Java EE Servlet JSP Tutorial- Cookbook 1
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Java EE Servlet JSP Tutorial- Cookbook 1
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http://wiki4.caucho.com/Java_EE_Tutorial_covering_JSP_2.2,_and_Servlets_3.0 This tutorial focuses on using Servlet's and JSP the right way. Servlet and JSP have evolved over the years, and now there is often more than one way to do things. For example, this tutorial uses EL and JSTL not JSP scriptlets, it uses JSPs in a Model 2/MVC style not in a model 1 style, etc. Consider it a tutorial that focuses only on the best practices and not the legacy ways to do things. There are other tutorials on this subject, but this tutorial is going to be different in that it is going to put all code into github, and you can follow along with Eclipse. Also instead of focusing on JSF, we are going to focus on JSP and Servlets as the main view technology. Java EE, JSP and Servlets have added a lot of features that are in other frameworks, making those other frameworks less relevant then they were before Java EE garnered these extra abilities. Even is you decide to use JSF, Struts, Stripes, Spring MVC, JSF, etc., this tutorial should help you have a better understanding of the JSP/Servlets core that they build on. We are going to start by building a simple bookstore. We will progressively add more features to the bookstore and as we do we will use more of Java EE/CDI, JSP and Servlets. For this tutorial, I am going to use Resin 4.0.x, but you could use any Java EE 6 Web Profile compliant application server.
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Java EE Servlet JSP Tutorial- Cookbook 1
- Java EE Servlet Tutorial First Cookbook- Getting started with Model 2: Servlet and JSP Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Open%Source,%Reliable%and%Lightweight% Java%EE%Applica;on%Server% RESIN PRO Web Profile Health System Cloud Support Thursday, May 3, 12
- Cookbook: Intro to Serlvets and JSP • This cookbook in the Java EE Servlet tutorial covers building a simple listing in JSP and Servlets. • This tutorial is part of Java EE Tutorial covering JSP_2.2, and Servlets 3.0. • The WIKI and step by step detailed instructions live here: • http://wiki4.caucho.com/ Building_a_simple_listing_in_JSP Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- About tutorial • Very liEle knowledge of HTML, Java and JSP is assumed • HTML and Java not covered length, but pointers in the right direc8on • Focus is Java Servlets and JSP (Java Server Pages) • Use whatever IDE you would like, but direc8ons focus on Eclipse Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- App you are building Sorting Remove Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Sidebar: Why Eclipse? • Best? No not really, best is IntelliJ • Eclipse is free and supports Java EE well • NetBeans and JDeveloper are from Oracle, they are good too Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Running tutorial app in Eclipse Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Windows? Try Linux... • Java is write once run anywhere, so you can develop Java anywhere • Most companies deploy Java on some flavor of Linux • You can use Windows for development, but... • Probably a good idea to get familiar with produc8on deployment environment anyway • If you are a Windows or OSX users, I suggest installing Ubuntu (hEp:// www.ubuntu.com/) or CentOS on VMWare or Virtual Box and making that your main development environment • You can make this tutorial work for you on OSX and Windows, but might be beEer just to go with a fric8onless approach. This way you can focus on the concepts instead of the configura8on woes • Cloud deployment for the most part == Linux Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Outline • 1 Optional: Getting started Eclipse Java EE IDE • 2 Resources • 3 What is going to be in the project • 4 Creating model and Repository objects for books • 4.1 Book model class • 4.2 Are you new to Java? • 4.3 BookRepository interface • 5 Servlets / JSP • 5.1 Servlet Background • 5.2 Creating your first Servlet • 5.2.1 BookListServlet listing • 5.2.2 Java EE / Servlets scopes (page, request, conversation, session, application) • 6 Creating your first JSP • 6.1 Templates/JSTL versus Java scriptlets • 6.1.1 /WEB-INF/pages/book-list.jsp listing • 6.1.2 HTML background • 6.1.3 JSTL c:forEach • 7 Setting up CDI • 7.1 CDI META-INF/beans.xml • 8 Deploying with Eclipse • 9 Deploying from the command line • 10 Cookbooks and Tutorials Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Using Eclipse to setup Web Project • First go here to get Eclipse for Java EE: Install Guide for Eclipse for Java EE Indigo or higher. • Screenshots to follows, but here is the basic steps to installing Eclipse and Java EE development environment in one go • Using Eclipse Indigo or higher Install Resin (lightweight, fast, easy to use Java EE 6 Web Profile server) plugin: 1. Go to File menu -> New Project -> Dynamic Web Project 2. In New Dynamic Web Project Dialog-> New Runtime... 