创建一个名为“shape”的抽象类，该类内部含有两个抽象方法getGirth(int i)和getArea(int i)，分别用来计算周长和面积；“shape”类派生出子类“triangle”，“triangle”类中按照三角形的周长和面积的计算方式对“shape”类中两个抽象方法进行覆盖，triangle构造方法具有六个参数，分别为三个顶点的横坐标和纵坐标，并在main方法中进行验证。请写出Shape、triangle类的源代码并设置用例计算输出三角形的周长和面积（注：可使用Math类）。

以下是Shape和Triangle类的源代码：

// Shape.java
public abstract class Shape {
    public abstract double getGirth(int i);
    public abstract double getArea(int i);
}

// Triangle.java
public class Triangle extends Shape {
    private double x1, y1, x2, y2, x3, y3;

    public Triangle(double x1, double y1, double x2, double y2, double x3, double y3) {
        this.x1 = x1;
        this.y1 = y1;
        this.x2 = x2;
        this.y2 = y2;
        this.x3 = x3;
        this.y3 = y3;
    }

    @Override
    public double getGirth(int i) {
        double a = Math.sqrt(Math.pow(x1-x2, 2) + Math.pow(y1-y2, 2));
        double b = Math.sqrt(Math.pow(x2-x3, 2) + Math.pow(y2-y3, 2));
        double c = Math.sqrt(Math.pow(x3-x1, 2) + Math.pow(y3-y1, 2));
        return a + b + c;
    }

    @Override
    public double getArea(int i) {
        double a = Math.sqrt(Math.pow(x1-x2, 2) + Math.pow(y1-y2, 2));
        double b = Math.sqrt(Math.pow(x2-x3, 2) + Math.pow(y2-y3, 2));
        double c = Math.sqrt(Math.pow(x3-x1, 2) + Math.pow(y3-y1, 2));
        double p = (a + b + c) / 2;
        return Math.sqrt(p * (p - a) * (p - b) * (p - c));
    }
}

以下是用例代码，用于输出三角形的周长和面积：

public class Main {
    public static void main(String[] args) {
        Triangle triangle = new Triangle(0, 0, 3, 0, 0, 4);
        System.out.printf("The girth of the triangle is %.2f.\n", triangle.getGirth(0));
        System.out.printf("The area of the triangle is %.2f.\n", triangle.getArea(0));
    }
}

运行后，输出结果为：

The girth of the triangle is 12.00.
The area of the triangle is 6.00.