用java编写一个代表三角形的类，其中3条边为三角形的属性，并封装有求三角形的面积和周长的方法。分别利用3条边为3、4、5和7、8、9的两个三角形进行测试。

Triangle.java

public class Triangle {
    private double side1;
    private double side2;
    private double side3;

    public Triangle(double side1, double side2, double side3) {
        this.side1 = side1;
        this.side2 = side2;
        this.side3 = side3;
    }

    public double getSide1() {
        return side1;
    }

    public double getSide2() {
        return side2;
    }

    public double getSide3() {
        return side3;
    }

    public double getArea() {
        double p = (side1 + side2 + side3) / 2.0;
        return Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
    }

    public double getPerimeter() {
        return side1 + side2 + side3;
    }
}

TestTriangle.java

public class TestTriangle {
    public static void main(String[] args) {
        Triangle triangle1 = new Triangle(3, 4, 5);
        System.out.println("Triangle 1:");
        System.out.println("Side 1: " + triangle1.getSide1());
        System.out.println("Side 2: " + triangle1.getSide2());
        System.out.println("Side 3: " + triangle1.getSide3());
        System.out.println("Area: " + triangle1.getArea());
        System.out.println("Perimeter: " + triangle1.getPerimeter());

        System.out.println();

        Triangle triangle2 = new Triangle(7, 8, 9);
        System.out.println("Triangle 2:");
        System.out.println("Side 1: " + triangle2.getSide1());
        System.out.println("Side 2: " + triangle2.getSide2());
        System.out.println("Side 3: " + triangle2.getSide3());
        System.out.println("Area: " + triangle2.getArea());
        System.out.println("Perimeter: " + triangle2.getPerimeter());
    }
}

Output:

Triangle 1:
Side 1: 3.0
Side 2: 4.0
Side 3: 5.0
Area: 6.0
Perimeter: 12.0

Triangle 2:
Side 1: 7.0
Side 2: 8.0
Side 3: 9.0
Area: 26.832815729997478
Perimeter: 24.0