public void recur(Graphics g, double x1, double x2, double y1, double y2, int range) {
?? ??? ??? ?double x3 = (x1 + x2) / 2;
?? ??? ??? ?double y3 = (y1 + y2) / 2;
?? ??? ??? ?if (x2-x1<= 15) {
?? ??? ??? ??? ?g.drawLine((int) x1, (int) y1, (int) x3, (int) y3);
?? ??? ??? ??? ?g.drawLine((int) x2, (int) y2, (int) x3, (int) y3);
?? ??? ??? ??? ?return;
?? ??? ??? ?}
?? ??? ??? ?Random rand=new Random();
?? ??? ??? ?int num=rand.nextInt(range);
?? ??? ??? ?recur(g, x1, x3, y1, y3-num, range);
?? ??? ??? ?recur(g, x3, x2, y3-num, y2, range);?? ??? ??? ??? ??? ?
?? ??? ?}

最終效果如下

很明顯這并不像山脈背景吧，然后我通過查閱相關資料了解到問題在于需要每次遞歸時需要將縱坐標隨機數(shù)值減小，改進后代碼如下

public void recur(Graphics g, double x1, double x2, double y1, double y2, int range) {
//range我用的是300，大家可以自己調(diào)節(jié)
?? ??? ??? ?double x3 = (x1 + x2) / 2;
?? ??? ??? ?double y3 = (y1 + y2) / 2;
?? ??? ??? ?if (x2-x1<= 1|range==0) {
?? ??? ??? ??? ?g.drawLine((int) x1, (int) y1, (int) x3, (int) y3);
?? ??? ??? ??? ?g.drawLine((int) x2, (int) y2, (int) x3, (int) y3);
?? ??? ??? ??? ?return;
?? ??? ??? ?}
?? ??? ??? ?Random rand=new Random();
?? ??? ??? ?int num=rand.nextInt(range*2)-range;
?? ??? ??? ?range*=0.5;
?? ??? ??? ?recur(g, x1, x3, y1, y3+num, range);
?? ??? ??? ?recur(g, x3, x2, y3+num, y2, range);?? ??? ??? ??? ??? ?
?? ??? ?}

效果很接近山脈

然后我又想可以使用Polygon類來對山脈進行顏色填充，同時傳入不同的透明度進行不同山脈的區(qū)別一定更美觀，廢話不多說，上代碼

public void recur(Graphics g, double x1, double x2, double y1, double y2, int range,int alp) {
? ? ? ? //實例range用的是300
? ? ? ? //四座山脈透明度分別為220，180，120，40
?? ??? ?double x3 = (x1 + x2) / 2;
?? ??? ?double y3 = (y1 + y2) / 2;
?? ??? ?if (x2-x1<= 1|range==0) {
?? ??? ??? ?g.drawLine((int) x1, (int) y1, (int) x3, (int) y3);
?? ??? ??? ?g.drawLine((int) x2, (int) y2, (int) x3, (int) y3);
?? ??? ??? ?Polygon p=new Polygon();
?? ??? ??? ?p.addPoint((int)x3, (int)y3);
?? ??? ??? ?p.addPoint((int)x1, (int)y1);
?? ??? ??? ?p.addPoint((int)x1, 800);
?? ??? ??? ?p.addPoint((int)x2, 800);
?? ??? ??? ?p.addPoint((int)x2, (int)y2);
?? ??? ??? ?g.setColor(new Color(0,0,0,alp));
?? ??? ??? ?g.fillPolygon(p);
?? ??? ??? ?return;
?? ??? ?}
?? ??? ?Random rand=new Random();
?? ??? ?int num=rand.nextInt(range*2)-range;
?? ??? ?range*=0.5;
? ? ? ? //上面的0.5也可以改變，他控制的是循環(huán)次數(shù)和山脈的陡峭度，大家可以改變嘗試
?? ??? ?recur(g, x1, x3, y1, y3+num, range,alp);
?? ??? ?recur(g, x3, x2, y3+num, y2, range,alp);
?? ?}