复习：GoF的23种设计模式之Composite模式（结构型）

Composite模式（合成、混合）

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。

示例代码：

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 list = new ArrayList();
    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 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 iterator = list.iterator();
        while (iterator.hasNext()) {
            iterator.next().printList(prefix + "/" + name);
        }
    }
}

UML类图