模拟Mybatis的实现方法-eolink官网

模拟Mybatis的实现方法

所需要用到的其他工具或技术:

项目管理工具 : Maven

测试运行工具 : Junit

数据库 : Derby

XML操作工具:Dom4j

继续不废话

Maven Dependencies:

junit

4.9

test

org.apache.derby

derby

10.10.2.0

org.apache.derby

derbyclient

10.10.2.0

dom4j

1.6.1

SQL 建表及数据插入（如果在第http://一节中作过，可以跳过此步）:

CREATE TABLE USER_TEST_TB(

ID INT PRIMARY KEY,

USERNAME VARCHAR(20) NOT NULL,

PASSWORD VARCHAR(20) NOT NULL,

NICKNAME VARCHAR(20) NOT NULL

);

INSERT INTO USER_TEST_TB VALUES(1,'1st','111','Jack');

INSERT INTO USER_TEST_TB VALUES(2,'2nd','222','Rose');

INSERT INTO USER_TEST_TB VALUES(3,'3rd','333','Will');

Mybatis配置文件 src/main/resource源目录下

test-mybatis-configuration.xml

value="jdbc:derby://localhost:1527/bjpowernode;create=true" />

User.java对象类(src/main/java/com/bjpowernode/poJaEkbSTLSractice目录下)

package com.bjpowernode.practice;

/**

* User Model

public class User

{

private String id;

private String username;

private String password;

private String nickname;

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 String getNickname()

{

return nickname;

}

public void setNickname(String nickname)

{

this.nickname = nickname;

}

Select.java 注解类（src/main/java/com/bjpowernode/practice/annotation目录下）

package com.bjpowernode.practice.annotation;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/** 标注此注解只能用在方法上 */

@Target(ElementType.METHOD)

/** 标注此注解生命周期是在Runtime运行时 */

@Retention(RetentionPolicy.RUNTIME)

public @interface Select

{

String value();

}

UserMapper.java 基于Annotation的配置类（src/main/java/com/bjpowernode/practice/annotation目录下）

package com.bjpowernode.practice.annotation;

import com.bjpowernode.practice.User;

import java.util.List;

public interface UserMapper

{

@Select("select * from USER_TEST_TB")

public List getUser();

}

Mapper.java 对象类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

/**

* 存储查询结果对象

public class Mapper

{

/**

* 返回类型

private String resultType;

/**

* 查询ＳＱＬ

private String querySql;

public String getResultType()

{

return resultType;

}

public void setResultType(String resultType)

{

this.resultType = resultType;

}

public String getQuerySql()

{

return querySql;

}

public void setQuerySql(String querySql)

{

this.querySql = querySql;

}

SQLSelectProxy.java AOP动态代理类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import com.bjpowernode.practice.annotation.Select;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.List;

public class SQLSelectProxy implements InvocationHandler

{

@Override

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable

{

/**

* 获得Mapper方法上的Select注解,以此来取得注解中的SQL语句

Select select = method.getAnnotation(Select.class);

if (!method.isAnnotationPresent(Select.class))

{

throw new RuntimeException("缺少@Select注解!");

}

PreparedStatement pstmt = null;

ResultSet rs = null;

Object obj = null;

try

{

pstmt = SqlSessionImpl.connection.prepareStatement(select.value());

rs = pstmt.executeQuery();

/**

* 获得Method的返回对象类型,此处应当作判断处理,当List的时候,当只返回一个对象的时候.

* 为了简单实现功能并与第一节中测试文件不发生冲突起见,此处当作List处理

String returnType = method.getGenericReturnType().toString();//java.util.List

if (returnType.startsWith(List.class.getName()))

{

//去掉我们不需要的字符串，得到List中的类型

returnType = returnType.replace(List.class.getName(), "").replace("<", "").replace(">", "");

}

else

{

// 返回其他对象应当作其他处理，此处为了简单起见，暂不处理

}

obj = SqlSessionImpl.executeQuery(rs, returnType);

}

finally

{

if (rs != null && !rs.isClosed())

{

rs.close();

