OJDBC版本不同引发的DATE问题

一般的数据库中，DATE字段仅仅表示日期，不包括日期信息，而Oracle数据库中的DATE数据类型是包括日期、时间的，对于不同的Oracle jdbc驱动版本，对于该问题的处理都有些区别，如果你使用9i或者11g
的驱动程序，可能不会发现什么困惑，不幸的话，你使用Oracle10g的JDBC驱动，问题就来了，你会发现时间不见了？
看下面的程序
• 表结构如下

create table t_test(
id int,
date1 date,
date2 timestamp,
primary key(id)
)

  • 程序如下

public class JdbcTestDate {
	public static void executeJdbc(boolean onlyHuiPiao) throws SQLException {
		Connection conn = null;
		Statement ptmt = null;
		try {
			Class.forName("oracle.jdbc.OracleDriver");
			conn = DriverManager.getConnection("jdbc:oracle:thin:@10.1.252.80:1521:newngboss", "so1", "so1");
			System.out.println(conn.getMetaData().getDriverName() + " " + conn.getMetaData().getDriverVersion());
			ResultSet rs = conn.createStatement().executeQuery("select date1,date2 from t_test");
			rs.next();
			printInfo(rs, 1);
			printInfo(rs, 2);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (ptmt != null)
				ptmt.close();
			if (conn != null)
				conn.close();
		}
	}

	public static void printInfo(ResultSet rs, int i) throws SQLException {
		ResultSetMetaData meta = rs.getMetaData();
		System.out.printf("Colname=%s,Type=%s,TypeName=%s,val=[%s];\n", meta.getColumnName(i), meta.getColumnType(i), meta
				.getColumnTypeName(i), rs.getObject(i).toString());
	}

	public static void main(String[] args) {
		try {
			executeJdbc(true);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}

 

 • 如果使用9i或者11g的驱动连接数据库，返回结果如下：
9i数据库JDBC
oracle.jdbc.driver.OracleConnection@16930e2
Oracle JDBC driver 9.2.0.8.0
Colname=DATE1,Type=91,TypeName=DATE,val=[2008-06-13 13:48:21.0];
Colname=DATE2,Type=93,TypeName=TIMESTAMP,val=[oracle.sql.TIMESTAMP@18d107f];

11g数据库JDBC
oracle.jdbc.driver.T4CConnection@a61164
Oracle JDBC driver 11.1.0.6.0-Production+
Colname=DATE1,Type=93,TypeName=DATE,val=[2008-06-13 13:48:21.0];
Colname=DATE2,Type=93,TypeName=TIMESTAMP,val=[oracle.sql.TIMESTAMP@c4aad3];

如果使用10g JDBC驱动，结果如下：
oracle.jdbc.driver.T4CConnection@1bac748
Oracle JDBC driver 10.2.0.2.0
Colname=DATE1,Type=91,TypeName=DATE,val=[2008-06-13];
Colname=DATE2,Type=93,TypeName=TIMESTAMP,val=[oracle.sql.TIMESTAMP@b8df17];

结果是让人困惑，时间怎么不见了？

 

对于该问题，在Oracle的JDBC FAQ中有提到解决办法：
Prior to 9.2, the Oracle JDBC drivers mapped the DATE SQL type to java.sql.Timestamp. This made a certain amount of sense because the Oracle DATE SQL type contains both date and time information as does java.sql.Timestamp. The more obvious mapping to java.sql.Date was somewhat problematic as java.sql.Date does not include time information. It was also the case that the RDBMS did not support the TIMESTAMP SQL type, so there was no problem with mapping DATE to Timestamp.

In 9.2 TIMESTAMP support was added to the RDBMS. The difference between DATE and TIMESTAMP is that TIMESTAMP includes nanoseconds and DATE does not. So, beginning in 9.2, DATE is mapped to Date and TIMESTAMP is mapped to Timestamp. Unfortunately if you were relying on DATE values to contain time information, there is a problem.

There are several ways to address this problem:

Alter your tables to use TIMESTAMP instead of DATE. This is probably rarely possible, but it is the best solution when it is.

Alter your application to use defineColumnType to define the columns as TIMESTAMP rather than DATE. There are problems with this because you really don't want to use defineColumnType unless you have to (see What is defineColumnType and when should I use it?).

Alter you application to use getTimestamp rather than getObject. This is a good solution when possible, however many applications contain generic code that relies on getObject, so it isn't always possible.

Set the V8Compatible connection property. This tells the JDBC drivers to use the old mapping rather than the new one. You can set this flag either as a connection property or a system property. You set the connection property by adding it to the java.util.Properties object passed to DriverManager.getConnection or to OracleDataSource.setConnectionProperties. You set the system property by including a -D option in your java command line.

  java -Doracle.jdbc.V8Compatible="true" MyApp

参照上面的解释，修改代码如下可以解决10g JDBC驱动的问题：
Properties prop=new Properties(); prop.setProperty("oracle.jdbc.V8Compatible","true"); prop.setProperty("user","so1"); prop.setProperty("password","so1"); conn = DriverManager.getConnection("jdbc:oracle:thin:@10.1.252.80:1521:newngboss", prop);

或者在系统变量中使用参数-Doracle.jdbc.V8Compatible="true"，例如
java -Doracle.jdbc.V8Compatible="true" MyApp

结果如下：
oracle.jdbc.driver.T4CConnection@9664a1
Oracle JDBC driver 10.2.0.2.0
Colname=DATE1,Type=93,TypeName=DATE,val=[2008-06-13 13:48:21.0];
Colname=DATE2,Type=93,TypeName=DATE,val=[oracle.sql.TIMESTAMP@1172e08];