3. In New Runtime Dialog -> Download Additional Server Adapters -> Select Resin (Java EE Web Profile) 4.0.x 4. (Click Next and Ok until it installs Resin runtime) 5. (Eclipse needs to restart) Setup new Web Project in Eclipse 1. File -> New Project -> Dynamic Web Project 2. In New Dynamic Web Project Dialog-> New Runtime...->Select Resin->Check create local server checkbox 3. Step 2 of New Runtime...->Click Download and Install (you only have to do this once) 4. Fill out project name etc. (bookstore). 5. (Click Next and Ok until you are done) Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Install Java EE 6 Web Profile • Go to File menu -‐> New Project -‐> Dynamic Web Project • In New Dynamic Web Project Dialog-‐> New Run8me... Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Crea8ng a new web project • Click OK and Finish and Restart to restart Eclipse • Crea8ng a new Web Project Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Crea8ng a simple Book lis8ng for our bookstore • Create a new Java class as follows: • Eclipse: Right Click "Java Resources" in Project Explorer -‐> New -‐> Class -‐> Package com.bookstore -‐> Class Name -‐> Book (That is the last 8me I will tell you how to create a class in Eclipse.) • Add 8tle, descrip8on, price, pubDate and id proper8es, and the toString and cloneMe methods as follows: Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Are you new to Java? • If you are new to Java and the Book class seems foreign to you, • Read up on Java a bit Official Java tutorial. • Read the first three trails (Ge>ng Started, Learning the Java Language and EssenBal Java Classes), • Skip ahead to Java Beans. Skimming is ok. • If you have programmed before, most things you will pick up on your own. • Then come back here :) • Reminder: The methods public String getId() and public void setId(String id) would define a property called id Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Repository Interface • First step in tutorial not going to actually talk to a database or use JDBC • For now, just using collec8on API • Repository object encapsulates how an object gets persisted, queried and updated (CRUD opera8ons) • Let’s define an interface for our CRUD opera8ons • Later we use JDBC/RDBMS (MySQL), JTA/RDBMS, JCache, MongoDB, etc. instead of collec8on API Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepository (DAO like object) • Eclipse: Right Click "Java Resources" in Project Explorer -‐> New -‐> Interface -‐> Package = com.bookstore -‐> Class Name = Book -‐> Click Finish Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepositoryImpl 1 of 4 • Actual BookRepositoryImpl just uses Java collec8on to store in memory (skim don’t read) Set’s up some test data Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepositoryImpl 2 of 4 • Helper methods to define test data, add method Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepositoryImpl 3 of 4 • Interface implementa8ons using collec8ons API Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepositoryImpl 4 of 4 • listBooks and removeBooks Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookRepositoryImpl wrap up • This BookRepositoryImpl really basic class. • Largely based on the collec8ons API • You can find out more informa8on about the Java collec8ons API at this tutorial trail. • A full discussion of collec8on API out of scope for cookbook • JDBC cookbook coming up in this tutorial series Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- @Applica8onScoped • One interesBng thing is BookRepositoryImpl uses @Applica2onScoped annotaBon • AnnotaBons allow you to add meta-‐data to Java objects. (To learn more see this annotaBons tutorial) • Applica2onScoped specifies a bean is applicaBon scoped • Scoping defines a lifecycle • how long an object will be around • ApplicaBonScoped means it will be around for the complete lifecycle of the Web ApplicaBon • This annotations has slightly different meanings depending on whether it is used with EJBs or Servlets. This annotation is part of the CDI support added to Java EE 6 to handle Java Dependency Injection. To learn more about CDI go see this tutorial Java Dependency Injection and this one part 2 both written by the same author that is writing this tutorial