Add Utils for handling MultiPart

Author: debuglevel

build.gradle

@@ -28,7 +28,7 @@ compileTestKotlin {
 }
 
 group 'de.debuglevel.sparkmicroserviceutils'
-version '0.0.21'
+version '0.0.22'
 
 sourceCompatibility = 1.8
 

src/main/kotlin/de/debuglevel/microservices/utils/multipart/MultipartUtils.kt

@@ -0,0 +1,83 @@
+package de.debuglevel.microservices.utils.multipart
+
+import mu.KotlinLogging
+import spark.Request
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.StandardCopyOption
+import javax.servlet.MultipartConfigElement
+import javax.servlet.http.Part
+
+object MultipartUtils {
+    private val logger = KotlinLogging.logger {}
+
+    /**
+     * Get the original file name of a multipart part
+     */
+    private fun getOriginalFilename(part: Part): String? {
+        for (cd in part.getHeader("content-disposition").split(";")) {
+            if (cd.trim { it <= ' ' }.startsWith("filename")) {
+                return cd.substring(
+                        cd
+                                .indexOf('=') + 1)
+                        .trim { it <= ' ' }
+                        .replace("\"", "")
+            }
+        }
+
+        return null
+    }
+
+    /**
+     * Get text from a multipart request.
+     *
+     * @param fieldName name of the field in the HTML form
+     */
+    fun getField(request: Request, fieldName: String): String {
+        setup(request)
+
+        return request.raw()
+                .getPart(fieldName)
+                .inputStream
+                .reader()
+                .use { it.readText() }
+    }
+
+    fun getCheckbox(request: Request, fieldName: String): Boolean {
+        setup(request)
+
+        return request.raw()
+                .parts
+                .filter { it.name == fieldName }
+                .filter { it.inputStream.reader().use { it -> it.readText() } == "on" }
+                .any()
+    }
+
+    /**
+     * Get a file from a multipart request.
+     *
+     * Copies the content form a multipart request field to a file and returns the path.
+     * Note: The file should be deleted after usage.
+     *
+     * @param fieldName name of the field in the HTML form
+     */
+    fun getFile(request: Request, fieldName: String): Path {
+        setup(request)
+
+        val temporarySurveyFile = createTempFile("sparkmicroserviceutils").toPath()
+        request.raw()
+                .getPart(fieldName) // getPart needs to use same "name" as input field in form
+                .inputStream
+                .use {
+                    Files.copy(it, temporarySurveyFile, StandardCopyOption.REPLACE_EXISTING)
+                }
+        logger.debug("Uploaded file '${getOriginalFilename(request.raw().getPart(fieldName))}' saved as '${temporarySurveyFile.toAbsolutePath()}'")
+        return temporarySurveyFile
+    }
+
+    private fun setup(request: Request) {
+        if (!request.attributes().contains("org.eclipse.jetty.multipartConfig")) {
+            request.attribute("org.eclipse.jetty.multipartConfig", MultipartConfigElement("/temp"))
+        }
+    }
+}