解，為實體和資料庫表建立對應關係

例如如下代碼：

@Table("user")
public class User {
    @Id(auto = true)
    @Column(value = "id")
    private Long id;

    @Column(value = "name", filterOperator = FilterOperator.LIKE)
    @OrderBy(orderPriority = 0)
    private String name;

    @OrderBy(order = Order.DESC, orderPriority = 1)
    private Integer age;

    private String email;

    @Transient
    private String test;
}

基於以上兩個原理，當方法被調用時，我們便可構建出相應的動態Sql，從而實現該通用Mapper。

四、代碼實現

1、自定義註解

1）@Table

瞭解Jpa的朋友一定很熟悉，這個就是為實體指定表名，實體不加這個註解就認為實體名與表名一致：

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Table {
    //表名，不指定則使用實體類名
    String value() default "";
}

2）@Column

指定完表名，該指定列名了，同樣的如果欄位不指定則認為欄位名與表列名一致：

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Column {
    //對應資料庫列名
    String value() default "";
    //查詢時的過濾類型
    FilterOperator filterOperator() default FilterOperator.EQ;
    //是否查詢，select是否帶上該欄位
    boolean selectable() default true;
    //是否插入，insert是否帶上該欄位
    boolean insertable() default true;
    //是否更新，update是否帶上該欄位
    boolean updatable() default true;
}

3）@Id

這個註解就是為了表明該欄位是否是資料庫主鍵。當然，這個註解可以與@Column合併，但為了更清晰，我還是決定單獨使用這個註解。並且，也方便後期擴展。

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Id {
    //主鍵是否自動生成
    boolean auto() default false;
}

4）@OrderBy

這個註解來標明查詢時的排序欄位，同時考慮如果排序欄位有多個，可定義優先順序：

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface OrderBy {
    //排序
    Order order() default Order.ASC;
    //多個排序欄位先後順序
    int orderPriority() default 0;
}

5）@Transient

考慮實體中有些欄位在資料庫中不存在的情況。使用這個註解來標註這樣的欄位：

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Transient {
}

2、幾個pojo，用來保存實體對應的信息

1）TableInfo，表示一個實體對應的資料庫表信息

public class TableInfo {
    //表對應的實體類型
    private Class<?> entityClass;

    //表名
    private String tableName;

    //列
    private List<ColumnInfo> columns;

    //是否聯合主鍵
    private boolean isUnionId;
}

2）ColumnInfo，表示實體中的一個欄位對應的資料庫表欄位信息

public class ColumnInfo {
    //對應的java類型
    private Class<?> fieldClass;
    private Field field;
    private FilterOperator filterOperator;
    //資料庫列
    private String column;
    //是否主鍵
    private boolean isPrimaryKey;
    //主鍵填充方式
    private boolean isPrimaryKeyAuto;
    //排序
    private Order orderBy;
    private int orderByPriority;
    //是否參與insert
    private boolean insertable;
    //是否參與update
    private boolean updatable;
    //是否參與select
    private boolean selectable;
}

以上只需要註意一點，如何判斷一個實體是否是聯合主鍵。這裡用的比較粗暴的方法，如果有多個欄位加了@Id，那麼認為是聯合主鍵。

3、定義開頭說的BaseMapper

這個BaseMapper的定義模仿了SpringDataJpa，它需要兩個泛型，T表示實體類型，K表示主鍵類型。

一般情況下K為簡單數據類型，比如Long，String；

聯合主鍵情況下，K為自定義的一個複雜數據類型，具體使用方法見文章最後章節。

public interface BaseMapper<T,K> {

    @InsertProvider(type = SqlProvider.class,method = "insert")
    @Options(useGeneratedKeys = true, keyProperty = "id",keyColumn = "id")
    int insert(T t);

    @InsertProvider(type = SqlProvider.class,method = "batchInsert")
    int batchInsert(@Param("list") List<T> entity);

    @DeleteProvider(type = SqlProvider.class,method = "deleteById")
    int deleteById(@Param("id") K id);

    @DeleteProvider(type = SqlProvider.class,method = "deleteBatchIds")
    int deleteBatchIds(@Param("ids") Collection<K> ids);

    @UpdateProvider(type = SqlProvider.class,method = "updateById")
    int updateById(T entity);