now. :) Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- @Applica8onScoped Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Model done, now controller • Now that we have a model • Book, BookRepository • Lets define our web controller • Servlet controller • and view • JSPs Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Servlet Background • A servlet is a Java class that handles HTTP requests • A Java web applica8on consists of one or more servlet bundled together with any JSPs and Java classes it needs into a war file (Web Applica8on Archive file). • Servlets run inside of a container (like Caucho's Resin) • End users typically use a Java Web Applica8on through a web browser like Apple Safari, Google Chrome, Mozilla FireFox or Internet Explorer Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Crea8ng your first Servlet • Eclipse: Right Click "Java Resources" in Project Explorer -‐> New -‐> Servlet -‐> Package = com.bookstore.web -‐> Class Name = BookListServlet -‐> Click Next -‐> Remove URL mapping, create new mapping /book/ Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Crea8ng your first Servlet (part 2) Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookListServlet • Note: This applica8on uses the REST style URL mappings • URLs that end in / imply you are working with a list • (like a directory of files). • URI /book/ implies a collecBon of books • Perfect since we want to show a list of books • Modify generated Servlet to only handle the doGet method • Change doGet method to forward to a JSP that we have not created yet that lives in WEB-‐INF Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- BookListServlet • Looks up books using bookRepo (injected with @Inject CDI) • Then forward to book-‐list.jsp to render book lis8ng Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Why JSP is in WEB-‐INF • WEB-‐INF is a meta directory folder for war files. • JSPs in WEB-‐INF folder can never be loaded directly from a browser • This allows us to force all JSPs to first go through our Servlet 8er (controllers) which is essen8al for a model 2 architecture (a form of MVC tailored for HTTP applica8ons), • We use model 2 throughout the tutorial • Consider pumng JSPs in WEB-‐INF a best prac8ce. Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- @WebServlet annota8on (BookListServlet) • @WebServlet("/book/") allow us to map this Servlet to handle requests for the URI / book/ • @WebServlet annota8on is a new feature of Servlets 3.0 • Avoids a lot of XML configura8on Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- @Inject (BookListServlet) • Servlet uses repository model object to look up a list of BookRepository books. • Java dependency injec8on used to inject BookRepository into the Servlet • @Inject etc. added in Java EE 6 Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- doGet (BookListServlet) • Servlet is controller in model 2 • Controller talks to the model (BookRepository to get a list of Book), • doGet method gets called when somebody loads the page from the browser and corresponds to HTTP GET • doGet method uses the request object (HEpServletRequest request) to put the list of books into request scope using setAEribute as follows: request.setAttribute puts books into request scope. But what is a scope? Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Understanding scopes • Servlets and Java EE have various scopes • page, request, conversa8on, session, applica8on • Page scope (10 to 200 milliseconds) • Request scope is around for one HTTP request (1/2 second to several seconds) • Session scope is around for the en8re user session (5 minutes to 90 minutes) • Conversa8on scope is around for one workflow (user registra8on, shopping cart, etc.). • Applica8on scope is around un8l web app shuts down Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Background on JSP • JSP pages are also Servlets • JSP is a templa8ng language to define Servlets that allows you to focus on the HTML instead of the Java code • JSP is like a Servlet turned inside out • Essen8ally a JSP page is translated and compiled into a servlets • JSP is similar to ASP and PHP in concept and scope • ASP predates JSP and early JSP and ASP use a lot of the same concepts Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- JSP scriptlets versus Templates • JSP allows mixing Java code and HTML (called Java scriptlets), but don’t • JSP adopted more of a classic templa8ng approach like • Freemarker, Velocity and Smarty (PHP based templaBng) • Don’t allow mixing the programming language with the templaBng language • Allows the templaBng language to be a simple view logic language, • Keeps the templates