Fix the problem of duplicate path separator in windows system (#1812)

* fix: duplicate path separator in windows system

* fix: code style

src/main/java/run/halo/app/handler/file/FilePathDescriptor.java

@@ -151,7 +151,7 @@ public final class FilePathDescriptor {
                 sb.append(first);
                 for (String segment : more) {
                     if (StringUtils.isNotBlank(segment)) {
-                        if (sb.length() > 0) {
+                        if (sb.length() > 0 && !endsWith(sb, separator)) {
                             sb.append(separator);
                         }
                         sb.append(segment);
@@ -162,6 +162,14 @@ public final class FilePathDescriptor {
             return path;
         }
 
+        static boolean endsWith(StringBuilder sb, String str) {
+            Assert.notNull(sb, "The stringBuilder must not be null.");
+            Assert.notNull(str, "The str must not be null.");
+            int len = sb.length();
+            int strLen = str.length();
+            return (len >= strLen && sb.substring(len - strLen).equals(str));
+        }
+
         /**
          * build file path object.
          *

src/test/java/run/halo/app/handler/file/FilePathDescriptorTest.java

@@ -1,5 +1,6 @@
 package run.halo.app.handler.file;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static run.halo.app.model.support.HaloConst.FILE_SEPARATOR;
@@ -87,4 +88,29 @@ public class FilePathDescriptorTest {
         assertEquals("/home/halo/2021/10/1.4.9.png", descriptor.getFullPath());
         assertEquals("2021/10/1.4.9.png", descriptor.getRelativePath());
     }
+
+    @Test
+    public void windowsSystem() {
+        FilePathDescriptor descriptor = new FilePathDescriptor.Builder()
+            .setBasePath("C:\\Users\\Halo NiuBi\\.halo\\")
+            .setSubPath("upload\\2022\\04\\")
+            .setSeparator("\\")
+            .setAutomaticRename(false)
+            .setRenamePredicate(builder -> true)
+            .setOriginalName("hello.jpg")
+            .build();
+
+        assertThat(descriptor).isNotNull();
+
+        assertThat(descriptor.getFullPath()).isEqualTo("C:\\Users\\Halo NiuBi\\"
+            + ".halo\\upload\\2022\\04\\hello.jpg");
+        assertThat(descriptor.getRelativePath()).isEqualTo("upload\\2022\\04\\hello.jpg");
+
+        assertThat(descriptor.getBasePath()).isEqualTo("C:\\Users\\Halo NiuBi\\.halo\\");
+        assertThat(descriptor.getSubPath()).isEqualTo("upload\\2022\\04\\");
+
+        assertThat(descriptor.getExtension()).isEqualTo("jpg");
+        assertThat(descriptor.getName()).isEqualTo("hello");
+        assertThat(descriptor.getFullName()).isEqualTo("hello.jpg");
+    }
 }