Mini version mybatis

public  class BootStrap {
     public  static  void Start () { 
        MySqlSession SQLSESSION = new new MySqlSession (); // outer SQLSESSION use, Mapper proxy generated,
         // TestMapper an interface, it is a dynamic agent, 
        TestMapper testMapper = sqlSession.getMapper (. TestMapper class );
         // Mapper to query, which calls the invoke method is to call sqlSession Mapper proxy, invoke a method which method to query the database,
         // query the database sqlSession method calls are methods of Executor, 
        the Test the Test = testMapper.selectByPrimaryKey (. 1 ); 
        System.out.println (Test); 
    } 

    public  static  void main(String[] args){
        start();
    }
}

public  class MySqlSession {
     Private the Executor Executor = new new SimpleExecutor (); 

    public <T> T between selectOne (Statement String, Object Parameter) {
         return executor.query (Statement, Parameter); 
    } 

    public <T> T getMapper (Class <T> clazz ) { // clazz is an interface, 
        return (T) the Proxy.newProxyInstance (clazz.getClassLoader (),
                 new new Class [] {} clazz, new new MapperProxy ( the this , clazz));
         // new new MapperProxy pass into the inside of the interface and SqlSession 

        // the JDK dynamic proxy time, new MapperProxy proxy (to achieve additional content before and after class method),
        // new new MapperProxy parameter is the interface implementation class.
        // the mybatis did not pass into the implementation class, using sqlSession to query the database for true operation. 

        // public class the implements the Advice InvocationHandler1 {
             // People people; // interface passed in Examples
             // public the Advice (People people) {
             //     this.people = people;
             // }
            // public Invoke Object (Object Proxy, Method, Method, Object [] args) throws the Throwable {
            //      before (); // front reinforcing
            //      Object value = Method.invoke (people, args); // delegator 
            // / After ();//后置增强
            //    return value;
           // }
        //}

        //public class MyTest {
          //  public static void main(String[] args) {
           //     People proxyObject = (People) Proxy1.newProxyInstance(MyTest.class.getClassLoader(),
            //            new Class<?>[] { People.class }, new Advice(new Jack()));
        
    }
}

public class MapperProxy<T> implements InvocationHandler {
    private final MySqlSession sqlSession;
    private final Class<T> mapperInterface;

    public MapperProxy(MySqlSession sqlSession, Class<T> mapperInterface) {
        this.sqlSession = sqlSession;//接口和sqlSession，
        this.mapperInterface = mapperInterface;
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (method.getDeclaringClass().getName().equals(TestMapperXml.nameSpace)) {
            String sql = TestMapperXml.methodSqlMapping.get(method.getName());
            System.out.println(String.format("SQL [ %s ], parameter [%s] ", sql, args[0]));
            return sqlSession.selectOne(sql, String.valueOf(args[0]));
        }
        return null;
    }
}

public interface Executor {
    <E> E query(String statement, Object parameter);
}

public class SimpleExecutor implements Executor {

    public <E> E query(String sql, Object parameter) {
        try {
            Connection conn = getConnection();
            PreparedStatement pstmt;
            pstmt = conn.prepareStatement(String.format(sql, Integer.parseInt(String.valueOf(parameter))));
            ResultSet rs = pstmt.executeQuery();
            Test test = new Test();
            while (rs.next()) {
                test.setId(rs.getInt(1));
                test.setName(rs.getString(2));
            }
            return (E) test;
        }
        return null;
    }

    public Connection getConnection() throws SQLException {
        String driver = "com.mysql.cj.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/upgrade?useUnicode=true&characterEncoding=utf-8&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC";
        String username = "root";
        String password = "123456";
        Connection conn = null;
        try {
            Class.forName(driver); //classLoader,加载对应驱动
            conn = DriverManager.getConnection(url, username, password);
        }
        return conn;
    }
}

public class CachingExecutor implements Executor {
    private GpConfiguration configuration;
    private SimpleExecutor delegate;
    private Map<String,Object> localCache = new HashMap();

    public CachingExecutor(SimpleExecutor delegate) {
        this.delegate = delegate;
    }

    public CachingExecutor(GpConfiguration configuration) {
        this.configuration = configuration;
    }

    public <E> E query(MapperRegistory.MapperData mapperData, Object parameter)
            throws Exception {
        //初始化StatementHandler --> ParameterHandler --> ResultSetHandler
        StatementHandler handler = new StatementHandler(configuration);
        Object result = localCache.get(mapperData.getSql());
        if( null != result){
            System.out.println("缓存命中");
            return (E)result;
        }
        result =  (E) delegate.query(mapperData,parameter);
        localCache.put(mapperData.getSql(),result);
        return (E)result;
    }
}

public interface TestMapper {
    Test selectByPrimaryKey(Integer userId);
}

public class TestMapperXml {
    public static final String nameSpace = "com.gupaoedu.mybatis.my.TestMapper";
    public static final Map<String, String> methodSqlMapping = new HashMap<String, String>();
    static {
        methodSqlMapping.put("selectByPrimaryKey", "select * from test where id = %d");
    }
}

Level cache is in update, delete the time will go to update the cache.

事务：都是用spring来管理事务的。

 <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property value="jdbc:mysql://localhost:3306/upgrade?useSSL=false" name="url"/>
                <property name="username" value="root"/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>