jdbc-数据库驱动
版本错误导致--查出的数据-时分秒全部显示为:00:00:00
（数据库中实际是，精确到时分秒的）
下面为这方面一个不错的文章解读：
date2 timestamp,
primary key(id)
)
1try{
2 Class.forName("oracle.jdbc.OracleDriver");
3 java.sql.Connection connection1 = DriverManager.getConnection("jdbc:oracle:thin:@192.168.8.200:1521:cdb", "sysusr", "sys");
4 System.out.println(connection1);
5 System.out.println(connection1.getMetaData().getDriverName()+""+connection1.getMetaData().getDriverVersion());
6 ResultSet rs = connection1.createStatement().executeQuery("select date1,date2 from t_test");
7 rs.next();
8 printInfo(rs,1);
9 printInfo(rs,2);
10 }
11 catch (Exception exception1) {
12 exception1.printStackTrace();
13 }
14
15
16publicstaticvoid printInfo(ResultSet rs,int i) throws SQLException{
17 ResultSetMetaData meta=rs.getMetaData();
18 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());
19 }
? 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驱动 【祺麻注：ojdbc6.jar】
oracle.jdbc.driver.T4CConnection@c2a132
Oracle JDBC driver 11.2.0.1.0
Colname=DATE1,Type=93,TypeName=DATE,val=[2012-11-19 15:11:37.0];
Colname=DATE2,Type=93,TypeName=TIMESTAMP,val=[2012-11-19 15:11:37.0];
如果使用10g JDBC驱动，结果如下： 用
class12.jar,
* oracle.jdbc.driver.T4CConnection@b0f13d
* Oracle JDBC driver 10.2.0.1.0
* Colname=DATE1,Type=91,TypeName=DATE,val=[2012-11-19];
* Colname=DATE2,Type=93,TypeName=TIMESTAMP,val=[oracle.sql.TIMESTAMP@1172e08];
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：
try{
Class.forName("oracle.jdbc.OracleDriver");
Properties prop=new Properties();
prop.setProperty("user","sysuser");
prop.setProperty("password","sys");
prop.setProperty("oracle.jdbc.V8Compatible","true");
java.sql.Connection connection1 = DriverManager.getConnection("jdbc:oracle:thin:@192.168.8.200:1521:cdb", prop);
System.out.println(connection1);
System.out.println(connection1.getMetaData().getDriverName()+""+connection1.getMetaData().getDriverVersion());
ResultSet rs = connection1.createStatement().executeQuery("select date1,date2 from t_test");
rs.next();
printInfo(rs,1);
printInfo(rs,2);
}
catch (Exception exception1) {
exception1.printStackTrace();
}
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];
-------------
【祺麻注：】
我的想法：避免使用class12.jar。而是使用ojdbc6.jar(11g的驱动，支持JDK６），具体可参考上一博
用CachedRowSetImpl时也会发生取不到时间的问题，处理结果是：改用ojdbc6.jar，不用class12.jar.
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