Fix the compatibility problem of ConfigUtil for Windows environment (#903)

sentinel-core/src/main/java/com/alibaba/csp/sentinel/util/ConfigUtil.java

@@ -45,7 +45,7 @@ public final class ConfigUtil {
      */
     public static Properties loadProperties(String fileName) {
         if (StringUtil.isNotBlank(fileName)) {
-            if (fileName.startsWith(File.separator)) {
+            if (absolutePathStart(fileName)) {
                 return loadPropertiesFromAbsoluteFile(fileName);
             } else if (fileName.startsWith(CLASSPATH_FILE_FLAG)) {
                 return loadPropertiesFromClasspathFile(fileName);
@@ -76,6 +76,16 @@ public final class ConfigUtil {
         return properties;
     }
 
+    private static boolean absolutePathStart(String path) {
+        File[] files = File.listRoots();
+        for (File file : files) {
+            if (path.startsWith(file.getPath())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
 
     private static Properties loadPropertiesFromClasspathFile(String fileName) {
         fileName = fileName.substring(CLASSPATH_FILE_FLAG.length()).trim();

sentinel-core/src/test/java/com/alibaba/csp/sentinel/util/ConfigUtilTest.java

@@ -49,7 +49,7 @@ public class ConfigUtilTest {
             }
             BufferedWriter out = new BufferedWriter(new FileWriter(file));
             out.write(LOG_OUTPUT_TYPE + "=" + logOutputType);
-            out.write("\n");
+            out.write(System.getProperty("line.separator"));
             out.write(LOG_DIR + "=" + dir);
             out.flush();
             out.close();