MyBatis学习（三）

发表于 2023-07-15 更新于 2023-08-16 分类于计算机学习，框架， MyBatis 阅读次数：

简单手写MyBatis框架

package com.xiaoguan.godbatis;

/**
 * 框架的常用类
 */
public class Const {
    private Const() {
    }

    public static final String UN_POOLED_DATASOURCE="UNPOOLED";
    public static final String POOLED_DATASOURCE="POOLED";
    public static final String JNDI_DATASOURCE="JNDI";
    public static final String JDBC_TRANSACTION="JDBC";
    public static final String MANAGED_TRANSACTION="MANAGED";
}

package com.xiaoguan.godbatis;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

/**
 * JDBC事务管理器
 */
public class JDBCTransaction implements Transaction{
    private DataSource dataSource;
    private boolean autoCommit;
    private Connection connection;
    @Override
    public Connection getConnection() {
        return connection;
    }

    public JDBCTransaction(DataSource dataSource, boolean autoCommit) {
        this.dataSource = dataSource;
        this.autoCommit = autoCommit;
    }

    @Override
    public void commit() {
        try {
            connection.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }

    @Override
    public void rollback() {
        try {
            connection.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void close() {
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void  openConnection(){
        if (connection == null) {
            try {
                connection = dataSource.getConnection();
                connection.setAutoCommit(autoCommit);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

package com.xiaoguan.godbatis;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.logging.Logger;

public class JNDIDataSource implements javax.sql.DataSource{
    @Override
    public Connection getConnection() throws SQLException {
        return null;
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {

    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {

    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}

package com.xiaoguan.godbatis;

import java.sql.Connection;

/**
 * Managed事务管理器
 */
public class ManagedTransaction implements Transaction{
    @Override
    public void commit() {

    }

    @Override
    public void rollback() {

    }

    @Override
    public void close() {

    }

    @Override
    public void openConnection() {

    }

    @Override
    public Connection getConnection() {
        return null;
    }
}

package com.xiaoguan.godbatis;

import java.util.Objects;

/**
 * 封装了一个sql标签
 */
public class MappedStatement {
    private String sql;
    /**
     * 要封装的结果集类型
     */
    private String resultType;

    public MappedStatement() {
    }

    public MappedStatement(String sql, String resultType) {
        this.sql = sql;
        this.resultType = resultType;
    }

    public String getSql() {
        return sql;
    }

    public void setSql(String sql) {
        this.sql = sql;
    }

    @Override
    public String toString() {
        return "MappedStatement{" +
                "sql='" + sql + '\'' +
                ", resultType='" + resultType + '\'' +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        MappedStatement that = (MappedStatement) o;
        return Objects.equals(getSql(), that.getSql()) && Objects.equals(getResultType(), that.getResultType());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getSql(), getResultType());
    }

    public String getResultType() {
        return resultType;
    }

    public void setResultType(String resultType) {
        this.resultType = resultType;
    }
}

package com.xiaoguan.godbatis;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.logging.Logger;

/**
 * POOLED
 * 从数据库连接池获取Connection连接池对象
 */
public class PooledDataSource implements javax.sql.DataSource{
    @Override
    public Connection getConnection() throws SQLException {
        return null;
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {

    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {

    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}

package com.xiaoguan.godbatis;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;

/**
 * 专门负责执行sql语句的会话对象
 */
public class SqlSession {
    private SqlSessionFactory sqlSessionFactory;

    public SqlSession(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    public int insert(String sqlId,Object pojo){
        int count=0;
        Connection connection=null;
        PreparedStatement ps=null;
        try {
            connection=sqlSessionFactory.getTransaction().getConnection();
            String godSql=sqlSessionFactory.getSqlMap().get(sqlId).getSql();
            String sql=godSql.replaceAll("#\\{[0-9a-zA-Z_$]*}","?");
            ps = connection.prepareStatement(sql);
            int fromIndex=0;
            int index=0;
            while (true){
                int jingIndex=godSql.indexOf("#",fromIndex);
                if (jingIndex<0) {
                    break;
                }
                index++;
                int youKuoHaoIndex=godSql.indexOf("}",fromIndex);
                String prepareName = godSql.substring(jingIndex + 2, youKuoHaoIndex).trim();
                String getMethodName="get"+prepareName.toUpperCase().charAt(0)+prepareName.substring(1);
                Method getMethod = pojo.getClass().getDeclaredMethod(getMethodName);
                Object propertyValue = getMethod.invoke(pojo);
                ps.setString(index,propertyValue.toString());
                fromIndex=youKuoHaoIndex+1;
            }
            count = ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }finally {
            if (ps != null) {
                try {
                    ps.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

