• mybatis

    1. 入门

      1. 引入配置文件创建SqlSessionFactory

      2. 不引入配置文件创建SqlSessionFactory

    2. XML配置

      1. properties（属性）

      2. settings（设置）

        1. mapUnderscoreToCamelCase 驼峰命名

      3. typeAliases（类型别名）

      4. typeHandlers（类型处理器）

      5. objectFactory（对象工厂）

      6. plugins（插件）

      7. environments（环境配置）

      8. databaseIdProvider（数据库厂商标识）

      9. mappers（映射器）

    入门

    1 引入配置文件创建SqlSessionFactory

    mybatis-config1.xml是mybatis的核心配置文件，用来配置mybatis系统参数，数据库参数，缓存，另外还需要引入具体的mapper文件。mapper1.xml是mybatis写sql的文件，mapper文件必须有唯一的namespace

    <?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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="primerConfig/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="string">
        select username from manage_user where id = #{id}
  </select>
</mapper>
    View Code
     @Test//引入配置文件
    public void t1() throws Exception {
        String resource = "primerConfig/mybatis-config1.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        String name = (String) sqlSession.selectOne("config1.selectManageUserName", "1");
        sqlSession.close();
    }
    View Code

    2 不引入配置文件创建SqlSessionFactory

    不引入mybatis配置文件，需要Configuration类，相当于mybatisconfig中的<configuation>标签。另外mapper文件也不存在了，则由注解代替

    package primer;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-26 10:39
* @notify 
* @version 1.0
*/

import org.apache.ibatis.annotations.Select;

public interface PrimerMapper {
    @Select("select username from manage_user where id = #{id}")
    String selectManageUserName(int id);
}
    View Code
    package primer;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-26 10:39
* @notify 
* @version 1.0
*/

import org.apache.ibatis.annotations.Select;

public interface PrimerMapper2 {
    @Select("select username from manage_user where id = #{id}")
    String selectManageUserName2(int id);
}
    View Code
    @Test//不引入配置文件创建SqlSessionFactory
    public void t2() {
        //连接池对象
        PooledDataSourceFactory pooledDataSourceFactory = new PooledDataSourceFactory();
        //数据源参数
        Properties properties = new Properties();
        properties.put("driver", "com.mysql.jdbc.Driver");
        properties.put("url", "jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&characterEncoding=utf8&useUnicode=true&useSSL=false");
        properties.put("username", "root");
        properties.put("password", "root");
        pooledDataSourceFactory.setProperties(properties);
        //获取数据源
        DataSource dataSource = pooledDataSourceFactory.getDataSource();
        //设置事务管理器
        TransactionFactory transactionFactory = new JdbcTransactionFactory();
        //创建上下文环境
        Environment environment = new Environment("development", transactionFactory, dataSource);
        //组装配置
        Configuration configuration = new Configuration(environment);
        //添加mapper
        configuration.addMapper(PrimerMapper.class);
        configuration.addMapper(PrimerMapper2.class);
        //获取sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
        //打开链接
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //方式1
        String selectManageUserName = (String) sqlSession.selectOne("selectManageUserName", 1);
        String selectManageUserName2 = (String) sqlSession.selectOne("selectManageUserName2", 1);
        //方式2
        PrimerMapper mapper = sqlSession.getMapper(PrimerMapper.class);
        String s = mapper.selectManageUserName(1);
        sqlSession.close();
    }
    View Code

    XML配置

    1 properties(属性)

    标签properties用于设置mybatis全局配置参数。内部定义property属性，或者引入外部文件，给mybatis注入属性，mybatis其他配置地方可使用${}引用参数。

    <?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>
        <property name="jdbc.driver" value="com.mysql.jdbc.Driver"/>
        <property name="jdbc.url"
                  value="jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
        <property name="jdbc.username" value="root"/>
        <property name="jdbc.password" value="root"/>

    </properties>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username-root}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-properties/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    以上配置为内部配置property属性，我们也可以引入外部的配置文件。properties使用resource属性或者url属性。

    jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&characterEncoding=utf8&useUnicode=true&useSSL=false
jdbc.username=root
jdbc.password=root
test.a=123
test.b=456
    View Code

