Composite模式例子
这个模式和我们的文件系统类似,我们将文件夹当作容器,单一文件当作内容,文件夹中可以迭代放入文件夹,文件夹可以放入内容。
Composite模式:能够使容器与内容具有一致性,创造出递归结构。
public class CompositeTest {
public static void main(String[] args) {
Directory root = new Directory("root");
Directory directory1 = new Directory("directory1");
Directory directory2 = new Directory("directory2");
Directory directory3 = new Directory("directory3");
root.add(directory1);
root.add(directory2);
directory2.add(directory3);
directory2.add( new FileComposite("file1", 200));
directory3.add( new FileComposite("file2", 1000));
root.printList("");
}
}
abstract class EntryComponent{
public abstract String getName();
public abstract int getSize();
public EntryComponent add(EntryComponent component) {
throw new RuntimeException();
}
protected abstract void printList(String prefix);
@Override
public String toString() {
return getName() + "(" + getSize() + ")";
}
}
class FileComposite extends EntryComponent{
private String name;
private int size;
public FileComposite(String name, int size) {
this.name = name;
this.size = size;
}
public String getName() {
return name;
}
public int getSize() {
return size;
}
protected void printList(String prefix) {
System.out.println(prefix+"/"+ this.toString());
}
}
class Directory extends EntryComponent{
private String name;
private final List<EntryComponent> list = new ArrayList<EntryComponent>();
public Directory(String name) {
this.name = name;
}
public EntryComponent add(EntryComponent component) {
list.add(component);
return this;
}
public String getName() {
return name;
}
public int getSize() {
Iterator<EntryComponent> iterator = list.iterator();
int size = 0;
while (iterator.hasNext()) {
size += iterator.next().getSize();
}
return size;
}
protected void printList(String prefix) {
System.out.println(prefix+"/"+ this.name);
Iterator<EntryComponent> iterator = list.iterator();
while (iterator.hasNext()) {
iterator.next().printList(prefix + "/" + name);
}
}
}