        return count;
    }

//    public static void main(String[] args) {
//        String sql="insert into dept values(#{deptno},#{dname},#{loc})";
//        int fromIndex=0;
//        int index=0;
//        while (true){
//            int jingIndex=sql.indexOf("#",fromIndex);
//            if (jingIndex<0) {
//                break;
//            }
//            index++;
//            System.out.println(index);
//            int youKuoHaoIndex=sql.indexOf("}",fromIndex);
//            String prepareName = sql.substring(jingIndex + 2, youKuoHaoIndex).trim();
//            System.out.println(prepareName);
//            fromIndex=youKuoHaoIndex+1;
//        }
//    }
    public Object selectOne(String sqlId,Object param){
        Object obj=null;
        Connection connection=sqlSessionFactory.getTransaction().getConnection();
        PreparedStatement ps=null;
        ResultSet rs=null;
        try {
            MappedStatement mappedStatement = sqlSessionFactory.getSqlMap().get(sqlId);
            String godsql = mappedStatement.getSql();
            String resultType = mappedStatement.getResultType();
            String sql=godsql.replaceAll("#\\{[0-9a-zA-Z_$]*}","?");
            ps = connection.prepareStatement(sql);
            ps.setString(1,param.toString());
            rs = ps.executeQuery();
            if(rs.next()){
                Class resultTypeClass = Class.forName(resultType);
                 obj = resultTypeClass.newInstance();
                ResultSetMetaData metaData = rs.getMetaData();
                int columnCount = metaData.getColumnCount();
                for (int i = 0; i < columnCount; i++) {
                    String propertyName = metaData.getColumnName(i+1);
                    String setMethodName="set"+propertyName.toUpperCase().charAt(0)+propertyName.substring(1);
                    Method setMethod = resultTypeClass.getDeclaredMethod(setMethodName,String.class);
                    setMethod.invoke(obj,rs.getString(propertyName));
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                   e.printStackTrace();
                }
            }
            if (ps != null) {
                try {
                    ps.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        return obj;
    }
    public void commit(){
        sqlSessionFactory.getTransaction().commit();
    }

    public void rollback(){
        sqlSessionFactory.getTransaction().rollback();
    }

    public void close(){
        sqlSessionFactory.getTransaction().close();
    }

}

package com.xiaoguan.godbatis;

import java.sql.Connection;
import java.util.Map;

public class SqlSessionFactory {
    /**
     * 事务管理器属性
     */
    private Transaction transaction;
    private Map<String,MappedStatement> sqlMap;
    public SqlSessionFactory(Transaction transaction, Map<String, MappedStatement> sqlMap) {
        this.transaction = transaction;
        this.sqlMap = sqlMap;
    }

    public SqlSessionFactory() {
    }

    public Transaction getTransaction() {
        return transaction;
    }

    public void setTransaction(Transaction transaction) {
        this.transaction = transaction;
    }

    public Map<String, MappedStatement> getSqlMap() {
        return sqlMap;
    }

    public void setSqlMap(Map<String, MappedStatement> sqlMap) {
        this.sqlMap = sqlMap;
    }

    /**
     * 获取sql会话对象
     * @return sqlSession
     */
    public SqlSession openSession(){
        transaction.openConnection();
        SqlSession sqlSession = new SqlSession(this);
        return sqlSession;
    }
}

package com.xiaoguan.godbatis;

import com.xiaoguan.utils.Resources;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

import javax.sql.DataSource;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 构建器对象
 */
public class SqlSessionFactoryBuilder {
    public SqlSessionFactoryBuilder() {
    }

