十二、Decorator 装饰器模式

public abstract class Display {
    public abstract int getColumns();
    public abstract int getRows();
    public abstract String getRowText(int row);
    public final void show(){
        for(int i=0;i<getRows();i++){
            System.out.println(getRowText(i));
        }
    }
}

public class StringDisplay extends Display{
    private String string;
    public StringDisplay(String string){
        this.string = string;
    }
    @Override
    public int getColumns() {
        return string.getBytes().length;
    }

    @Override
    public int getRows() {
        return 1;
    }

    @Override
    public String getRowText(int row) {
        if(row == 0){
            return string;
        }else{
            return null;
        }
    }
}

public abstract class Border extends Display{
    protected  Display display;
    protected  Border(Display display){
        this.display = display;
    }
}

public class FullBorder extends Border{
    public FullBorder(Display display){
        super(display);
    }

    @Override
    public int getColumns() {
        return 1+display.getColumns()+1;
    }

    @Override
    public int getRows() {
        return 1+display.getRows()+1;
    }

    @Override
    public String getRowText(int row) {
        if(row ==0){
            return "+"+makeLine(‘-‘,display.getColumns())+"+";
        }else if(row ==display.getRows()+1){
            return  "+"+makeLine(‘-‘,display.getColumns())+"+";
        }else{
            return "|"+display.getRowText(row-1)+"|";
        }
    }

    private String makeLine(char ch,int count){
        StringBuffer buf = new StringBuffer();
        for(int i=0;i<count;i++){
            buf.append(ch);
        }
        return buf.toString();
    }
}

public class SideBorder extends Border{
    private char borderChar;
    public SideBorder(Display display,char ch){
        super(display);
        this.borderChar = ch;
    }
    @Override
    public int getColumns() {
        return 1 + display.getColumns() + 1;
    }

    @Override
    public int getRows() {
        return display.getRows();
    }

    @Override
    public String getRowText(int row) {
        return borderChar+display.getRowText(row)+borderChar;
    }
}