Uploading and Downloading Files in Web Dynpro Java

Transcription

1 SAP NetWeaver '04 Web Dynpro Java Tutorials Uploading and Downloading Files in Web Dynpro Java Document Version 1.00 Dezember 2005

2 SAP AG Neurottstraße Walldorf Germany T +49/18 05/ F +49/18 05/ Copyright 2005 SAP AG. All rights reserved. No part of this publication may be reproduced or transmitted in any form or for any purpose without the express permission of SAP AG. The information contained herein may be changed without prior notice. Some software products marketed by SAP AG and its distributors contain proprietary software components of other software vendors. Microsoft, Windows, Outlook, and PowerPoint are registered trademarks of Microsoft Corporation. IBM, DB2, DB2 Universal Database, OS/2, Parallel Sysplex, MVS/ESA, AIX, S/390, AS/400, OS/390, OS/400, iseries, pseries, xseries, zseries, z/os, AFP, Intelligent Miner, WebSphere, Netfinity, Tivoli, and Informix are trademarks or registered trademarks of IBM Corporation in the United States and/or other countries. SAP, R/3, mysap, mysap.com, xapps, xapp, SAP NetWeaver, and other SAP products and services mentioned herein as well as their respective logos are trademarks or registered trademarks of SAP AG in Germany and in several other countries all over the world. All other product and service names mentioned are the trademarks of their respective companies. Data contained in this document serves informational purposes only. National product specifications may vary. These materials are subject to change without notice. These materials are provided by SAP AG and its affiliated companies ("SAP Group") for informational purposes only, without representation or warranty of any kind, and SAP Group shall not be liable for errors or omissions with respect to the materials. The only warranties for SAP Group products and services are those that are set forth in the express warranty statements accompanying such products and services, if any. Nothing herein should be construed as constituting an additional warranty. Oracle is a registered trademark of Oracle Corporation. UNIX, X/Open, OSF/1, and Motif are registered trademarks of the Open Group. Citrix, ICA, Program Neighborhood, MetaFrame, WinFrame, VideoFrame, and MultiWin are trademarks or registered trademarks of Citrix Systems, Inc. HTML, XML, XHTML and W3C are trademarks or registered trademarks of W3C, World Wide Web Consortium, Massachusetts Institute of Technology. Java is a registered trademark of Sun Microsystems, Inc. Disclaimer Some components of this product are based on Java. Any code change in these components may cause unpredictable and severe malfunctions and is therefore expressively prohibited, as is any decompilation of these components. Any Java Source Code delivered with this product is only to be used by SAP s Support Services and may not be modified or altered in any way. Documentation on SAP Service Marketplace You can find this documentation at service.sap.com/instguidesnw04 JavaScript is a registered trademark of Sun Microsystems, Inc., used under license for technology invented and implemented by Netscape. MaxDB is a trademark of MySQL AB, Sweden.

3 Typographic Conventions Icons Type Style Example Text Example text EXAMPLE TEXT Example text Represents Words or characters quoted from the screen. These include field names, screen titles, pushbuttons labels, menu names, menu paths, and menu options. Cross-references to other documentation. Emphasized words or phrases in body text, graphic titles, and table titles. Technical names of system objects. These include report names, program names, transaction codes, table names, and key concepts of a programming language when they are surrounded by body text, for example, SELECT and INCLUDE. Output on the screen. This includes file and directory names and their paths, messages, names of variables and parameters, source text, and names of installation, upgrade and database tools. Example text Exact user entry. These are words or characters that you enter in the system exactly as they appear in the documentation. <Example text> Variable user entry. Angle brackets indicate that you replace these words and characters with appropriate entries to make entries in the system. EXAMPLE TEXT Keys on the keyboard, for example, F2 or ENTER. Icon Meaning Caution Example Note Recommendation Syntax

