Mybatis(一)、mybatis环境搭建以及实体类及其配置

一、基础框架搭建

1、引入mybatisjar包

2、加载configuration配置文件，命名resource.xml

resource.xml配置文件代码展示

<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeAliases><!--指定使用到的数据类型别名 -->
<typeAlias alias="string" type="java.lang.String" />
<typeAlias alias="list" type="java.util.List" />
<typeAlias alias="student" type="com.lattice.student.entity.StudentEntity" />
<typeAlias alias="teacher" type="com.lattice.teacher.entity.TeacherEntity" />
</typeAliases>

<environments default="development"><!--配置数据库连接 -->
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatic?characterEncoding=utf-8" />
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>

<mappers><!--加载实体类配置文件 -->
<mapper resource="com/lattice/student/entity/StudentEntity.xml"/>
<mapper resource="com/lattice/teacher/entity/TeacherEntity.xml"/>

</mappers>

</configuration>

二、将配置文件加载到项目中

1、选中项目，右键，点properties，再选java buildPath  then  add folder。

2、加载jar包，右键，点properties，再选java buildPath  libraries  then  add external jars 。

三、创建实体类及实体类配置

1、根据数据库中对应的表，创建StudentEntity.java,及StudentEntity.xml

public class StudentEntity implements Serializable {

private static final long serialVersionUID = 1L;
private String s_id;
private String s_name;
private int s_age;
private String s_loginName;
private String s_passWord;
private TeacherEntity teacherEntity;
public String getS_id() {
return s_id;
}
public void setS_id(String s_id) {
this.s_id = s_id;
}
public String getS_name() {
return s_name;
}
public void setS_name(String s_name) {
this.s_name = s_name;
}
public int getS_age() {
return s_age;
}
public void setS_age(int s_age) {
this.s_age = s_age;
}
public String getS_loginName() {
return s_loginName;
}
public void setS_loginName(String s_loginName) {
this.s_loginName = s_loginName;
}
public String getS_passWord() {
return s_passWord;
}
public void setS_passWord(String s_passWord) {
this.s_passWord = s_passWord;
}
public TeacherEntity getTeacherEntity() {
return teacherEntity;
}
public void setTeacherEntity(TeacherEntity teacherEntity) {
this.teacherEntity = teacherEntity;
}
@Override
public String toString() {
return "StudentEntity [s_id=" + s_id + ", s_name=" + s_name
+ ", s_age=" + s_age + ", s_loginName=" + s_loginName
+ ", s_passWord=" + s_passWord + ", teacher="
+ teacherEntity.getT_name() + "]";
}

}
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="student">
<!--表示结果集,id表示结果集名称  type表示结果集的类型  这里的student表示别名 可以使用别名也可以使用类地址  -->
<resultMap id="student" type="student" >
<id property="s_id" column="s_id" /><!-- 主键 -->
<result property="s_name" column="s_name" /><!-- 其他列名 -->
<result property="s_age" column="s_age" /><!-- 其他列名 -->
<result property="s_loginName" column="s_loginName" /><!-- 其他列名 -->
<result property="s_passWord" column="s_passWord" /><!-- 其他列名 -->
<association property="teacherEntity" column="t_id" select="teacher.selectTeacher"></association>
</resultMap>

<!--通过老师T_id查询队形的学生，来为教师实体类的学生对象列表的赋值，以此完成在查询到这个教师对应的所有学生-->

<select id="selectStudentByT_id" resultMap="student" parameterType="string">
select * from student where t_id=#{t_id}
</select>
</mapper>

2、创键TeacherEntity.java及TeacherEntity.xml

public class TeacherEntity {
private String t_id;
private String t_name;
private String t_age;
private List studentEntityList;//配置与student表的一对多的级联关系
public String getT_id() {
return t_id;
}
public void setT_id(String t_id) {
this.t_id = t_id;
}
public String getT_name() {
return t_name;
}
public void setT_name(String t_name) {
this.t_name = t_name;
}
public String getT_age() {
return t_age;
}
public void setT_age(String t_age) {
this.t_age = t_age;
}
public List getStudentEntityList() {
return studentEntityList;
}
public void setStudentEntityList(List studentEntityList) {
this.studentEntityList = studentEntityList;
}

}

<!-- TeacherEntity.xml -->
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="teacher">
<!--表示结果集,id表示结果集名称  type表示结果集的类型  这里的student表示别名 可以使用别名也可以使用类地址  -->
<resultMap id="teacher" type="teacher" >
<id property="t_id" column="t_id" /><!-- 主键 -->
<result property="t_name" column="t_name" /><!-- 其他列名 -->
<result property="t_age" column="t_age" /><!-- 其他列名 -->
<collection property="studentEntityList" column="t_id" select="student.selectStudentByT_id"></collection>
</resultMap>

<select id="selectTeacher" resultMap="teacher" parameterType="string">
select * from teacher where t_id=#{t_id}
</select>
</mapper>