mybatis入门（二）--简单入门例子

king71

　　下面介绍一个最基本的Mybatis入门程序(java project ---oracle数据库)。
　　      1.首先在数据库中创建表create table t_user(id number(11),username varchar2(20));
　　 
　　      2.Eclipse---New--JavaProject,导入相关jar包。（自己测试，随便建了个javaproject工程）

　　      在src下面分别添加vo、maps、dao以及util包。
　　 
　　      3.在根目录下建立文件mybatis.cfg.xml,当然名称可以随便自定义，具体内容如下：
　　

<?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>
<!-- 引入外部文件 -->
<properties resource="config.properties"></properties>
<!-- end properties -->
<typeAliases>
<typeAlias alias="User" type="com.mybatis.test.vo.User" />
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${driver}" />
<property name="url" value="${url}" />
<property name="username" value="${username}" />
<property name="password" value="${password}" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/mybatis/test/maps/User.xml" />
</mappers>
</configuration>
　　上面代码段中出现

<!-- 引入外部文件 -->
<properties resource="config.properties"></properties>
<!-- end properties --
　　在根目录下新建文件config.properties,具体内容如下：

driver=oracle.jdbc.driver.OracleDriver
url=jdbc:oracle:thin:@10.45.218.152:1431:SZSTAGE
username=root
password=root
　　4.在vo包下面新建使实体类User.java,具体内容如下：

package com.mybatis.test.vo;
public class User {
private int id;
private String userName;
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;
}
@Override
public String toString()
{return "id is:"+id+" name is: "+ userName;}
}
　　5.在maps包下新建xml文件User.xml,具体代码如下：

<?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="User">
<select id="selectUser" parameterType="int" resultType="User">
select * from t_user where id = #{id}
</select>
<select id="selectAllUser" resultType="User">
select id, username from t_user
</select>
<insert id="insertUser" parameterType="User">
insert into t_user(id,username) values (#{id}, #{userName})
</insert>
</mapper>
　　6.在util包中新建辅助类DBUtil,具体内容如下：

package com.mybatis.test.util;
import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class DBUtil {
private static String resource = "mybatis.cfg.xml";
private static Reader reader;
private static SqlSessionFactory sqlSessionFactory;
public static SqlSessionFactory getSqlSessionFactory()
{
try {
reader = Resources.getResourceAsReader(resource);
} catch (IOException e) {
System.out.println("IO异常");}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
return sqlSessionFactory;
}
}
　　7.在dao包中新建类UserDAO，具体代码如下：

package com.mybatis.test.dao;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.mybatis.test.util.DBUtil;
import com.mybatis.test.vo.User;
public class UserDAO {
private static SqlSessionFactory sqlSessionFactory = DBUtil
.getSqlSessionFactory();
/**
* 通过id获得User
*
* @param id
* @return
*/
public User getUserById(int id) {
SqlSession session = sqlSessionFactory.openSession();
try {
User user = (User) session.selectOne("User.selectUser", id);
return user;
} finally {
session.close();
}
}
public List<User> getAllUser() {
SqlSession session = sqlSessionFactory.openSession();
try {
List<User> users = (List<User>) session.selectList("User.selectAllUser");
return users;
} finally {
session.close();
}
}
public int addUser(User user) {
SqlSession session = sqlSessionFactory.openSession();
try {
int i = session.insert("User.insertUser", user);
if(i >= 1) session.commit();
return i;
} finally {
session.close();
}
}

　　 8.在util包中新建Test类，进行测试，具体内容如下：

package com.mybatis.test.util;
import java.util.List;
import com.mybatis.test.dao.UserDAO;
import com.mybatis.test.vo.User;
public class Test {
public static void main(String[] args) {
UserDAO userDao = new UserDAO();
User user = new User();
user.setId(4);
user.setUserName("Zhuzi");
//添加
System.out.println(userDao.addUser(user));
//查询
System.out.println(userDao.getUserById(4));
List<User> users = userDao.getAllUser();
for (User u : users) {
System.out.println(u);
}
}
}