IUserDao

package com.siyi.dao;import com.siyi.domain.User;
import com.siyi.mybatis.annotations.Select;import java.util.List;public interface IUserDao {/*** 查询所有操作* @return*/@Select("select * from user")List<User> findAll();
}

User

package com.siyi.domain;import java.io.Serializable;
import java.util.Date;public class User implements Serializable {private static final long serialVersionUID = 1L;private Integer id;private String username;private Date birthday;private String sex;private String address;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", birthday=" + birthday +", sex='" + sex + '\'' +", address='" + address + '\'' +'}';}
}

Select

package com.siyi.mybatis.annotations;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;/*** 查询注解*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Select {public String value();
}

Configuration

package com.siyi.mybatis.cfg;import java.util.HashMap;
import java.util.Map;public class Configuration {private String driver;private String url;private String username;private String password;private Map<String,Mapper> mappers = new HashMap<String, Mapper>();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;}public Map<String, Mapper> getMappers() {return mappers;}public void setMappers(Map<String, Mapper> mappers) {this.mappers.putAll(mappers);//追加}
}

Mapper

package com.siyi.mybatis.cfg;/*** 用于封装执行的sql语句和结果类型的全限定类名*/
public class Mapper {private String queryString;//sqlprivate String resultType;//实体类全限定名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;}
}

Resources

package com.siyi.mybatis.io;import java.io.InputStream;/*** 使用类加载器读取配置文件的类*/
public class Resources {/*** 根据传入的参数获取字节输入流* @param filePath* @return*/public static InputStream getResourceAsStream(String filePath) {return Resources.class.getClassLoader().getResourceAsStream(filePath);}
}

DefaultSqlSession

package com.siyi.mybatis.sqlsession.defaults;import com.siyi.mybatis.cfg.Configuration;
import com.siyi.mybatis.sqlsession.SqlSession;
import com.siyi.mybatis.sqlsession.proxy.MapperProxy;
import com.siyi.mybatis.utils.DataSourceUtil;import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.SQLException;/*** SqlSession接口的实现类*/
public class DefaultSqlSession implements SqlSession {private Configuration cfg;private Connection conn;public DefaultSqlSession(Configuration cfg){this.cfg = cfg;conn = DataSourceUtil.getConnection(cfg);}/*** 用于创建代理对象* @param daoInterfaceClass* @param <T>* @return*/public <T> T getMapper(Class<T> daoInterfaceClass) {return (T) Proxy.newProxyInstance(daoInterfaceClass.getClassLoader(),new Class[]{daoInterfaceClass},new MapperProxy(cfg.getMappers(),conn));}/*** 用于释放资源*/public void close() {if(conn == null) return;try {conn.close();} catch (SQLException e) {e.printStackTrace();}}
}

DefaultSqlSessionFactory

package com.siyi.mybatis.sqlsession.defaults;import com.siyi.mybatis.cfg.Configuration;
import com.siyi.mybatis.sqlsession.SqlSession;
import com.siyi.mybatis.sqlsession.SqlSessionFactory;/*** SqlSessionFactory接口的实现类*/
public class DefaultSqlSessionFactory implements SqlSessionFactory {private Configuration cfg;public DefaultSqlSessionFactory(Configuration cfg){this.cfg = cfg;}/*** 用于创建一个新的操作数据库对象* @return*/public SqlSession openSession() {return new DefaultSqlSession(cfg);}
}

MapperProxy

package com.siyi.mybatis.sqlsession.proxy;import com.siyi.mybatis.cfg.Mapper;
import com.siyi.mybatis.utils.Executor;import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.util.Map;public class MapperProxy implements InvocationHandler {//map的key是全限定类名+方法名private Map<String, Mapper> mappers;private Connection conn;public MapperProxy(Map<String,Mapper> mappers, Connection conn){this.mappers = mappers;this.conn = conn;}/*** 用户对方法进行增强,调用selectList方法* @param proxy* @param method* @param args* @return* @throws Throwable*/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Mapper mapper = mappers.get(key);//5.判断是否有mapperif(mapper == 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(mapper,conn);}
}

