Simple factory pattern example of java interface oriented programming

This paper illustrates the simple factory pattern of java interface oriented programming. Share with you for your reference, as follows:

One code

interface Output
{
  // 接口里定义的成员变量只能是常量
  int MAX_CACHE_LINE = 50;
  // 接口里定义的普通方法只能是public的抽象方法
  void out();
  void getData( String msg );
}
class Printer implements Output {
  private String[] printData
      = new String[MAX_CACHE_LINE];
  // 用以记录当前需打印的作业数
  private int datanum = 0;
  public void out() {
    // 只要还有作业，继续打印
    while (datanum > 0) {
      System.out.println("打印机打印：" + printData[0]);
      // 把作业队列整体前移一位，并将剩下的作业数减1
      System.arraycopy(printData,1,printData,--datanum);
    }
  }
  public void getData( String msg ) {
    if (datanum >= MAX_CACHE_LINE) {
      System.out.println("输出队列已满，添加失败");
    } else {
      // 把打印数据添加到队列里，已保存数据的数量加1。
      printData[datanum++] = msg;
    }
  }
}
class BetterPrinter implements Output
{
  private String[] printData
      = new String[MAX_CACHE_LINE * 2];
  // 用以记录当前需打印的作业数
  private int datanum = 0;
  public void out()
  {
    // 只要还有作业，继续打印
    while(datanum > 0)
    {
      System.out.println("高速打印机正在打印：" + printData[0]);
      // 把作业队列整体前移一位，并将剩下的作业数减1
      System.arraycopy(printData,--datanum);
    }
  }
  public void getData(String msg)
  {
    if (datanum >= MAX_CACHE_LINE * 2)
    {
      System.out.println("输出队列已满，添加失败");
    }
    else
    {
      // 把打印数据添加到队列里，已保存数据的数量加1。
      printData[datanum++] = msg;
    }
  }
}
class Computer
{
  private Output out;
  public Computer(Output out)
  {
   this.out = out;
  }
  // 定义一个模拟获取字符串输入的方法
  public void keyIn(String msg)
  {
   out.getData(msg);
  }
  // 定义一个模拟打印的方法
  public void print()
  {
   out.out();
  }
}
public class OutputFactory
{
  public Output getOutput()
  {
//  return new Printer();
    return new BetterPrinter();
  }
  public static void main(String[] args)
  {
    OutputFactory of = new OutputFactory();
    Computer c = new Computer(of.getOutput());
    c.keyIn("轻量级Java EE企业应用实战");
    c.keyIn("疯狂Java讲义");
    c.print();
  }
}

II. Operation

Three kinds of Graphs

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