4 Contents 1 UPLOADING AND DOWNLOADING FILES IN WEB DYNPRO IMPORTING THE PROJECT TEMPLATE USING THE UI ELEMENTS FILEUPLOAD AND FILEDOWNLOAD FILE UPLOAD DEFINING THE CONTEXT AND VIEW LAYOUT IMPLEMENTING THE FILEUPLOADVIEW CONTROLLER RUNNING THE APPLICATION - FILE UPLOAD FILE DOWNLOAD DEFINING THE CONTEXT AND VIEW LAYOUT IMPLEMENTING THE FILEDOWNLOADVIEW CONTROLLER RUNNING THE APPLICATION - FILE DOWNLOAD... 15

5 Uploading and Downloading Files in Web Dynpro Java December Uploading and Downloading Files in Web Dynpro Java Introduction The Web Dynpro UI Element Library provides two special UI elements (FileDownload and FileUpload) with which you can either download files from the Web Dynpro runtime environment or upload files to the Web Dynpro runtime environment. This is performed using declarative data binding. Here, Web Dynpro runtime automatically transports different types of MIME files between the client-side user interface or UI element and the server-side controller context. The context attributes required for storing MIME files in the context must meet128% two conditions with regard to their data type. Firstly, the data type must be the Java Dictionary Simple Type com.sap.dictionray.binary. Secondly, the context attribute must have a modifiable simple data type at runtime, as method call IWDAttributeInfo.getModifiableSimpleType()has to run when the controller is initialized. This makes it possible to store additional metadata for a MIME file (like file size, file type, file name) in the attribute information (IWDAttributeInfo API) of a context attribute at node level. In the context attribute itself, only the MIME file s binary data record is saved as a byte array. This tutorial will show you how to upload and download MIME files using the UI elements FileUpload and FileDownload. Using the Virus Scan Interface To enhance your system s virus protection when working with files or documents processed by your Web Dynpro applications, you can add external virus scanners to your SAP system using the Virus Scan Interface. To connect the FileUpload service contained in the Web Dynpro runtime environment to a virus scanner, you need to activate the predefined virus scan profile webdynpro_fileupload. This profile is delivered as of SAP NetWeaver '04 SP Stack 13, and must be activated/deactivated by the SAP J2EE Engine administrator. When delivered, profile webdynpro_fileupload is initially switched off. The Virus Scan Interface cannot be used for the Web Dynpro FileDownload service. Note that the example application presented in this tutorial does not use the Virus Scan Interface. For more details, open SAP Netweaver Help and refer to the section Setting up the Virus Scan Provider [Extern]. Preview The screenshots displayed below show the three views in the tutorial application. When the application is launched, the WelcomeView appears, from where you can navigate to the file upload or file download scenarios. Uploading and Downloading Files in Web Dynpro 1

6 Uploading and Downloading Files in Web Dynpro Java December 2005 Graphic 1: The WelcomeView In the FileUploadView, you can upload a file from your computer to the server-side controller context. Once a MIME object has been uploaded, the system displays details of the uploaded file, such as file name, file ending and file size. Graphic 2: The FileUploadView In the FileDownloadView, you can upload an image file in the example project from the controller context and display it on the user interface. Graphic 3: The FileDownloadView Objectives On completion of this tutorial, you will be able to:! Use the UI element FileUpload.! Use the UI element FileDownload.! Assign the simple data type binary to context attributes so that they can store MIME Uploading and Downloading Files in Web Dynpro 2

7 ... Importing the Project Template December 2005 files.! Use modifiable binary data types in context programming to store file information. Prerequisites Systems, Installations, and Authorizations SAP NetWeaver Developer Studio is installed on your PC. You can access the SAP J2EE Engine. Knowledge Java programming language Web Dynpro application development Next Step: Importing a Project Template [Page 3] 2 Importing the Project Template The SAP Developer Network (SDN) provides the following Web Dynpro projects for this tutorial: The project template TutWD_FileUpDownload_Init (the starting point for this tutorial) The Web Dynpro project provided (TutWD_FileUpDownload) The projects can be downloaded as zip files under Home Developer Areas Web Application Server Web Dynpro Code Samples. Prerequisites You can access SAP Developer Network ( You have installed SAP NetWeaver Developer Studio. Procedure Importing the Project Template into the SAP NetWeaver Developer Studio 1. Call the SAP Developer Network at and log on with your user ID and password. If you do not have a user ID yet, you need to register before you can proceed. 2. Choose Home Developer Areas Web Application Server Web Dynpro Code Samples and then choose the section UI Elements. 3. Navigate to the example application (38) - Web Dynpro FileUpload and FileDownload. Uploading and Downloading Files in Web Dynpro 3