}

if (pstmt != null && !pstmt.isClosed())

{

pstmt.close();

}

return obj;

}

SqlSession.java Mybatis模拟接口（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.util.List;

/**

* 模拟SqlSession

public interface SqlSession

{

public T getMapper(Class clazz);

public List selectList(String query) throws Exception;

}

SqlSessionFactory.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.io.IOException;

import java.io.InputStream;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.dom4j.Document;

import org.dom4j.DocumentException;

import org.dom4j.Element;

import org.dom4j.io.SAXReader;

/**

* 模拟SqlSessionFactory

public class SqlSessionFactory

{

private InputStream configuration;

public SqlSession openSession() throws IOException

{

SqlSessionImpl session = new SqlSessionImpl();

loadConfigurations(session);

return session;

}

/**

* 通过Ｄｏｍ４ｊ读取配置文件信息

* @param session

* @throws IOException

private void loadConfigurations(final SqlSessionImpl session) throws IOException

{

try

{

Document document = new SAXReader().read(configuration);

Element root = document.getRootElement();

List mappers = root.element("mappers").elements("mapper");

for (Element mapper : mappers)

{

if (mapper.attribute("resource") != null)

{

session.setXmlSQLs(loadXMLConfiguration(mapper.attribute("resource").getText()));

}

if (mapper.attribute("class") != null)

{

}

catch (Exception e)

{

System.out.println("读取配置文件错误!");

}

finally

{

configuration.close();

}

/**

* 通过ｄｏｍ４ｊ读取Ｍａｐｐｅｒ．ｘｍｌ中的信息

* @param resource

* @return

* @throws DocumentException

* @throws IOException

private Map loadXMLConfiguration(String resource) throws DocumentException, IOException

{

Map map = new HashMap();

InputStream is = null;

try

{

is = this.getClass().getClassLoader().getResourceAsStream(resource);

Document document = new SAXReader().read(is);

Element root = document.getRootElement();

if (root.getName().equalsIgnoreCase("mapper"))

{

String namespace = root.attribute("namespace").getText();

for (Element select : (List) root.elements("select"))

{

Mapper mapperModel = new Mapper();

mapperModel.setResultType(select.attribute("resultType").getText());

mapperModel.setQuerySql(select.getText().trim());

map.put(namespace + "." + select.attribute("id").getText(), mapperModel);

}

finally

{

is.close();

}

return map;

}

public InputStream getConfiguration()

{

return configuration;

}

public void setConfiguration(InputStream configuration)

{

this.configuration = configuration;

}

SqlSessionFactoryBuilder.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.io.InputStream;

/**

* 模拟SqlSessionFactoryBuilder

public class SqlSessionFactoryBuilder

{

public SqlSessionFactory build(InputStream is)

{

SqlSessionFactory sessionFactory = new SqlSessionFactory();

sessionFactory.setConfiguration(is);

return sessionFactory;

}

SqlSessionImpl.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.ArrayList;

import java.util.List;

import java.util.Map;

/**

* 模拟SqlSessionImpl

public class SqlSessionImpl implements SqlSession

{

/** DB connection */

public static Connection connection;

private Map xmlSQLs;

private List annotationClasses;

public SqlSessionImpl()

{

/**

* driverString 和 connString 应该是从配置文件读取，这里简化了

final String driverString = "org.apache.derby.jdbc.ClientDriver";

final String connString = "jdbc:derby://localhost:1527/bjpowernode;create=true";

try

{

Class.forName(driverString);

/** 获得DB连接 */

connection = DriverManager.getConnection(connString);

}

catch (Exception e)

{

System.out.println("获取DBConnection出错！");

}

/**

* 基于Annotation的数据库操作

@Override

public T getMapper(Class clazz)

{

T clazzImpl =

(T) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[] {clazz}, new SQLSelectProxy());

return clazzImpl;

}

/**

* 基于XML的查询操作

@Override

public List selectList(String query) throws Exception

{

PreparedStatement pstmt = null;

