Fix: Setting file with same content should not make bean dirty

(cherry picked from commit 62c4acd36a)

ebean-api/src/main/java/io/ebean/bean/EntityBeanIntercept.java

@@ -6,6 +6,11 @@ import io.ebean.ValuePair;
 
 import javax.persistence.EntityNotFoundException;
 import javax.persistence.PersistenceException;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
 import java.io.Serializable;
 import java.math.BigDecimal;
 import java.net.URL;
@@ -910,9 +915,38 @@ public final class EntityBeanIntercept implements Serializable {
       // use the string format to determine if dirty
       return !obj1.toString().equals(obj2.toString());
     }
+    if (obj1 instanceof File && obj2 instanceof File) {
+      File file1 = (File) obj1;
+      File file2 = (File) obj2;
+      if (file1.exists() && file2.exists() && file1.length() == file2.length()) {
+        return notEqualContent(file1, file2);
+      }
+    }
     return !obj1.equals(obj2);
   }
 
+  private static boolean notEqualContent(File file1, File file2) {
+    try (InputStream is1 = new FileInputStream(file1); InputStream is2 = new FileInputStream(file2)) {
+      byte[] buf1 = new byte[16384];
+      byte[] buf2 = new byte[16384];
+      int len1;
+      int len2;
+      while ((len1 = is1.read(buf1)) != -1 && (len2 = is2.read(buf2)) != -1) {
+        if (len1 != len2) {
+          return true;
+        }
+        if (!Arrays.equals(buf1, buf2)) {
+          // it does not matter, if we compare more than len1/len2 as the remainig
+          // bytes in the buffers are either 0 or equals from the prev. loop.
+          return true;
+        }
+      }
+      return false;
+    } catch (IOException e) {
+      return true; // handle them as "not equals"
+    }
+  }
+
   /**
    * Called when a BeanCollection is initialised automatically.
    */

ebean-test/src/test/java/org/tests/types/TestFileType.java

@@ -12,6 +12,7 @@ import java.io.PrintStream;
 import java.net.URL;
 
 import static org.junit.jupiter.api.Assertions.*;
+import static org.assertj.core.api.Assertions.assertThat;
 
 public class TestFileType extends BaseTestCase {
 
@@ -184,6 +185,31 @@ public class TestFileType extends BaseTestCase {
     DB.delete(bean3);
   }
 
+  @Test
+  void test_FileDirty() throws Exception {
+    SomeFileBean bean0 = new SomeFileBean();
+    bean0.setName("afile");
+    bean0.setContent(file);
+
+    DB.save(bean0);
+
+    SomeFileBean bean1 = DB.find(SomeFileBean.class)
+        .select("name, file")
+        .setId(bean0.getId())
+        .findOne();
+
+    assertThat(bean1.getContent())
+        .isNotEqualTo(file) // not same file object, but same content
+        .hasSameBinaryContentAs(file);
+
+    assertFalse(DB.beanState(bean1).isDirty());
+    bean1.setContent(file);
+    assertFalse(DB.beanState(bean1).isDirty());
+    bean1.setContent(file2);
+    assertTrue(DB.beanState(bean1).isDirty());
+
+  }
+
   private File getFile(String resource) {
     URL url = getClass().getResource(resource);
     return new File(url.getFile());