    属性注入的顺序是，先使用<property>属性值，在使用resource覆盖，最终直接写入属性值覆盖。最终生效的则是相反。

    不管是<property>注入的属性还是外部文件，最终mybatis都将其封装到sqlSessionFactory->configuration->variables中。另外当我们使用${}时，如果没有映射到对应的key，也可以设置默认值。但我们需要先开启默认值。

    删除<property>和外部配置文件的jdbc.password使其不存在。发现现在注入的值为${jdbc.password}字面量字符串。

    <?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="configuration-properties/db.properties">
        <!-- 启用默认值特性 -->
        <property name="org.apache.ibatis.parsing.PropertyParser.enable-default-value" value="true"/>
        <property name="test.c" value="678"/>
        <property name="jdbc.driver" value="com.mysql.jdbc.Driver"/>
        <property name="jdbc.url"
                  value="jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
        <property name="jdbc.username" value="root"/>

    </properties>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password:root}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-properties/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    开启默认值，并设置默认值。默认值的使用方式是使用 value="${jdbc.password:root}"如果变量不存在，则使用:后的字符串默认值。

    如果：符号已经被占用，我们还可以自定义分割符号。

    <?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="configuration-properties/db.properties">
        <!-- 启用默认值特性 -->
        <property name="org.apache.ibatis.parsing.PropertyParser.enable-default-value" value="true"/>
        <!-- 修改默认值的分隔符 默认的 ： 和 ？： -->
        <property name="org.apache.ibatis.parsing.PropertyParser.default-value-separator" value="-"/>
        <property name="test.c" value="678"/>
        <property name="jdbc.driver" value="com.mysql.jdbc.Driver"/>
        <property name="jdbc.url"
                  value="jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
        <property name="jdbc.username" value="root"/>

    </properties>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password-root}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-properties/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    2 settings（设置）

    2.1 mapUnderscoreToCamelCase 驼峰命名

    <?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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-sittings-mapUnderscoreToCamelCase/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="configurationSittingsMapUnderscoreToCamelCase.ManageUser">
        select * from manage_user where id = #{id}
  </select>
</mapper>
    View Code
    package configurationSittingsMapUnderscoreToCamelCase;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-27 07:35
* @notify 
* @version 1.0
*/

import org.apache.ibatis.type.Alias;

import java.util.Date;

public class ManageUser {
    private String id;
    private String username;
    private String password;
    private Date createDate;
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    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;
    }

    public Date getCreateDate() {
        return createDate;
    }

    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }
}
    View Code

    在数据库中字段create_date映射pojo属性createDate是不行的。此时我们开启自动驼峰命名规则映射可以解决这个问题。

    <?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>
    <!-- 开启驼峰命名映射-->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-sittings-mapUnderscoreToCamelCase/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    3 类型别名（typeAliases）

    在写mapper文件时，必不可少的，我们要给PreparedStatement和Statement指定入参。或者结果集映射返回值。必然的我们需要指定类型。mybatis预选帮我们设置好了常用类型的别名。https://mybatis.org/mybatis-3/zh/configuration.html#typeAliases

    package configurationTypeAliases;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-27 07:35
* @notify 
* @version 1.0
*/

import java.util.Date;

public class ManageUser {
    private String id;
    private String username;
    private String password;
    private Date createDate;
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    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;
    }

    public Date getCreateDate() {
        return createDate;
    }

    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }
}
    View 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>
    <!-- 设置别名 -->
    <typeAliases>
        <typeAlias type="configurationTypeAliases.ManageUser" alias="abc"/>
<!--        <package name="configurationTypeAliases"/>-->
    </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://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-typeAliases/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <!-- 入参使用别名 -->
    <select id="selectManageUserName" resultType="string" parameterType="abc">
        select username from manage_user where id = #{id}
  </select>
</mapper>
    View Code

