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1、目的#xff1a;梳理一下MyBatis运行时的几个对象#xff0c;我们需要搞清楚他们的作用#xff0c;进而需要理解mybatis的整个工作流程和执行原理。
2、简要概括各个类
2.1 Resources
作用#xff1a;编写资源加载类#xff0c;使用类加载器加载 配置文件(myb…目录
1、目的梳理一下MyBatis运行时的几个对象我们需要搞清楚他们的作用进而需要理解mybatis的整个工作流程和执行原理。
2、简要概括各个类
2.1 Resources
作用编写资源加载类使用类加载器加载 配置文件(mybatis-config.xml )即读取mybatis-config.xml
2.2 SqlSessionFactoryBuilder
作用将配置资源封装成Configuration对象并且将该资源对象传到工厂对象中
2.2.1 Configuration
作用配置类 -- 把所有的配置信息 都装进去
2.2.2 MappedStatement
作用用来封装 sql语句 和 查询结果集即返回值类型
2.3 SqlSessionFactory
2.4 SqlSession
2.5 ProxyFactory
3、测试 1、目的梳理一下MyBatis运行时的几个对象我们需要搞清楚他们的作用进而需要理解mybatis的整个工作流程和执行原理。 mybatis-config.xml
mapper.xml mapper.xml mapper.xml...
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Resources
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|----InputStream
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SqlSessionFactoryBuilder
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|----Configuration(conn, Mapnamespace.id, MappedStatement(sql, resultType))
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SqlSessionFactory
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|----Configuration(conn, Mapnamespace.id, MappedStatement(sql, resultType))
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SqlSession
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|----conn, Mapnamespace.id, MappedStatement(sql, resultType)
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ProxyFactory
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|----MappedStatement(sql, resultType), conn
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Executor
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输入出映射 2、简要概括各个类
2.1 Resources
作用编写资源加载类使用类加载器加载 配置文件(mybatis-config.xml )即读取mybatis-config.xml package com.by.io;import java.io.InputStream;public class Resources {//根据文件名称加载类路径下面的配置文件public static InputStream getResourceAsStream(String filePath){return Resources.class.getClassLoader().getResourceAsStream(filePath);}
} 2.2 SqlSessionFactoryBuilder
作用将配置资源封装成Configuration对象并且将该资源对象传到工厂对象中 package com.by.builder;import com.by.cfg.Configuration;
import com.by.factory.DefaultSqlSessionFactory;
import com.by.factory.SqlSessionFactory;
import com.by.utils.XMLConfigBuilder;import java.io.InputStream;public class SqlSessionFactoryBuilder {/*** 构建SqlSessionFactory对象* param in* return*/public SqlSessionFactory build(InputStream in){Configuration configuration XMLConfigBuilder.loadConfiguration(in);return new DefaultSqlSessionFactory(configuration);}
} 2.2.1 Configuration
作用配置类 -- 把所有的配置信息 都装进去 package com.by.cfg;import com.by.mapping.MappedStatement;import java.util.HashMap;
import java.util.Map;public class Configuration {private String driver;private String url;private String username;private String password;/**Mapcom.by.dao.UserDao.findAll, MappedStatement */private MapString, MappedStatement mappers new HashMapString,MappedStatement();public MapString, MappedStatement getMappers() {return mappers;}public void setMappers(MapString, MappedStatement mappers) {this.mappers.putAll(mappers);//此处需要使用追加的方式}public String getDriver() {return driver;}public void setDriver(String driver) {this.driver driver;}public String getUrl() {return url;}public void setUrl(String url) {this.url url;}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;}
} 2.2.2 MappedStatement
作用用来封装 sql语句 和 查询结果集即返回值类型
package com.by.mapping;public class MappedStatement {private String queryString;//SQLprivate String resultType;//实体类的全限定类名public String getQueryString() {return queryString;}public void setQueryString(String queryString) {this.queryString queryString;}public String getResultType() {return resultType;}public void setResultType(String resultType) {this.resultType resultType;}
} 2.3 SqlSessionFactory package com.by.factory;
public interface SqlSessionFactory {//获取SQLSession对象public SqlSession openSession();
}
package com.by.factory;import com.by.cfg.Configuration;
import com.by.session.DefaultSqlSession;
import com.by.session.SqlSession;public class DefaultSqlSessionFactory implements SqlSessionFactory {private Configuration cfg;public DefaultSqlSessionFactory(Configuration cfg) {this.cfg cfg;}/*** 获取一个SqlSession对象* return*/Overridepublic SqlSession openSession() {return new DefaultSqlSession(cfg);}
} 2.4 SqlSession public interface SqlSession {//获取代理对象public T T getMapper(ClassT tClass);//释放资源void close();
}
package com.by.session;import com.by.utils.DataSourceUtil;
import com.by.cfg.Configuration;import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.SQLException;public class DefaultSqlSession implements SqlSession {private Configuration cfg;private Connection conn;public DefaultSqlSession(Configuration cgf){this.cfg cgf;this.conn DataSourceUtil.getConnection(cfg);}/** 创建代理对象*/Overridepublic T T getMapper(ClassT tClass) {/*** tClass.getClassLoader()类加载器* new Class[]{tClass}Class数组让代理对象和被代理对象有相同的行为* new ProxyFactory调用真实角色附加自己的操作*/return (T) Proxy.newProxyInstance(tClass.getClassLoader(),new Class[]{tClass},new ProxyFactory(cfg.getMappers(),conn));}Overridepublic void close() {try {conn.close();} catch (SQLException e) {e.printStackTrace();}}
} 2.5 ProxyFactory package com.by.session;import com.by.mapping.MappedStatement;
import com.by.utils.Executor;import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.util.Map;public class ProxyFactory implements InvocationHandler {private MapString, MappedStatement mappers;private Connection conn;public ProxyFactory(MapString, MappedStatement mappers, Connection conn){this.mappers mappers;this.conn conn;}//调用代理对象的任何方法都会在这执行public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {//1.获取方法名String methodName method.getName();//2.获取方法所在类的名称String className method.getDeclaringClass().getName();//3.组合keyString key className.methodName;//4.获取mappers中的Mapper对象MappedStatement mappedStatement mappers.get(key);//5.判断是否有mapperif(mappedStatement null){throw new IllegalArgumentException(传入的参数有误);}//6.调用工具类执行查询所有return new Executor().selectList(mappedStatement,conn);}
} 3、测试
//1.读取配置文件InputStream in Resources.getResourceAsStream(SqlMapConfig.xml);//2.创建SqlSessionFactory工厂SqlSessionFactoryBuilder builder new SqlSessionFactoryBuilder();SqlSessionFactory factory builder.build(in);System.out.println(----- factory);//3.使用工厂生产SqlSession对象SqlSession session factory.openSession();//4.使用SqlSession创建Dao接口的代理对象UserDao userDao session.getMapper(UserDao.class);//5.使用代理对象执行方法ListUser users userDao.findAll();for(User user : users){System.out.println(user);}//6.释放资源session.close();in.close();
