Mybatis的详细使用教程

mybatis所需要的jar包：

需要引用两个jar包，一个是mybatis，另一个是mysql-connector-java，如果是maven工程的话，pom里如下添加依赖就可以了。

<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>

数据准备：

在mysql中造点数据进行测试用：

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：

需要两类配置文件，一类是mybatis的配置文件mybatis-config.xml，示例中是一个很简单配置，详细的配置网上有很多说明。

<?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> 
 <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="url" value="jdbc:mysql://192.168.71.38:3306/mybatis_test"/> 
    <property name="username" value="root"/> 
    <property name="password" value="123456"/> 
   </datasource> 
  </environment> 
 </environments> 
 <mappers> 
  <mapper resource="mappers/usermapper.xml" /> 
 </mappers> 
</configuration>

另一类是数据访问接口映射文件：示例中是usermapper.xml。这个文件一般放在src/main/resource下面或子目录下mybatis就可以找到了，在mybatis-config.xml中由mappers/mapper节点的resource指定。

<?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="test.mybatis.usermapper">
 <!-- 这里namespace必须是usermapper接口的路径” -->
 <insert id="insertuser" parametertype="user">
  insert into user(name,age) values(#{name},#{age})
  <!-- 这里sql结尾不能加分号，否则报“ora-00911”的错误 -->
 </insert>
 <!-- 这里的id必须和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>

对应这个映射文件就是test.mybatis这个命名空间下的usermapper这个接口，只是定义了访问数据表的接口：

package test.mybatis;
public interface usermapper {
 public void insertuser(user user);
 public user getuser(string name);
}

需要一个pojo:user.java

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();
 }
}

测试：

通过mybatis操作数据库用到的是一个叫sqlsession的类，这个类是通过sqlsessionfactory产生的，一般建议在全局维护一个sqlsessionfactory就可以了。

testmybatis.java
package 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;
 }
}

测试代码如下：

testmybatis.java
package 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();// 这里一定要提交，不然数据进不去数据库中
  } 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会用log4j记录日志，但是开启debug模式貌似对性能影响非常厉害。

2、mybatis的查询缓存对性能的影响非常大，启用和不启用差距非常大

以上所述是小编给大家介绍的mybatis的详细使用教程，希望对大家有所帮助