SqlSession

package com.siyi.mybatis.sqlsession;import com.siyi.dao.IUserDao;/*** 自定义mybatis中和数据库交互的核心类* 他可以创建dao接口的代理对象*/
public interface SqlSession {/*** 根据参数创建一个代理对象* @param daoInterfaceClass* @param <T>* @return*/public <T>T getMapper(Class<T> daoInterfaceClass) ;/*** 释放资源*/public void close();
}

SqlSessionFactory

package com.siyi.mybatis.sqlsession;public interface SqlSessionFactory {/*** 用于打开一个新的SqlSession对象* @return*/SqlSession openSession();
}

SqlSessionFactoryBuilder

package com.siyi.mybatis.sqlsession;import com.siyi.mybatis.cfg.Configuration;
import com.siyi.mybatis.sqlsession.defaults.DefaultSqlSessionFactory;
import com.siyi.mybatis.utils.XMLConfigBuilder;import java.io.InputStream;/*** 用于创建一个SqlSessionFactory对象*/
public class SqlSessionFactoryBuilder {public SqlSessionFactory build(InputStream config) {Configuration cfg = XMLConfigBuilder.loadConfiguration(config);return new DefaultSqlSessionFactory(cfg);}
}

DataSourceUtil

package com.siyi.mybatis.utils;import com.siyi.mybatis.cfg.Configuration;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class DataSourceUtil {/*** 用于获取连接* @param cfg* @return*/public static Connection getConnection(Configuration cfg) {try {Class.forName(cfg.getDriver());return DriverManager.getConnection(cfg.getUrl(), cfg.getUsername(), cfg.getPassword());} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}return null;}
}

Executor

package com.siyi.mybatis.utils;import com.siyi.mybatis.cfg.Mapper;import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List;/*** @author 黑马程序员* @Company http://www.ithiema.com* 负责执行SQL语句，并且封装结果集*/
public class Executor {public <E> List<E> selectList(Mapper mapper, Connection conn) {PreparedStatement pstm = null;ResultSet rs = null;try {//1.取出mapper中的数据String queryString = mapper.getQueryString();//select * from userString resultType = mapper.getResultType();//com.itheima.domain.UserClass domainClass = Class.forName(resultType);//2.获取PreparedStatement对象pstm = conn.prepareStatement(queryString);//3.执行SQL语句，获取结果集rs = pstm.executeQuery();//4.封装结果集List<E> list = new ArrayList<E>();//定义返回值while(rs.next()) {//实例化要封装的实体类对象E obj = (E)domainClass.newInstance();//取出结果集的元信息：ResultSetMetaDataResultSetMetaData rsmd = rs.getMetaData();//取出总列数int columnCount = rsmd.getColumnCount();//遍历总列数for (int i = 1; i <= columnCount; i++) {//获取每列的名称，列名的序号是从1开始的String columnName = rsmd.getColumnName(i);//根据得到列名，获取每列的值Object columnValue = rs.getObject(columnName);//给obj赋值：使用Java内省机制（借助PropertyDescriptor实现属性的封装）PropertyDescriptor pd = new PropertyDescriptor(columnName,domainClass);//要求：实体类的属性和数据库表的列名保持一种//获取它的写入方法Method writeMethod = pd.getWriteMethod();//把获取的列的值，给对象赋值writeMethod.invoke(obj,columnValue);}//把赋好值的对象加入到集合中list.add(obj);}return list;} catch (Exception e) {throw new RuntimeException(e);} finally {release(pstm,rs);}}private void release(PreparedStatement pstm,ResultSet rs){if(rs != null){try {rs.close();}catch(Exception e){e.printStackTrace();}}if(pstm != null){try {pstm.close();}catch(Exception e){e.printStackTrace();}}}
}