    @UpdateProvider(type = SqlProvider.class,method = "updateSelectiveById")
    int updateSelectiveById(T entity);

    @SelectProvider(type = SqlProvider.class,method = "selectById")
    T selectById(@Param("id") K id);

    @SelectProvider(type = SqlProvider.class,method = "selectBatchIds")
    List<T> selectBatchIds(@Param("ids") Collection<K> ids);

    @SelectProvider(type = SqlProvider.class,method = "selectAll")
    List<T> selectAll();

    @SelectProvider(type = SqlProvider.class,method = "selectPage")
    List<T> selectPage(PageRequest<T> pageRequest);

    @SelectProvider(type = SqlProvider.class,method = "selectCount")
    Long selectCount(T entity);

}

4、SqlProvider

public class SqlProvider<T> {
    private static Logger logger = LoggerFactory.getLogger(SqlProvider.class);
    private static Map<Class<?>, TableInfo> tableCache = new ConcurrentHashMap<>();

    public String insert(T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        String intoColumns = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isInsertable)
                .map(ColumnInfo::getColumn)
                .collect(Collectors.joining(","));
        String values = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isInsertable)
                .map(ColumnInfo::variable)
                .collect(Collectors.joining(","));
        String sql = new SQL()
                .INSERT_INTO(tableName)
                .INTO_COLUMNS(intoColumns)
                .INTO_VALUES(values).toString();
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String batchInsert(@Param("list" ) List<?> entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        String intoColumns = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isInsertable)
                .map(ColumnInfo::getColumn)
                .collect(Collectors.joining(","));
        String values = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isInsertable)
                .map(column->column.variableWithPrefix("item"))
                .collect(Collectors.joining(","));
        String sql = new SQL()
                .INSERT_INTO(tableName)
                .INTO_COLUMNS(intoColumns).toString();
        sql += " values ";
        sql += "<foreach collection=\"list\" item=\"item\" separator=\",\">" +
                "  <trim prefix=\"(\" suffix=\")\" suffixOverrides=\",\">" +
                "    " + values +
                "  </trim>" +
                "</foreach>";
        sql = "<script>"+sql+"</script>";
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String deleteById(@Param("id") T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        String[] where = null;
        if (tableInfo.isUnionId()){
            where = tableInfo.getColumns()
                    .stream()
                    .filter(ColumnInfo::isPrimaryKey)
                    .map(columnInfo -> columnInfo.getColumn()+" = #{id."+columnInfo.getField().getName()+"}")
                    .toArray(String[]::new);
        }else {
            where = tableInfo.getColumns()
                    .stream()
                    .filter(ColumnInfo::isPrimaryKey)
                    .map(columnInfo -> columnInfo.getColumn()+" = #{id}")
                    .toArray(String[]::new);
        }
        String sql = new SQL()
                .DELETE_FROM(tableName)
                .WHERE(where)
                .toString();
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String deleteBatchIds(@Param("ids") Collection<?> entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        if (tableInfo.isUnionId()){
            String[] where = new String[entity.size()];
            for (int i = 0; i < entity.size(); i++){
                List<String> list = new ArrayList<>();
                String s = "%s=#{ids[%d].%s}";
                for (ColumnInfo columnInfo:tableInfo.getColumns()){
                    if (columnInfo.isPrimaryKey()){
                        list.add(String.format(s,columnInfo.getColumn(),i,columnInfo.getField().getName()));
                    }
                }
                where[i] = "("+StringUtils.join(list," and ")+")";
            }
            String sql = "delete from %s where %s ";
            sql = String.format(sql,tableName,StringUtils.join(where," or "));
            logger.info("sql->{},params->{}",sql,entity);
            return sql;
        }else {
            String idName = tableInfo.getColumns()
                    .stream()
                    .filter(ColumnInfo::isPrimaryKey)
                    .findFirst()
                    .get()
                    .getColumn();
            String sql = "DELETE FROM %s WHERE %s IN (%s) ";
            String[] arr = new String[entity.size()];
            for (int i = 0; i < entity.size(); i++){
                arr[i] = "#{ids["+i+"]}";
            }
            sql = String.format(sql,tableName,idName,StringUtils.join(arr,","));
            logger.info("sql->{},params->{}",sql,entity);
            return sql;
        }
    }

