享元模式

在屏幕中显示一个文本文档，其中相同的字符串“java”共享同一个对象，而这些字符串的颜色和大小可以不同。现使用享元模式设计一个方案实现字符串对象的共享，要求绘制类图并编程实现。

import java.awt.*;
import javax.swing.*;
public class Client
{
    public static void main(String args[])
    {
        Share_String nd1,nd2,nd3,nd4,nd5;
        String_Factory df=new String_Factory();
        
        JFrame jf = new JFrame();//窗口    
        JPanel jp = new JPanel();//面板
        jf.setVisible(true);
        jf.setTitle("享元模式");
        jf.setBounds(100, 100, 500, 500);
        jf.add(jp);
        
        nd1=df.get_Sh_string("JAVA");
        nd1.use(new Propertyy(15,Color.black,nd1,jp));
        
        nd2=df.get_Sh_string("JAVA");
        nd2.use(new Propertyy(22,Color.GREEN,nd2,jp));
        
        nd3=df.get_Sh_string("JAVA");
        nd3.use(new Propertyy(25,Color.red,nd3,jp));
        
    }
}

import java.awt.Font;

import javax.swing.JLabel;

public class JJava implements Share_String
{
    private String type;
    
    public JJava(String type)
    {
        this.type=type;
    }
    
    public String getType()
    {
        return this.type;
    }
    public void setType(String tmp)
    {
        this.type=tmp;
    }
    
    public void use(Propertyy port)
    {
        JLabel jl1 = new JLabel(port.getNd1().getType());
        Font f = new Font("宋体",Font.PLAIN,port.getZihao());
        jl1.setFont(f);
        jl1.setForeground(port.getColor());
        port.getJPanel().add(jl1);
    }
}

import java.awt.Color;
import java.awt.Font;

import javax.swing.JLabel;
import javax.swing.JPanel;

public class Propertyy
{
    private int font_size;
    private Color color; 
    private Share_String str;
    private JPanel jp;
    
    public Propertyy(int font_size,Color color, Share_String str,JPanel jp)
    {
        this.color=color;    
        this.font_size=font_size;
        this.str=str;
        this.jp=jp;
    }
    
    
    public int getZihao()
    {
        return this.font_size;
    }
    
    public Color getColor()
    {
        return this.color;
    }
    public Share_String getNd1()
    {
        return this.str;
    }
    public JPanel getJPanel()
    {
        return this.jp;
    }
    
}

public interface Share_String
{
    public String getType();
    public void use(Propertyy port);
}

import java.util.*;

public class String_Factory
{
    private ArrayList strs = new ArrayList();
    
    public String_Factory()
    {
        Share_String nd1=new JJava("JAVA");
        strs.add(nd1);
    }
    
    public Share_String get_Sh_string(String type)
    {
        if(type.equalsIgnoreCase("JAVA"))
        {
            return (Share_String)strs.get(0);
        }
        else
        {
            return null;
        }
    }
    
    public int getTotalDevice()
    {
        return strs.size();
    }
    
}

享元模式的关键在于return object。返回的是类似C语言的指针，不会重复开辟空间复制一个对象返回。