java——mybatis——Mybatis註解開發——@Select查詢——查詢所有條數
阿新 • • 發佈:2022-12-04
DAO介面:
package com.sunxl.dao; import com.sunxl.pojo.User; import org.apache.ibatis.annotations.*; import java.util.List; public interface UserDao { @Select("select * from users") List<User> findAll(); @Insert("insert into users (name,age) values(#{name},#{age})") @SelectKey(statement= "select last_insert_id()", keyProperty = "id", keyColumn = "id", resultType = int.class ,before = false) int saveUser(User user); @Update("update users set name = #{name},age = #{age} where id = #{id}") int updateUser(User user); @Delete("delete from users where id = #{id}")int deleteUser(Integer id); @Select("select count(*) from users") int findTotal(); // // User findById(Integer id); // // List<User> findByName(String name); }
測試執行:
import com.sunxl.dao.UserDao; import com.sunxl.pojo.User; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.IOException; import java.io.InputStream; import java.util.List; public class MybatisTest { public static void main(String[] args) throws IOException { // InputStream config = Resources.getResourceAsStream("mybatis-config.xml"); // // SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); // SqlSessionFactory factory = builder.build(config); // SqlSession ss = factory.openSession(); // UserDao userdao = ss.getMapper(UserDao.class); // // // List<User> users = userdao.findAll(); // // for (User user: users){ // System.out.println(user); // } // // // ss.commit(); // ss.close(); // config.close(); InputStream config = Resources.getResourceAsStream("mybatis-config.xml"); SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); SqlSessionFactory factory = builder.build(config); SqlSession ss = factory.openSession(); UserDao userdao = ss.getMapper(UserDao.class); int a = userdao.findTotal(); System.out.println(a); ss.commit(); ss.close(); config.close(); } }
PS:因為之前刪除了第一條記錄。故總數只有1004條