Mybbatis學習之道（一）
阿新 • • 發佈：2017-08-04
org unit primary sas oca manage result ava namespace
本例子為采用的mysql+maven+mybatis構建。
初步學習mybatis：
mybatis為一個半自動框架，相對於hibernate來說他更加輕巧，學習成本更低。
1.新建一個maven工程
2.在maven中配置依賴jar包
1 <dependencies> 2 <dependency> 3 <groupId>junit</groupId> 4 <artifactId>junit</artifactId> 5 <version>4.11</version> 6 <scope>test</scope> 7 </dependency> 8 <dependency> 9 <groupId>org.mybatis</groupId> 10 <artifactId>mybatis</artifactId> 11 <version>3.4.1</version> 12 </dependency> 13 <dependency> 14 <groupId>mysql</groupId> 15 <artifactId>mysql-connector-java</artifactId> 16 <version>5.1.40</version> 17 </dependency> 18 </dependencies>
3.新建一個jdbc.properties文件
1 jdbc.driver=org.gjt.mm.mysql.Driver 2 jdbc.url=jdbc:mysql://localhost:3306/mybatisStudy 3 jdbc.username=root 4 jdbc.password=123456
4.創建mybatis配置文件
propertis:導入配置文件
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 5 <configuration> 6 <properties resource="jdbc.properties"></properties> 7 <!--設置一些配置信息--> 8 <settings> 9 <setting name="useGeneratedKeys" value="true"/> 10 </settings> 11 <!--設置別名--> 12 <typeAliases> 13 <typeAlias type="cn.lonecloud.d1.model.Blog" alias="Blog"></typeAlias> 14 </typeAliases> 15 <environments default="development"> 16 <environment id="development"> 17 <transactionManager type="JDBC"/> 18 <dataSource type="POOLED"> 19 <property name="driver" value="${jdbc.driver}"/> 20 <property name="url" value="${jdbc.url}"/> 21 <property name="username" value="${jdbc.username}"/> 22 <property name="password" value="${jdbc.password}"/> 23 </dataSource> 24 </environment> 25 </environments> 26 <!--mapper對應的文件--> 27 <mappers> 28 <mapper resource="mapper/BlogMapper.xml"></mapper> 29 </mappers> 30 </configuration>
5創建數據庫
1 SET NAMES utf8; 2 SET FOREIGN_KEY_CHECKS = 0; 3 4 -- ---------------------------- 5 -- Table structure for `blog` 6 -- ---------------------------- 7 DROP TABLE IF EXISTS `blog`; 8 CREATE TABLE `blog` ( 9 `id` varchar(32) NOT NULL DEFAULT ‘‘, 10 `name` varchar(255) DEFAULT ‘‘, 11 PRIMARY KEY (`id`) 12 ) ENGINE=InnoDB DEFAULT CHARSET=utf8; 13 14 SET FOREIGN_KEY_CHECKS = 1;
6.創建POJO類
1 package cn.lonecloud.d1.model; 2 3 /** 4 * Created by lonecloud on 17/3/17. 5 */ 6 public class Blog { 7 private String id; 8 9 private String name; 10 11 public String getId() { 12 return id; 13 } 14 15 @Override 16 public String toString() { 17 return "Blog{" + 18 "id=‘" + id + ‘\‘‘ + 19 ", name=‘" + name + ‘\‘‘ + 20 ‘}‘; 21 } 22 23 public void setId(String id) { 24 this.id = id; 25 } 26 27 public String getName() { 28 return name; 29 } 30 31 public void setName(String name) { 32 this.name = name; 33 } 34 }
.7創建對應的接口類
由於mybatis是接口式編程，會將對應的接口通過映射的方式在其容器中通過代理方式創建出一個對象，所以不需要創建實現類
1 package cn.lonecloud.d1.dao; 2 3 import cn.lonecloud.d1.model.Blog; 4 5 /** 6 * Created by lonecloud on 17/3/17. 7 * mybatis接口式編程 8 */ 9 public interface BlogMapper { 10 Blog selectOne(String id); 11 }
8.編寫對應的mapper文件
namespce:命名空間,為對這個mapper文件進行唯一性標示，最好使用對應的接口全類名
select:篩選語句相當於說明這是一個select查詢 id標明為該類下面的某個方法，
resultType:返回數據類型，
#{id}:為傳遞過來的參數，最好是和參數名相同
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 5 <mapper namespace="cn.lonecloud.d1.dao.BlogMapper"> 6 <select id="selectOne" resultType="Blog"> 7 select * from Blog where id = #{id} 8 </select> 9 </mapper>
9.編寫測試類：
1 package cn.lonecloud.d1; 2 3 import cn.lonecloud.d1.dao.BlogMapper; 4 import cn.lonecloud.d1.model.Blog; 5 import org.apache.ibatis.io.Resources; 6 import org.apache.ibatis.session.SqlSession; 7 import org.apache.ibatis.session.SqlSessionFactory; 8 import org.apache.ibatis.session.SqlSessionFactoryBuilder; 9 import org.junit.Test; 10 11 import java.io.IOException; 12 import java.io.InputStream; 13 14 /** 15 * Created by lonecloud on 17/3/17. 16 */ 17 public class SessionTest { 18 19 SqlSessionFactory sqlSessionFactory; 20 @Test 21 public void session() throws IOException { 22 String resource = "mybatis-config.xml";//配置文件 23 InputStream inputStream = Resources.getResourceAsStream(resource);//讀取配置文件 24 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//獲取sqlSession 對象 25 System.out.println(sqlSessionFactory); 26 SqlSession session = sqlSessionFactory.openSession();//打開session 27 try{ 28 BlogMapper blogMapper = session.getMapper(BlogMapper.class); 29 Blog blog = blogMapper.selectOne("sasa"); 30 System.out.println(blog); 31 }finally { 32 session.close(); 33 } 34 } 35 }
註意的是SqlSession位非線程安全的類，這個如果定義為類變量會導致線程安全性問題！！
本例子共享於gitOSChina中：鏈接
Mybbatis學習之道（一）