如何更改进度条模式颜色

Question

我在我的应用程序中使用进度条一切正常工作是变化是35％以下的颜色但问题是它显示双重效果看图像http://imgur.com/SMU3xG3它的颜色变为红色但也显示双重效果我将改为黑????

progressBar = (ProgressBar) findViewById(R.id.signalLevel);
private String getSignalLevelString(int level) {
    String signalLevelString = "Weak";
    level=35;
    if (level >= EXCELLENT_LEVEL)
    {
        signalLevelString = "High";
    progressBar.getProgressDrawable().setColorFilter(Color.GREEN, Mode.MULTIPLY);
    }

    else if (level <= GOOD_LEVEL)
    {
        signalLevelString = "Weak";
        progressBar.getProgressDrawable().setColorFilter(Color.RED,  Mode.MULTIPLY);
    }

    return signalLevelString;
}

XML代码：

<ProgressBar
    android:id="@+id/signalLevel"
    android:layout_width="60dp"
    android:layout_height="wrap_content"
    android:indeterminate="false"
    android:progress="100" 
   style="@style/progressStyle"/>