XMLConfigBuilder

package com.siyi.mybatis.utils;import com.siyi.mybatis.annotations.Select;
import com.siyi.mybatis.cfg.Configuration;
import com.siyi.mybatis.cfg.Mapper;
import com.siyi.mybatis.io.Resources;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.List;
import java.util.Map;/*** @author 黑马程序员* @Company http://www.ithiema.com*  用于解析配置文件*/
public class XMLConfigBuilder {/*** 解析主配置文件，把里面的内容填充到DefaultSqlSession所需要的地方* 使用的技术：*      dom4j+xpath*/public static Configuration loadConfiguration(InputStream config){try{//定义封装连接信息的配置对象（mybatis的配置对象）Configuration cfg = new Configuration();//1.获取SAXReader对象SAXReader reader = new SAXReader();//2.根据字节输入流获取Document对象Document document = reader.read(config);//3.获取根节点Element root = document.getRootElement();//4.使用xpath中选择指定节点的方式，获取所有property节点List<Element> propertyElements = root.selectNodes("//property");//5.遍历节点for(Element propertyElement : propertyElements){//判断节点是连接数据库的哪部分信息//取出name属性的值String name = propertyElement.attributeValue("name");if("driver".equals(name)){//表示驱动//获取property标签value属性的值String driver = propertyElement.attributeValue("value");cfg.setDriver(driver);}if("url".equals(name)){//表示连接字符串//获取property标签value属性的值String url = propertyElement.attributeValue("value");cfg.setUrl(url);}if("username".equals(name)){//表示用户名//获取property标签value属性的值String username = propertyElement.attributeValue("value");cfg.setUsername(username);}if("password".equals(name)){//表示密码//获取property标签value属性的值String password = propertyElement.attributeValue("value");cfg.setPassword(password);}}//取出mappers中的所有mapper标签，判断他们使用了resource还是class属性List<Element> mapperElements = root.selectNodes("//mappers/mapper");//遍历集合for(Element mapperElement : mapperElements){//判断mapperElement使用的是哪个属性Attribute attribute = mapperElement.attribute("resource");if(attribute != null){System.out.println("使用的是XML");//表示有resource属性，用的是XML//取出属性的值String mapperPath = attribute.getValue();//获取属性的值"com/itheima/dao/IUserDao.xml"//把映射配置文件的内容获取出来，封装成一个mapMap<String, Mapper> mappers = loadMapperConfiguration(mapperPath);//给configuration中的mappers赋值cfg.setMappers(mappers);}else{System.out.println("使用的是注解");//表示没有resource属性，用的是注解//获取class属性的值String daoClassPath = mapperElement.attributeValue("class");//根据daoClassPath获取封装的必要信息Map<String,Mapper> mappers = loadMapperAnnotation(daoClassPath);//给configuration中的mappers赋值cfg.setMappers(mappers);}}//返回Configurationreturn cfg;}catch(Exception e){throw new RuntimeException(e);}finally{try {config.close();}catch(Exception e){e.printStackTrace();}}}/*** 根据传入的参数，解析XML，并且封装到Map中* @param mapperPath    映射配置文件的位置* @return  map中包含了获取的唯一标识（key是由dao的全限定类名和方法名组成）*          以及执行所需的必要信息（value是一个Mapper对象，里面存放的是执行的SQL语句和要封装的实体类全限定类名）*/private static Map<String,Mapper> loadMapperConfiguration(String mapperPath)throws IOException {InputStream in = null;try{//定义返回值对象Map<String,Mapper> mappers = new HashMap<String,Mapper>();//1.根据路径获取字节输入流in = Resources.getResourceAsStream(mapperPath);//2.根据字节输入流获取Document对象SAXReader reader = new SAXReader();Document document = reader.read(in);//3.获取根节点Element root = document.getRootElement();//4.获取根节点的namespace属性取值String namespace = root.attributeValue("namespace");//是组成map中key的部分//5.获取所有的select节点List<Element> selectElements = root.selectNodes("//select");//6.遍历select节点集合for(Element selectElement : selectElements){//取出id属性的值      组成map中key的部分String id = selectElement.attributeValue("id");//取出resultType属性的值  组成map中value的部分String resultType = selectElement.attributeValue("resultType");//取出文本内容            组成map中value的部分String queryString = selectElement.getText();//创建KeyString key = namespace+"."+id;//创建ValueMapper mapper = new Mapper();mapper.setQueryString(queryString);mapper.setResultType(resultType);//把key和value存入mappers中mappers.put(key,mapper);}return mappers;}catch(Exception e){throw new RuntimeException(e);}finally{in.close();}}/*** 根据传入的参数，得到dao中所有被select注解标注的方法。* 根据方法名称和类名，以及方法上注解value属性的值，组成Mapper的必要信息* @param daoClassPath* @return*/private static Map<String,Mapper> loadMapperAnnotation(String daoClassPath)throws Exception{//定义返回值对象Map<String,Mapper> mappers = new HashMap<String, Mapper>();//1.得到dao接口的字节码对象Class daoClass = Class.forName(daoClassPath);//2.得到dao接口中的方法数组Method[] methods = daoClass.getMethods();//3.遍历Method数组for(Method method : methods){//取出每一个方法，判断是否有select注解boolean isAnnotated = method.isAnnotationPresent(Select.class);if(isAnnotated){//创建Mapper对象Mapper mapper = new Mapper();//取出注解的value属性值Select selectAnno = method.getAnnotation(Select.class);String queryString = selectAnno.value();mapper.setQueryString(queryString);//获取当前方法的返回值，还要求必须带有泛型信息Type type = method.getGenericReturnType();//List<User>//判断type是不是参数化的类型if(type instanceof ParameterizedType){//强转ParameterizedType ptype = (ParameterizedType)type;//得到参数化类型中的实际类型参数Type[] types = ptype.getActualTypeArguments();//取出第一个Class domainClass = (Class)types[0];//获取domainClass的类名String resultType = domainClass.getName();//给Mapper赋值mapper.setResultType(resultType);}//组装key的信息//获取方法的名称String methodName = method.getName();String className = method.getDeclaringClass().getName();String key = className+"."+methodName;//给map赋值mappers.put(key,mapper);}}return mappers;}
}

