浅谈Mybatis Plus的BaseMapper的方法是如何注入的

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我是靠谱客的博主殷勤云朵，这篇文章主要介绍浅谈Mybatis Plus的BaseMapper的方法是如何注入的，现在分享给大家，希望可以做个参考。

Mybatis Plus的BaseMapper的方法

我们在用的时候经常就是生产自定义的Mapper继承自BaseMapper，然后我们就可以使用了，但是有没想过BaseMapper里的方法是怎么被注入到mybatis里的，也没看到什么xml啊，今天我们就来看看是怎么回事。

Mybatis Plus的初始化方法

MybatisPlusAutoConfiguration中的SqlSessionFactory

在创建的时候会创建MybatisSqlSessionFactoryBean，然后设置MybatisConfiguration作为配置类。

MybatisConfiguration是继承自Configuration的：

自定义了一个MybatisMapperRegistry注册器，后面会用到。

BaseMapper方法的注入的过程

MybatisSqlSessionFactoryBean的初始化后方法afterPropertiesSet调用buildSqlSessionFactory创建SqlSessionFactory：

其实就会去解析自定义的mapper的xml文件：

其中有个addMapper的方法，是前面MybatisConfiguration调用的。

会解析出对应的类型，然后内部调用MybatisMapperRegistry的方法：

内部最后是MybatisMapperAnnotationBuilder去解析的：

里面会进行基本的SQL方法注入：

完成每个方法的注入：

注入的实现：

其实每一个AbstractMethod的子类都会实现自己的injectMappedStatement：

最后会去枚举类SqlMethod中获取对应的枚举，里面就是类似定义在xml中的信息，最后转换为sqlSource再进行封装：

SqlMethod 枚举值：

复制代码

public enum SqlMethod {
    /**
     * 插入
     */
    INSERT_ONE("insert", "插入一条数据（选择字段插入）", "<script>nINSERT INTO %s %s VALUES %sn</script>"),
    UPSERT_ONE("upsert", "Phoenix插入一条数据（选择字段插入）", "<script>nUPSERT INTO %s %s VALUES %sn</script>"),

/**
     * 删除
     */
    DELETE_BY_ID("deleteById", "根据ID 删除一条数据", "<script>nDELETE FROM %s WHERE %s=#{%s}n</script>"),
    DELETE_BY_MAP("deleteByMap", "根据columnMap 条件删除记录", "<script>nDELETE FROM %s %sn</script>"),
    DELETE("delete", "根据 entity 条件删除记录", "<script>nDELETE FROM %s %s %sn</script>"),
    DELETE_BATCH_BY_IDS("deleteBatchIds", "根据ID集合，批量删除数据", "<script>nDELETE FROM %s WHERE %s IN (%s)n</script>"),

/**
     * 逻辑删除
     */
    LOGIC_DELETE_BY_ID("deleteById", "根据ID 逻辑删除一条数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),
    LOGIC_DELETE_BY_MAP("deleteByMap", "根据columnMap 条件逻辑删除记录", "<script>nUPDATE %s %s %sn</script>"),
    LOGIC_DELETE("delete", "根据 entity 条件逻辑删除记录", "<script>nUPDATE %s %s %s %sn</script>"),
    LOGIC_DELETE_BATCH_BY_IDS("deleteBatchIds", "根据ID集合，批量逻辑删除数据", "<script>nUPDATE %s %s WHERE %s IN (%s) %sn</script>"),

/**
     * 修改
     */
    UPDATE_BY_ID("updateById", "根据ID 选择修改数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),
    UPDATE("update", "根据 whereEntity 条件，更新记录", "<script>nUPDATE %s %s %s %sn</script>"),

/**
     * 逻辑删除 -> 修改
     */
    LOGIC_UPDATE_BY_ID("updateById", "根据ID 修改数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),

/**
     * 查询
     */
    SELECT_BY_ID("selectById", "根据ID 查询一条数据", "SELECT %s FROM %s WHERE %s=#{%s} %s"),
    SELECT_BY_MAP("selectByMap", "根据columnMap 查询一条数据", "<script>SELECT %s FROM %s %sn</script>"),
    SELECT_BATCH_BY_IDS("selectBatchIds", "根据ID集合，批量查询数据", "<script>SELECT %s FROM %s WHERE %s IN (%s) %s</script>"),
    SELECT_ONE("selectOne", "查询满足条件一条数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_COUNT("selectCount", "查询满足条件总记录数", "<script>%s SELECT COUNT(%s) FROM %s %s %sn</script>"),
    SELECT_LIST("selectList", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_PAGE("selectPage", "查询满足条件所有数据（并翻页）", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_MAPS("selectMaps", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_MAPS_PAGE("selectMapsPage", "查询满足条件所有数据（并翻页）", "<script>n %s SELECT %s FROM %s %s %sn</script>"),
    SELECT_OBJS("selectObjs", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>");

private final String method;
    private final String desc;
    private final String sql;

