Mybatis的SqlRunner执行流程

    SqlRunner exec = new SqlRunner(connection);    
    Map<String, Object> row = exec.selectOne("SELECT * FROM PRODUCT WHERE PRODUCTID = ?", "FI-SW-01");
    connection.close();
    assertEquals("FI-SW-01", row.get("PRODUCTID"));

TypeHandlerRegistry类中TYPE_HANDLER_MAP 的初始化过程

  public TypeHandlerRegistry() {
    //构造函数里注册系统内置的类型处理器
	  //以下是为多个类型注册到同一个handler
    register(Boolean.class, new BooleanTypeHandler());
    register(boolean.class, new BooleanTypeHandler());
    register(JdbcType.BOOLEAN, new BooleanTypeHandler());
    register(JdbcType.BIT, new BooleanTypeHandler());

    register(Byte.class, new ByteTypeHandler());
    register(byte.class, new ByteTypeHandler());
    register(JdbcType.TINYINT, new ByteTypeHandler());

    register(Short.class, new ShortTypeHandler());
    register(short.class, new ShortTypeHandler());
    register(JdbcType.SMALLINT, new ShortTypeHandler());

    register(Integer.class, new IntegerTypeHandler());
    register(int.class, new IntegerTypeHandler());
    register(JdbcType.INTEGER, new IntegerTypeHandler());

    register(Long.class, new LongTypeHandler());
    register(long.class, new LongTypeHandler());

    register(Float.class, new FloatTypeHandler());
    register(float.class, new FloatTypeHandler());
    register(JdbcType.FLOAT, new FloatTypeHandler());

    register(Double.class, new DoubleTypeHandler());
    register(double.class, new DoubleTypeHandler());
    register(JdbcType.DOUBLE, new DoubleTypeHandler());

	  //以下是为同一个类型的多种变种注册到多个不同的handler
    register(String.class, new StringTypeHandler());
    register(String.class, JdbcType.CHAR, new StringTypeHandler());
    register(String.class, JdbcType.CLOB, new ClobTypeHandler());
    register(String.class, JdbcType.VARCHAR, new StringTypeHandler());
    register(String.class, JdbcType.LONGVARCHAR, new ClobTypeHandler());
    register(String.class, JdbcType.NVARCHAR, new NStringTypeHandler());
    register(String.class, JdbcType.NCHAR, new NStringTypeHandler());
    register(String.class, JdbcType.NCLOB, new NClobTypeHandler());
    register(JdbcType.CHAR, new StringTypeHandler());
    register(JdbcType.VARCHAR, new StringTypeHandler());
    register(JdbcType.CLOB, new ClobTypeHandler());
    register(JdbcType.LONGVARCHAR, new ClobTypeHandler());
    register(JdbcType.NVARCHAR, new NStringTypeHandler());
    register(JdbcType.NCHAR, new NStringTypeHandler());
    register(JdbcType.NCLOB, new NClobTypeHandler());

    register(Object.class, JdbcType.ARRAY, new ArrayTypeHandler());
    register(JdbcType.ARRAY, new ArrayTypeHandler());

    register(BigInteger.class, new BigIntegerTypeHandler());
    register(JdbcType.BIGINT, new LongTypeHandler());

    register(BigDecimal.class, new BigDecimalTypeHandler());
    register(JdbcType.REAL, new BigDecimalTypeHandler());
    register(JdbcType.DECIMAL, new BigDecimalTypeHandler());
    register(JdbcType.NUMERIC, new BigDecimalTypeHandler());

    register(Byte[].class, new ByteObjectArrayTypeHandler());
    register(Byte[].class, JdbcType.BLOB, new BlobByteObjectArrayTypeHandler());
    register(Byte[].class, JdbcType.LONGVARBINARY, new BlobByteObjectArrayTypeHandler());
    register(byte[].class, new ByteArrayTypeHandler());
    register(byte[].class, JdbcType.BLOB, new BlobTypeHandler());
    register(byte[].class, JdbcType.LONGVARBINARY, new BlobTypeHandler());
    register(JdbcType.LONGVARBINARY, new BlobTypeHandler());
    register(JdbcType.BLOB, new BlobTypeHandler());

    register(Object.class, UNKNOWN_TYPE_HANDLER);
    register(Object.class, JdbcType.OTHER, UNKNOWN_TYPE_HANDLER);
    register(JdbcType.OTHER, UNKNOWN_TYPE_HANDLER);

    register(Date.class, new DateTypeHandler());
    register(Date.class, JdbcType.DATE, new DateOnlyTypeHandler());
    register(Date.class, JdbcType.TIME, new TimeOnlyTypeHandler());
    register(JdbcType.TIMESTAMP, new DateTypeHandler());
    register(JdbcType.DATE, new DateOnlyTypeHandler());
    register(JdbcType.TIME, new TimeOnlyTypeHandler());

    register(java.sql.Date.class, new SqlDateTypeHandler());
    register(java.sql.Time.class, new SqlTimeTypeHandler());
    register(java.sql.Timestamp.class, new SqlTimestampTypeHandler());

    // issue #273
    register(Character.class, new CharacterTypeHandler());
    register(char.class, new CharacterTypeHandler());
  }

回到流程中

 

 

 

 

原始的jdbc代码 

/*
	执行DQL语句
*/

import java.sql.*;
import java.util.*;

public class JDBCTest05 {
	public static void main(String[] args) {
		// 1、注册驱动
		// 2、建立连接
		// 3、获取数据库操作对象
		// 4、执行sql语句
		// 5、获取查询结果集
		// 6、释放资源
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		
		try{
			ResourceBundle rb = ResourceBundle.getBundle("jdbc");
			String driver = rb.getString("driver");
			String url = rb.getString("url");
			String user = rb.getString("user");
			String password = rb.getString("password");

			Class.forName(driver);

			conn = DriverManager.getConnection(url,user,password);

			stmt = conn.createStatement();

			rs = stmt.executeQuery("select empno,ename,sal from emp");
	
			while(rs.next()){
				/*
				String empno = rs.getString(1);
				String ename = rs.getString(2);
				String sal = rs.getString(3);
				System.out.println(empno + "," + ename + "," + sal);
				*/
				
				/*
				// 按下标取出，程序不健壮
				String empno = rs.getString("empno");
				String ename = rs.getString("ename");
				String sal = rs.getString("sal");
				System.out.println(empno + "," + ename + "," + sal);
				*/
				
				/*
				// 以指定的格式取出
				int empno = rs.getInt(1);
				String ename = rs.getString(2);
				double sal = rs.getDouble(3);
				System.out.println(empno + "," + ename + "," + (sal + 100));
				*/

				int empno = rs.getInt("empno");
				String ename = rs.getString("ename");
				double sal = rs.getDouble("sal");
				System.out.println(empno + "," + ename + "," + (sal + 200));
			}

		} catch(Exception e){
			e.printStackTrace();
		}finally{
			if(rs != null){
				try{
					rs.close();
				} catch (Exception e){
					e.printStackTrace();
				}
			}
			if(stmt != null){
				try{
					stmt.close();
				} catch (Exception e){
					e.printStackTrace();
				}
			}
			if(conn != null){
				try{
					conn.close();
				} catch (Exception e){
					e.printStackTrace();
				}
			}
		}
	}
}