目录
反射机制优化工厂类
1.先写一个反射的小Demo
2.写一个工厂类使用例子
（1）IMessage只有一个实现类NewsPaper
（2）IMessage添加一个实现类NetReport

反射机制优化工厂类

1.先写一个反射的小Demo

clazz.newInstance();相当于new java.util.Date();得到一个实例对象

package com.liangyehao;
public class Demo01 {
    public static void main(String[] args) throws
            ClassNotFoundException, IllegalAccessException, InstantiationException {
        //获取类对象
        Class<?> clazz = Class.forName("java.util.Date");
        //反射获得实例对象,相当于 new java.util.Date();
        Object object = clazz.newInstance();
        //输出实例对象
        System.out.println(object);
    }
}

2.写一个工厂类使用例子

（1）IMessage只有一个实现类NewsPaper

• 编写一个接口IMessage，定义了send方法

  package com.liangyehao.factoryDemo;
  public interface IMessage {
      public void send(String msg); 
  }
  

• 编写IMessage实现类NewsPaper.java

  package com.liangyehao.factoryDemo.impl;
  
  import com.liangyehao.factoryDemo.IMessage;
  
  public class NewsPaper implements IMessage {
      public void send(String msg) {
          System.out.println("【报纸内容】"+msg);
      }
  }
  

• 编写工厂类MessageFactory.java

  package com.liangyehao.factoryDemo;
  import com.liangyehao.factoryDemo.impl.NewsPaper;
  public class MessageFactory {
  
      private MessageFactory(){}
  
      public static IMessage getInstance(String className){
          if("newspaper".equals(className)){
              return new NewsPaper();
          }
          return null;
      }
  }
  

• 编写测试类

  package com.liangyehao.factoryDemo;
  public class MessageTest {
      public static void main(String[] args) {
          IMessage message = MessageFactory.getInstance("newspaper");
          message.send("Hello liangyehao");
      }
  }
  

• 测试输出

  【报纸内容】Hello liangyehao

（2）IMessage添加一个实现类NetReport

• 编写NetReport.java

  package com.liangyehao.factoryDemo.impl;
  import com.liangyehao.factoryDemo.IMessage;
  public class NetReport implements IMessage{
      public void send(String msg) {
          System.out.println("{网络报道}"+msg);
      }
  }
  

• 工厂类添加实现

  package com.liangyehao.factoryDemo;
  
  import com.liangyehao.factoryDemo.impl.NetReport;
  import com.liangyehao.factoryDemo.impl.NewsPaper;
  
  public class Factory {
      public Factory(){}
  
      public static IMessage getInstance(String type){
          if(type.equals("newspaper")){
              return new NewsPaper();
          }else if(type.equals("netreport")){
              return new NetReport();
          }
          return null;
      }
  }
  
  

  即增加了：

  else if(type.equals("netreport")){
              return new NetReport();
          }
  

• 测试类测试NetReport

  package com.liangyehao.factoryDemo;
  public class IMessageTest {
      public static void main(String[] args) {
          IMessage newsPaper = Factory.getInstance("netreport");
              newsPaper.send("Hello liangyehao");
      }
  }
  

• 输出结果

  {网络报道}Hello liangyehao