[java] IDEA-355048 Support binary files (.class) in split mode

GitOrigin-RevId: ea7a098ef33476d53dd8bf061810835510885466

java/java-frontback-psi-impl/src/com/intellij/ide/highlighter/JavaClassFileType.java

@@ -0,0 +1,51 @@
+// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.ide.highlighter;
+
+import com.intellij.core.JavaPsiBundle;
+import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.ui.IconManager;
+import com.intellij.ui.PlatformIcons;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NonNls;
+import org.jetbrains.annotations.NotNull;
+
+import javax.swing.*;
+
+public final class JavaClassFileType implements FileType {
+  public static final @NonNls String DEFAULT_EXTENSION = "class";
+  public static final @NonNls String DOT_DEFAULT_EXTENSION = ".class";
+  public static final JavaClassFileType INSTANCE = new JavaClassFileType();
+
+  private JavaClassFileType() {
+  }
+
+  @Override
+  public @NotNull String getName() {
+    return "CLASS";
+  }
+
+  @Override
+  public @NotNull String getDescription() {
+    return JavaPsiBundle.message("filetype.class.description");
+  }
+
+  @Override
+  public @Nls @NotNull String getDisplayName() {
+    return JavaPsiBundle.message("filetype.class.display.name");
+  }
+
+  @Override
+  public @NotNull String getDefaultExtension() {
+    return DEFAULT_EXTENSION;
+  }
+
+  @Override
+  public Icon getIcon() {
+    return IconManager.getInstance().getPlatformIcon(PlatformIcons.JavaClassFileType);
+  }
+
+  @Override
+  public boolean isBinary() {
+    return true;
+  }
+}

java/java-frontback-psi-impl/src/com/intellij/java/frontback/psi/impl/JavaLangLevelProjectCustomDataSynchronizer.kt

@@ -37,4 +37,7 @@ class JavaLangLevelProjectCustomDataSynchronizer : ProjectCustomDataSynchronizer
 class LanguageLevelHolder(val languageLevel: LanguageLevel)
 
 @Serializable
-class NullableLanguageLevelHolder(val languageLevel: LanguageLevel?)
+class NullableLanguageLevelHolder(val languageLevel: LanguageLevel?)
+
+@Serializable
+class ClassFileInformation(val isClassFile: Boolean?)