    扫描包别名，通常的单个指定别名会比较麻烦，所以我们可以扫描包路径，生成别名。

    <?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>
    <!-- 设置别名 -->
    <typeAliases>
<!--        <typeAlias type="configurationTypeAliases.ManageUser" alias="abc"/>-->
        <package name="configurationTypeAliases"/>
    </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://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-typeAliases/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <!-- 入参使用别名 -->
    <select id="selectManageUserName" resultType="string" parameterType="manaGeuser">
        select username from manage_user where id = #{id}
  </select>
</mapper>
    View Code

    使用包扫描不限制类名大小写。同样我们可以强制要求pojo类的别名。使用@Alias注解

    package configurationTypeAliases;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-27 07:35
* @notify 
* @version 1.0
*/

import org.apache.ibatis.type.Alias;

import java.util.Date;

@Alias(value = "def")
public class ManageUser {
    private String id;
    private String username;
    private String password;
    private Date createDate;
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    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;
    }

    public Date getCreateDate() {
        return createDate;
    }

    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }
}
    View Code

    一个类可以有多个别名，我们可以在sqlSessionFactory->configuration->typeAliasRegistry->TYPE_ALIASES下寻找定义的别名。其中已经有mybatis预定义的别名。

    4 类型转换器（typeHandlers）

    无论是 MyBatis 在预处理语句（PreparedStatement）中设置一个参数时，还是从结果集中取出一个值时， 都会用类型处理器将获取的值以合适的方式转换成 Java 类型。就是说，在mapper中，我们的Statement入参和返回值都需要经过类型转换器，入参从java类型转成jdbc类型，返回值从jdbc类型转换成java类型。mybatis已经定义了大部分常用的类型转换器。https://mybatis.org/mybatis-3/zh/configuration.html#typeHandlers 下边我们自定义一个String类型转换器，覆盖mybatis定义的转换器。给入参字符串自动拼接，和返回值自动拼接。

    package configurationTypeHandlers;/*
 * @auther 顶风少年
 * @mail dfsn19970313@foxmail.com
 * @date 2019-12-30 08:17
 * @notify
 * @version 1.0
 */

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

@MappedJdbcTypes(value = {JdbcType.VARCHAR,JdbcType.CHAR},includeNullJdbcType = true)
@MappedTypes(value = String.class)
public class ExampleTypeHandler extends BaseTypeHandler<String> {

    public void setNonNullParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException {
        System.out.println(parameter);
        ps.setString(i, parameter+"d");
    }

    public String getNullableResult(ResultSet rs, String columnName) throws SQLException {
        System.out.println("columnName");
        return rs.getString(columnName)+"---";
    }

    public String getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        System.out.println("columnIndex");
        return rs.getString(columnIndex)+"|||";
    }

    public String getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        System.out.println("CallableStatement");
        return cs.getString(columnIndex)+"%%%";
    }
}
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="string">
        select username from manage_user where username = #{username}
  </select>
</mapper>
    View Code

    继承BaseTypeHandler类，set（）方法是入参，get（）是返回值。上边代码片段，我们试图将String和varchar char 互相转换。在ExampleTypeHandler上使用@MappedJdbcTypes和@MappedTypes指定要转换的类型。注意如果需要set（）生效则需要在@MappedTypes使用includeNullJdbcType=true。然后在mybatis全局配置文件使用这个自定义类型转换器。

    <?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>
    <typeHandlers>
        <typeHandler handler="configurationTypeHandlers.ExampleTypeHandler"/>
    </typeHandlers>
    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-typeHandlers/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    <typeHandler/>有属性jdbcType和javaType会覆盖ExampleTypeHandler类上的@MappedJdbcTypes和@MappedTypes

    5 对象工厂（ObjectFactory）

    Statement返回结果集为pojo时，mybatis会帮我们实例化pojo对象。默认的会调用DefaultObjectFactory，我们可以继承此类，然后对返回pojo进行改造。setProperties()方法将<objectFactory/>中的<property/>属性映射到参数中，我们可将其设置为成员变量，在create（）方法中使用。

    package configurationObjectFactory;/*
 * @auther 顶风少年
 * @mail dfsn19970313@foxmail.com
 * @date 2019-12-27 07:35
 * @notify
 * @version 1.0
 */


import java.util.Date;

public class ObjectFactoryManageUser {
    private String id;
    private String username;
    private String password;
    private Date createDate;
    private String prp;


    public ObjectFactoryManageUser() {
    }

    public void setPrp(String prp) {
        this.prp = prp;
    }
}
    View 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>
    <objectFactory type="configurationObjectFactory.ExampleObjectFactory">
        <property name="prp" value="AAA"/>
    </objectFactory>