8 Importing the Project Template December Download the zip file TutWD_FileUpDownload_Init.zip containing the project template TutWD_FileUpDownload_Init and save the zip file to any directory on your local hard disk or directly to the work area of SAP NetWeaver Developer Studio. 5. Extract the content of the zip file TutWD_FileUpDownload_Init.zip to the work area of SAP NetWeaver Developer Studio or to any directory on your local hard disk. 6. Start SAP NetWeaver Developer Studio. 7. Import the Web Dynpro project TutWD_ FileUpDownload _Init: a. In the menu, choose File Import b. In the next window, choose Existing Project into Workspace and click Next to confirm. c. Choose Browse, open the folder in which you saved the project TutWD_ FileUpDownload _Init, and select this project. d. Confirm by choosing Finish 8. The Web Dynpro Explorer now displays the Web Dynpro project TutWD_FileUpDownload _Init; allowing you to edit it and work through the tutorial. Tabular Project Structure Once you have imported the project template into the SAP NetWeaver Developer Studio, you will see the following structure in the Web Dynpro Explorer. Web Dynpro Project Structure Web Dynpro Project: TutWD_FileUpDownload_Init Web Dynpro Application: FileUpDownloadApp Web Dynpro Component: FileUpDownloadComp View: WelcomeView In this view, you can choose to either upload or download a file. View: FileUploadView In this view, you can upload a file from your computer. View-Layout: contains pre-defined UI elements Actions: ToWelcomeView, UploadFile View FileDownloadView In this view, you can download an image file from the archive of the example application. When the View Controller is initialized, this file is stored in the view controller context. View-Layout: contains pre-defined UI elements Actions: ToWelcomeView Window: FileUpDownloadComp Contains the three views described above together with the definition of the View Composition (navigation links between inbound and outbound plugs). Uploading and Downloading Files in Web Dynpro 4

9 Using the UI Elements FileUpload and FileDownload December 2005 Next Step: src mimes Components com.sap.tc.webdynpro.tutorial.fileupdownload.fileupdownloadcomp This directory contains image file sap.jpg, which is required for the file download. Using the UI Elements FileUpload and FileDownload [Page 5] 3 Using the UI Elements FileUpload and FileDownload Prerequisites You have imported the initial project according to the instructions provided. Further Procedure Once you have successfully imported the initial project TutWD_FileUpDownload, you can start developing the file upload and file download functionality. The further procedure is divided thematically into two sections that can be worked through independently of one another. File Upload Defining the Context and View Layout [Page 5] File Download Defining the Context and View Layout [Page 10] 4 File Upload Defining the Context and View Layout Process Flow In this step, you define a binary-type context attribute in the FileUploadView context and then bind a FileUpload UI element to it. Declaring a Binary-Type Context Attribute To save a MIME file in the controller context after it has been uploaded from the user interface to the server, you first need to define a binary-type attribute. 1. Switch to the FileUploadView (TutWD_FileUpDownload_Init Web Dynpro Web Dynpro Components FileUpDownloadComp Views FileUploadView) 2. Choose the Context tab page and add a value attribute with the name FileResource. 3. Switch to the perspective view Properties and enter binary under type. Uploading and Downloading Files in Web Dynpro 5

