Mybatis所需要的jar包：
需要引用兩個jar包，一個是mybatis，另一個是MySQL-connector-Java，如果是maven工程的話，pom里如下添加依賴就可以了。
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<dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.2.3</version></dependency><dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.26</version></dependency> |
數據準備：
在MySQL中造點數據進行測試用：
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CREATE DATABASE mybatis_test;CREATE TABLE user( age INTEGER NOT NULL, name VARCHAR(64) NOT NULL DEFAULT '');insert user values(18,'zhanjindong');insert user values(20,'zhangsan'); |
配置文件：
需要兩類配置文件，一類是MyBatis的配置文件mybatis-config.xml，示例中是一個很簡單配置，詳細的配置網上有很多說明。
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"<configuration> <settings> <!-- changes from the defaults for testing --> <setting name="cacheEnabled" value="false" /> <setting name="useGeneratedKeys" value="true" /> <setting name="defaultExecutorType" value="REUSE" /> </settings> <typeAliases> <typeAlias alias="User" type="test.mybatis.User"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="jdbc"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="username" value="root"/> <property name="password" value="123456"/> </dataSource> </environment> </environments> <mappers> <mapper resource="mappers/UserMapper.xml" /> </mappers> </configuration> |
另一類是數據訪問接口映射文件：示例中是UserMapper.xml。這個文件一般放在src/main/resource下面或子目錄下mybatis就可以找到了，在mybatis-config.xml中由mappers/mapper節點的resource指定。
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<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"<mapper namespace="test.mybatis.UserMapper"> <!-- 這里namespace必須是UserMapper接口的路徑” --> <insert id="insertUser" parameterType="User"> insert into user(name,age) values(#{name},#{age}) <!-- 這里sql結尾不能加分號，否則報“ORA-00911”的錯誤 --> </insert> <!-- 這里的id必須和UserMapper接口中的接口方法名相同 --> <select id="getUser" resultType="User" parameterType="java.lang.String"> select * from user where name=#{name} </select></mapper> |
對應這個映射文件就是test.mybatis這個命名空間下的UserMapper這個接口，只是定義了訪問數據表的接口：
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package test.mybatis;public interface UserMapper { public void insertUser(User user); public User getUser(String name);} |
需要一個POJO:User.java
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package test.mybatis;public class User { private String name; private Integer age; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public User(String name, Integer age) { super(); this.name = name; this.age = age; } public User() { super(); }} |
測試：
通過MyBatis操作數據庫用到的是一個叫SqlSession的類，這個類是通過SqlSessionFactory產生的，一般建議在全局維護一個SqlSessionFactory就可以了。
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TestMyBatis.javapackage test.mybatis;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 MyBatisUtil { private final static SqlSessionFactory sqlSessionFactory; static { String resource = "mybatis-config.xml"; Reader reader = null; try { reader = Resources.getResourceAsReader(resource); } catch (IOException e) { System.out.println(e.getMessage()); } sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader); } public static SqlSessionFactory getSqlSessionFactory() { return sqlSessionFactory; }} |
測試代碼如下：
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TestMyBatis.javapackage test.mybatis;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;public class TestMyBatis { static SqlSessionFactory sqlSessionFactory = null; static { sqlSessionFactory = MyBatisUtil.getSqlSessionFactory(); } public static void main(String[] args) { testAdd(); getUser(); } public static void testAdd() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = new User("lisi", new Integer(25)); userMapper.insertUser(user); sqlSession.commit();// 這里一定要提交，不然數據進不去數據庫中 } finally { sqlSession.close(); } } public static void getUser() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = userMapper.getUser("zhangsan"); System.out.println("name: " + user.getName() + "|age: " + user.getAge()); } finally { sqlSession.close(); } }} |
1、mybatis會用log4j記錄日志，但是開啟debug模式貌似對性能影響非常厲害。
2、mybatis的查詢緩存對性能的影響非常大，啟用和不啟用差距非常大
以上所述是小編給大家介紹的Mybatis的詳細使用教程，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言，小編會及時回復大家的！