ResultSet rs = null;

try

{

/** 简单的PreparedStateme JDBC实现 */

pstmt = connection.prepareStatement(xmlSQLs.get(query).getQuerySql());

rs = pstmt.executeQuery();

/** 执行查询操作 */

return executeQuery(rs, xmlSQLs.get(query).getResultType());

}

finally

{

if (!rs.isClosed())

{

rs.close();

}

if (!pstmt.isClosed())

{

pstmt.close();

}

/**

* 执行查询操作，并将查询到的结果与配置中的ResultType根据变量名一一对应，通过反射调用Set方法注入各个变量的值

* @param rs

* @param type

* @return

* @throws Exception

public static List executeQuery(ResultSet rs, String type) throws Exception

{

int count = rs.getMetaData().getColumnCount();

List columnNames = new ArrayList();

for (int i = 1; i <= count; i++)

{

columnNames.add(rs.getMetaData().getColumnName(i));

}

final List list = new ArrayList

while (rs.next())

{

Class modelClazz = Class.forName(type);

Object obj = modelClazz.newInstance();

for (Method setMethods : modelClazz.getMethods())

{

for (String columnName : columnNames)

{

if (setMethods.getName().equalsIgnoreCase("set" + columnName))

{

setMethods.invoke(obj, rs.getString(columnName));

}

list.add(obj);

}

return list;

}

public Map getXmlSQLs()

{

return xmlSQLs;

}

public void setXmlSQLs(Map xmlSQLs)

{

this.xmlSQLs = xmlSQLs;

}

public List getAnnotationClasses()

{

return annotationClasses;

}

public void setAnnotationClasses(List annotationClasses)

{

this.annotationClasses = annotationClasses;

}

UserMapper.xml 基于XML的Mapper配置文件（src/main/java/com/bjpowernode/practice/xml目录下）

select *

from USER_TEST_TB

TestMyBatis.java 测试类(src/test/java/com/bjpowernode/practice目录下)

package com.bjpowernode.practice;

import com.bjpowernode.practice.annotation.UserMapper;

import com.bjpowernode.practice.simulation.SqlSession;

import com.bjpowernode.practice.simulation.SqlSessionFactory;

import com.bjpowernode.practice.simulation.SqlSessionFactoryBuilder;

import com.bjpowernode.practice.simulation.SqlSessionImpl;

import java.io.InputStream;

import java.sql.SQLException;

import java.text.MessageFormat;

import java.util.List;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

public class TestMyBatis

{

/** 配置置文件 */

private String source;

private InputStream inputStream;

private SqlSessionFactory sqlSessionFactory;

@Before

public void setUp()

{

source = "test-mybatis-configuration.xml";

}

/**

* 基于XML格式配置的测试方法

@Test

public void testXMLConfingure()

{

try

{

/**

* 获得Session

inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession session = sqlSessionFactory.openSession();

/**

* 执行Ｑｕｅｒｙ操作

List users = (List) session.selectList("com.bjpowernode.practice.UserMapper.getUser");

System.out.println("Query by XML configuration...");

/**

* 打印结果

this.printUsers(users);

}

catch (Exception e)

{

e.printStackTrace();

}

/**

* 基于Annotation配置的测试方法

@Test

public void testAnnotationConfingure()

{

try

{

inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession session = sqlSessionFactory.openSession();

UserMapper userMapper = session.getMapper(UserMapper.class);

System.out.println("\r\nQuery by annotation configuration...");

this.printUsers(userMapper.getUser());

}

catch (Exception e)

{

e.printStackTrace();

}

@After

public void clearUp() throws SQLException

{

if (SqlSessionImpl.connection != null && !SqlSessionImpl.connection.isClosed())

{

SqlSessionImpl.connection.close();

}

private void printUsers(final List users)

{

int count = 0;

for (User user : users)

{

System.out.println(MessageFormat.format("==User[{0}]=================", ++count));

System.out.println("User Id: " + user.getId());

System.out.println("User UserName: " + user.getUsername());

System.out.println("User Password: " + user.getPassword());

System.out.println("User nickname: " + user.getNickname());