10 File Upload Defining the Context and View Layout December 2005 Binding a FileUpload UI Element in the View Layout After defining the binary-type context attribute FileResource, you can bind a new FileUpload UI element to it. To trigger the upload process for a selected file on the user interface, a Button UI element is inserted next to it. 4. Switch to the Layout tab page. 5. In the perspective view Outline, add a UI element of type FileUpload with the name FileUpload1 as a child of the FileUpload group. Move this element to below the Label UI element FileUploadLabel. 6. Under the FileUpload UI element, add a Button UI element with the name UploadButton. 7. Define the individual UI element properties according to the following table. Properties Value FileUpload1 of type FileUpload Elementproperties data Elementproperties filename Elementproperties tooltip FileResource (Data binding to context attribute) FileName (Data binding to context attribute) Select a file from your file system UploadButton of type Button Elementproperties tooltip Event onaction Upload selected file UploadFile Result In this step, you have defined data binding between a FileUpload UI element and assigned the corresponding types to value attributes in the context (see the graphic below). To start uploading a file on the user interface, you have also added a new Button UI element and bound its onaction event to the UploadFile action. If you want to automatically transport MIME files and their type information at runtime using data binding, additional controller coding is required in the next step. UI Element FileUpload UI / View Layout Browse View Context Java Dictionary Types Property data Attribute Name FileResource Attribute Type ddic:com.sap.dictionary.binary Property filename Data binding Attribute Name FileName Attribute Type ddic:com.sap.dictionary.string Design Time Next Step: Implementing the FileUploadView Controller [Page 7] Uploading and Downloading Files in Web Dynpro 6

11 Implementing the FileUploadView Controller December Implementing the FileUploadView Controller Prerequisites You have defined a binary-type value attribute in the FileUploadView context. The Modifiable Binary Data Type Before you initialize the view controller, we would like to explain the concept of modifiable binary data types in Web Dynpro. This provides the basis for the automatic data transport of MIME objects between the UI and the context using data binding. You have defined the binary-type attribute FileResource in the view context. However, this type cannot be bound directly by UI elements (such as FileUpload, FileDownload) as there is no general method of formatting and parsing binary data without knowledge of type metadata. However, as a binary-type context attribute only stores a Java byte array at runtime, the metadata required for handling MIME files, such as file type, file size or file name, has to be saved somewhere else. This metadata can be stored using the type information belonging to a context attribute (more precisely, the context attribute information of type IWDAttributeInfo). As this type information is variable rather than static at runtime, the binary data type of the context attribute needs to be made modifiable by calling method IWDAttributeInfo.getModifiableSimpleType(). The required type information can then be accessed in the controller coding using the IWDModifiableBinaryType API. This is illustrated in the graphic below. UI Element FileUpload C:/SAP.jpg UI / View Layout Property data Property filename Browse Data binding View Context Attribute Info (FileResource) Roote Node Modifable Binary Type Runtime Roote Node Element FileResource FileName SAP.jpg Mime Type, File Size, File Extension Type Metadata Attribute Value Type Byte Array: byte[] Attribute Value Type String This approach involves one major restriction. When moving a MIME file s metadata to the attribute information, it is not possible to store several MIME files of different types in a single node with cardinality 1..n. Although it is possible to store a different byte array in each node element (in a value attribute within the node element, to be more precise) all attribute values share common attribute information. In the Web Dynpro context model, the attribute information is associated with the node instance, not with the node element instance. Consequently, the upload and download functionality displayed here cannot be represented in a table at row level. The Java Dictionary will include a new data type for this in the next NetWeaver Release. Uploading and Downloading Files in Web Dynpro 7

