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0.单表+@Fetch 注解 + fetchFilter 方法

 @Data @ResultEntity(SysUser.class) public class SysUserVo {      private Integer id;      private String userName;      private String password;      private Integer roleId;      private LocalDateTime create_time;      @Fetch(source = SysUser.class, property = "roleId", target = SysRole.class, targetProperty = "id")     private List<SysRoleVo> sysRoles;  }

 List<SysUserVO> list = QueryChain.of(sysUserMapper)         .from(SysUser.class)         .fetchFilter(SysUserVO::getRoles,where->where.eq(SysRole::getStatus,1))         .returnType(SysUserVO.class)         .list();

fetchFilter方法是对@Fetch注解的增强，没有特殊要求一般，可忽略

1. 单表查询

 SysUser sysUser = QueryChain.of(sysUserMapper)         .eq(SysUser::getId, 1)         .eq(SysUser::getUserName,'admin')         .get();

2.VO 映射

 @Data @ResultEntity(SysUser.class) public class SysUserVo {      private Integer id;      private String userName;      //字段名字不一样时     @ResultEntityField(property = "password")     private String pwd;  }

 SysUserVO sysUserVO = QueryChain.of(sysUserMapper)         .eq(SysUser::getId, 1)         .eq(SysUser::getUserName,'admin')         .returnType(SysUserVO.class)         .list();

3. join 查询

 @Data @ResultEntity(SysUser.class) public class SysUserVo {      private Integer id;      private String userName;      //字段名字不一样时     @ResultEntityField(property = "password")     private String pwd;          //映射一个对象 1对1     @NestedResultEntity(target = SysRole.class)     prviate SysRole sysRole;          //映射多个对象 1对多     @NestedResultEntity(target = SysRole.class)     prviate List<SysRole> sysRoles;  }

 List<SysUserRoleVO> list = QueryChain.of(sysUserMapper)         .from(SysUser.class)         .join(SysUser.class, SysRole.class)         .returnType(SysUserRoleVO.class)         .list();