编码设置FrameLayout子View的layout_gravity,gravity

方法：

setLayoutParams: 用来设置带有layout前缀的属性，所有子View attach到父View都会有LayoutParams，但是parentView.addView(childView)之前，childView.getLayoutParams（）会返回null。

根据源码：

public void setLayoutParams(ViewGroup.LayoutParams params) {
if (params == null) {
throw new NullPointerException("Layout parameters cannot be null");
}
mLayoutParams = params;
resolveLayoutParams();
if (mParent instanceof ViewGroup) {
((ViewGroup) mParent).onSetLayoutParams(this, params);
}
requestLayout();
}

可以看出要想使setlayoutParams生效，必须有父View，就是调用了addView
setGravity：用来设置内部的子View。

代码：

mTitleBar = new LinearLayout(context);
mTitleBar.setLayoutParams(new LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 200));
mTitleBar.setBackgroundColor(Color.BLACK);

TextView textView = new TextView(context);
textView.setText("lfjasodijfaodjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj");
mTitleBar.addView(textView);
LinearLayout.LayoutParams textParams = new LinearLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);
textView.setLayoutParams(textParams);
textView.setGravity(Gravity.END);

mBottomBar = new LinearLayout(context);
TextView bottomTV = new TextView(context);
bottomTV.setText("lfjasodijfaodjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj");
mBottomBar.addView(bottomTV);

this.addView(mTitleBar);
this.addView(mBottomBar);

FrameLayout.LayoutParams frameLayoutParams = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, 70);
frameLayoutParams.gravity = Gravity.TOP;
mTitleBar.setLayoutParams(frameLayoutParams);

FrameLayout.LayoutParams frameLayoutParams2 = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, 70);
frameLayoutParams2.gravity = Gravity.BOTTOM;
mBottomBar.setLayoutParams(frameLayoutParams2);

效果是：



两个TextView，在两个LinearLayout中，上面的TextView gravity是右边。两个LinearyLayout在FrameLayout中layout_gravity一个Top一个Bottom