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;
---------------------