Java知识点总结：想看的可以从这里进入
3.2、IService接口
BaseMapper 是用在Mapper中，而IService是在Service层使用的封装接口，它进一步封装 CRUD 。为了和BaseMapper 中方法进行区分，它采用了不同的前缀：
- get 查询单行
- remove 删除
- list 查询集合
- page 分页
- save新增
- update修改
IService还有一个实现的类ServiceImpl，在使用使用时分别对应service接口和impl实现类。
public interface UserService extends IService<User> {
}
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}
3.2.1、新增
-
新增一条记录
@Resource private UserService userService; @Test public void testServcie(){ User user = new User(); user.setUsername("service增加"); user.setPassword("12321"); boolean save = userService.save(user); System.out.println("是否成功："+save); } -
批量操作
@Resource private UserService userService; @Test public void testServcie(){ List<User> users = new ArrayList<>(); User user1 = new User("批量增加1","123"); users.add(user1); User user2 = new User("批量增加2","123"); users.add(user2); User user3 = new User("批量增加3","123"); users.add(user3); User user4 = new User("批量增加4","123"); users.add(user4); User user5 = new User("批量增加5","123"); users.add(user5); boolean save = userService.saveBatch(users); System.out.println("是否成功："+save); } -
设置批次数量
public void testServcie(){ List<User> users = new ArrayList<>(); User user1 = new User("指定数量批量增加6","123"); users.add(user1); User user2 = new User("指定数量批量增加7","123"); users.add(user2); User user3 = new User("指定数量批量增加8","123"); users.add(user3); User user4 = new User("指定数量批量增加9","123"); users.add(user4); User user5 = new User("指定数量批量增加10","123"); users.add(user5); boolean save = userService.saveBatch(users,2); System.out.println("是否成功："+save); }
3.2.2、查询
1、单行查询
-
根据id查询
@Test public void testServcie(){ User user = userService.getById(1); System.out.println(user); }
2、多行查询
-
根据ID批量查询
@Test public void testServcie(){ List<Integer> list = Arrays.asList(1, 2, 3); List<User> users = userService.listByIds(list); users.forEach(System.out::println); }
-
查询所有
@Test public void testServcie(){ //返回list List<User> list = userService.list(); System.out.println(list); //返回map List<Map<String, Object>> maps = userService.listMaps(); System.out.println(maps); List<Object> objects = userService.listObjs(); System.out.println(objects); }
3.2.3、删除
-
根据id删除
@Test public void testServcie(){ boolean b = userService.removeById(21); } -
根据实体的id删除
@Test public void testServcie(){ User user = userService.getById(22); boolean b = userService.removeById(user); } -
批量删除
@Test public void testServcie(){ List<Integer> list = Arrays.asList(23, 24, 25); boolean b = userService.removeByIds(list); } -
根据Map条件删除
@Test public void testServcie(){ Map<String ,Object> map = new HashMap<>(); map.put("username","批量增加5"); map.put("password","123"); boolean b = userService.removeByMap(map); }
3.2.4、修改
-
根据ID修改
@Test public void testServcie(){ User user = userService.getById(27); user.setUsername("修改1"); user.setPassword("213123"); boolean b = userService.updateById(user); } -
批量修改
@Test public void testServcie(){ List<Integer> list = Arrays.asList(28, 29, 30); List<User> users = userService.listByIds(list); users.forEach(user -> { user.setUsername("批量修改"); }); boolean b = userService.updateBatchById(users); }
3.2.5、修改或更新
3.2.6、分页
在Mybatis-plus中提供了有关分页的接口和实现类 IPage 和 Page
public class Page<T> implements IPage<T> {
private static final long serialVersionUID = 8545996863226528798L;
//用来存放查询出来的数据
protected List<T> records = Collections.emptyList();
//返回的数据总数
protected long total = 0;
// 每页显示条数，默认 10
protected long size = 10;
//当前页，默认1
protected long current = 1;
// 排序字段信息
@Setter
protected List<OrderItem> orders = new ArrayList<>();
//自动优化 COUNT SQL
protected boolean optimizeCountSql = true;
// 是否进行 count 查询
protected boolean searchCount = true;
public Page() {
}
/**
* 有参构造函数
* @param current 当前页
* @param size 每页显示条数
*/
public Page(long current, long size) {
this(current, size, 0);
}
public Page(long current, long size, long total) {
this(current, size, total, true);
}
public Page(long current, long size, boolean searchCount) {
this(current, size, 0, searchCount);
}
public Page(long current, long size, long total, boolean searchCount) {
if (current > 1) {
this.current = current;
}
this.size = size;
this.total = total;
this.searchCount = searchCount;
}
//是否存在上一页
public boolean hasPrevious() {
return this.current > 1;
}
//是否存在下一页
public boolean hasNext() {
return this.current < this.getPages();
}
..........
}
-
配置
-
使用Spring时，在Spring的配置文件中先配置mybatis-plus内置的分页插件
<!-- 配置mybatis-plus的分页拦截器--> <bean id="paginationInnerInterceptor" class="com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor"/> <!-- 配置mybatis-plus的分页拦截器插件 --> <bean id="mybatisPlusInterceptor" class="com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor"> <property name="interceptors" > <list> <ref bean="paginationInnerInterceptor"/> </list> </property> </bean> <!-- 将插件加入到MybatisSqlSessionFactoryBean 中--> <bean class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean"> <!--加载连接池--> <property name="dataSource" ref="dataSource"/> <!-- 设置MyBatis配置文件的路径（可以不设置） --> <property name="configLocation" value="classpath:mybatis-config.xml"/> <!--加载映射文件路径--> <property name="mapperLocations" value="classpath:mapping/*.xml"/> <!--分页插件生效 --> <property name="plugins"> <array> <ref bean="mybatisPlusInterceptor"/> </array> </property> </bean> -
使用SpringBoot时配置时，在配置类中配置
@Bean public MybatisPlusInterceptor mybatisPlusInterceptor() { MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor(); interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL)); return interceptor; }
-
-
分页查询数据
@Test public void testServcie(){ Page<User> page = userService.page(new Page<>(1,5)); System.out.println("总数据："+page.getTotal()); List<User> users = page.getRecords(); users.forEach(System.out::println); }
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3.2.7、查询记录数
@Test
public void testServcie(){
long count = userService.count();
System.out.println(count);
}
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