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MyBatis注解(单表)

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1、MyBatis注解开发前的准备

1.1、MyBatis常用注解

@Insert:实现新增 @Update:实现更新 @Delete:实现删除 @Select:实现查询 @Result:实现结果集封装 @Results:可以与@Result 一起使用,封装多个结果集 @ResultMap:实现引用@Results 定义的封装 @One:实现一对一结果集封装 @Many:实现一对多结果集封装 @SelectProvider: 实现动态SQL映射 @CacheNamespace:实现注解二级缓存的使用

1.2、注解开发前的准备

1.2.1、创建项目

GroupId:com.tyschool
ArtifactId:mb005
Version:1.0-SNAPSHOT

1.2.2、编写pom.xml配置文件

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.tyschool</groupId> <artifactId>mb005</artifactId> <version>1.0-SNAPSHOT</version> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>1.9</maven.compiler.source> <maven.compiler.target>1.9</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.11</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies> </project>

1.2.3、编写SqlMapConfig.xml配置文件

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <properties resource="db.properties"></properties> <settings> <setting name="logImpl" value="STDOUT_LOGGING" /> </settings> <typeAliases> <package name="com.tyschool.mb005.javabean"/> </typeAliases> <environments default="mysql"> <environment id="mysql"> <transactionManager type="JDBC"></transactionManager> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}"/> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> </dataSource> </environment> </environments> </configuration>

数据源文件db.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.1.123:3306/mybatis?serverTimezone=UTC
jdbc.username=root
jdbc.password=Root12345

2、完成单表的CRUD

2.1、需求介绍

完成学生表的CRUD

2.2、编写Students.java文件

import java.io.Serializable; public class Students implements Serializable { private int sid; private String sname; private String ssex; private int sage; private int cid; public int getSid() { return sid; } public void setSid(int sid) { this.sid = sid; } public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } public String getSsex() { return ssex; } public void setSsex(String ssex) { this.ssex = ssex; } public int getSage() { return sage; } public void setSage(int sage) { this.sage = sage; } public int getCid() { return cid; } public void setCid(int cid) { this.cid = cid; } @Override public String toString() { return "Students{" + "sid=" + sid + ", sname='" + sname + '\'' + ", ssex='" + ssex + '\'' + ", sage=" + sage + ", cid=" + cid + '}'; } }

2.3、编写IStudentsDao.java文件

import java.util.List; import com.tianyi.javabean.Students; public interface IStudentsDao { List<Students> findAll(); Students findById(int sid); int addStudents(Students students); int updateStudents(Students students); int deleteStudents(int sid); int addCount(); List<Students> findByName(String name); }

配置映射

<mappers> <package name="com.tyschool.mb005.students.dao"/> </mappers>

2.4、创建测试类MbStudentsTest.java

package com.tianyi.test; import com.tianyi.dao.IStudentsDao; 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 org.junit.After; import org.junit.Before; import java.io.IOException; import java.io.InputStream; public class MbStudentsTest { private InputStream in; private SqlSession session; private IStudentsDao studentsDao; @Before public void init()throws IOException { in= Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder(); SqlSessionFactory factory=builder.build(in); session=factory.openSession(true); studentsDao=session.getMapper(IStudentsDao.class); } @After public void destroy() throws IOException { //session.commit(); session.close(); in.close(); } }

3、CRUD操作-上

3.1、查询所有学生信息

3.1.1、修改findAll()方法

@Select("select * from students") @Results(id="studentsMap",value={ @Result(id=true,column = "sid",property = "sid"), @Result(column = "sname",property = "sname"), @Result(column = "ssex",property = "ssex"), @Result(column = "sage",property = "sage") }) List<Students> findAll();

3.3.2、编写测试方法

@Test public void findAll(){ List<Students> list=studentsDao.findAll(); for (Students s:list) { System.out.println(s); } }

3.2、根据ID查询学生信息

3.2.1、修改findByID()方法

@Select("select * from students where sid=#{sid}") @ResultMap("studentsMap") Students findById(int sid);

3.2.2、编写测试方法

@Test public void findById(){ Students s=studentsDao.findById(3); System.out.println(s); }

3.3、增加学生的记录

3.3.1、修改addStudents()方法

@Insert("insert into students(sname,ssex,sage)values(#{sname},#{ssex},#{sage})") @SelectKey(keyColumn = "sid",keyProperty="sid",resultType = Integer.class,before = false,statement = {"select last_insert_id()"}) int addStudents(Students students);

3.3.2、编写测试方法

@Test public void addStudents(){ Students s=new Students(); s.setSname("张九"); s.setSsex("男"); s.setSage(19); studentsDao.addStudents(s); }

4、CRUD操作-下

4.1、修改学生的信息

4.1.1、修改updateStudents()方法

@Update("update students set sname=#{sname},ssex=#{ssex},sage=#{sage} where sid=#{sid}") int updateStudents(Students students);

4.1.2、编写测试方法

@Test public void updateStudents(){ Students s=studentsDao.findById(2); s.setSname("李好"); studentsDao.updateStudents(s); }

4.2、删除指定ID的学生信息

4.2.1、修改deleteStudents()方法

@Delete("delete from students where sid=#{sid}") int deleteStudents(int sid);

4.2.2、编写测试方法

@Test public void deleteStudents(){ studentsDao.deleteStudents(9); }

5、统计与模糊查询

5.1、查询学生表中所有记录

5.1.1、修改addCount()方法

@Select("select count(*) from students") int addCount();

5.1.2、编写测试方法

@Test public void addCount(){ int n=studentsDao.addCount(); System.out.println(n); }

5.2、通过学生姓名模糊查询学生信息

5.2.1、修改findByName()方法

@Select("select * from students where sname like #{sname}") List<Students> findByName(String sname);

5.2.2、编写测试方法

@Test public void findByName(){ List<Students> list =studentsDao.findByName("李%"); for(Students s:list){ System.out.println(s); } }
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