12 Implementing the FileUploadView Controller December 2005 Process Flow The view controller FileUploadView.java is implemented in two steps: initializing the controller and handling the UploadFile action in method onactionuploadfile(). Implementing the Hook Method wddoinit() 1. Switch to the Implementation tab page and insert the following program code in method wddoinit(): wddoinit() FileUploadView.java javadoc:wddoinit() /** Hook method called to initialize controller. */ public void wddoinit() { //@@begin wddoinit() // get attribute info for context attribute "FileResource" IWDAttributeInfo attributeinfo = wdcontext.getnodeinfo().getattribute( IPrivateFileUploadView.IContextElement.FILE_RESOURCE); // make the context attribute's simple type modifiable. // Only with this line of code the binary data (stored within the // context attribute) can be parsed. The Web Dynpro Runtime stores // the mime-object s metadata within the attribute s type metadata. attributeinfo.getmodifiablesimpletype(); // set the file details invisible wdcontext.currentcontextelement().setdetailsvisibility( WDVisibility.NONE); //@@end Implementing the Action Event Handler onactionuploadfile() After the UploadFile action has been triggered on the user interface, the chosen file is transported to the context attribute FileResource. Whereas only the binary data is stored in the context attribute, the associated file information, like MIME type, file size or fie name, is written to the type metadata of the modifiable binary data type. This metadata is stored in the attribute information of a context attribute. 2. Insert the following program code in method onactionuploadfile (). onactionuploadfile() //@@begin javadoc:onactionuploadfile(serverevent) /** Declared validating event handler. */ //@@end public void onactionuploadfile( com.sap.tc.webdynpro.progmodel.api.iwdcustomevent wdevent) { //@@begin onactionuploadfile(serverevent) // get attribute info for context attribute 'FileResource' IWDAttributeInfo attributeinfo = wdcontext.getnodeinfo().getattribute( IPrivateFileUploadView.IContextElement.FILE_RESOURCE); // get modifiable binary type from the attribute info, // requires type cast. IWDModifiableBinaryType binarytype = Uploading and Downloading Files in Web Dynpro 8

13 Implementing the FileUploadView Controller December 2005 (IWDModifiableBinaryType) attributeinfo.getmodifiablesimpletype(); IPrivateFileUploadView.IContextElement element = wdcontext.currentcontextelement(); // if a file in the 'FileResource' attribute exists if (element.getfileresource()!= null) { try { String mimetype = binarytype.getmimetype().tostring(); byte[] file = element.getfileresource(); // get the size of the uploaded file element.setfilesize(this.getfilesize(file)); // get the extension of the uploaded file element.setfileextension( binarytype.getmimetype().getfileextension()); // NOTE: context attribute 'FileName' must not be set // because the FileUpload-UI-element property 'filename' // is bound to it. Consequently the filename is automatically // written to the context after file upload. // set the details visibility attribute element.setdetailsvisibility(wdvisibility.visible); // report success message wdcomponentapi.getmessagemanager().reportmessage( IMessageFileUpDownloadComp.SF_UPLOAD, new Object[] { binarytype.getfilename(), false); catch (Exception e) { throw new WDRuntimeException(e); // if no file in the 'FileResource' attribute exists else { // set the details visibility attribute, hide details element.setdetailsvisibility(wdvisibility.none); // report error message IWDMessageManager msgmgr = wdcomponentapi.getmessagemanager(); msgmgr.reportcontextattributemessage( element, attributeinfo, IMessageFileUpDownloadComp.NO_FILE, new Object[] { "", true); // clear the FileResource context value attribute element.setfileresource(null); //@@end 3. Add the required import rows using the key combination STRG+SHIFT+O. 4. In the Web Dynpro tools, save the current project metadata by choosing Save All Metadata. Next Step: Running the Application - File Upload [Page 10] Uploading and Downloading Files in Web Dynpro 9

14 ... Running the Application - File Upload December Running the Application - File Upload Now that you have reached this stage, you can launch the developed example application in the Web Browser as described below, and then carry out a file upload. Prerequisites The SAP J2EE Engine has been launched. Procedure Save all Metadata 1. Save the current status of the metadata for your project. Rebuild Project 2. In the Web Dynpro Explorer, open the context menu for the project node TutWD_FileUpDownload_Init and choose Rebuild Project. Deploy new archive and run 3. Open the context menu for application object FileUpDownloadApp and choose Deploy new archive and run. Result Test your application by clicking on the File Upload link. By choosing the Browse button, you can now select a file to upload from your local file system. To start uploading, choose Upload File. Once the file has been uploaded, the system displays details of the uploaded file and a success message. Next Step: File Download Defining the Context and View Layout [Page 10] 7 File Download Defining the Context and View Layout Process Flow In this step, you will define data binding between a FileDownload UI element and a binarytype context attribute. Declaring a Binary-Type Context Attribute When the file is downloaded, a MIME file saved in the context is downloaded by user to the client. To allow this, first define a new binary-type context attribute in the view context. When the FileDownload controller is initialized, a MIME object should be saved in a binary attribute. You now create this attribute. Switch to the FileDownloadView (TutWD_FileUpDownload_Init Web Dynpro Web Dynpro Components FileUpDownloadComp Views FileDownloadView) Uploading and Downloading Files in Web Dynpro 10