SqlMethod(String method, String desc, String sql) {
        this.method = method;
        this.desc = desc;
        this.sql = sql;
    }

public String getMethod() {
        return method;
    }

public String getDesc() {
        return desc;
    }

public String getSql() {
        return sql;
    }
}

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public enum SqlMethod {
    /**
     * 插入
     */
    INSERT_ONE("insert", "插入一条数据（选择字段插入）", "<script>nINSERT INTO %s %s VALUES %sn</script>"),
    UPSERT_ONE("upsert", "Phoenix插入一条数据（选择字段插入）", "<script>nUPSERT INTO %s %s VALUES %sn</script>"),

    /**
     * 删除
     */
    DELETE_BY_ID("deleteById", "根据ID 删除一条数据", "<script>nDELETE FROM %s WHERE %s=#{%s}n</script>"),
    DELETE_BY_MAP("deleteByMap", "根据columnMap 条件删除记录", "<script>nDELETE FROM %s %sn</script>"),
    DELETE("delete", "根据 entity 条件删除记录", "<script>nDELETE FROM %s %s %sn</script>"),
    DELETE_BATCH_BY_IDS("deleteBatchIds", "根据ID集合，批量删除数据", "<script>nDELETE FROM %s WHERE %s IN (%s)n</script>"),

    /**
     * 逻辑删除
     */
    LOGIC_DELETE_BY_ID("deleteById", "根据ID 逻辑删除一条数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),
    LOGIC_DELETE_BY_MAP("deleteByMap", "根据columnMap 条件逻辑删除记录", "<script>nUPDATE %s %s %sn</script>"),
    LOGIC_DELETE("delete", "根据 entity 条件逻辑删除记录", "<script>nUPDATE %s %s %s %sn</script>"),
    LOGIC_DELETE_BATCH_BY_IDS("deleteBatchIds", "根据ID集合，批量逻辑删除数据", "<script>nUPDATE %s %s WHERE %s IN (%s) %sn</script>"),

    /**
     * 修改
     */
    UPDATE_BY_ID("updateById", "根据ID 选择修改数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),
    UPDATE("update", "根据 whereEntity 条件，更新记录", "<script>nUPDATE %s %s %s %sn</script>"),

    /**
     * 逻辑删除 -> 修改
     */
    LOGIC_UPDATE_BY_ID("updateById", "根据ID 修改数据", "<script>nUPDATE %s %s WHERE %s=#{%s} %sn</script>"),

    /**
     * 查询
     */
    SELECT_BY_ID("selectById", "根据ID 查询一条数据", "SELECT %s FROM %s WHERE %s=#{%s} %s"),
    SELECT_BY_MAP("selectByMap", "根据columnMap 查询一条数据", "<script>SELECT %s FROM %s %sn</script>"),
    SELECT_BATCH_BY_IDS("selectBatchIds", "根据ID集合，批量查询数据", "<script>SELECT %s FROM %s WHERE %s IN (%s) %s</script>"),
    SELECT_ONE("selectOne", "查询满足条件一条数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_COUNT("selectCount", "查询满足条件总记录数", "<script>%s SELECT COUNT(%s) FROM %s %s %sn</script>"),
    SELECT_LIST("selectList", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_PAGE("selectPage", "查询满足条件所有数据（并翻页）", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_MAPS("selectMaps", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>"),
    SELECT_MAPS_PAGE("selectMapsPage", "查询满足条件所有数据（并翻页）", "<script>n %s SELECT %s FROM %s %s %sn</script>"),
    SELECT_OBJS("selectObjs", "查询满足条件所有数据", "<script>%s SELECT %s FROM %s %s %sn</script>");

    private final String method;
    private final String desc;
    private final String sql;

    SqlMethod(String method, String desc, String sql) {
        this.method = method;
        this.desc = desc;
        this.sql = sql;
    }

    public String getMethod() {
        return method;
    }

    public String getDesc() {
        return desc;
    }

    public String getSql() {
        return sql;
    }
}