smaller and more readable. • JSP uses JSTL and the Unified EL to accomplish things that Smarty, Freemarker and Velocity accomplish • Using JSTL/EL instead of Java scriptlets approach is a best prac8ce Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Crea8ng a JSP in Eclipse Create a folder under WebContent/WEB-INF called pages Right click WebContent/WEB-INF/pages, then select New->JSP File use the file name book-list.jsp Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Modify book-‐list.jsp to match the following Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- book-‐list.jsp page direc8ve • Let's break this down some. • First setup page using JSP page direc8ve: • page direc8ve sayshow we want the characters encoded and what the mime type of the page is. Consider it boiler plate for now Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Using JSTL core library • Next we import the JSTL core library, under the tag c as follows: HTML background Most of the page is boiler plate and simple HTML. If you are new to HTML, try this HTML tutorial. Then come back here. Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Using JSTL core c:forEach • Using c:forEach to iterate through the books in request scope ! <c:forEach var="book" items="${books}"> ! ! <tr> ! ! ! <td>${book.title}</td> ! ! ! <td>${book.description}</td> ! ! ! <td>${book.price}</td> ! ! ! <td>${book.pubDate}</td> ! ! </tr> ! </c:forEach> Syntax like${books}, ${book.title}, ${book.price} ${book.pubDate} is Unified EL. EL is expression language Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- JSTL c:forEach • Where did the books come from? • ${books} is the same books that we put into request scope in the //BookListServlet.doGet method ! ! request.setAttribute("books", bookRepo.listBooks()); ! ! <c:forEach var="book" items="${books}"> ! ! <tr> ! ! ! <td>${book.title}</td> ! ! ! <td>${book.description}</td> ! ! ! <td>${book.price}</td> ! ! ! <td>${book.pubDate}</td> ! ! </tr> ! </c:forEach> Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Semng up Java Dependency Injec8on • To setup Java Dependency Injec8on (CDI), you need to create a beans.xml file • beans.xml need to go into META-‐INF • META-‐INF is a special directory for jar files and Java classpath entries to hold • beans.xml can be completely blank or just empty $ pwd ~/workspace/javaee-tutorial/bookstore/src/META-INF $ touch beans.xml To get Eclipse to quit complaining about the blank file not having the right format, fill it as follows: META-INF/beans.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/ beans_1_0.xsd"> </beans> Note: the @Inject Java dependency injection will not work without this file. Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Deploying applica8on with Eclipse • Deploying with Eclipse • Right click the BookListServlet in the Project Explorer • Choose Run As-‐>Run On Server... • "Select Manually Define a New Server" • Choose Resin-‐>Resin 4.0 from the Server List • Click "Download addi8onal Server adapters” Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Deploying applica8on with Eclipse • Right click BookListServlet in project explorer then choose Run -‐> Run On Server • Select Resin then Click Next-‐> then click “Download and Install” Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Applica8on Running in Eclipse Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Applica8on Running in FireFox Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- Deploying from the command line Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12
- End of first cookbook in tutorial • Cook books and Tutorials • Building a simple lis8ng in JSP: covers model 2, Servlets, JSP intro. <You just finished this one> • Java EE Servlet tutorial : Adding create, update and delete to the bookstore lisBng: covers more interacBons. • Java EE Servlet tutorial : Using JSPs to create header, footer area, forma>ng, and basic CSS for bookstore. • Java EE Servlet tutorial : Adding MySQL and JDBC to bookstore example.Java EE Servlet tutorial : Adding validaBon and JSP tag files to bookstore example. • Java EE Servlet tutorial : Adding I18N support to bookstore example. • Java EE Servlet tutorial : Load tesBng and health monitoring using bookstore example. • Java EE Servlet tutorial : Se>ng up clustering and session replicaBon. • Java EE Servlet tutorial : Se>ng up security for bookstore example. • Java EE Servlet tutorial : File uploads for bookstore example. • Java EE Servlet tutorial : Using JPA for bookstore example. • Java EE Servlet tutorial : Using JCache for bookstore example. Caucho Home | Contact Us | Caucho Blog | Wiki | Applica8on Server Thursday, May 3, 12