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今天小编给大家分享一下MyBatisPlus查询对象怎么转QueryWrapper工具类的相关知识点，内容详细，逻辑清晰，相信大部分人都还太了解这方面的知识，所以分享这篇文章给大家参考一下，希望大家阅读完这篇文章后有所收获，下面我们一起来了解一下吧。
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在使用MyBatisPlus技术实际项目中，尤其是后台管理系统之类的项目中，经常会出现大量的需要将查询对象转换成QueryWrapper的应用场景，这时候就需要编写出现大量的转换代码，比如：
@Getter
@Setter
@ToString(callSuper = true)
public class MemberQuery extends BaseQuery {
/**
* 昵称
*/
private String nickname;
/**
* 性别：1女 2男 3未知
*/
private Integer gender;
/**
* 生日：下限
*/
private LocalDate start;
/**
* 生日：上限
*/
private LocalDate end;
/**
* 电话
*/
private String tel;
/**
* 外键：角色编号
*/
private Long roleId;
/**
* 状态：1未激活 2激活
*/
private Integer state;
@Builder
public MemberQuery(Integer pageNum, Integer pageSize, String nickname, Integer gender, LocalDate start, LocalDate end, String tel, Long roleId, Integer state) {
super(pageNum, pageSize);
this.nickname = nickname;
this.gender = gender;
this.start = start;
this.end = end;
this.tel = tel;
this.roleId = roleId;
this.state = state;
}
}上面查询类引用的BaseQuery封装了分页信息，具体代码如下：
@Setter
@ToString
@AllArgsConstructor
public class BaseQuery {
/**
* 页码
*/
private Integer pageNum;
/**
* 页面大小
*/
private Integer pageSize;
public Integer getPageNum() {
return pageNum == null ? 1 : pageNum;
}
public Integer getPageSize() {
return pageSize == null ? GlobalConst.PAGE_SIZE : pageSize;
}
}@PostMapping("/list")
public ResultBean list(@RequestBody MemberQuery memberQuery) {
IPage page = new Page<>(memberQuery.getPageNum(), memberQuery.getPageSize());
LambdaQueryWrapper queryWrapper = new LambdaQueryWrapper<>();
if (memberQuery.getNickname() != null) {
queryWrapper.like(Member::getNickname, memberQuery.getNickname());
}
if (memberQuery.getTel() != null) {
queryWrapper.like(Member::getTel, memberQuery.getTel());
}
if (memberQuery.getGender() != null) {
queryWrapper.eq(Member::getGender, memberQuery.getGender());
}
if (memberQuery.getRoleId() != null) {
queryWrapper.eq(Member::getRoleId, memberQuery.getRoleId());
}
if (memberQuery.getState() != null) {
queryWrapper.eq(Member::getState, memberQuery.getState());
}
if (memberQuery.getStart() != null) {
queryWrapper.ge(Member::getBirth,memberQuery.getStart());
}
if(memberQuery.getEnd() != null){
queryWrapper.le(Member::getBirth,memberQuery.getEnd());
}
memberService.page(page, queryWrapper);
PageBean pageBean = PageBean.init(page);
return ResultBeanUtil.success().buildData("pageBean",pageBean);
} 上面大量的转换代码，不仅写起来烦琐，而且也不优雅。此时可以采用注解+反射技术编写一个工具类：将Query对象转换成Wrapper，具体代码如下：
public interface Logic {
String and = "AND";
String or = "OR";
}Between
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Between {
String logic() default Logic.and;
}EQ
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface EQ {
String logic() default Logic.and;
String value() default "";
}IN
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface IN {
String logic() default Logic.and;
String value() default "";
}Like
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Like {
String logic() default "AND";
String value() default "";
}NE
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface NE {
String logic() default Logic.and;
String value() default "";
}@Getter @Setter @NoArgsConstructor @AllArgsConstructor public class RangeBean{ /** * 下限 */ private T start; /** * 上限 */ private T end; }
public class QueryWrapperUtil{ /** * 将查询对象转换成MyBatisPlus中的QueryWrapper * @param query * @param * @return */ public static QueryWrapper build(Object query) { QueryWrapper queryWrapper = new QueryWrapper<>(); //获取Query类中都有哪些属性 final Field[] fields = query.getClass().getDeclaredFields(); for (Field field : fields) { field.setAccessible(true); java.lang.Object fieldValue = null; try { fieldValue = field.get(query); } catch (IllegalAccessException e) { e.printStackTrace(); } if (fieldValue != null) { //获取Query类属性上的注解 final Annotation[] annotations = field.getAnnotations(); for (Annotation annotation : annotations) { //获取Query类属性的名称 final String fieldName = field.getName(); //获取Query类对应的表字段名 final String columnName = StringUtil.hump2underscore(fieldName); //获取Query类属性上的注解类型的字节码 final Class annotationType = annotation.annotationType(); if (EQ.class == annotationType) { EQ eq = (EQ) annotation; fun(eq.logic(), queryWrapper); queryWrapper.eq(columnName, fieldValue); } else if (Like.class == annotationType) { Like like = (Like) annotation; fun(like.logic(), queryWrapper); queryWrapper.like(columnName, fieldValue); } else if (IN.class == annotationType) { IN in = (IN) annotation; fun(in.logic(), queryWrapper); queryWrapper.in(columnName, fieldValue); } else if (NE.class == annotationType) { NE ne = (NE) annotation; fun(ne.logic(), queryWrapper); queryWrapper.ne(columnName, fieldValue); } else if (Between.class == annotationType) { Between between = (Between) annotation; fun(between.logic(), queryWrapper); RangeBean rangeBean = (RangeBean) fieldValue; queryWrapper.between(columnName, rangeBean.getStart(), rangeBean.getEnd()); } } } } return queryWrapper; } /** * 添加or关系 * @param logic * @param queryWrapper * @param */ private static void fun(String logic, QueryWrapper queryWrapper) { if ("or".equalsIgnoreCase(logic)) { queryWrapper.or(); } } }
@PostMapping("/list")
public ResultBean list(@RequestBody MemberQuery memberQuery) {
IPage page = new Page<>(memberQuery.getPageNum(), memberQuery.getPageSize());
QueryWrapper queryWrapper = QueryWrapperUtil.build(memberQuery);
memberService.page(page, queryWrapper);
PageBean pageBean = PageBean.init(page);
return ResultBeanUtil.success().addData("pageBean",pageBean);
} 以上就是“MyBatisPlus查询对象怎么转QueryWrapper工具类”这篇文章的所有内容，感谢各位的阅读！相信大家阅读完这篇文章都有很大的收获，小编每天都会为大家更新不同的知识，如果还想学习更多的知识，请关注创新互联行业资讯频道。