}

以上就是基于XML以及Annotation的方式对Mybatis实现了一个简单的模拟。旨在理解Mybatis的工作原理。

笔者一直觉得当学习一个工具类技术的时候，路线应该是

1.实现一个小例子

2.找材料理解其中原理

3.学习技术细节，并动手全部实现

4.在全部学完之后动手做一个小项目，尽可能的使用这个在技术中的各个环节。

总结

以上所述是给大家介绍的模拟Mybatis的实现方法，希望对大家有所帮助，如果大家有任何疑问请给我留言，会及时回复大家的。在此也非常感谢大家对我们网站的支持！

value="jdbc:derby://localhost:1527/bjpowernode;create=true" />

User.java对象类(src/main/java/com/bjpowernode/poJaEkbSTLSractice目录下)

package com.bjpowernode.practice;

/**

* User Model

public class User

{

private String id;

private String username;

private String password;

private String nickname;

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 String getNickname()

{

return nickname;

}

public void setNickname(String nickname)

{

this.nickname = nickname;

}

Select.java 注解类（src/main/java/com/bjpowernode/practice/annotation目录下）

package com.bjpowernode.practice.annotation;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/** 标注此注解只能用在方法上 */

@Target(ElementType.METHOD)

/** 标注此注解生命周期是在Runtime运行时 */

@Retention(RetentionPolicy.RUNTIME)

public @interface Select

{

String value();

}

UserMapper.java 基于Annotation的配置类（src/main/java/com/bjpowernode/practice/annotation目录下）

package com.bjpowernode.practice.annotation;

import com.bjpowernode.practice.User;

import java.util.List;

public interface UserMapper

{

@Select("select * from USER_TEST_TB")

public List getUser();

}

Mapper.java 对象类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

/**

* 存储查询结果对象

public class Mapper

{

/**

* 返回类型

private String resultType;

/**

* 查询ＳＱＬ

private String querySql;

public String getResultType()

{

return resultType;

}

public void setResultType(String resultType)

{

this.resultType = resultType;

}

public String getQuerySql()

{

return querySql;

}

public void setQuerySql(String querySql)

{

this.querySql = querySql;

}

SQLSelectProxy.java AOP动态代理类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import com.bjpowernode.practice.annotation.Select;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.List;

public class SQLSelectProxy implements InvocationHandler

{

@Override

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable

{

/**

* 获得Mapper方法上的Select注解,以此来取得注解中的SQL语句

Select select = method.getAnnotation(Select.class);

if (!method.isAnnotationPresent(Select.class))

{

throw new RuntimeException("缺少@Select注解!");

}

PreparedStatement pstmt = null;

ResultSet rs = null;

Object obj = null;

try

{

pstmt = SqlSessionImpl.connection.prepareStatement(select.value());

rs = pstmt.executeQuery();

/**

* 获得Method的返回对象类型,此处应当作判断处理,当List的时候,当只返回一个对象的时候.

* 为了简单实现功能并与第一节中测试文件不发生冲突起见,此处当作List处理

String returnType = method.getGenericReturnType().toString();//java.util.List

if (returnType.startsWith(List.class.getName()))

{

//去掉我们不需要的字符串，得到List中的类型

returnType = returnType.replace(List.class.getName(), "").replace("<", "").replace(">", "");

}

else

{

// 返回其他对象应当作其他处理，此处为了简单起见，暂不处理

}

obj = SqlSessionImpl.executeQuery(rs, returnType);

}

finally

{

if (rs != null && !rs.isClosed())

{

rs.close();

}

if (pstmt != null && !pstmt.isClosed())

{

pstmt.close();

}

return obj;

}

SqlSession.java Mybatis模拟接口（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.util.List;

/**

* 模拟SqlSession

public interface SqlSession

{

public T getMapper(Class clazz);

public List selectList(String query) throws Exception;

}

SqlSessionFactory.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.io.IOException;

import java.io.InputStream;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.dom4j.Document;

import org.dom4j.DocumentException;

import org.dom4j.Element;

import org.dom4j.io.SAXReader;

