As mentioned above, we are going to register a JDBC datasource to the JNDI. In this example, we haven chosen H2 database, which is very convenient for prototyping. But any other database platform can be used as well.<\/p>\n
H2 runs through a single JAR file, which can be obtained from central Maven Repository<\/a>.<\/p>\n In this example, we assume that we have JCG Example records that are stored in an H2 database. There is a single table named As we have mentioned earlier, H2 is very convenient for prototyping and development environments. It is very easy to have a running H2 database once we have the JAR file . All we have to do is, running the simple shell command in the directory of the JAR file.<\/p>\n This command immediately starts an H2 in server mode. In addition to this, it fires a browser window that gives us a Web based console to create and configure H2 databases.<\/p>\n On the browser window, we can connect the database altering the following infomation:<\/p>\n If it is the first time that we connect to this url, H2 creates a database file named jcgdb.mv.db<\/i> in our home directory and opens a console that enables us to execute SQL scripts.<\/p>\n We can create our Then we insert two rows to this table:<\/p>\n Now our database is ready with one table and two rows, which will suffice for this example.<\/p>\n We will create the Maven project in Eclipse, applying the steps below:<\/p>\n After creating our project, we are going to add following dependencies to our pom.xml<\/i>:<\/p>\n The first two dependencies are common for almost all embedded Jetty applications. jetty-plus<\/i> and jetty-jndi<\/i> are required for JNDI lookups. Finally, h2<\/i> is required for the H2 database driver and datasource. After adding these, the dependencies section of our pom looks like:<\/p>\n In embedded Jetty, we register our dependencies to the server programmatically. In order to keep things simple, we will run our Server through the main Java class, which is named The source code of JettyJndiExampleMain.java<\/em><\/span><\/p>\n Our web application is a simple web application, with a Servlet that queries the database and returns the result as the HTTP response.<\/p>\n The web application can be configured following the steps below:<\/p>\n Our web.xml<\/i> file looks like as follows:<\/p>\n web.xml<\/em><\/span><\/p>\n Here we have defined a Servlet named JndiExampleServlet.java<\/em><\/span><\/p>\n DatabaseUtil.java<\/em><\/span><\/p>\n In the source code, you can see that, the datasource is retrieved from JNDI through the following snippet:<\/p>\n You should notice that, JNDI configuration abstracts the datasource from the application so that our application does not know (and care) about the URL,username and password and driver and in most cases the vendor of the datasource.<\/p>\n When we run our main class and try to access http:\/\/localhost:8080\/jetty-jndi-example<\/a>, we can see the Servlet response below:<\/p>\n2. Structure of the Example<\/h2>\n
JCGEXAMPLE<\/code> with only two columns (ID<\/code> and ARTICLE_NAME<\/code>). For simplicity we have skipped other types of integrity and database constraints. We will query content of this table through a Servlet deployed in a Jetty web application. We will access the datasource through a JNDI lookup.<\/p>\n3. Setting the H2 Database<\/h2>\n
java -cp h2*.jar org.h2.tools.Server<\/pre>\n
![\"H2](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/08\/jnd1.jpg\")
<\/a>\n
