ADD file via upload

BasicShapeConverter.java

@@ -0,0 +1,36 @@
+package tiaozhanti;
+
+import jichuti.Circle;
+import jichuti.Square;
+
+public class BasicShapeConverter implements ShapeConverter {
+    @Override
+    public Shape convert(Shape source, Class<? extends Shape> targetType) {
+        // 圆形 → 椭圆形（保持面积相等）
+        if (source instanceof Circle && targetType == Oval.class) {
+            Circle circle = (Circle) source;
+            double radius = circle.getRadius();
+            return new Oval(circle.getColor(), radius, radius);  // 椭圆退化为圆形
+        }
+
+        // 椭圆形 → 圆形（保持面积相等）
+        if (source instanceof Oval && targetType == Circle.class) {
+            Oval oval = (Oval) source;
+            double area = oval.getArea();
+            double radius = Math.sqrt(area / Math.PI);  // 从面积反推半径
+            return (Shape) new Circle(oval.getColor(), radius);
+        }
+
+        // 正方形 → 圆形（保持面积相等）
+        if (source instanceof Square && targetType == Circle.class) {
+            Square square = (Square) source;
+            double area = square.getArea();
+            double radius = Math.sqrt(area / Math.PI);
+            return (Shape) new Circle(square.getColor(), radius);
+        }
+
+        throw new UnsupportedOperationException(
+            "不支持转换：" + source.getClass().getSimpleName() + " → " + targetType.getSimpleName()
+        );
+    }
+}