this.setInputType(EditorInfo.TYPE_TEXT_VARIATION_PASSWORD);密文密码
this.setInputType(EditorInfo.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD); 明文密码

this.setTransformationMethod(HideReturnsTransformationMethod.getInstance());显示明文密码
this.setTransformationMethod(PasswordTransformationMethod.getInstance());显示密文密码

public class TogglePasswordVisibilityEditText extends EditText {
//切换drawable的引用
private Drawable visibilityDrawable;
private boolean visibililty = false;
public TogglePasswordVisibilityEditText(Context context) {
 this(context, null);
}
public TogglePasswordVisibilityEditText(Context context, AttributeSet attrs) {
 //指定了默认的style属性
 this(context, attrs, android.R.attr.editTextStyle);
}
public TogglePasswordVisibilityEditText(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 init();
}
private void init() {
 //获得该EditText的left ,top ,right,bottom四个方向的drawable
 Drawable[] compoundDrawables = getCompoundDrawables();
 visibilityDrawable = compoundDrawables[2];
 if (visibilityDrawable == null) {
  visibilityDrawable = getResources().getDrawable(R.drawable.ic_visibility_off_black_24dp);
 }
}
/**
 * 用按下的位置来模拟点击事件
 * 当按下的点的位置 在 EditText的宽度 - (图标到控件右边的间距 + 图标的宽度) 和
 * EditText的宽度 - 图标到控件右边的间距 之间就模拟点击事件，
 */
@Override
public boolean onTouchEvent(MotionEvent event) {
 int action = event.getAction();
 if (action == MotionEvent.ACTION_UP) {
  if (getCompoundDrawables()[2] != null) {
   boolean xFlag = false;
   boolean yFlag = false;
   //得到用户的点击位置，模拟点击事件
   xFlag = event.getX() > getWidth() - (visibilityDrawable.getIntrinsicWidth() + getCompoundPaddingRight
     ()) &&
     event.getX() < getWidth() - (getTotalPaddingRight() - getCompoundPaddingRight());
   if (xFlag) {
    visibililty = !visibililty;
    if (visibililty) {
     visibilityDrawable = getResources().getDrawable(R.drawable.ic_visibility_black_24dp);
     /*this.setInputType(EditorInfo.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD);*/
     this.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
    } else {
     //隐藏密码
     visibilityDrawable = getResources().getDrawable(R.drawable.ic_visibility_off_black_24dp);
     //this.setInputType(EditorInfo.TYPE_TEXT_VARIATION_PASSWORD);
     this.setTransformationMethod(PasswordTransformationMethod.getInstance());
    }
    //将光标定位到指定的位置
    CharSequence text = this.getText();
    if (text instanceof Spannable) {
     Spannable spanText = (Spannable) text;
     Selection.setSelection(spanText, text.length());
    }
    //调用setCompoundDrawables方法时，必须要为drawable指定大小，不然不会显示在界面上
    visibilityDrawable.setBounds(0, 0, visibilityDrawable.getMinimumWidth(),
      visibilityDrawable.getMinimumHeight());
    setCompoundDrawables(getCompoundDrawables()[0],
      getCompoundDrawables()[1], visibilityDrawable, getCompoundDrawables()[3]);
   }
  }
 }
 return super.onTouchEvent(event);
 }
}