    /**
     * 返回指向godbatis-config.xml的SqlSessionFactory对象
     * @param in
     * @return SqlSessionFactory
     */
    public SqlSessionFactory build(InputStream in){
        SqlSessionFactory sqlSessionFactory=null;
        try {
            SAXReader reader=new SAXReader();
            Document document = reader.read(in);
            Element environments = (Element) document.selectSingleNode("/configuration/environments");
            String environmentsDefault = environments.attributeValue("default");
            Element environment = (Element) document.selectSingleNode("/configuration/environments/environment[@id='" + environmentsDefault + "']");
            //获取事务管理器节点
            Element transactionManager = environment.element("transactionManager");
            Element dataSourceElt = environment.element("dataSource");
            List<String> sqlMapperXMLPath= new ArrayList<>();
            List<Node> nodes = document.selectNodes("//mapper");
            nodes.forEach(node -> {
                Element mapperElts = (Element) node;
                String resource = mapperElts.attributeValue("resource");
                sqlMapperXMLPath.add(resource);
            });
            DataSource dataSource=getDataSource(dataSourceElt);
            Transaction transaction=getTransaction(dataSource,transactionManager);
            Map<String, MappedStatement> sqlMap=getMappedStatements(sqlMapperXMLPath);
            sqlSessionFactory = new SqlSessionFactory(transaction,sqlMap);
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        return sqlSessionFactory;

    }

    private Map<String, MappedStatement> getMappedStatements(List<String> sqlMapperXMLPath) {
        Map<String, MappedStatement> stringMappedStatementMap =new HashMap<>();
        sqlMapperXMLPath.forEach(sqlFile->{
            try {
                SAXReader saxReader = new SAXReader();
                Document document = saxReader.read(Resources.getResourceAsStream(sqlFile));
                Element mapperElements = (Element) document.selectSingleNode("mapper");
                String namespace = mapperElements.attributeValue("namespace");
                List<Element> mapperChildElements = mapperElements.elements();
                mapperChildElements.forEach(element -> {
                    String id = element.attributeValue("id");
                    String sqlId=namespace+"."+id;
                    String resultType = element.attributeValue("resultType");
                    String sql = element.getTextTrim();
                    MappedStatement mappedStatement = new MappedStatement(sql, resultType);
                    stringMappedStatementMap.put(sqlId,mappedStatement);
                });
            } catch (DocumentException e) {
                e.printStackTrace();
            }
        });
        return stringMappedStatementMap;
    }

    private Transaction getTransaction(DataSource dataSource, Element transactionManager) {
        Transaction transaction=null;
        String JDBCType = transactionManager.attributeValue("type").trim().toUpperCase();
        if (Const.JDBC_TRANSACTION.equals(JDBCType)) {
            transaction =new JDBCTransaction(dataSource,false);
        }
        if (Const.MANAGED_TRANSACTION.equals(JDBCType)) {
            transaction=new ManagedTransaction();
        }
        return transaction;

    }

    private DataSource getDataSource(Element dataSourceElt) {
        Map<String,String> map=new HashMap<>();
        String dataSourceType = dataSourceElt.attributeValue("type").trim().toUpperCase();
        List<Element> propertyElts = dataSourceElt.elements("property");
        propertyElts.forEach(propertyElt ->{
            String name = propertyElt.attributeValue("name");
            String value = propertyElt.attributeValue("value");
            map.put(name,value);
        });
        DataSource dataSource=null;
        if (Const.UN_POOLED_DATASOURCE.equals(dataSourceType)) {
            dataSource=new UnPooledDataSource(map.get("driver"),map.get("url"),map.get("username"),map.get("password"));
        }
        if (Const.POOLED_DATASOURCE.equals(dataSourceType)) {
            dataSource=new PooledDataSource();
        }
        if (Const.JNDI_DATASOURCE.equals(dataSourceType)) {
            dataSource=new JNDIDataSource();
        }
        return dataSource;


    }
}

package com.xiaoguan.godbatis;

import java.sql.Connection;

/**
 * 事务管理接口
 */
public interface Transaction {
    /**
     * 提交事务，管理事务，关闭事务
     */
    void commit();
    void rollback();
    void close();
    void  openConnection();
    Connection getConnection();
}

package com.xiaoguan.godbatis;


import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.logging.Logger;