JCGEXAMPLE<\/code> table running the following SQL command:<\/p>\nCREATE CACHED TABLE PUBLIC.JCGEXAMPLE(\n ID INTEGER,\n ARTICLE_NAME VARCHAR(255)\n)\n<\/pre>\n
insert into JCGEXAMPLE values( 1,'Jetty JNDI Example');\ninsert into JCGEXAMPLE values(2,'Jetty JMX Example');\n<\/pre>\n
4. JNDI in Embedded Jetty<\/h2>\n
4.1 Creating the Maven Project in Eclipse<\/h3>\n
\n
\n
\t<dependencies>\n\t\t<dependency>\n\t\t\t<groupId>org.eclipse.jetty<\/groupId>\n\t\t\t<artifactId>jetty-server<\/artifactId>\n\t\t\t<version>9.2.11.v20150529<\/version>\n\t\t<\/dependency>\n\n\t\t<dependency>\n\t\t\t<groupId>org.eclipse.jetty<\/groupId>\n\t\t\t<artifactId>jetty-webapp<\/artifactId>\n\t\t\t<version>9.2.11.v20150529<\/version>\n\n\t\t<\/dependency>\n\n\t\t<dependency>\n\t\t\t<groupId>org.eclipse.jetty<\/groupId>\n\t\t\t<artifactId>jetty-plus<\/artifactId>\n\t\t\t<version>9.2.11.v20150529<\/version>\n\t\t<\/dependency>\n\n\t\t<dependency>\n\t\t\t<groupId>org.eclipse.jetty<\/groupId>\n\t\t\t<artifactId>jetty-jndi<\/artifactId>\n\t\t\t<version>9.2.11.v20150529<\/version>\n\t\t<\/dependency>\n\n\n\t\t<dependency>\n\t\t\t<groupId>com.h2database<\/groupId>\n\t\t\t<artifactId>h2<\/artifactId>\n\t\t\t<version>1.4.188<\/version>\n\t\t<\/dependency>\n\n\t<\/dependencies>\n<\/pre>\n
4.2 Registering resources in JNDI<\/h3>\n
JettyJndiExampleMain<\/code>. In our main class, we will initialize a Jetty Server, append a web application context and register a datasource for JNDI.<\/p>\nJettyJndiExampleMain<\/code> decorated with source comments is below:<\/p>\npackage com.javacodegeeks.snippets.enterprise.jettyjndi;\n\nimport org.eclipse.jetty.server.Server;\nimport org.eclipse.jetty.util.resource.Resource;\nimport org.eclipse.jetty.webapp.WebAppContext;\nimport org.eclipse.jetty.xml.XmlConfiguration;\nimport org.h2.jdbcx.JdbcDataSource;\n\npublic class JettyJndiExampleMain {\n\n\tpublic static void main(String[] args) {\n\t\ttry {\n\t\t\t\/\/ 1.We are creating the service\n\t\t\tServer server = new Server(8080);\n\n\t\t\t\/\/ 2.We are enabling Jetty-plus configuration\n\t\t\torg.eclipse.jetty.webapp.Configuration.ClassList classlist = org.eclipse.jetty.webapp.Configuration.ClassList.setServerDefault(server);\n\t\t\tclasslist.addAfter(\"org.eclipse.jetty.webapp.FragmentConfiguration\", \"org.eclipse.jetty.plus.webapp.EnvConfiguration\", \"org.eclipse.jetty.plus.webapp.PlusConfiguration\");\n\n\t\t\t\/\/ 3.We are creating the web-application context\n\t\t\tWebAppContext ctx = new WebAppContext();\n\t\t\tctx.setResourceBase(\"src\/main\/webapp\");\n\t\t\tctx.setContextPath(\"\/jetty-jndi-example\");\n\n\t\t\t\/\/ 4.We are creating the data-source here\n\t\t\tJdbcDataSource dataSource = new JdbcDataSource();\n\t\t\tdataSource.setUrl(\"jdbc:h2:tcp:\/\/localhost\/~\/jcgdb\");\n\t\t\tdataSource.setUser(\"sa\");\n\n\t\t\t\/\/ 5.Here we are registring the datasource for our server\n\t\t\tnew org.eclipse.jetty.plus.jndi.Resource(server, \"jdbc\/jcgDS\", dataSource);\n\n\t\t\t\/\/ 6.Handler setting and application registration code\n\t\t\tserver.setHandler(ctx);\n\t\t\tserver.start();\n\t\t\tserver.join();\n\t\t} catch (Exception exc) {\n\t\t\texc.printStackTrace();\n\t\t}\n\n\t}\n}\n\n<\/pre>\n\n
4.3 Configuring the Web Application<\/h3>\n
