blocks|key|519862|text|此命令加载可用于DriverManager实例的Oracle+jdbc驱动程序类。装入类后，系统可以使用它连接到Oracle。或者，您可以使用DriverManager的registerDriver方法，并将其与所需的JDBC驱动程序实例一起传递。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519863|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

This command loads class of Oracle jdbc driver to be available for DriverManager instance. After the class is loaded system can connect to Oracle using it. As an alternative you can use registerDriver method of DriverManager and pass it with instance of JDBC driver you need.

blocks|key|736424|text|它注册驱动程序；形式如下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|736425|public+class+SomeDriver+implements+Driver+{
++static+{
++++try+{
++++++DriverManager.registerDriver(new+SomeDriver());
++++}+catch+(SQLException+e)+{
++++++//+TODO+Auto-generated+catch+block
++++}
++}

++//etc:+implemented+methods
}|code-block|syntax|javascript|736426|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

It registers the driver; something of the form:

<pre><code>public class SomeDriver implements Driver {
 static {
 try {
 DriverManager.registerDriver(new SomeDriver());
 } catch (SQLException e) {
 // TODO Auto-generated catch block
 }
 }

 //etc: implemented methods
}
</code></pre>

blocks|key|736487|text|在Java6之前，DriverManager类不知道您要使用哪个JDBC驱动程序。Class.forName("...")是预加载驱动程序类的一种方式。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|736488|如果您使用的是Java+6，则不再需要执行此操作。|736489|entityMap^0|9|D|15|K|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

Pre Java 6 the <code>DriverManager</code> class wouldn't have known which JDBC driver you wanted to use. <code>Class.forName("...")</code> was a way on pre-loading the driver classes.

If you are using Java 6 you no longer need to do this.

blocks|key|736552|text|use+the+jdbc.drivers+System+property的一个替代方法是在启动JVM时在命令行上指定所需的驱动程序。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|736553|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1,5,0/docs/api/java/sql/DriverManager.html^0|0|10|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

An alternative would to <a href="http://download.oracle.com/javase/1,5,0/docs/api/java/sql/DriverManager.html" rel="nofollow">use the jdbc.drivers System property</a> to specify your required drivers(s) on the command line when you start the JVM.

blocks|key|520109|text|使用oracle.jdbc.OracleDriver，而不是oracle.jdbc.driver.OracleDriver。如果驱动程序jar文件在"WEB-INF\lib“目录中，如果您使用的是Tomcat，则不需要注册它。将其另存为test.jsp并将其放入您的web目录，然后在Tomcat+manager中重新部署您的web应用程序文件夹：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|520110|<%25@+page+import="java.sql.*"+%25>

<HTML>
<HEAD>
<TITLE>Simple+JSP+Oracle+Test</TITLE>
</HEAD><BODY>
<%25
Connection+conn+=+null;
try+{
++++Class.forName("oracle.jdbc.OracleDriver");
++++conn+=+DriverManager.getConnection("jdbc:oracle:thin:@XXX.XXX.XXX.XXX:XXXX:dbName",+"user",+"password");
++++Statement+stmt+=+conn.createStatement();
++++out.println("Connection+established!");
}
catch+(Exception+ex)
{
++++out.println("Exception:+"+%2B+ex.getMessage()+%2B+"");

}
finally
{
++++if+(conn+!=+null)+{
++++++++try+{
++++++++++++conn.close();+++
++++++++}
++++++++catch+(Exception+ignored)+{
++++++++++++//+ignore
++++++++}
++++}
}

%25>|code-block|syntax|javascript|520111|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use oracle.jdbc.OracleDriver, not oracle.jdbc.driver.OracleDriver. You do not need to register it if the driver jar file is in the "WEB-INF\lib" directory, if you are using Tomcat. Save this as test.jsp and put it in your web directory, and redeploy your web app folder in Tomcat manager:

<pre><code>&lt;%@ page import="java.sql.*" %&gt;

&lt;HTML&gt;
&lt;HEAD&gt;
&lt;TITLE&gt;Simple JSP Oracle Test&lt;/TITLE&gt;
&lt;/HEAD&gt;&lt;BODY&gt;
&lt;%
Connection conn = null;
try {
 Class.forName("oracle.jdbc.OracleDriver");
 conn = DriverManager.getConnection("jdbc:oracle:thin:@XXX.XXX.XXX.XXX:XXXX:dbName", "user", "password");
 Statement stmt = conn.createStatement();
 out.println("Connection established!");
}
catch (Exception ex)
{
 out.println("Exception: " + ex.getMessage() + "");

}
finally
{
 if (conn != null) {
 try {
 conn.close(); 
 }
 catch (Exception ignored) {
 // ignore
 }
 }
}

%&gt;
</code></pre>

What will the command 

<pre><code>Class.forName("oracle.jdbc.driver.OracleDriver")
</code></pre>

exactly do while connecting to a Oracle database? Is there an alternate way of doing the same thing?

What is the actual use of Class.forName("oracle.jdbc.driver.OracleDriver") while connecting to a database?

Oracle数据库

数据库

Java

该命令将是什么Class.forName("oracle.jdbc.driver.OracleDriver")在连接到Oracle数据库时到底要做什么？有没有其他方法可以做同样的事情？

问连接到数据库时Class.forName("oracle.jdbc.driver.OracleDriver")的实际用途是什么？
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问连接到数据库时Class.forName("oracle.jdbc.driver.OracleDriver")的实际用途是什么？
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