/**
 * 数据源的实现类UNPPPLED
 * 不使用数据库连接池，每一次都新建对象
 */
public class UnPooledDataSource implements javax.sql.DataSource {
    private String url;
    private  String username;
    private  String password;

    public UnPooledDataSource(String driver, String url, String username, String password) {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        this.url = url;
        this.username = username;
        this.password = password;
    }

    @Override
    public Connection getConnection() throws SQLException {
        Connection connection = DriverManager.getConnection(url, username, password);
        return connection;
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {

    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {

    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}

package com.xiaoguan.pojo;

import java.util.Objects;

/**
 * 封装汽车相关信息的普通java类
 */
public class Car {
    //建议使用包装类
    private Long id;
    private String carNum;
    private  String brand;
    private Double guidePrice;
    private String produceTime;
    private String carType;

    public Car() {
    }

    public Car(Long id, String carNum, String brand, Double guidePrice, String produceTime, String carType) {
        this.id = id;
        this.carNum = carNum;
        this.brand = brand;
        this.guidePrice = guidePrice;
        this.produceTime = produceTime;
        this.carType = carType;
    }

    @Override
    public String toString() {
        return "Car{" +
                "id=" + id +
                ", carNum='" + carNum + '\'' +
                ", brand='" + brand + '\'' +
                ", guidePrice=" + guidePrice +
                ", produceTime='" + produceTime + '\'' +
                ", carType='" + carType + '\'' +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Car car = (Car) o;
        return Objects.equals(getId(), car.getId()) && Objects.equals(getCarNum(), car.getCarNum()) && Objects.equals(getBrand(), car.getBrand()) && Objects.equals(getGuidePrice(), car.getGuidePrice()) && Objects.equals(getProduceTime(), car.getProduceTime()) && Objects.equals(getCarType(), car.getCarType());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getId(), getCarNum(), getBrand(), getGuidePrice(), getProduceTime(), getCarType());
    }

    public Long getId() {
        return id;
    }

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

    public String getCarNum() {
        return carNum;
    }

    public void setCarNum(String carNum) {
        this.carNum = carNum;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public Double getGuidePrice() {
        return guidePrice;
    }

    public void setGuidePrice(Double guidePrice) {
        this.guidePrice = guidePrice;
    }

    public String getProduceTime() {
        return produceTime;
    }

    public void setProduceTime(String produceTime) {
        this.produceTime = produceTime;
    }

    public String getCarType() {
        return carType;
    }

    public void setCarType(String carType) {
        this.carType = carType;
    }
}

package com.xiaoguan.utils;

import java.io.InputStream;

/**
 * 专门完成类路径的加载
 */
public class Resources {
    private Resources() {
    }

    /**
     * 从类路径加载资源
     * @param resource
     * @return InputStream
     */
    public static InputStream getResourceAsStream(String resource){
        return ClassLoader.getSystemClassLoader().getResourceAsStream(resource);
    }
}

package com.xiaoguan.pojo;

import java.util.Objects;

public class User {
    private String id;
    private String name;
    private  String age;

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age='" + age + '\'' +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(getId(), user.getId()) && Objects.equals(getName(), user.getName()) && Objects.equals(getAge(), user.getAge());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getId(), getName(), getAge());
    }

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public User(String id, String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public User() {
    }
}

package com.xiaoguan.test;

import com.xiaoguan.godbatis.SqlSession;
import com.xiaoguan.godbatis.SqlSessionFactory;
import com.xiaoguan.godbatis.SqlSessionFactoryBuilder;
import com.xiaoguan.pojo.User;
import com.xiaoguan.utils.Resources;
import org.junit.Test;

public class GodBatisTest {
    @Test
    public void testSelectOne(){
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Object obj = sqlSession.selectOne("xiaoguan.selectById", "224");
        System.out.println(obj);
//        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void testInsertUser(){
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        User user = new User("222", "xiaoguan", "22");
        int count = sqlSession.insert("xiaoguan.insertUser", user);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void testSqlSessionFactory(){
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory build = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("mybatis-config.xml"));
        System.out.println(build);
    }
}

package com.xiaoguan.test;

