awt画带箭头的函数

public void drawAL(int sx, int sy, int ex, int ey, Graphics2D g2)
    {
        g2.setStroke(new BasicStroke(1.5f)) ;
        double H = 8; // 箭头高度  
        double L = 3.5; // 底边的一半  
        int x3 = 0;
        int y3 = 0;
        int x4 = 0;
        int y4 = 0;
        double awrad = Math.atan(L / H); // 箭头角度  
        double arraow_len = Math.sqrt(L * L + H * H); // 箭头的长度  
        double[] arrXY_1 = rotateVec(ex - sx, ey - sy, awrad, true, arraow_len);
        double[] arrXY_2 = rotateVec(ex - sx, ey - sy, -awrad, true, arraow_len);
        double x_3 = ex - arrXY_1[0]; // (x3,y3)是第一端点  
        double y_3 = ey - arrXY_1[1];
        double x_4 = ex - arrXY_2[0]; // (x4,y4)是第二端点  
        double y_4 = ey - arrXY_2[1];

        Double X3 = new Double(x_3);
        x3 = X3.intValue();
        Double Y3 = new Double(y_3);
        y3 = Y3.intValue();
        Double X4 = new Double(x_4);
        x4 = X4.intValue();
        Double Y4 = new Double(y_4);
        y4 = Y4.intValue();
        // 画线  
        g2.drawLine(sx, sy, ex, ey);
        GeneralPath triangle = new GeneralPath();
        triangle.moveTo(ex, ey);
        triangle.lineTo(x3, y3); 
        triangle.lineTo(x4, y4);
        triangle.closePath();
        //实心箭头  
        g2.fill(triangle);
        //非实心箭头  
        //g2.draw(triangle);  

    }

    // 计算  
    public double[] rotateVec(int px, int py, double ang, boolean isChLen, double newLen)
    {

        double mathstr[] = new double[2];
        // 矢量旋转函数，参数含义分别是x分量、y分量、旋转角、是否改变长度、新长度  
        double vx = px * Math.cos(ang) - py * Math.sin(ang);
        double vy = px * Math.sin(ang) + py * Math.cos(ang);
        if (isChLen) {
            double d = Math.sqrt(vx * vx + vy * vy);
            vx = vx / d * newLen;
            vy = vy / d * newLen;
            mathstr[0] = vx;
            mathstr[1] = vy;
        }
        return mathstr;
    }