使用 XML 配置 MyBatis

<?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>
    <properties resource="application.properties">
        <property name="username" value="db_user" />
        <property name="password" value="verysecurepwd" />
    </properties>
    <settings>
        <setting name="cacheEnabled" value="true" />
    </settings>
    <typeAliases>
        <typeAlias alias="Tutor" type="com.mybatis3.domain.Tutor" />
        <package name="com.mybatis3.domain" />
    </typeAliases>
    <typeHandlers>
        <typeHandler handler="com.mybatis3.typehandlers.PhoneTypeHandler" />
        <package name="com.mybatis3.typehandlers" />
    </typeHandlers>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driverClassName}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
        <environment id="production">
            <transactionManager type="MANAGED" />
            <dataSource type="JNDI">
                <property name="data_source" value="java:comp/jdbc/MyBatisDemoDS" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/mybatis3/mappers/StudentMapper.xml" />
        <mapper url="file:///D:/mybatisdemo/mappers/TutorMapper.xml" />
        <mapper class="com.mybatis3.mappers.TutorMapper" />
    </mappers>
</configuration>

<environments default="shoppingcart">
    <environment id="shoppingcart">
        <transactionManager type="MANAGED" />
        <dataSource type="JNDI">
            <property name="data_source" value="java:comp/jdbc/ ShoppingcartDS" />
        </dataSource>
    </environment>
    <environment id="reports">
        <transactionManager type="MANAGED" />
        <dataSource type="JNDI">
            <property name="data_source" value="java:comp/jdbc/ReportsDS" />
        </dataSource>
    </environment>
</environments>

inputStream = Resources.getResourceAsStream("mybatis-config.xml");
defaultSqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
cartSqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream, "shoppingcart");
reportSqlSessionFactory = new SqlSessionFactoryBuilder().
build(inputStream, "reports");

<dataSource type="POOLED">
    <property name="driver" value="${jdbc.driverClassName}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
</dataSource>

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatisdemo
jdbc.username=root
jdbc.password=admin

<properties resource="application.properties">
    <property name="jdbc.username" value="db_user" />
    <property name="jdbc.password" value="verysecurepwd" />
</properties>
<dataSource type="POOLED">
    <property name="driver" value="${jdbc.driverClassName}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
</dataSource>

<properties resource="application.properties">
   <property name="jdbc.username" value="db_user" />
   <property name="jdbc.password" value="verysecurepwd" />
</properties>

public class PhoneNumber {
    private String countryCode;
    private String stateCode;
    private String number;
 
    public PhoneNumber() {
    }
 
    public PhoneNumber(String countryCode, String stateCode, String number) {
        this.countryCode = countryCode;
        this.stateCode = stateCode;
        this.number = number;
    }
 
    public PhoneNumber(String string) {
        if (string != null) {
            String[] parts = string.split("-");
            if (parts.length > 0)
                this.countryCode = parts[0];
            if (parts.length > 1)
                this.stateCode = parts[1];
            if (parts.length > 2)
                this.number = parts[2];
        }
    }
 
    public String toString() {
        return countryCode + "-" + stateCode + "-" + number;
    }
    // Setters and getters
}
 
public class Student {
    private Integer id;
    private String name;
    private String email;
    private PhoneNumber phone;
    // Setters and getters
}

<insert id="insertStudent" parameterType="Student">
    insert into students(name,email,phone)
    values(#{name},#{email},#{phone})
</insert> 
这里，phone 参数需要传递给#{phone}；而 phone 对象是 PhoneNumber 类型。然而，MyBatis 并不知道该怎样来处
理这个类型的对象。
为了让 MyBatis 明白怎样处理这个自定义的 Java 对象类型，如 PhoneNumber，我们可以创建一个自定义的类型处理
器，如下所示：
1. MyBatis 提供了抽象类 BaseTypeHandler<T> ，我们可以继承此类创建自定义类型处理器。
Java Code
package com.mybatis3.typehandlers;
 
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import com.mybatis3.domain.PhoneNumber;
 
public class PhoneTypeHandler extends BaseTypeHandler<PhoneNumber> {
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, PhoneNumber parameter, JdbcType jdbcType)
            throws SQLException {
        ps.setString(i, parameter.getAsString());
    }
 
    @Override
    public PhoneNumber getNullableResult(ResultSet rs, String columnName) throws SQLException {
        return new PhoneNumber(rs.getString(columnName));
    }
 
    @Override
    public PhoneNumber getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return new PhoneNumber(rs.getString(columnIndex));
 
    }
 
    @Override
    public PhoneNumber getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return new PhoneNumber(cs.getString(columnIndex));
    }
}
2. 我们使用 ps.setString()和 rs.getString()方法是因为 phone 列是 VARCHAR 类型。
3. 一旦我们实现了自定义的类型处理器，我们需要在 mybatis-config.xml 中注册它：
XML Code
<?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>
    <properties resource="application.properties" />
    <typeHandlers>
        <typeHandler handler="com.mybatis3.typehandlers. PhoneTypeHandler" />
    </typeHandlers>
</configuration>
注册 PhoneTypeHandler 后, MyBatis 就能够将 Phone 类型的对象值存储到 VARCHAR 类型的列上。
7 全局参数设置 Settings
为满足应用特定的需求，MyBatis 默认的全局参数设置可以被覆盖(overridden)掉，如下所示：
XML Code
<settings>
    <setting name="cacheEnabled" value="true" />
    <setting name="lazyLoadingEnabled" value="true" />
    <setting name="multipleResultSetsEnabled" value="true" />
    <setting name="useColumnLabel" value="true" />
    <setting name="useGeneratedKeys" value="false" />
    <setting name="autoMappingBehavior" value="PARTIAL" />
    <setting name="defaultExecutorType" value="SIMPLE" />
    <setting name="defaultStatementTimeout" value="25000" />
    <setting name="safeRowBoundsEnabled" value="false" />
    <setting name="mapUnderscoreToCamelCase" value="false" />
    <setting name="localCacheScope" value="SESSION" />
    <setting name="jdbcTypeForNull" value="OTHER" />
    <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode ,toString" />
</settings>
8 SQL 映射定义 Mappers
Mapper XML 文件中包含的 SQL 映射语句将会被应用通过使用其 statementid 来执行。我们需要在 mybatisconfig.xml 文件中配置 SQL Mapper 文件的位置。
XML Code
<mappers>
    <mapper resource="com/mybatis3/mappers/StudentMapper.xml" />
    <mapper url="file:///D:/mybatisdemo/app/mappers/TutorMapper.xml" />
    <mapper class="com.mybatis3.mappers.TutorMapper" />
    <package name="com.mybatis3.mappers" />
</mappers>
以上每一个<mapper> 标签的属性有助于从不同类型的资源中加载映射 mapper：
? resource 属性用来指定在 classpath 中的 mapper 文件。
? url 属性用来通过完全文件系统路径或者 web URL 地址来指向 mapper 文件
? class 属性用来指向一个 mapper 接口
? package 属性用来指向可以找到 Mapper 接口的包名