public interface Tool {
    void draw();
    void erace();
}
class RoundTool implements Tool {
    @Override
    public void draw() {
        System.out.println("绘制一个圆形");
    }
    @Override
    public void erace() {
        System.out.println("擦除一个圆形");
    }
}
class SquareTool implements Tool {
    @Override
    public void draw() {
        System.out.println("绘制一个方形");
    }
    @Override
    public void erace() {
        System.out.println("擦除一个方形");
    }
}
class TriangeTool implements Tool {
    @Override
    public void draw() {
        System.out.println("绘制一个三角形");
    }
    @Override
    public void erace() {
        System.out.println("擦除一个三角形");
    }
}
public class DrawToolFactory {
    public static Tool getDrawTool(String type){
        Tool tool=null;
        if(type.equalsIgnoreCase("round")){
            tool=new RoundTool();
            System.out.println("初始化圆形工具！");
        }else if(type.equalsIgnoreCase("square")){
            tool=new SquareTool();
            System.out.println("初始化方形工具！");
        }else if(type.equalsIgnoreCase("triange")){
            tool=new TriangeTool();
            System.out.println("初始化三角形工具！");
        }else{
            throw new UnsupportedClassVersionError("不支持的类型");
        }
        return tool;
    }
}
/**
 * 解析器
 */
public class XMLUtil {
    public static String getDrawTool() {
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document doc;
            doc=builder.parse(new File("config.xml"));
            NodeList nl=doc.getElementsByTagName("drawType");
            Node classNode=nl.item(0).getFirstChild();
            String drawType=classNode.getNodeValue().trim();
            return drawType;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}
/**
 * xml
 */
<?xml version="1.0"?>
<config>
    <drawType>triange</drawType>
</config>
/**
 * 运行类
 */
public static void main(String[]args){
        Tool round= DrawToolFactory.getDrawTool("round");
        round.draw();
        round.erace();
        Tool square= DrawToolFactory.getDrawTool("square");
        square.draw();
        square.erace();
        Tool triange=DrawToolFactory.getDrawTool(XMLUtil.getDrawTool());
        triange.draw();
        Tool tool=DrawToolFactory.getDrawTool("error");
    }