Class aClass = Class.forName(xxx.xx.xx);
Object anInstance = aClass.newInstance();


Class.forName("").newInstance()返回的是object
but there is some limit for this method to create instance
that is your class constructor should no contain parameters, and you should cast the instance manually.

Class Driver{
protected static Driver current;
public static Driver getDriver(){
return current;
}
}

Class MyDriver extends Driver{
static{
Driver.current=new MyDriver();
}
MyDriver(){}
}

用時(shí):
Class.forName("MyDriver");
Driver d=Driver.getDriver();

有的jdbc連接數(shù)據(jù)庫(kù)的寫(xiě)法里是Class.forName(xxx.xx.xx);而有一些：Class.forName(xxx.xx.xx).newInstance()，為什么會(huì)有這兩種寫(xiě)法呢？

Class.forName(xxx.xx.xx) 返回的是一個(gè)類,
.newInstance() 后才創(chuàng)建一個(gè)對(duì)象

Class.forName(xxx.xx.xx);的作用是要求JVM查找并加載指定的類，也就是說(shuō)JVM會(huì)執(zhí)行該類的靜態(tài)代碼段

在JDBC規(guī)范中明確要求這個(gè)Driver類必須向DriverManager注冊(cè)自己，即任何一個(gè)JDBC Driver的Driver類的代碼都必須類似如下：
public class MyJDBCDriver implements Driver {
static {
DriverManager.registerDriver(new MyJDBCDriver());
}
}

所以我們?cè)谑褂肑DBC時(shí)只需要Class.forName(XXX.XXX);就可以了