public interface Visitor {

public void visitString(StringElement stringE);

public void visitFloat(FloatElement floatE);

public void visitCollection(Collection> collection);

public void visitInt(IntElement inte);

}访问者接口实现类

public class ConcreteVisitor implements Visitor{

public void visitCollection(Collection> collection) {

Iterator> iterator = collection.iterator();

while (iterator.hasNext()) {

Object o = iterator.next();

if (o instanceof Visitable) {

((Visitable)o).accept(this);

}

}

}

public void visitFloat(FloatElement floatE) {

System.out.println(floatE.getFe());

}

public void visitString(StringElement stringE) {

System.out.println(stringE.getSe());

}

@Override

public void visitInt(IntElement inte) {

System.out.println(inte.getInts());

}

}操作类的接口：

public interface Visitable {

public void accept(Visitor visitor);

}操作类的具体实现类：

public class FloatElement implements Visitable{

private Float fe;

public FloatElement(Float fe) {

this.fe = fe;

}

public Float getFe() {

return this.fe;

}

public void accept(Visitor visitor) {

visitor.visitFloat(this);

}

}

public class IntElement implements Visitable{

private int ints;

public int getInts() {

return ints;

}

public IntElement(int i){

this.ints = i;

}

@Override

public void accept(Visitor visitor) {

visitor.visitInt(this);

}

}

public class StringElement implements Visitable{

private String se;

public StringElement(String se) {

this.se = se;

}

public String getSe() {

return this.se;

}

public void accept(Visitor visitor) {

visitor.visitString(this);

}

}测试类：

public class Test {

public static void main(String[] args) {

Visitor visitor = new ConcreteVisitor();

Visitable se = new StringElement("abc");

se.accept(visitor);

Visitable fe = new FloatElement(new Float(1.5));

fe.accept(visitor);

System.out.println("===========");

List result = new ArrayList();

result.add(new StringElement("abc"));

result.add(new StringElement("abc"));

result.add(new StringElement("abc"));

result.add(new FloatElement(new Float(1.5)));

result.add(new FloatElement(new Float(1.5)));

result.add(new FloatElement(new Float(1.5)));

visitor.visitCollection(result);

Visitable is = new IntElement(2);

is.accept(visitor);

}

}

posted on 2013-04-18 16:20 杨军威 阅读(131) 评论(0)  编辑  收藏