    public String updateById(T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        String[] where = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isPrimaryKey)
                .map(columnInfo -> columnInfo.getColumn()+" = "+columnInfo.variable())
                .toArray(String[]::new);
        String sql = new SQL().UPDATE(tableName).SET(tableInfo.updateSetColumn()).WHERE(where).toString();
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String updateSelectiveById(T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        String[] where = tableInfo.getColumns()
                .stream()
                .filter(ColumnInfo::isPrimaryKey)
                .map(columnInfo -> columnInfo.getColumn()+" = "+columnInfo.variable())
                .toArray(String[]::new);
        String sql = new SQL().UPDATE(tableName).SET(tableInfo.updateSetSelectiveColumn(entity)).WHERE(where).toString();
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String selectById(@Param("id")T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String[] where = null;
        if (tableInfo.isUnionId()){
            where = tableInfo.getColumns().stream().filter(ColumnInfo::isPrimaryKey)
                    .map(columnInfo -> columnInfo.getColumn()+" = #{id."+columnInfo.getField().getName()+"}")
                    .toArray(String[]::new);
        }else {
            where = tableInfo.getColumns().stream().filter(ColumnInfo::isPrimaryKey)
                    .map(columnInfo -> columnInfo.getColumn()+" = #{id}")
                    .toArray(String[]::new);
        }
        String sql = new SQL()
                .SELECT(tableInfo.selectColumnAsProperty())
                .FROM(tableInfo.getTableName())
                .WHERE(where)
                .toString();
        logger.info("sql->{},params->{}",sql,entity);
        return sql;
    }

    public String selectBatchIds(@Param("ids")Collection<?> entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        String tableName = tableInfo.getTableName();
        if (tableInfo.isUnionId()){
            String[] where = new String[entity.size()];
            for (int i = 0; i < entity.size(); i++){
                List<String> list = new ArrayList<>();
                String s = "%s=#{ids[%d].%s}";
                for (ColumnInfo columnInfo:tableInfo.getColumns()){
                    if (columnInfo.isPrimaryKey()){
                        list.add(String.format(s,columnInfo.getColumn(),i,columnInfo.getField().getName()));
                    }
                }
                where[i] = "("+StringUtils.join(list," and ")+")";
            }
            String sql = "select %s from %s where %s";
            sql = String.format(sql,tableInfo.selectColumnAsProperty(),tableInfo.getTableName(),StringUtils.join(where," or "));
            logger.info("sql->{},params->{}",sql,entity);
            return sql;
        }else {
            String idName = tableInfo.getColumns()
                    .stream()
                    .filter(ColumnInfo::isPrimaryKey)
                    .findFirst()
                    .get()
                    .getColumn();
            String sql = "select %s from %s where %s in (%s) ";
            String[] arr = new String[entity.size()];
            for (int i = 0; i < entity.size(); i++){
                arr[i] = "#{ids["+i+"]}";
            }
            sql = String.format(sql,tableInfo.selectColumnAsProperty(),tableName,idName,StringUtils.join(arr,","));
            logger.info("sql->{},params->{}",sql,entity);
            return sql;
        }
    }

    public String selectAll(T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        SQL sql =  new SQL()
                .SELECT(tableInfo.selectColumnAsProperty())
                .FROM(tableInfo.getTableName());
        String orderBy = tableInfo.orderByColumn();
        if (StringUtils.isNotEmpty(orderBy)){
            sql.ORDER_BY(orderBy);
        }
        return sql.toString();
    }

