android 使用代码实现 RelativeLayout布局

参照以下博客和代码：

1 http://blog.csdn.net/gf771115/article/details/8237229

2 http://blog.csdn.net/love_world_/article/details/8426935

RelativeLayout rl = new RelativeLayout(this);

Button btn1 = new Button(this);
btn1.setText("----------------------");
btn1.setId(1);

RelativeLayout.LayoutParams lp1 = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp1.addRule(RelativeLayout.ALIGN_PARENT_TOP);
lp1.addRule(RelativeLayout.CENTER_HORIZONTAL, RelativeLayout.TRUE);
// btn1 位于父 View 的顶部，在父 View 中水平居中
rl.addView(btn1, lp1 );

Button btn2 = new Button(this);
btn2.setText("|\n|\n|\n|\n|\n|");
btn2.setId(2);

RelativeLayout.LayoutParams lp2 = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp2.addRule(RelativeLayout.BELOW, 1);
lp2.addRule(RelativeLayout.ALIGN_LEFT, 1);
// btn2 位于 btn1 的下方、其左边和 btn1 的左边对齐
rl.addView(btn2, lp2);

Button btn3 = new Button(this);
btn3.setText("|\n|\n|\n|\n|\n|");
btn3.setId(3);

RelativeLayout.LayoutParams lp3 = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp3.addRule(RelativeLayout.BELOW, 1);
lp3.addRule(RelativeLayout.RIGHT_OF, 2);
lp3.addRule(RelativeLayout.ALIGN_RIGHT, 1);
// btn3 位于 btn1 的下方、btn2 的右方且其右边和 btn1 的右边对齐（要扩充）
rl.addView(btn3,lp3);

Button btn4 = new Button(this);
btn4.setText("--------------------------------------------");
btn4.setId(4);

RelativeLayout.LayoutParams lp4 = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp4.addRule(RelativeLayout.BELOW, 2);
lp4.addRule(RelativeLayout.CENTER_HORIZONTAL, RelativeLayout.TRUE);
// btn4 位于 btn2 的下方，在父 Veiw 中水平居中
rl.addView(btn4,lp4);


setContentView(rl);