网上找了很多，还是没有直接的解决办法，button没有setstyle这个方法。因此我的解决办法如下：
直接动态设置各个属性
Button themeBtn = new Button(this);
themeBtn.setText(entry.getKey());
LayoutParams lparams = new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.MATCH_PARENT);
themeBtn.setLayoutParams(lparams);
themeBtn.setTextAppearance(this, R.style.ImageCategoryThemeBtn);
themeBtn.setPadding(DensityUtils.dp2px(this, 8), 0, DensityUtils.dp2px(this, 8), 0);
themeBtn.setBackgroundResource(R.drawable.selector_bt_gray2blue);
v_theme.addView(themeBtn);
style：
<style name="ImageCategoryThemeBtn" parent="@android:style/Widget.Button">
<item name="android:textColor">@color/image_theme</item>
<item name="android:textSize">@dimen/imageThemeBtnTextSize</item>
</style>