15 File Download Defining the Context and View Layout December 2005 Choose the Context tab page and add a value attribute with the name FileResource. Switch to the perspective view Properties and enter binary under type. Binding a FileDownload UI Element in the View Layout After defining the binary-type context attribute FileResource, you can bind a new FileDownload UI element to it. This UI element is displayed as a link on the user interface. When this link is selected, the MIME file saved in the context attribute is automatically transported to the user interface. With the transfer of the associated MIME type, the clientside connected software can be started so that you can display the MIME file. 1. Choose the Layout tab page. 2. In the perspective view Outline, add an UI element of type FileDownload with the name FileDownload1 as a child of the FileDownload group. Move this element in front of the Button UI element BackButton. 3. Define the individual UI element properties according to the following table. Properties Value FileDownload1 of type FileDownload Elementproperties data Elementproperties layoutdata Elementproperties text FileResource (Data binding to context attribute) MatrixHeadData Download File! Web Dynpro defines _blank as the default value for the property target in the UI elements FileDownload and LinkToURL. Although the target values _top, _parent, and _self can be used, you are advised not to do so, as this will cause the Web Dynpro application to crash. Whereas target value _blank always causes a new target window to open, entering a target value like "SameWindow" causes a downloaded file to always open in the same target window (not the window of the application) if the UI element FileDownload is clicked more than once. In the case of UI element LinkToURL, an exit plug with URL parameters should be used instead of the target value _self. Uploading and Downloading Files in Web Dynpro 11

16 Implementing the FileDownloadView Controller December 2005 Result Note that no events are bound to an action when using UI element FileDownload. This means that is not possible to store a file on-demand in the associated context attribute in the action event handler; that is, after the data download has been triggered by the user. Instead, the file to be downloaded has to be stored in the context attribute by controller coding before it is displayed on the user interface. If you are using UI element FileDownload as the cell editor for a table column, all MIME files displayed in the table using download links have to be saved at runtime. In the next NetWeaver Release, the Web Dynpro Programming Model will include the on-demand stream concept. In this step, you have defined data binding between a FileUpload UI element and a binarytype context attribute. If you want to be able to display a downloaded MIME file on the client side, additional controller coding is required in the next step. By using a modifiable binary data type, you can transfer type information that is required for displaying binary data stored in the context attribute to the client. Next Step: Implementing the FileDownloadView Controller [Page 12] 8 Implementing the FileDownloadView Controller Prerequisites You have defined a binary-type value attribute in the FileDownloadView context. You have read the section about modifiable binary data types in Implementing the FileUploadView Controller [Page 7]. Process Flow In this example, most of the controller implementation required for the file download is in method wddoinit(), which is called when the view controller is created. In the View Controller, private method byte[] : getbytearrayfromresourcepath(string resourcepath) is also implemented. This method returns the byte array for the URL address of a MIME file. Unlike file upload, no action event handling takes places after the download process has been triggered. The MIME file selected for downloading is therefore stored in the context at the controller initialization stage. Uploading and Downloading Files in Web Dynpro 12

