mybatis-plus简称MP是一个 Mybatis 的增强工具，在 Mybatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
这是官方给的定义，关于mybatis-plus的更多介绍及特性，可以参考mybatis-plus官网 。那么它是怎么增强的呢？其实就是它已经封装好了一些crud方法，我们不需要再写xml了，直接调用这些方法就行，就类似于JPA。
下面是在MP为基础封装了一个查询类，实现了如果需要增加查询条件只需在前端修改即可。
- SearchModel
public class SearchModel<T> {
private Integer pageIndex;
private Integer pageSize;
private List<Field> fields;
private String orderField;
private boolean isAsc;
public IPage<T> getPage() {
IPage<T> page = new Page<>(pageIndex, pageSize);
if (!StringUtil.isEmptyOrNull(orderField)) {
OrderItem orderItem = new OrderItem();
orderItem.setAsc(isAsc);
orderItem.setColumn(orderField);
page.orders().add(orderItem);
}
return page;
}
public QueryWrapper<T> getQueryModel() {
QueryWrapper<T> queryWrapper = new QueryWrapper<>();
for (Iterator iter = this.fields.iterator(); iter.hasNext(); ) {
Field field = (Field) iter.next();
switch (field.getQueryMethod()) {
case eq:
queryWrapper.eq(true, field.getName(), field.getValue());
break;
case like:
queryWrapper.like(true, field.getName(), field.getValue());
}
}
if (!StringUtil.isEmptyOrNull(orderField)) {
queryWrapper.orderBy(true, isAsc, orderField);
}
return queryWrapper;
}
}- Field
public class Field {
public Field(String name, Object value) {
this.name = name;
this.value = value;
this.queryMethod = QueryMethod.eq;
}
public Field(String name, Object value, QueryMethod queryMethod) {
this.name = name;
this.value = value;
this.queryMethod = queryMethod;
}
private String name;
private Object value;
private QueryMethod queryMethod;
}- QueryMethod
public enum QueryMethod {
eq, like
} {
"fields": [
{
"value": "v",
"name": "project_code",
"queryMethod": "eq"
},
{
"name": "type",
"queryMethod": "like",
"value": "b"
},
{
"name": "id",
"queryMethod": "like",
"value": "a"
}
],
"pageIndex": 1,
"pageSize": 8,
"orderField": "type",
"isAsc": "false"
}在api中传入上面的json对象即可完成一个查询服务,查询条件通过前端传入的字段控制
- IBaseService
public interface IBaseService<T> {
T save(T entity) throws Exception;
boolean saveBatch(Collection<T> entityList);
// TableId 注解存在更新记录，否插入一条记录
boolean saveOrUpdate(T entity);
// 根据updateWrapper尝试更新，否继续执行saveOrUpdate(T)方法
boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper);
// 批量修改插入
boolean saveOrUpdateBatch(Collection<T> entityList);
// 根据 entity 条件，删除记录
boolean remove(Wrapper<T> queryWrapper);
// 根据 ID 删除
boolean removeById(Serializable id);
// 根据 columnMap 条件，删除记录
boolean removeByMap(Map<String, Object> columnMap);
// 删除（根据ID 批量删除）
boolean removeByIds(Collection<? extends Serializable> idList);
List<T> list();
// 查询列表
List<T> list(SearchModel<T> searchModel);
// 查询（根据ID 批量查询）
Collection<T> listByIds(Collection<? extends Serializable> idList);
// 查询（根据 columnMap 条件）
Collection<T> listByMap(Map<String, Object> columnMap);
// 翻页查询
IPage<T> page(SearchModel<T> searchModel);
T selectById(Serializable id);
T selectOne(Wrapper<T> queryWrapper);
}- BaseServiceImpl
public class BaseServiceImpl<M extends BaseMapper<T>, T> implements IBaseService<T> {
@Autowired
private M baseMapper;
@Override
public T save(T entity) throws Exception {
baseMapper.insert(entity);
return entity;
}
@Transactional(rollbackFor = RuntimeException.class)
@Override
public boolean saveBatch(Collection<T> entityList) {
Integer size = entityList.size();
for (T entity : entityList) {
baseMapper.insert(entity);
size++;
}
return size == entityList.size();
}
@Override
public boolean saveOrUpdate(T entity) {
int rs = baseMapper.updateById(entity);
if (rs > 0) return true;
return baseMapper.insert(entity) > 0;
}
@Override
public boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper) {
return false;
}
@Transactional(rollbackFor = RuntimeException.class)
@Override
public boolean saveOrUpdateBatch(Collection<T> entityList) {
for (T entity : entityList) {
saveOrUpdate(entity);
}
return true;
}
@Override
public boolean remove(Wrapper<T> queryWrapper) {
return baseMapper.delete(queryWrapper) > 0;
}
@Override
public boolean removeById(Serializable id) {
return baseMapper.deleteById(id) > 0;
}
@Override
public boolean removeByMap(Map<String, Object> columnMap) {
return baseMapper.deleteByMap(columnMap) > 0;
}
@Override
public boolean removeByIds(Collection<? extends Serializable> idList) {
return baseMapper.deleteBatchIds(idList) > 0;
}
@Override
public List<T> list() {
return baseMapper.selectList(new QueryWrapper<T>());
}
@Override
public List<T> list(SearchModel<T> searchModel) {
return baseMapper.selectList(searchModel.getQueryModel());
}
@Override
public Collection<T> listByIds(Collection<? extends Serializable> idList) {
return baseMapper.selectBatchIds(idList);
}
@Override
public Collection<T> listByMap(Map<String, Object> columnMap) {
return baseMapper.selectByMap(columnMap);
}
@Override
public IPage<T> page(SearchModel<T> searchModel) {
return baseMapper.selectPage(searchModel.getPage(), searchModel.getQueryModel());
}
@Override
public T selectById(Serializable id) {
return baseMapper.selectById(id);
}
@Override
public T selectOne(Wrapper<T> queryWrapper) {
return baseMapper.selectOne(queryWrapper);
}
}MP实现了mapper层基础的CRUD方法，这里把一些常用的service层的方法整理了一下，又减少了一些代码量
- Maven
<!-- https://mvnrepository.com/artifact/com.github.codeinghelper/mp-plus -->
<dependency>
<groupId>com.github.codeinghelper</groupId>
<artifactId>mp-plus</artifactId>
<version>0.0.1</version>
</dependency>
- Gradle
// https://mvnrepository.com/artifact/com.github.codeinghelper/mp-plus
compile group: 'com.github.codeinghelper', name: 'mp-plus', version: '0.0.1'
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