import java.io.*;
class ClassInstance implements Cloneable, Serializable {
      private String str = "测试...";
      public void fun(){
            System.out.println(str);
      }
      public ClassInstance(String str){
            System.out.println("有参类的实例化");
            this.str += str;
      }
      public ClassInstance(){
            System.out.println("无参类的实例化");
      }
      public Object clone(){
            return this;
      }
}
2.ClassInstanceTest.java
import java.io.*;
import java.lang.reflect.*;
public class ClassInstanceTest{
      public static void main(String[] args) throws ClassNotFoundException, InstantiationException,
      IllegalAccessException, IOException,InvocationTargetException, NoSuchMethodException{
            //第一种类的实例化方式 
            ClassInstance ci01 = new ClassInstance("01");
            ci01.fun();
            //第二种类的实例化方式 
            ClassInstance ci02 = (ClassInstance) Class.forName("ClassInstance").newInstance();
            ci02.fun();
            //第三种类的实例化方式 
            ClassInstance ci03 = (ClassInstance) ci01.clone();
            ci03.fun();
            //第四种类的实例化方式 
            FileOutputStream fos = new FileOutputStream("ci.tmp");
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            oos.writeObject(ci01);
            oos.close();
            fos.close();
            FileInputStream fis = new FileInputStream("ci.tmp");
            ObjectInputStream ois = new ObjectInputStream(fis);
            ClassInstance ci04 = (ClassInstance) ois.readObject();
            ois.close();
            fis.close();
            ci04.fun();
            System.out.println("--------------------额外测试--------------------");  
            ClassInstance ci05 = null;
            //额外的思考 在第二种类实例化的方式中有没有一种方法实现有参数的构造方式 
            //获得类的构造信息 
            Constructor[] ctor = Class.forName("ClassInstance").getDeclaredConstructors();
            //找到我们需要的构造方法 
            for(int i=0;i<ctor.length;i++ ){
                  Class[] cl = ctor[i].getParameterTypes();
                  if(cl.length == 1){
                        //实例化对象 
                  ci05 = (ClassInstance) Class.forName("ClassInstance").getConstructor(cl).newInstance(new Object[]{"05"});
                  }
            }
            ci05.fun();
      }
}

public class ClassInstance{
      public ClassInstance(){
      }
      public ClassInstance getInstance(){
            return new ClassInstance();
      }
}