Java Scanner Readable

通过implements(实现)Readbale interface(接口)的 read() method(方法) 实现自己添加字符到buffer里,然后读取

//策略模式
package object;

//: interfaces/RandomWords.java
// Implementing an interface to conform to a method.
import java.nio.*;//Readable 接口在java.nio里面
import java.util.*; public class RandomWords implements Readable {
 private static Random rand = new Random(47);
 private static final char[] capitals = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
 private static final char[] lowers = "abcdefghijklmnopqrstuvwxyz".toCharArray(); 
private static final char[] vowels = "aeiou".toCharArray();
private int count; //设置读入多少行
public RandomWords(int count) { 
this.count = count; 
}
public int read(CharBuffer cb) {
 //read()方法来自Readable接口,Sanner()里也有用到 
if(count-- == 0) return -1; // Indicates end of input 
 cb.append(capitals[rand.nextInt(capitals.length)]); //从cpitals里面每次读出一个字符并添加到buffer里面 
for(int i = 0; i < 4; i++) { 
cb.append(vowels[rand.nextInt(vowels.length)]);//从vowels里面每次读出four char 字符并添加到buffer里面 
cb.append(lowers[rand.nextInt(lowers.length)]);//append()方法:添加字符到buffer里面  
} 
cb.append(" "); //在这里空格和'\n'功能一样
 return 10; // Number of characters appended  
}
 public static void main(String[] args) {
 Scanner s = new Scanner(new RandomWords(10)); 
                           // new RandomWords(10)可以换做任意实现了Readable接口的类所生成的对象
while(s.hasNext()) //hasNext()通过调用readInput()方法调用read()方法知道read()返回-1结束

      System.out.println(s.next());
  }
} /* Output:
Yazeruyac
Fowenucor
Goeazimom
Raeuuacio
Nuoadesiw
Hageaikux
Ruqicibui
Numasetih
Kuuuuozog
Waqizeyoy
*///:~

我们再次使用了适配器模式,但在本例中,被适配的类可以通过继承和实现Readable接口来创建,因此通过使用interface关键字提供的伪多重继承机制,我们可以生产既是RandomDoubles又是Readable的新类,在这种方式中,我们可以在任何现有类之上添加新的接口,所以这意味着让方法接受接口类型,是一种让任何类都可以对该方法进行适配的方式

//: interfaces/RandomDoubles.java
package object;
import java.util.*;

public class RandomDoubles {
  private static Random rand = new Random(47);
  public double next() { return rand.nextDouble(); }
  public static void main(String[] args) {
    RandomDoubles rd = new RandomDoubles();
    for(int i = 0; i < 7; i ++)
      System.out.print(rd.next() + " ");
  }
} /* Output:
0.7271157860730044 0.5309454508634242 0.16020656493302599 0.18847866977771732 0.5166020801268457 0.2678662084200585 0.2613610344283964
*///:~

//: interfaces/AdaptedRandomDoubles.java
// Creating an adapter with inheritance.
package object;
import java.nio.*;
import java.util.*;
import object.*;
public class AdaptedRandomDoubles extends RandomDoubles
implements Readable {
private int count;
public AdaptedRandomDoubles(int count) {
this.count = count;
}
public int read(CharBuffer cb) {
if(count-- == 0)
return -1;
String result = Double.toString(next()) + " ";
cb.append(result);
return result.length();
}
public static void main(String[] args) {
Scanner s = new Scanner(new AdaptedRandomDoubles(7));
while(s.hasNextDouble())
System.out.print(s.nextDouble() + " ");
}
} /* Output:
0.7271157860730044 0.5309454508634242 0.16020656493302599 0.18847866977771732 0.5166020801268457 0.2678662084200585 0.2613610344283964
*///:~

二

//: interfaces/AdaptedRandomDoubles.java //读取字符数组
// Creating an adapter with inheritance.
package object;
import java.nio.*;
import java.util.*;
class CharSequence {
    private static Random rand = new Random(47);
    private static final char[] capitals =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
    private static final char[] lowers =
            "abcdefghijklmnopqrstuvwxyz".toCharArray();
    private static final char[] vowels =
            "aeiou".toCharArray();
    char[] generate() {
        char[] buffer = new char[10];
        int idx = 0;
        buffer[idx++] = capitals[rand.nextInt(capitals.length)];
        for(int i = 0; i < 4; i++)
        {
            buffer[idx++] = vowels[rand.nextInt(vowels.length)];
            buffer[idx++] = lowers[rand.nextInt(lowers.length)];
            }
        buffer[idx] = ' ';
  return buffer;
  }
}
class E16_AdaptedCharSequence extends CharSequence
implements Readable {
    private int count;
    public E16_AdaptedCharSequence(int count) {
        this.count = count;
        }
    public int read(CharBuffer cb) {
        if(count-- == 0)
            return -1; // Indicates end of input
        char[] buffer = generate();
        cb.put(buffer);  //将buffer字符数组输出到流
        return buffer.length;
        }
    public static void main(String[] args) {
        Scanner s =
                new Scanner(new E16_AdaptedCharSequence(10));
        while(s.hasNext())
            System.out.println(s.next());
        }
    }