Mybatis:輕量級的框架,無侵入式的,ORM
JDBC---DbUtils-->MyBatis(半自動)--->Hibernate(全自動)
避免硬編碼
Mybatis配置步驟
1.在Eclipse新建Java工程。
2.在工程目錄下新建lib目錄將mybatis-3.2.7.jar\mysql-connector-java-5.0.4-bin.jar拷貝到目錄下,選中兩個jar包右鍵buildpath-->add to buildpath。
3.在src目錄下新建Mybatis配置文件conf.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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost/數據庫名"/>
<property name="username" value="數據庫用戶名"/>
<property name="password" value="數據庫密碼"/>/
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/scope/dao/userInfoMapper.xml"/>
</mappers>
</configuration>
4.編寫實體類UserInfo.java
package com.scope.dao;
//實體類
public class UserInfo {
private int uid;//用戶編號
private String username;//用戶名
private String password;//密碼
public int getUid() {
return uid;
}
public void setUid(int uid) {
this.uid = uid;
}
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;
}
@Override
public String toString() {
return "UserInfo [uid=" + uid + ", username=" + username + ", password="
+ password + "]";
}
}
5.編寫映射文件userInfoMapper.xml,最好與實體類位於同一個包下
<?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="com.scope.dao.UserInfoMapper">
<select id="getUser" parameterType="int" resultType="com.scope.dao.UserInfo">
select * from user_info where uid=#{uid}
</select>
</mapper>
6.編寫測試類Test.javapackage com.neusoft.test;
import java.io.IOException;
import java.io.InputStream;
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 com.scope.dao.UserInfo;
public class Test {
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
InputStream stream=Resources.getResourceAsStream("conf.xml");
SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(stream);
SqlSession session=factory.openSession();//連接上數據庫
String statement="com.scope.dao.UserInfoMapper.getUser";
UserInfo user= session.selectOne(statement, 1);
System.out.println(user.toString());
session.close();
}
}
工程目錄結構如上圖所示7.總結:
1)conf.xml配置文件中<environments></environments>標籤中可以包含多個<environment></environment>標籤,一個<environment>可以配置一個數據源,可以在<environments></environments>標籤對中配置多個數據源,可以同事包含Mysql和SqlServer或者Oracle數據源。
2)conf.xml文件中
<mappers>
<mapper resource="com/scope/dao/userInfoMapper.xml"/>
</mappers>
用來只是映射文件的路徑
3)userInfoMapper.xml映射文件中
<mapper namespace="com.scope.dao.UserInfoMapper">
<select id="getUser" parameterType="int" resultType="com.scope.dao.UserInfo">
select * from user_info where uid=#{uid}
</select>
</mapper>
id:唯一標識這個sql語句
parameterType: 表示這條SQL接受的參數類型,可以是MyBatis系統定義或者自定義的別名,比如int、string、float等,也可以是全限定名,比如com.scope.dao.UserInfo。
resultType:表示這條SQL返回的結果類型,與parameterType一樣,可以是系統定義的別名,也可以是類的全限定名,比如com.scope.dao.UserInfo。
其中#{xxx}用來獲取參數。在這裏#{uid}獲取的是UserInfo user= session.selectOne(statement, 1);這條語句裏面的1。
4)Test.java測試文件中
InputStream stream=Resources.getResourceAsStream("conf.xml");//通過Resources.getResourceAsStream以字節流方式讀取Mybatis配置文件
SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(stream);//創建一個SqlSessionFactory對象,用來打開session對象連接數據庫
SqlSession session=factory.openSession();//連接上數據庫
String statement="com.scope.dao.UserInfoMapper.getUser";//statement對象爲映射文件中的命名空間+id
UserInfo user= session.selectOne(statement, 1);
8.數據庫表結構如下圖