    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-ObjectFactory/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    package configurationObjectFactory;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-30 10:47
* @notify 
* @version 1.0
*/

import org.apache.ibatis.reflection.factory.DefaultObjectFactory;

import java.util.List;
import java.util.Properties;

public class ExampleObjectFactory extends DefaultObjectFactory {

    Properties properties = new Properties();

    @Override
    public <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs){
        T ret = super.create(type,constructorArgTypes,constructorArgs);
        if(ObjectFactoryManageUser.class.isAssignableFrom(type)){
            ObjectFactoryManageUser objectFactoryManageUser =(ObjectFactoryManageUser) ret;
            objectFactoryManageUser.setPrp((String) properties.get("prp"));
        }
        return ret;
    }

    @Override
    public void setProperties(Properties properties) {
      this.properties = properties;
    }
}
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="configurationObjectFactory.ObjectFactoryManageUser">
        select * from manage_user where id = #{id}
  </select>
</mapper>
    View Code

    6 插件（plugins）

    MyBatis 允许你在已映射语句执行过程中的某一点进行拦截调用。如果你想做的不仅仅是监控方法的调用，那么你最好相当了解要重写的方法的行为。 因为如果在试图修改或重写已有方法的行为的时候，你很可能在破坏 MyBatis 的核心模块。 这些都是更低层的类和方法，所以使用插件的时候要特别当心。以下代码片段是对返回值拦截。

    package configurationPlugins;/*
 * @auther 顶风少年
 * @mail dfsn19970313@foxmail.com
 * @date 2019-12-30 16:28
 * @notify
 * @version 1.0
 */

import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.resultset.ResultSetHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

import java.sql.Statement;
import java.util.Properties;

/*
    注解接收数组，类型为@Signature
    而@Signature三个参数分别是，要拦截的类，要拦截的方法，方法参数。
    注意可拦截的类和方法为
    //执行sql
    Executor (update, query, flushStatements, commit, rollback, getTransaction, close, isClosed)
    //获取、设置参数
    ParameterHandler (getParameterObject, setParameters)
    //处理结果集
    ResultSetHandler (handleResultSets, handleOutputParameters)
    //记录sql
    StatementHandler (prepare, parameterize, batch, update, query)
 */
@Intercepts(value = {@Signature(
        type = ResultSetHandler.class,
        method = "handleResultSets",
        args = {Statement.class})})
public class ExamplePlugin implements Interceptor {

    private Properties properties = new Properties();

    //拦截类
    public Object intercept(Invocation invocation) throws Throwable {
        System.out.println(properties.getProperty("timeout"));
        return invocation.proceed();
    }

    //返回当前插件
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }
    
    //将xml配置的property绑定到成员变量上
    public void setProperties(Properties properties) {
        this.properties = properties;
    }
}
    View 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>
    <!-- 配置插件 -->
    <plugins>
        <plugin interceptor="configurationPlugins.ExamplePlugin">
            <property name="timeout" value="100"/>
        </plugin>
    </plugins>
    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="configuration-plugins/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="string">
        select username from manage_user where id = #{id}
  </select>
</mapper>
    View Code

    7 环境配置（environments）

    使用mybatis，在可能的情况下我们会有多种环境，例如测试环境，生产环境等。我们可以通过配置environment来确定使用的环境。

    <?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="development2">

        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>

        <environment id="development2">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root2"/>
            </dataSource>
        </environment>

    </environments>
    <mappers>
        <mapper resource="configuration-environments/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    每个environment有唯一的id，在environment标签上使用default属性，表示要使用的是哪个environment。以上我们使用environment2，但是他的密码是错误的，所以连接失败。

    另外我们还可以在创建sqlSessionFactory时，指定要使用的环境，但是这样会使default失效。

    关于环境的事务管理器，数据源配置可查看 https://mybatis.org/mybatis-3/zh/configuration.html#environments

