Decorator Mode of design pattern

The decorator pattern is to create a decorator and then pass the decorator in, and it is already decorated.

For example, I pass a house in, when out of the house planted a flower, this is a flower decorator;

I passed another decorator, and came out and brushed the wall, a decorator who painted the wall.

Now we are decorated with coffee, many kinds of coffee, so we need a super class.

Decorators are a lot of spices.

Here's the code:

Public abstract class Beverage {    String description = "Unknow beverage";    Public String getdescription () {        return description;    }    public abstract double Cost ();}

Public abstract class Condimentdecorator extends beverage {public    abstract String getdescription ();

public class Espresso extends beverage {public    Espresso () {        description = "Espresso";    }    @Override public    double Cost () {        return 1.99;    }}

public class Houseblend extends beverage {public    houseblend () {        description = "Houseblend";    }    @Override public    double Cost () {        return.;    }}

public class Mocha extends Condimentdecorator {    beverage beverage;    Public Mocha (Beverage beverage) {        this.beverage = beverage;    }    @Override public    String getdescription () {        return beverage.getdescription () + ", Mocha";    }    @Override public    double Cost () {        return beverage.cost () +.    }}

public class Soy extends Condimentdecorator {    beverage beverage;    Public Soy (Beverage beverage) {        this.beverage = beverage;    }    @Override public    String getdescription () {        return beverage.getdescription () + ", Soy";    }    @Override public    double Cost () {        return beverage.cost () +.    }}

public class Whip extends Condimentdecorator {    beverage beverage;    Public Whip (Beverage beverage) {        this.beverage = beverage;    }    @Override public    String getdescription () {        return beverage.getdescription () + ", Whip";    }    @Override public    double Cost () {        return beverage.cost () +.    }}

The following is a test class:

public class Starbuzzcoffee {    @Test public    void Test () {        Beverage beverage = new Espresso ();        Beverage = new Soy (beverage);        System.out.println (beverage.getdescription () + "$" + beverage.cost ());        Beverage Beverage1 = new Houseblend ();        Beverage1 = new Mocha (beverage1);        Beverage1 = new Soy (beverage1);        Beverage1 = new Whip (beverage1);        System.out.println (beverage1.getdescription () + "$" + beverage1.cost ());}    }

Operation Result:

The point to note is:

decorators need to inherit the decorator, because the way to rewrite the decorator ...

if necessary, you need to declare a decorator inside the decorator, store the previous adorner, and store the object for the call to rewrite (not mandatory)...

I/O in the JDK is the decorator pattern used.

The following uses decorator mode to write an implementation that makes the letters in the stream all lowercase:

public class Lowercaseinputstream extends filterinputstream{public    Lowercaseinputstream (InputStream in) {        Super (in);    }    public int read () throws IOException {        int c = Super.read ();        return (c = =-1 c:character.tolowercase ((char) c));    }    public int read (byte[] b, int offset, int len) throws IOException {        int result = Super.read (b, offset, len);        for (int i = offset; i < Offset+result; i++) {            b[i] = (byte) character.tolowercase ((char) b[i]);        }        return result;}    }

The test classes are as follows:

public class Inputtest {    @Test public    void Testinputstream () throws IOException {        int c;        try{            InputStream in = new Lowercaseinputstream (new Bufferedinputstream (New FileInputStream ("H:\\workspace\\idea\ \dp\\src\\test\\resource\\test.txt ")));            while ((c = in.read ()) >= 0) {                System.out.print ((char) c);            }            In.close ();        } catch (IOException e) {            e.printstacktrace ();}}    }

To create a new Test.txt file:

Operation Result:

Decorator Mode of design pattern