1. 1 Servlet/JSP Miscellaneous Representation and Management of Data on the Web

2. 2 Uploading Files with Servlets

3. 3 Handling Uploads with Package Commons FileUpload Commons FileUpload is a package of Apache for handling uploaded files in the Servlet side Files are sent in the body of post requests Using this package, uploaded files are temporarily written into the memory or the disk (depending on the file size) You can set the size threshold beyond which files are written to disk

4. 4 Handling Uploads with Package Commons FileUpload Servlets read the file from the disk or memory In Tomcat, the default temporary directory is $CATALINA_BASE/temp/ However, you can specify a temporary directory of your own (e.g., /tmp ) What if a very big file is uploaded? -You can define the maximal size of uploaded files -Exception is thrown for larger files

5. 5 Example 1 Upload Files and Parameters <form action="upload1" method="post" enctype="multipart/form-data"> File: upload1.html

6. 6 public class Upload1 extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { DiskFileUpload upload = new DiskFileUpload(); upload.setSizeThreshold(1000); upload.setSizeMax(60000); try { List items = upload.parseRequest(request); Iterator it = items.iterator(); FileItem item = (FileItem) it.next(); response.setContentType(item.getContentType()); response.setContentLength((int)item.getSize()); Upload1.java

7. 7 InputStream is = item.getInputStream(); OutputStream os = response.getOutputStream(); byte[] buffer = new byte[4096]; int read = -1; while((read=is.read(buffer))>=0) os.write(buffer,0,read); } catch (FileUploadException exp) { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println(" Error : " + exp.getMessage() + " "); } Upload1.java

8. 8 Example 2 Upload Files and Parameters <form action="upload2" method="post" enctype="multipart/form-data"> Parameter x: File: Parameter y: upload2.html

9. 9 List items = upload.parseRequest(request); Iterator it = items.iterator(); out.println(" "); while (it.hasNext()) { FileItem item = (FileItem) it.next(); if (item.isFormField()) out.println(" Field : " + item.getFieldName() + " = " + item.getString() + " "); else out.println(" File " + ": parameter name: " + item.getFieldName() + ", file name: " + item.getName() + ", file size: " + item.getSize() + " bytes, file type: " + item.getContentType() + " "); } out.println(" "); Upload2.java

10. 10 Example 3 The latter example reflected a common design problem: combining complex HTML code and Java code in a Servlet or a JSP -Java code for processing parameters and uploaded files -HTML code for generating the (dynamic) response An accepted solution is to process the parameters in a Servlet, and forward the request to a JSP for generating the response -Attributes can be sent to the JSP The next example also uses JSTL

11. 11 JSTL JSTL stands for JSP Standard Tag Library This is a regular tag library that can be imported to your page, like the ones we created in the past This library includes some standard actions that are common in JSP, like iteration and conditions over EL expressions, parsing/manipulation of XML and database access More details can be found in Sun's J2EE Tut.Sun's J2EE Tut

12. 12 Example 3 Upload Files and Parameters <form action="upload3" method="post" enctype="multipart/form-data"> Parameter x: File: Parameter y: upload3.html

13. 13 List formParams = new LinkedList(); List files = new LinkedList(); List items = upload.parseRequest(request); Iterator it = items.iterator(); while (it.hasNext()) { FileItem item = (FileItem) it.next(); if (item.isFormField())formParams.add(item); else files.add(item); } request.setAttribute("formParams",formParams); request.setAttribute("files",files); this.getServletContext().getRequestDispatcher ("/WEB-INF/jsp/upload3.jsp").forward(request,response); Upload3.java

14. 14 Submitted Parameters Submitted Parameters: Parameter : name: ${item.fieldName}, value: ${item.string} File : name: ${item.name}, length: ${item.size}, size: type:${item.contentType} /WEB-INF/jsp/upload3.jsp

15. 15 A Question What is the advantage of redirecting to JSP pages that are under WEB-INF?

16. 16 Managing User Authentication with Tomcat

17. 17 A Reminder create table users ( username varchar(30) not null primary key, pass varchar(30) not null ); create table users_roles ( username varchar(30) not null, role varchar(30) not null, primary key (username,role), foreign key (username) references users(username) );

18. 18 In server.xml <Realm className="org.apache.catalina.realm.JDBCRealm" driverName="oracle.jdbc.driver.OracleDriver" connectionURL= "jdbc:oracle:thin:snoopy/snoopy@sol4:1521:stud" userTable="users" userNameCol="username" userCredCol="pass" userRoleTable="users_roles" roleNameCol="role"/>

19. 19 User Tables What if we do not have one table that stores usernames and passwords? What if we only have one role for the all users? What if we wanted the above information to be stored in several tables (e.g., users and administrators) The idea is to use views rather than real tables

20. 20 Creating Views create view up as (select username u, pass p from users union select u,p from admin); create view ur as (select username u, 'myRole' r from users union select u, 'admin' r from admin);

21. 21 Fixing server.xml <Realm className="org.apache.catalina.realm.JDBCRealm" driverName="oracle.jdbc.driver.OracleDriver" connectionURL= "jdbc:oracle:thin:snoopy/snoopy@sol4:1521:stud" userTable="up" userNameCol="u" userCredCol="p" userRoleTable="ur" roleNameCol="r"/>