Converting a File to a MultipartFile (#15180)

* Converting a File to a MultipartFile

* Converting a File to a MultipartFile

spring-web-modules/spring-mvc-java-2/pom.xml

@@ -41,6 +41,11 @@
             <artifactId>jaxb-runtime</artifactId>
             <version>${jaxb-runtime.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-fileupload</groupId>
+            <artifactId>commons-fileupload</artifactId>
+            <version>${commons-fileupload.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -57,6 +62,7 @@
         <javax.version>4.0.1</javax.version>
         <spring.mvc.version>5.2.2.RELEASE</spring.mvc.version>
         <jaxb-runtime.version>2.3.5</jaxb-runtime.version>
+        <commons-fileupload.version>1.5</commons-fileupload.version>
     </properties>
 
 </project>

spring-web-modules/spring-mvc-java-2/src/test/java/com/baeldung/multipart/file/ConvertFileToMultipartFileUnitTest.java

@@ -0,0 +1,45 @@
+package com.baeldung.multipart.file;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+
+import org.apache.commons.fileupload.FileItem;
+import org.apache.commons.fileupload.disk.DiskFileItem;
+import org.apache.commons.io.IOUtils;
+import org.junit.jupiter.api.Test;
+import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.multipart.commons.CommonsMultipartFile;
+import org.springframework.mock.web.MockMultipartFile;
+
+public class ConvertFileToMultipartFileUnitTest {
+
+    @Test
+    public void givenFile_whenCreateMultipartFile_thenContentMatch() throws IOException {
+        File file = new File("src/main/resources/targetFile.tmp");
+        byte[] fileBytes = Files.readAllBytes(file.toPath());
+        MultipartFile multipartFile = new MockMultipartFile("file", file.getName(), "text/plain", fileBytes);
+        String fileContent = new String(multipartFile.getBytes());
+        assertEquals("Hello World", fileContent);
+        assertEquals("targetFile.tmp", multipartFile.getOriginalFilename());
+    }
+
+    @Test
+    public void givenFile_whenCreateMultipartFileUsingCommonsMultipart_thenContentMatch() throws IOException {
+        File file = new File("src/main/resources/targetFile.tmp");
+        FileItem fileItem = new DiskFileItem("file", Files.probeContentType(file.toPath()), false, file.getName(), (int) file.length(), file.getParentFile());
+        InputStream input = new FileInputStream(file);
+        OutputStream outputStream = fileItem.getOutputStream();
+        IOUtils.copy(input, outputStream);
+        MultipartFile multipartFile = new CommonsMultipartFile(fileItem);
+        String fileContent = new String(multipartFile.getBytes());
+        assertEquals("Hello World", fileContent);
+        assertEquals("targetFile.tmp", multipartFile.getOriginalFilename());
+    }
+
+}