    8 数据库厂商标识（databaseIdProvider）

    在正式开发中，我们可能会需要配置多种数据库。不同的数据库会有不同的方言，下面我们模拟这种情况。

    <?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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <databaseIdProvider type="DB_VENDOR">
        <property name="SQL Server" value="sqlserver"/>
        <property name="DB2" value="db2"/>
        <property name="Oracle" value="oracle" />
        <property name="MySQL" value="mysql" />
    </databaseIdProvider>
    <mappers>
        <mapper resource="configuration-databaseIdProvider/mapper1.xml"/>
    </mappers>
</configuration>
    View Code
    <?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="config1">
    <select id="selectManageUserName" resultType="string" databaseId="mysql">
        select username from manage_user where id = 2
  </select>
    <select id="selectManageUserName" resultType="string">
        select username from manage_user where id = 1
  </select>
</mapper>
    View Code

    在mybatis配置文件中使用<databaseIdProvider/>标签，<property/>声明数据库名称和别名。在mapper中，可以给Statement指定数据库。可以看到，上边的代码片段，我们有两个id相同的查询语句。其中一个指定的有databaseId，mybatis会优先使用带有数据库标识的，如果发现标识不存在，或者数据库类型不匹配，才会转向使用不带标识的Statement。

    9 映射器（mappers）

    最终我们的目的是执行sql语句，我们在mybatis配置文件中引入mapper文件，或者mapper类。

    1 使用相对于类路径的资源引用

    <?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="config1">
    <select id="selectManageUserName" resultType="string">
        select username from manage_user where id = #{id}
  </select>
</mapper>
    View 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>
    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 使用相对于类路径的资源引用 -->
        <mapper resource="configuration-mappers/mapper1.xml"/>
    </mappers>
</configuration>
    View Code

    2 使用完全限定资源定位符（URL）

    <?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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 使用相对于类路径的资源引用 -->
<!--        <mapper resource="configuration-mappers/mapper1.xml"/>-->
<!--        使用完全限定资源定位符（URL）-->
        <mapper url="file:\c:workspacemybatissrcmain
esourcesconfiguration-mappersmapper1.xml"/>
    </mappers>
</configuration>
    View Code

    3 使用映射器接口实现类的完全限定类名,引入mapper接口 

    package configurationMappers;/*
* @auther 顶风少年 
* @mail dfsn19970313@foxmail.com
* @date 2019-12-26 10:39
* @notify 
* @version 1.0
*/

import org.apache.ibatis.annotations.Select;

public interface PrimerMapper {
    @Select("select username from manage_user where id = #{id}")
    String selectManageUserName(int id);
}
    View 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>
    <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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 使用相对于类路径的资源引用 -->
<!--        <mapper resource="configuration-mappers/mapper1.xml"/>-->
<!--        使用完全限定资源定位符（URL）-->
<!--        <mapper url="file:\c:workspacemybatissrcmain
esourcesconfiguration-mappersmapper1.xml"/>-->
<!--        使用映射器接口实现类的完全限定类名-->
        <mapper class="configurationMappers.PrimerMapper"/>
    </mappers>
</configuration>
    View Code

    4 将包内的映射器接口实现全部注册为映射器 

    <?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:3306/petstore?serverTimezone=GMT%2B8&amp;characterEncoding=utf8&amp;useUnicode=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 使用相对于类路径的资源引用 -->
<!--        <mapper resource="configuration-mappers/mapper1.xml"/>-->
<!--        使用完全限定资源定位符（URL）-->
<!--        <mapper url="file:\c:workspacemybatissrcmain
esourcesconfiguration-mappersmapper1.xml"/>-->
<!--        使用映射器接口实现类的完全限定类名-->
<!--        <mapper class="configurationMappers.PrimerMapper"/>-->
        <!-- 将包内的映射器接口实现全部注册为映射器 -->
        <package name="configurationMappers"/>
    </mappers>
</configuration>
    View Code
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  • 原文地址：https://www.cnblogs.com/zumengjie/p/12105632.html
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