17 Implementing the FileDownloadView Controller December 2005 Implementing the Hook Method wddoinit() Creating a Modifiable Binary Data Type To save the type information for a MIME file, the binary data type of the context attribute FileResource must be modifiable. In the context attribute itself, only the MIME file s binary data is saved as a byte array. For further details, see the section about modifiable binary data types (in Implementing the FileUploadView Controller [Page 7]). 1. Switch to the Implementation tab page and insert the following program code in method wddoinit(): wddoinit() FileDownloadView.java //@@begin javadoc:wddoinit() /** Hook method called to initialize controller. */ //@@end public void wddoinit() { //@@begin wddoinit() // get attribute info for context attribute 'FileResource' IWDAttributeInfo attributeinfo = wdcontext.getnodeinfo().getattribute( IPrivateFileDownloadView.IContextElement.FILE_RESOURCE); // create a modifiable binary type for the context attribute // which stores the MIME-object. IWDModifiableBinaryType binarytype = (IWDModifiableBinaryType) attributeinfo.getmodifiablesimpletype();... //@@end Reading a MIME File from the Project and Storing the File in the Context To allow you to download a file in the example application, the template project TutWD_ FileUpDownload _Init contains the image file sap.jpg. This image file is stored in the project directory src mimes Components com.sap.tc.webdynpro.tutorial.fileupdownload.fileupdownloadcomp and is deployed in the project archive on the SAP J2EE Server. You can use Web Dynpro service class WDURLGenerator to access this image file in the View Controller and save it in the binary-type context attribute FileResource. The type information - such as file name and file type - required for displaying the MIME file on the client has to be stored in the modifiable binary data types of the context attribute FileResource. 2. Insert the following program code in method wddoinit(): wddoinit() FileDownloadView.java //@@begin javadoc:wddoinit() /** Hook method called to initialize controller. */ //@@end public void wddoinit() { //@@begin wddoinit()... Uploading and Downloading Files in Web Dynpro 13

18 Implementing the FileDownloadView Controller December 2005 try { // The image file 'sap.jpg' is deployed with // the Web Dynpro project(under src/mimes/components...). // The resource path (URL) for this mime objects can be accessed // using the WDURLGenerator service. String resourcepath = WDURLGenerator.getResourcePath( wdcomponentapi.getdeployableobjectpart(), FileDownloadView.FILE_NAME); // retrieve byte array for given resource path and store it // in context value attribute 'FileResource' wdcontext.currentcontextelement().setfileresource( this.getbytearrayfromresourcepath(resourcepath)); // set binary type metadata. Without setting the mime type // the client does not know how to open the downloaded file. binarytype.setfilename(filedownloadview.file_name); binarytype.setmimetype(wdwebresourcetype.jpg_image); catch (WDAliasResolvingException e) { wdcomponentapi.getmessagemanager().reportexception( e.getlocalizedmessage(), true); catch (Exception e) { throw new WDRuntimeException(e); //@@end 3. In the last User Coding Area (between //@@begin others and //@@end) in the View Controller, the project template already contains the following program code: Final User Coding Area FileDownloadView.java //@@begin others /** * Returns a byte array for a given file resource path */ private byte[] getbytearrayfromresourcepath(string resourcepath) throws FileNotFoundException, IOException { FileInputStream in = new FileInputStream(new File(resourcePath)); ByteArrayOutputStream out = new ByteArrayOutputStream(); int length; byte[] part = new byte[10 * 1024]; while ((length = in.read(part))!= -1) { out.write(part, 0, length); in.close(); return out.tobytearray(); // store image file name in constant FILE_NAME private static final String FILE_NAME = "sap.jpg"; //@@end Utility method getbytearrayfromresourcepath() returns a byte array for a specified file path. This byte array is then stored in the binary-type context attribute. The name of the image file sap.jpg in the project is stored in class constant FILE_NAME. 4. Add the required import rows using the key combination STRG+SHIFT+O. Uploading and Downloading Files in Web Dynpro 14

19 Running the Application - File Download December In the Web Dynpro tools, save the current project metadata by choosing Save All Metadata. Next Step: Running the Application - File Download [Page 15] 9 Running the Application - File Download Now that you have reached this stage, you can launch the completed example application in the Web Browser as described below, and then download image file sap.jpg from the project. Prerequisites The SAP J2EE Engine has been launched. Procedure Save all Metadata 1. Save the current status of the metadata for your project. Deploy new archive and run 2. Open the application context menu: Web Dynpro Applications FileUpDownloadApp and choose Deploy new archive and run. Result Test your application. To do this, navigate to the File Download view by choosing the File Download link. This displays a download link that allows you to download the image file from the example application. Using the file information transferred to the client, the image file is displayed in an image-display program installed on the client computer. Uploading and Downloading Files in Web Dynpro 15