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JndiExampleServlet<\/code> which queries the datasource.<\/li>\n<\/ol>\n<web-app xmlns=\"http:\/\/java.sun.com\/xml\/ns\/javaee\" xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\n\txsi:schemaLocation=\"http:\/\/java.sun.com\/xml\/ns\/javaee http:\/\/java.sun.com\/xml\/ns\/javaee\/web-app_2_5.xsd\"\n\tversion=\"2.5\">\n\t<display-name>JSP Example Application<\/display-name>\n\n\t<servlet>\n\t\t<servlet-name>jndiservlet<\/servlet-name>\n\t\t<servlet-class>com.javacodegeeks.snippets.enterprise.jettyjndi.JndiExampleServlet<\/servlet-class>\n\n\t<\/servlet>\n\n\t<servlet-mapping>\n\t\t<servlet-name>jndiservlet<\/servlet-name>\n\t\t<url-pattern>\/*<\/url-pattern>\n\t<\/servlet-mapping>\n\n\t<resource-ref>\n\t\t<res-ref-name>jdbc\/jcgDS<\/res-ref-name>\n\t\t<res-type>org.h2.jdbcx.JdbcDataSource<\/res-type>\n\t\t<res-auth>Container<\/res-auth>\n\t<\/resource-ref>\n<\/web-app>\n<\/pre>\n
JndiExampleServlet<\/code> and mapped it to the all URLs under our application. In the bottom part, we have mentioned the JNDI resource that we are going to use in this application.[ulp id=’xFHGZUmgemwCMrAR’]<\/p>\nJndiExampleServlet<\/code> is a simple Servlet that uses the class DatabaseUtil<\/code> and returns the query result as the response.<\/p>\npackage com.javacodegeeks.snippets.enterprise.jettyjndi;\n\nimport java.io.IOException;\nimport java.util.List;\n\nimport javax.servlet.ServletException;\nimport javax.servlet.http.HttpServlet;\nimport javax.servlet.http.HttpServletRequest;\nimport javax.servlet.http.HttpServletResponse;\n\nimport com.javacodegeeks.snippets.enterprise.jettyjndi.dbutils.DatabaseUtil;\n\npublic class JndiExampleServlet extends HttpServlet {\n\n\t@Override\n\tprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {\n\n\t\tList<String> articleNames = DatabaseUtil.getArticleNames();\n\t\tfor (String articleName : articleNames) {\n\t\t\tresp.getOutputStream().println(articleName);\n\t\t}\n\t}\n}\n<\/pre>\nDatabaseUtil<\/code> is a Data Access Object like class that handles all database related operations including the JNDI lookup.<\/p>\npackage com.javacodegeeks.snippets.enterprise.jettyjndi.dbutils;\nimport java.sql.Connection;\nimport java.sql.ResultSet;\nimport java.sql.Statement;\nimport java.util.ArrayList;\nimport java.util.List;\n\nimport javax.naming.InitialContext;\nimport javax.sql.DataSource;\n\npublic class DatabaseUtil {\n\n\tpublic static void main(String[] args) {\n\n\t\tList<String> articleNames = getArticleNames();\n\n\t\tSystem.out.println(articleNames);\n\n\t}\n\n\tprivate static Connection createConnection() {\n\t\ttry {\n\t\t\tInitialContext ctx = new InitialContext();\n\t\t\t\/\/ Here we lookup the datasource with the name\n\t\t\t\/\/ \"java:comp\/env\/jdbc\/jcgDS\"\n\t\t\tDataSource ds = (DataSource) ctx.lookup(\"java:comp\/env\/jdbc\/jcgDS\");\n\t\t\treturn ds.getConnection();\n\t\t} catch (Exception exc) {\n\t\t\texc.printStackTrace();\n\t\t\treturn null;\n\t\t}\n\t}\n\n\tpublic static List<String> getArticleNames() {\n\n\t\tConnection conn = createConnection();\n\t\tList<String> articleNames = new ArrayList<String>();\n\t\ttry {\n\t\t\tStatement stmt = conn.createStatement();\n\t\t\tResultSet rs = stmt.executeQuery(\"SELECT * from JCGEXAMPLE\");\n\t\t\twhile (rs.next()) {\n\t\t\t\tString articleName = rs.getString(\"ARTICLE_NAME\");\n\t\t\t\tif (articleName != null) {\n\t\t\t\t\tarticleNames.add(articleName);\n\t\t\t\t}\n\t\t\t}\n\t\t\tconn.close();\n\n\t\t} catch (Exception e) {\n\t\t\tthrow new RuntimeException(e);\n\t\t}\n\t\treturn articleNames;\n\t}\n\n}\n<\/pre>\nInitialContext ctx = new InitialContext();\n\/\/ Here we lookup the datasource with the name \"java:comp\/env\/jdbc\/jcgDS\"\nDataSource ds = (DataSource) ctx.lookup(\"java:comp\/env\/jdbc\/jcgDS\");\n<\/pre>\n
4.4 Demo<\/h3>\n
![\"Servlet](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/08\/jnd2.jpg\")
<\/a>