/**

* 模拟SqlSessionFactory

public class SqlSessionFactory

{

private InputStream configuration;

public SqlSession openSession() throws IOException

{

SqlSessionImpl session = new SqlSessionImpl();

loadConfigurations(session);

return session;

}

/**

* 通过Ｄｏｍ４ｊ读取配置文件信息

* @param session

* @throws IOException

private void loadConfigurations(final SqlSessionImpl session) throws IOException

{

try

{

Document document = new SAXReader().read(configuration);

Element root = document.getRootElement();

List mappers = root.element("mappers").elements("mapper");

for (Element mapper : mappers)

{

if (mapper.attribute("resource") != null)

{

session.setXmlSQLs(loadXMLConfiguration(mapper.attribute("resource").getText()));

}

if (mapper.attribute("class") != null)

{

}

catch (Exception e)

{

System.out.println("读取配置文件错误!");

}

finally

{

configuration.close();

}

/**

* 通过ｄｏｍ４ｊ读取Ｍａｐｐｅｒ．ｘｍｌ中的信息

* @param resource

* @return

* @throws DocumentException

* @throws IOException

private Map loadXMLConfiguration(String resource) throws DocumentException, IOException

{

Map map = new HashMap();

InputStream is = null;

try

{

is = this.getClass().getClassLoader().getResourceAsStream(resource);

Document document = new SAXReader().read(is);

Element root = document.getRootElement();

if (root.getName().equalsIgnoreCase("mapper"))

{

String namespace = root.attribute("namespace").getText();

for (Element select : (List) root.elements("select"))

{

Mapper mapperModel = new Mapper();

mapperModel.setResultType(select.attribute("resultType").getText());

mapperModel.setQuerySql(select.getText().trim());

map.put(namespace + "." + select.attribute("id").getText(), mapperModel);

}

finally

{

is.close();

}

return map;

}

public InputStream getConfiguration()

{

return configuration;

}

public void setConfiguration(InputStream configuration)

{

this.configuration = configuration;

}

SqlSessionFactoryBuilder.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.io.InputStream;

/**

* 模拟SqlSessionFactoryBuilder

public class SqlSessionFactoryBuilder

{

public SqlSessionFactory build(InputStream is)

{

SqlSessionFactory sessionFactory = new SqlSessionFactory();

sessionFactory.setConfiguration(is);

return sessionFactory;

}

SqlSessionImpl.java Mybatis模拟类（src/main/java/com/bjpowernode/practice/simulation目录下）

package com.bjpowernode.practice.simulation;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.ArrayList;

import java.util.List;

import java.util.Map;

/**

* 模拟SqlSessionImpl

public class SqlSessionImpl implements SqlSession

{

/** DB connection */

public static Connection connection;

private Map xmlSQLs;

private List annotationClasses;

public SqlSessionImpl()

{

/**

* driverString 和 connString 应该是从配置文件读取，这里简化了

final String driverString = "org.apache.derby.jdbc.ClientDriver";

final String connString = "jdbc:derby://localhost:1527/bjpowernode;create=true";

try

{

Class.forName(driverString);

/** 获得DB连接 */

connection = DriverManager.getConnection(connString);

}

catch (Exception e)

{

System.out.println("获取DBConnection出错！");

}

/**

* 基于Annotation的数据库操作

@Override

public T getMapper(Class clazz)

{

T clazzImpl =

(T) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[] {clazz}, new SQLSelectProxy());

return clazzImpl;

}

/**

* 基于XML的查询操作

@Override

public List selectList(String query) throws Exception

{

PreparedStatement pstmt = null;

ResultSet rs = null;

try

{

/** 简单的PreparedStateme JDBC实现 */

pstmt = connection.prepareStatement(xmlSQLs.get(query).getQuerySql());

rs = pstmt.executeQuery();

/** 执行查询操作 */

return executeQuery(rs, xmlSQLs.get(query).getResultType());

}

finally

{

if (!rs.isClosed())

{

rs.close();

}

if (!pstmt.isClosed())

{

pstmt.close();

