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Oracle Programming. Instructor: Xintao Wu. architecture. JDBC. JDBC (Java Database Connectivity ). JDBC enables programmers to use SQL queries from within java programs to access databases. JDBC provides transparent access to relational databases from different vendors. JDBC steps.
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Oracle Programming Instructor: Xintao Wu Xintao Wu
architecture Xintao Wu
JDBC Xintao Wu
JDBC (Java Database Connectivity ) • JDBC enables programmers to use SQL queries from within java programs to access databases. • JDBC provides transparent access to relational databases from different vendors. Xintao Wu
JDBC steps • Create the database in your dbms • Register the database as a data source • Import java.sql.* at the beginning of your java file. • Connect to a JDBC source • Connection con = DriverManager.getConnection(“jdbc:oracle:thin:@coit-ora01:1521:class”,”user”,”passwd”) • Create an SQL statement • Statement stmt = con.createStatement(); • stmt.executeUpdate("INSERT INTO sailor VALUES(22,'dustin',7,45.0)"); Xintao Wu
JDBC Step • Execute the statement • ResultSet rs = stmt.executeQuery(“Select * from …”) • Parse the result • rs.next(), rs.getFloat • ResultSetMetaData contains the information about column • Close the statement and connection • stmt.close() • con.close Xintao Wu
Useful resources • JDBC tutorial http://java.sun.com/docs/books/tutorial/jdbc/index.html • UNCC COIT http://coit-servlet01.uncc.edu:8080/support/? • Example http://www.cs.uncc.edu/~xwu/WEB-INF/classes/SampleJDBC.java Xintao Wu
Java Servlets • Web servers understand requests for pages in http and return their response in HTML format • Static html vs. dynamic html • The webpage is based on data submitted by the user • The data changes frequently (a weather-report) • Web pages uses information from a database(stock) • Maintain separate data about each client for personalization purposes(cookies). • Java servlets are programs that extend the functionality of a web server and useful for building dynamic web pages on the fly. Xintao Wu
Java Servlet Advantage • Works as a lightweight thread directly with the JVM rather than create a new process • Load once to memory and used by all threads • Share data among each other Xintao Wu
How to run servlets • Your machine, Java servlet development kit(JSDK) • COIT • consult the webpage http://coit-servlet01.uncc.edu:8080/support/Examples.html • Consult TA Xintao Wu
Examples • HelloWorld • http://coit-servlet01.uncc.edu:8080/xwu/servlet/HelloWorld • http://www.cs.uncc.edu/~xwu/WEB-INF/classes/HelloWorld.java • More examples • http://coit-servlet01.uncc.edu:8080/support/Examples.html • DBServlet • http://coit-servlet01.uncc.edu:8080/xwu/DBServlet.html • http://www.cs.uncc.edu/~xwu/WEB-INF/classes/DBServlet.java Xintao Wu
JDBC and Servlet • Summary: • 1. Download PUTTY and WinSCP • 2. Download HelloWorld, SampleJDBC and DBServlet source code • 3. Modify them and upload to your own space • 4. Compile and run it • http://coit-servlet01.uncc.edu:8080/xwu/ojdbc14.jar • export CLASSPATH=$CLASSPATH:~/public_html/WEB-INF/classes/ojdbc14.jar Xintao Wu
Some links • http://coit-servlet01.uncc.edu:8080/support • http://www.chiark.greenend.org.uk/~sgtatham/putty Xintao Wu
Some files you need • http://www.cs.uncc.edu/~xwu/5160/ojdbc14.jar • http://www.cs.uncc.edu/~xwu/5160/servlet-api.jar • http://www.cs.uncc.edu/~xwu/5160/.bashrc • Visit the following to set up JDBC and servlet enviorment Note: We don’t need bashrc file for the new system Xintao Wu
Summary • 3-tire architecture • APIs such as JDBC and ODBC introduce a layer of abstraction between application and DBMS • Choose your language from JSP, Servlet, ASP, VC++, VB. Xintao Wu