先创建一个Point类，然后定义Triangle类。在Triangle类中定义三个Point的实体来表示一个三角形的三个点，再定义一个方法setTri对这三个点进行初始化，然后定义两个方法求三角形的周长、面积。在main()中创建一个三角形对象，求给定三点的三角形的周长、面积。

首先，我们可以创建一个名为`Point`的类，它包含坐标信息：

public class Point {
    double x;
    double y;

    public Point(double x, double y) {
        this.x = x;
        this.y = y;
    }

    // getters and setters for x and y coordinates
}

接着，我们定义`Triangle`类，它内部持有三个`Point`类型的成员变量，并提供用于初始化的`setTri`方法以及计算周长和面积的方法：

public class Triangle {
    private Point point1;
    private Point point2;
    private Point point3;

    public Triangle(Point p1, Point p2, Point p3) {
        setTri(p1, p2, p3);
    }

    public void setTri(Point p1, Point p2, Point p3) {
        this.point1 = p1;
        this.point2 = p2;
        this.point3 = p3;
    }

    public double getPerimeter() {
        return Math.abs(point1.x - point2.x) + Math.abs(point2.x - point3.x) + Math.abs(point3.x - point1.x)
                + Math.abs(point1.y - point2.y) + Math.abs(point2.y - point3.y) + Math.abs(point3.y - point1.y);
    }

    public double getArea() {
        double a = Math.abs((point1.x + point2.x + point3.x) / 2);
        double b = Math.abs((point1.y + point2.y + point3.y) / 2);
        return Math.sqrt(a * (a - point1.x) * (a - point2.x) * (a - point3.x)
                        + b * (b - point1.y) * (b - point2.y) * (b - point3.y));
    }
}

// In main method
public static void main(String[] args) {
    Point p1 = new Point(0, 0);
    Point p2 = new Point(5, 0);
    Point p3 = new Point(0, 4); // Example points for a right triangle

    Triangle triangle = new Triangle(p1, p2, p3);
    System.out.println("Triangle perimeter: " + triangle.getPerimeter());
    System.out.println("Triangle area: " + triangle.getArea());