RelativeLayout有方法addRule可以动态设置alignParent、margin、控件相对位置的设置，比如需要设置childView右边距离RelativeLayout右边距为20dp：
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); View childView = findViewById(R.id.child1); RelativeLayout parent = findViewById(R.id.parent); RelativeLayout.LayoutParams lps = (RelativeLayout.LayoutParams) childView.getLayoutParams(); lps.rightMargin = dip2px(this, 20.0f); lps.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); } public static int dip2px(Context context, float dipValue) { final float scale = context.getResources().getDisplayMetrics().density; return (int) (dipValue * scale + 0.5f); }最终效果图： 上面的例子是相对于父布局的，再举一个相对于子控件的例子，实现下面的效果图： 红色childview2位于白色view左边20dp 代码：
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); View childView = findViewById(R.id.child1); RelativeLayout parent = findViewById(R.id.parent); RelativeLayout.LayoutParams lps = (RelativeLayout.LayoutParams) childView.getLayoutParams(); lps.rightMargin = dip2px(this, 20.0f); lps.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); View childView2 = findViewById(R.id.child2); RelativeLayout.LayoutParams lps2 = (RelativeLayout.LayoutParams) childView2.getLayoutParams(); //lps2.addRule(RelativeLayout.BELOW,R.id.child1); lps2.rightMargin = dip2px(this, 20.0f); lps2.addRule(RelativeLayout.LEFT_OF, R.id.child1); }这时候addRule方法就要带一个view的id值。
有了这个addRule方法就可以设置很多其他属性了，通过源码可知RelativeLayout是使用mRules这个数组来记录哪种属性使用到了，一共有22种属性：
/** * Rule that aligns a child's right edge with another child's left edge. */ public static final int LEFT_OF = 0; /** * Rule that aligns a child's left edge with another child's right edge. */ public static final int RIGHT_OF = 1; /** * Rule that aligns a child's bottom edge with another child's top edge. */ public static final int ABOVE = 2; /** * Rule that aligns a child's top edge with another child's bottom edge. */ public static final int BELOW = 3; /** * Rule that aligns a child's baseline with another child's baseline. */ public static final int ALIGN_BASELINE = 4; /** * Rule that aligns a child's left edge with another child's left edge. */ public static final int ALIGN_LEFT = 5; /** * Rule that aligns a child's top edge with another child's top edge. */ public static final int ALIGN_TOP = 6; /** * Rule that aligns a child's right edge with another child's right edge. */ public static final int ALIGN_RIGHT = 7; /** * Rule that aligns a child's bottom edge with another child's bottom edge. */ public static final int ALIGN_BOTTOM = 8; /** * Rule that aligns the child's left edge with its RelativeLayout * parent's left edge. */ public static final int ALIGN_PARENT_LEFT = 9; /** * Rule that aligns the child's top edge with its RelativeLayout * parent's top edge. */ public static final int ALIGN_PARENT_TOP = 10; /** * Rule that aligns the child's right edge with its RelativeLayout * parent's right edge. */ public static final int ALIGN_PARENT_RIGHT = 11; /** * Rule that aligns the child's bottom edge with its RelativeLayout * parent's bottom edge. */ public static final int ALIGN_PARENT_BOTTOM = 12; /** * Rule that centers the child with respect to the bounds of its * RelativeLayout parent. */ public static final int CENTER_IN_PARENT = 13; /** * Rule that centers the child horizontally with respect to the * bounds of its RelativeLayout parent. */ public static final int CENTER_HORIZONTAL = 14; /** * Rule that centers the child vertically with respect to the * bounds of its RelativeLayout parent. */ public static final int CENTER_VERTICAL = 15; /** * Rule that aligns a child's end edge with another child's start edge. */ public static final int START_OF = 16; /** * Rule that aligns a child's start edge with another child's end edge. */ public static final int END_OF = 17; /** * Rule that aligns a child's start edge with another child's start edge. */ public static final int ALIGN_START = 18; /** * Rule that aligns a child's end edge with another child's end edge. */ public static final int ALIGN_END = 19; /** * Rule that aligns the child's start edge with its RelativeLayout * parent's start edge. */ public static final int ALIGN_PARENT_START = 20; /** * Rule that aligns the child's end edge with its RelativeLayout * parent's end edge. */ public static final int ALIGN_PARENT_END = 21;