}

/**

* 执行查询操作，并将查询到的结果与配置中的ResultType根据变量名一一对应，通过反射调用Set方法注入各个变量的值

* @param rs

* @param type

* @return

* @throws Exception

public static List executeQuery(ResultSet rs, String type) throws Exception

{

int count = rs.getMetaData().getColumnCount();

List columnNames = new ArrayList();

for (int i = 1; i <= count; i++)

{

columnNames.add(rs.getMetaData().getColumnName(i));

}

final List list = new ArrayList

while (rs.next())

{

Class modelClazz = Class.forName(type);

Object obj = modelClazz.newInstance();

for (Method setMethods : modelClazz.getMethods())

{

for (String columnName : columnNames)

{

if (setMethods.getName().equalsIgnoreCase("set" + columnName))

{

setMethods.invoke(obj, rs.getString(columnName));

}

list.add(obj);

}

return list;

}

public Map getXmlSQLs()

{

return xmlSQLs;

}

public void setXmlSQLs(Map xmlSQLs)

{

this.xmlSQLs = xmlSQLs;

}

public List getAnnotationClasses()

{

return annotationClasses;

}

public void setAnnotationClasses(List annotationClasses)

{

this.annotationClasses = annotationClasses;

}

UserMapper.xml 基于XML的Mapper配置文件（src/main/java/com/bjpowernode/practice/xml目录下）

select *

from USER_TEST_TB

TestMyBatis.java 测试类(src/test/java/com/bjpowernode/practice目录下)

package com.bjpowernode.practice;

import com.bjpowernode.practice.annotation.UserMapper;

import com.bjpowernode.practice.simulation.SqlSession;

import com.bjpowernode.practice.simulation.SqlSessionFactory;

import com.bjpowernode.practice.simulation.SqlSessionFactoryBuilder;

import com.bjpowernode.practice.simulation.SqlSessionImpl;

import java.io.InputStream;

import java.sql.SQLException;

import java.text.MessageFormat;

import java.util.List;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

public class TestMyBatis

{

/** 配置置文件 */

private String source;

private InputStream inputStream;

private SqlSessionFactory sqlSessionFactory;

@Before

public void setUp()

{

source = "test-mybatis-configuration.xml";

}

/**

* 基于XML格式配置的测试方法

@Test

public void testXMLConfingure()

{

try

{

/**

* 获得Session

inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession session = sqlSessionFactory.openSession();

/**

* 执行Ｑｕｅｒｙ操作

List users = (List) session.selectList("com.bjpowernode.practice.UserMapper.getUser");

System.out.println("Query by XML configuration...");

/**

* 打印结果

this.printUsers(users);

}

catch (Exception e)

{

e.printStackTrace();

}

/**

* 基于Annotation配置的测试方法

@Test

public void testAnnotationConfingure()

{

try

{

inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession session = sqlSessionFactory.openSession();

UserMapper userMapper = session.getMapper(UserMapper.class);

System.out.println("\r\nQuery by annotation configuration...");

this.printUsers(userMapper.getUser());

}

catch (Exception e)

{

e.printStackTrace();

}

@After

public void clearUp() throws SQLException

{

if (SqlSessionImpl.connection != null && !SqlSessionImpl.connection.isClosed())

{

SqlSessionImpl.connection.close();

}

private void printUsers(final List users)

{

int count = 0;

for (User user : users)

{

System.out.println(MessageFormat.format("==User[{0}]=================", ++count));

System.out.println("User Id: " + user.getId());

System.out.println("User UserName: " + user.getUsername());

System.out.println("User Password: " + user.getPassword());

System.out.println("User nickname: " + user.getNickname());

}

以上就是基于XML以及Annotation的方式对Mybatis实现了一个简单的模拟。旨在理解Mybatis的工作原理。

笔者一直觉得当学习一个工具类技术的时候，路线应该是

1.实现一个小例子

2.找材料理解其中原理

3.学习技术细节，并动手全部实现

4.在全部学完之后动手做一个小项目，尽可能的使用这个在技术中的各个环节。

总结

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265 2023-04-07

模拟Mybatis的实现方法

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