IService接口和ServiceImpl实现类（Mybatis-Plus对service层的封装）
短信预约 -IT技能 免费直播动态提醒
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 {} @Servicepublic class UserServiceImpl extends ServiceImpl implements UserService {} 3.2.1、新增
-
新增一条记录
@Resourceprivate UserService userService;@Testpublic 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);}![image-20230306113912564]()
-
批量操作
@Resourceprivate UserService userService;@Testpublic void testServcie(){ Listusers = 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);} ![image-20230306114731705]()
-
设置批次数量
public void testServcie(){ Listusers = 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);} ![image-20230306114954565]()
3.2.2、查询
1、单行查询
-
根据id查询
@Testpublic void testServcie(){ User user = userService.getById(1); System.out.println(user);}![image-20230306124359229]()
2、多行查询
-
根据ID批量查询
@Testpublic void testServcie(){ Listlist = Arrays.asList(1, 2, 3); List users = userService.listByIds(list); users.forEach(System.out::println);} ![image-20230306124647126]()
-
查询所有
@Testpublic void testServcie(){ //返回list Listlist = userService.list(); System.out.println(list); //返回map List ![image-20230306125554522]()
3.2.3、删除
-
根据id删除
@Testpublic void testServcie(){ boolean b = userService.removeById(21);}![image-20230306120252382]()
-
根据实体的id删除
@Testpublic void testServcie(){ User user = userService.getById(22); boolean b = userService.removeById(user);}![image-20230306120455791]()
-
批量删除
@Testpublic void testServcie(){ Listlist = Arrays.asList(23, 24, 25); boolean b = userService.removeByIds(list);} ![image-20230306120634151]()
-
根据Map条件删除
@Testpublic void testServcie(){ Mapmap = new HashMap<>(); map.put("username","批量增加5"); map.put("password","123"); boolean b = userService.removeByMap(map);} ![image-20230306120900709]()
3.2.4、修改
-
根据ID修改
@Testpublic void testServcie(){ User user = userService.getById(27); user.setUsername("修改1"); user.setPassword("213123"); boolean b = userService.updateById(user);}![image-20230306121740680]()
-
批量修改
@Testpublic void testServcie(){ Listlist = Arrays.asList(28, 29, 30); List users = userService.listByIds(list); users.forEach(user -> { user.setUsername("批量修改"); }); boolean b = userService.updateBatchById(users);} ![image-20230306122251212]()
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 implements IPage { private static final long serialVersionUID = 8545996863226528798L; //用来存放查询出来的数据 protected List 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 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() { } 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
-
分页查询数据
@Testpublic void testServcie(){ Pagepage = userService.page(new Page<>(1,5)); System.out.println("总数据："+page.getTotal()); List users = page.getRecords(); users.forEach(System.out::println);} ![image-20230306133721050]()
3.2.7、查询记录数
@Testpublic void testServcie(){ long count = userService.count(); System.out.println(count);}
来源地址：https://blog.csdn.net/yuandfeng/article/details/129660661
免责声明：
① 本站未注明“稿件来源”的信息均来自网络整理。其文字、图片和音视频稿件的所属权归原作者所有。本站收集整理出于非商业性的教育和科研之目的，并不意味着本站赞同其观点或证实其内容的真实性。仅作为临时的测试数据，供内部测试之用。本站并未授权任何人以任何方式主动获取本站任何信息。
② 本站未注明“稿件来源”的临时测试数据将在测试完成后最终做删除处理。有问题或投稿请发送至: 邮箱/279061341@qq.com QQ/279061341