IUserDao.xml

<?xml version="1.0" encoding="UTF-8"?><mapper namespace="com.siyi.dao.IUserDao"><!--配置查询所有--><select id="findAll" resultType="com.siyi.domain.User">select * from user</select>
</mapper>

sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- mybatis的主配置文件 -->
<configuration><!--配置环境--><environments default="mysql"><!-- 配置mysql的环境 --><environment id="mysql"><!-- 配置事务的类型 --><transactionManager type="JDBC"></transactionManager><!-- 配置数据源（连接池）--><dataSource type="POOLED"><!-- 配置连接数据库的四个基本信息 --><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/mybatis"/><property name="username" value="root"/><property name="password" value="root"/></dataSource></environment></environments><!--指定映射配置文件的位置，映射配置文件指的是每个dao独立的配置文件--><mappers><!--<mapper resource="com/siyi/dao/IUserDao.xml"/>--><mapper class="com.siyi.dao.IUserDao"/></mappers>
</configuration>

MybatisTest

package com.siyi.test;import com.siyi.dao.IUserDao;
import com.siyi.domain.User;
import com.siyi.mybatis.io.Resources;
import com.siyi.mybatis.sqlsession.SqlSession;
import com.siyi.mybatis.sqlsession.SqlSessionFactory;
import com.siyi.mybatis.sqlsession.SqlSessionFactoryBuilder;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class MybatisTest {public static void main(String[] args) throws IOException {//1.读取配置文件InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");//2.创建 SqlSessionFactoy工厂SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();SqlSessionFactory factory = builder.build(in);//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IUserDao userDao = session.getMapper(IUserDao.class);//5.使用代理对象执行方法List<User> users = userDao.findAll();for (User user:users){System.out.println(user);}//6.释放资源session.close();in.close();}
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.siyi</groupId><artifactId>mybatis_design</artifactId><version>1.0-SNAPSHOT</version><dependencies><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.32</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version></dependency><dependency><groupId>dom4j</groupId><artifactId>dom4j</artifactId><version>1.6.1</version></dependency><dependency><groupId>jaxen</groupId><artifactId>jaxen</artifactId><version>1.1.6</version></dependency></dependencies>
</project>