这个问题完全把我难住了。我已经在这个线程中尝试了所有的东西，但无论我做什么，我都不能改变下划线的颜色，除了默认的蓝色。

I finally figured out what was going on. I was (incorrectly) using android.widget.EditText when making a new instance (but the rest of my components were from the appcompat library). I should have used android.support.v7.widget.AppCompatEditText. I replaced new EditText(this) with new AppCompatEditText(this) and the problem was instantly solved. It turns out, if you are actually using AppCompatEditText, it will just respect the accentColor from your theme (as mentioned in several comments above) and no additional configuration is necessary.

下面是TextInputLayout在支持设计库中的部分源代码(更新为23.2.0版本)，它以更简单的方式改变EditText的底线颜色:

private void updateEditTextBackground() {
    ensureBackgroundDrawableStateWorkaround();

    final Drawable editTextBackground = mEditText.getBackground();
    if (editTextBackground == null) {
        return;
    }

    if (mErrorShown && mErrorView != null) {
        // Set a color filter of the error color
        editTextBackground.setColorFilter(
                AppCompatDrawableManager.getPorterDuffColorFilter(
                        mErrorView.getCurrentTextColor(), PorterDuff.Mode.SRC_IN));
    }
    ...
}

在23.2.0中，如果您想通过编程方式更改颜色，上述所有代码似乎都变得毫无用处。

如果你想支持所有平台，以下是我的方法:

/**
 * Set backgroundTint to {@link View} across all targeting platform level.
 * @param view the {@link View} to tint.
 * @param color color used to tint.
 */
public static void tintView(View view, int color) {
    final Drawable d = view.getBackground();
    final Drawable nd = d.getConstantState().newDrawable();
    nd.setColorFilter(AppCompatDrawableManager.getPorterDuffColorFilter(
            color, PorterDuff.Mode.SRC_IN));
    view.setBackground(nd);
}

要动态更改EditText背景，可以使用ColorStateList。

int[][] states = new int[][] {
    new int[] { android.R.attr.state_enabled}, // enabled
    new int[] {-android.R.attr.state_enabled}, // disabled
    new int[] {-android.R.attr.state_checked}, // unchecked
    new int[] { android.R.attr.state_pressed}  // pressed
};

int[] colors = new int[] {
    Color.BLACK,
    Color.RED,
    Color.GREEN,
    Color.BLUE
};

ColorStateList colorStateList = new ColorStateList(states, colors);

这个关于ColorStateList的答案太棒了。

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>

    <item name="colorControlNormal">@color/colorAccent</item>
    <item name="colorControlActivated">@color/colorAccent</item>
    <item name="colorControlHighlight">@color/colorAccent</item>

</style>

公认的答案是更基于每个样式的东西，但最有效的做法是在你的AppTheme样式中添加colorAccent属性，像这样:

<style name="AppTheme.Base" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="colorAccent">@color/colorAccent</item>
        <item name="android:editTextStyle">@style/EditTextStyle</item>
</style>

<style name="EditTextStyle" parent="Widget.AppCompat.EditText"/>

colorAccent属性用于在整个应用程序中为小部件着色，因此应该用于一致性

我用这个方法改变了线条的颜色与PorterDuff，没有其他的绘图。

public void changeBottomColorSearchView(int color) {
    int searchPlateId = mSearchView.getContext().getResources().getIdentifier("android:id/search_plate", null, null);
    View searchPlate = mSearchView.findViewById(searchPlateId);
    searchPlate.getBackground().setColorFilter(color, PorterDuff.Mode.SRC_IN);
}