    public String selectPage(PageRequest<T> entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        SQL sql = new SQL()
                .SELECT(tableInfo.selectColumnAsProperty())
                .FROM(tableInfo.getTableName());
        String[] where = tableInfo.getColumns().stream()
                .filter(column -> {
                    Field field = column.getField();
                    T bean = entity.getPageParams();
                    Object value = Util.getFieldValue(bean, field);
                    if (value == null) {
                        return false;
                    }
                    return StringUtils.isNotEmpty(value.toString());
                })
                .map(column -> {
                    String param = " #{pageParams." + column.getField().getName()+"}";
                    if (column.getFilterOperator() == FilterOperator.LIKE){
                        param = "concat('%', "+param+", '%')";
                    }
                    if (column.getFilterOperator() == FilterOperator.LEFTLIKE){
                        param = "concat("+param+", '%')";
                    }
                    if (column.getFilterOperator() == FilterOperator.RIGHTLIKE){
                        param = "concat('%', "+param+")";
                    }
                    return column.getColumn()+column.filterOperator()+param;
                })
                .toArray(String[]::new);
        sql.WHERE(where);
        if (StringUtils.isNotEmpty(entity.getOrder())){
            ColumnInfo columnInfo = tableInfo.getColumns().stream()
                    .filter(columnInfo1 -> columnInfo1.getField().getName().equalsIgnoreCase(entity.getOrder()))
                    .findFirst().orElse(null);
            if (columnInfo != null){
                String direction = entity.getOrderDirection();
                direction = (StringUtils.isEmpty(direction) || direction.equalsIgnoreCase("asc"))?" asc ":" desc ";
                sql.ORDER_BY(columnInfo.getColumn() + direction);
            }
        }else {
            String orderBy = tableInfo.orderByColumn();
            if (StringUtils.isNotEmpty(orderBy)){
                sql.ORDER_BY(orderBy);
            }
        }
        sql.OFFSET("#{offset}").LIMIT("#{pageSize}");
        String s = sql.toString();
        logger.info("sql->{},params->{}",s,entity);
        return s;
    }

    public String selectCount(T entity, ProviderContext context){
        TableInfo tableInfo = getTableInfo(context);
        SQL sql = new SQL()
                .SELECT("count(1)")
                .FROM(tableInfo.getTableName());
        String[] where = tableInfo.getColumns().stream()
                .filter(column -> {
                    Field field = column.getField();
                    Object value = Util.getFieldValue(entity, field);
                    if (value == null) {
                        return false;
                    }
                    return StringUtils.isNotEmpty(value.toString());
                })
                .map(column -> {
                    String param = " #{" + column.getField().getName()+"}";
                    if (column.getFilterOperator() == FilterOperator.LIKE){
                        param = "concat('%', "+param+", '%')";
                    }
                    if (column.getFilterOperator() == FilterOperator.LEFTLIKE){
                        param = "concat("+param+", '%')";
                    }
                    if (column.getFilterOperator() == FilterOperator.RIGHTLIKE){
                        param = "concat('%', "+param+")";
                    }
                    return column.getColumn()+column.filterOperator()+param;
                })
                .toArray(String[]::new);
        sql.WHERE(where);
        String s = sql.toString();
        logger.info("sql->{},params->{}",s,entity);
        return s;
    }

    private TableInfo getTableInfo(ProviderContext context){
        Class<?> clz = getEntityType(context);
        return tableCache.computeIfAbsent(context.getMapperType(), t-> Util.tableInfo(clz));
    }

    private Class<?> getEntityType(ProviderContext context) {
        return Stream.of(context.getMapperType().getGenericInterfaces())
                .filter(ParameterizedType.class::isInstance)
                .map(ParameterizedType.class::cast)
                .filter(type -> type.getRawType() == BaseMapper.class)
                .findFirst()
                .map(type -> type.getActualTypeArguments()[0])
                .filter(Class.class::isInstance)
                .map(Class.class::cast)
                .orElseThrow(() -> new IllegalStateException("未找到BaseMapper的泛型類 " + context.getMapperType().getName() + "."));
    }


