程式碼較多，請耐心看完，一定能學會！！！
首先不使用註解方式把環境配置好：
1、目錄結構：
2、根據資料庫中的 user 表，寫一個 user 的實體類 （cn.henu.domain.User.java）
package cn.henu.domain;
import java.util.Date;
public class User {
private int id;
private String username;
private String password;
private Date birthday;
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", birthday=" + birthday +
'}';
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
}
3、寫一個持久層檔案，裡面定義一些運算元據庫的方法（cn.henu.mapper.UserMapper.java）
package cn.henu.mapper;
import cn.henu.domain.User;
import java.util.List;
public interface UserMapper {
//插入操作
public void save(User user);
//更新操作
public void update(User user);
//刪除操作
public void delete(int id);
//根據id查詢
public User findById(int id);
//查詢全部
public List<User> findAll();
}
4、寫一個對映檔案，裡面寫SQL語句（cn/henu/mapper/UserMapper.xml）
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.henu.mapper.UserMapper">
<insert id="save" parameterType="user">
insert into user values (#{id},#{username},#{password},#{birthday})
</insert>
<update id="update" parameterType="user">
update user set username = #{username},password = #{password} where id = #{id}
</update>
<delete id="delete" parameterType="int">
delete from user where id = #{id}
</delete>
<select id="findById" parameterType="int" resultType="user">
select * from user where id = #{id}
</select>
<select id="findAll" resultType="user">
select * from user
</select>
</mapper>
5、編寫 Spring 核心配置檔案（SqlMapConfig.xml）
<?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>
<!--通過properties標籤載入外部的properties檔案-->
<properties resource="jdbc.properties"></properties>
<!--自定義別名-->
<typeAliases>
<typeAlias type="cn.henu.domain.User" alias="user"></typeAlias>
</typeAliases>
<!--配置資料來源環境-->
<environments default="developement">
<environment id="developement">
<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>
<!--載入對映檔案-->
<mappers>
<mapper resource="cn/henu/mapper/UserMapper.xml"></mapper>
</mappers>
</configuration>
6、編寫一個測試類，來測試這些運算元據庫的方法（cn.henu.test.MybatisTest.java）
package cn.henu.test;
import cn.henu.domain.User;
import cn.henu.mapper.UserMapper;
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.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class MybatisTest {
private UserMapper mapper;
@Before
public void before() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
mapper = sqlSession.getMapper(UserMapper.class);
}
@Test//測試插入
public void testSave(){
User user = new User();
user.setUsername("tom");
user.setPassword("abc");
mapper.save(user);
}
@Test//測試更新
public void testUpdate(){
User user = new User();
user.setId(18);
user.setUsername("lucy");
user.setPassword("123");
mapper.update(user);
}
@Test//測試刪除
public void testDelete(){
mapper.delete(18);
}
@Test//測試根據id查詢使用者
public void testFindById(){
User user = mapper.findById(2);
System.out.println(user);
}
@Test//測試查詢全部使用者
public void testFindAll(){
List<User> all = mapper.findAll();
for (User user : all) {
System.out.println(user);
}
}
}
7、執行第6步的每一個Test方法，並且檢視資料庫中相應的表，都能正確執行，而且能夠成功運算元據庫。下面在此基礎上介紹註解方式
1、將對映檔案 UserMapper.xml 中的SQL語句全部使用註解的形式寫在 UserMapper.java 中（cn.henu.mapper.UserMapper.java）
package cn.henu.mapper;
import cn.henu.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface UserMapper {
//插入操作
@Insert("insert into user values (#{id},#{username},#{password},#{birthday})")
public void save(User user);
//更新操作
@Update("update user set username = #{username},password = #{password} where id = #{id}")
public void update(User user);
//刪除操作
@Delete("delete from user where id = #{id}")
public void delete(int id);
//根據id查詢
@Select("select * from user where id = #{id}")
public User findById(int id);
//查詢全部
@Select("select * from user")
public List<User> findAll();
}
2、修改 Spring 核心配置檔案（SqlMapConfig.xml）
<?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>
<!--通過properties標籤載入外部的properties檔案-->
<properties resource="jdbc.properties"></properties>
<!--自定義別名-->
<typeAliases>
<typeAlias type="cn.henu.domain.User" alias="user"></typeAlias>
</typeAliases>
<!--配置資料來源環境-->
<environments default="developement">
<environment id="developement">
<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>
<!--使用註解，載入下面的對映關係-->
<mappers>
<!--指定介面所在的包-->
<package name="cn.henu.mapper"/>
</mappers>
</configuration>
3、刪除對映檔案 UserMapper.xml（UserMapper.xml 已經沒用了）
4、執行上面第6步的測試類，依然能夠正確執行，並且能夠成功運算元據庫