import org.dom4j.*;
import org.dom4j.io.SAXReader;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;

public class ParseXMLByDom4jTest {
    @Test
    public void testParseSqlMapperXML() throws DocumentException {
        SAXReader saxReader = new SAXReader();
        Document carMapper = saxReader.read(ClassLoader.getSystemClassLoader().getResourceAsStream("CarMapper.xml"));
        String xpath="/mapper";
        Element mapper =(Element) carMapper.selectSingleNode(xpath);
        String namespace = mapper.attributeValue("namespace");
        System.out.println(namespace);
        List<Element> elements = mapper.elements();
        elements.forEach(element -> {
            String id = element.attributeValue("id");
            System.out.println(id);
            //获取resultType
            String resultType = element.attributeValue("resultType");
            System.out.println(resultType);
            //获取标签中的sql语句
            String text = element.getTextTrim();
            System.out.println(text);
            String sql = text.replaceAll("#\\{[0-9A-Za-z_$]*}", "?");
            System.out.println(sql);
        });


    }
    @Test
    public void testParseMybatisConfigXML() throws DocumentException {
        SAXReader saxReader = new SAXReader();
        InputStream resourceAsStream = ClassLoader.getSystemClassLoader().getResourceAsStream("mybatis-config.xml");
        Document document = saxReader.read(resourceAsStream);
//        Element rootElement = document.getRootElement();
//        String rootElementName = rootElement.getName();
//        System.out.println(rootElementName);//获取根节点
        String xpath="/configuration/environments";
        Element environments =(Element) document.selectSingleNode(xpath);
        String defaultValue = environments.attributeValue("default");
        xpath="/configuration/environments/environment[@id='"+defaultValue+"']";
        Element environment = (Element) document.selectSingleNode(xpath);
        Element transactionManager = environment.element("transactionManager");//element用来获取孩子节点
        String transactionType = transactionManager.attributeValue("type");
//        System.out.println("事务管理器类型："+transactionType);
        Element dataSource = environment.element("dataSource");
        String dataSourceType = dataSource.attributeValue("type");
//        System.out.println("数据源类型"+dataSourceType);
        List<Element> properties = dataSource.elements("property");

        properties.forEach(propertyElement ->{
            String name = propertyElement.attributeValue("name");
            String value = propertyElement.attributeValue("value");
            System.out.println(name+"="+value);
        });
        //获取所有的map标签
        xpath="//mappers";//不想从根开始写可以用//来代替
        Element mappers =(Element) document.selectSingleNode(xpath);
        List<Element> mapper = mappers.elements("mapper");
        mapper.forEach(mapperValue -> {
            String resourceValue = mapperValue.attributeValue("resource");
            System.out.println(resourceValue);
        });

    }
}

框架的测试

package com.xiaoguan.pojo;

import java.util.Objects;

public class User {
    private String id;
    private String name;
    private String age;

    public User() {
    }

    public User(String id, String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(getId(), user.getId()) && Objects.equals(getName(), user.getName()) && Objects.equals(getAge(), user.getAge());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getId(), getName(), getAge());
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age='" + age + '\'' +
                '}';
    }
}

<?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="UNPOOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="68963120g"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

<?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="xiaoguan">
    <insert id="testgabatis" >
        insert into t_user values(#{id},#{name},#{age});
    </insert>
    <select id="select" resultType="com.xiaoguan.pojo.User">
        select * from t_user where id=#{id};
    </select>
</mapper>

package com.xiaoguan.test;

import com.xiaoguan.godbatis.SqlSession;
import com.xiaoguan.godbatis.SqlSessionFactory;
import com.xiaoguan.godbatis.SqlSessionFactoryBuilder;
import com.xiaoguan.pojo.User;
import com.xiaoguan.utils.Resources;
import org.junit.Test;

public class UserMapperTest {
    @Test
    public void testInsert(){
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("godbatis.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        User user = new User("1234567", "xiaoguan", "23");
        int count = sqlSession.insert("xiaoguan.testgabatis", user);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void testSelect(){
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("godbatis.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Object objUser = sqlSession.selectOne("xiaoguan.select", 1234567);
        System.out.println(objUser);
        sqlSession.close();
    }
}