}

5、實體類轉TableInfo

public static TableInfo tableInfo(Class<?> entityClass) {
        TableInfo info = new TableInfo();
        info.setEntityClass(entityClass);
        Table table = entityClass.getAnnotation(Table.class);
        String tableName = entityClass.getSimpleName();
        if (table != null && StringUtils.isNotEmpty(table.value())){
            tableName = table.value();
        }
        info.setTableName(tableName);
        Field[] allFields = getFields(entityClass);
        Field[] fields = Stream.of(allFields)
                //過濾@Transient註解的field
                .filter(field -> !field.isAnnotationPresent(Transient.class))
                .toArray(Field[]::new);
        List<ColumnInfo> columns = new ArrayList<>();
        int idCount = 0;
        for (Field field:fields){
            ColumnInfo columnInfo = new ColumnInfo();
            columnInfo.setFieldClass(field.getDeclaringClass());
            columnInfo.setField(field);
            Id id = field.getAnnotation(Id.class);
            idCount = idCount + (id == null?0:1);
            columnInfo.setPrimaryKey(id == null?Boolean.FALSE:Boolean.TRUE);
            columnInfo.setPrimaryKeyAuto(id == null?Boolean.FALSE:id.auto());
            Column column = field.getAnnotation(Column.class);
            String columnName = field.getName();
            if (column != null && StringUtils.isNotEmpty(column.value())){
                columnName = column.value();
            }
            columnInfo.setColumn(columnName);
            FilterOperator filterOperator = FilterOperator.EQ;
            if (column != null && column.filterOperator() != null){
                filterOperator = column.filterOperator();
            }
            columnInfo.setFilterOperator(filterOperator);

            if (columnInfo.isPrimaryKeyAuto()){
                columnInfo.setInsertable(false);
            }else {
                columnInfo.setInsertable(true);
                if (column != null){
                    columnInfo.setInsertable(column.insertable());
                }
            }
            columnInfo.setUpdatable(true);
            columnInfo.setSelectable(true);
            if (column != null){
                columnInfo.setSelectable(column.selectable());
                columnInfo.setUpdatable(column.updatable());
            }
            OrderBy orderBy = field.getAnnotation(OrderBy.class);
            if (orderBy != null){
                columnInfo.setOrderBy(orderBy.order());
                columnInfo.setOrderByPriority(orderBy.orderPriority());
            }
            columns.add(columnInfo);
        }
        if (idCount > 1){
            info.setUnionId(Boolean.TRUE);
        }
        info.setColumns(columns);
        return info;
    }

6、字典欄位自動翻譯

簡單實現思路：對需要翻譯的欄位加上@FieldTrans註解來表明這個欄位需要翻譯，通過AOP方式對結果數據進行增強，來將欄位進行翻譯更新。

此部分內容留待後續實現，同時調研一下是否還有更優雅簡單的實現方式。

7、數據許可權

我們先來思考一下數據許可權到底要幹啥？一句話來概括：查一張表的數據時在where條件中追加“and 控制許可權的列 in (???)”。

簡單實現方法：在控制許可權的欄位加上@DataAuthrity註解來表明通過這個欄位控制許可權，而???的內容肯定是由業務代碼來生成的，因此考慮給這個註解增加一個屬性，用來指明許可權數據由執行哪個介面或方法來獲取。

此部分內容留待後續實現，同時調研一下是否還有更優雅簡單的實現方式。

五、使用示例

1、資料庫表

CREATE TABLE `user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

2、實體

@Table("user")
public class User {
    @Id(auto = true)
    @Column(value = "id")
    private Long id;

    @Column(value = "name", filterOperator = FilterOperator.LIKE)
    @OrderBy(orderPriority = 0)
    private String name;

    @OrderBy(order = Order.DESC, orderPriority = 1)
    private Integer age;

    private String email;

    @Transient
    private String test;
}

3、Mapper

public interface UserMapper extends BaseMapper<User, Long> {

}

至此，不需要寫任何mapper.xml，UserMapper已經具備了增刪改查能力。

4、聯合主鍵示例

public class User1 {
    @Id
    @Column(value = "id1")
    private String id1;
    
    @Id
    @Column(value = "id2")
    private String id2;
    
    @Column(value = "name", filterOperator = FilterOperator.LIKE)
    @OrderBy(orderPriority = 0)
    private String name;
    
    @OrderBy(order = Order.DESC, orderPriority = 1)
    private Integer age;
    
    private String email;
    
    @Transient
    private String test;
}


public class User1Id {
    private String id1;
    private String id2;
}


public interface User1Mapper extends BaseMapper<User1,User1Id> {
}

六、總結

本輪子目前基本上不值一提，但相信後面我再把字典翻譯、通用數據許可權加上的話，仍然會不值一提。

實際上輪子本身不重要，開發過程中的各種思考、試驗更重要吧。

歡迎閱讀，歡迎轉載，轉載請註明出處，求你了。

開發一個MyBatis通用Mapper的輪子