ch.16 jdbc (java database connectivity)
DESCRIPTION
Ch.16 JDBC (Java DataBase Connectivity). PIKE Lab. 석사 2 학기 이 은 정. CONTENTS. Introduction Needed Software Generating XML from JDBC Using XML for distributed JDBC App. Summary. INTRODUCTION(1/2). Challenge - PowerPoint PPT PresentationTRANSCRIPT
Ch.16 JDBCCh.16 JDBC(Java DataBase Connectivity)(Java DataBase Connectivity)
PIKE Lab.PIKE Lab.
석사 석사 22 학기학기이 은 정이 은 정
CONTENTSCONTENTS
• IntroductionIntroduction• Needed SoftwareNeeded Software• Generating XML from JDBCGenerating XML from JDBC• Using XML for distributed JDBC Using XML for distributed JDBC
App.App.• SummarySummary
INTRODUCTION(1/2)INTRODUCTION(1/2)
• Challenge– To create JDBC Applications that allow
platform_neutral, device_independent access to data
By XML-enabling the JDBC applicationBy XML-enabling the JDBC application
• XML with J2EE + Standard Internet Protocol(HTTP) Enterprise applications that provide universal data
access to JDBC data sources
INTRODUCTION(2/2)INTRODUCTION(2/2)
• In this chapter…– Some examples of how to integrate XML with JDBC in J2EE ahow to integrate XML with JDBC in J2EE a
pplicationspplications that are device-and –platform independent universal data access
• There’re 2 scenarios…– Generating XML from a JDBC data source
• A XML gateway architecture for JDBC– Using XML to update a JDBC data source
• How to use WebRowSets to distributed JDBC applications
Needed SoftwareNeeded Software
• JDK1.3 - http://java.sun.com
• Xalan XSLT Processor for Java - http://xml.apache.org
• Java packages to implement the WebRowSet framework– sun.jdbc.rowset Package
– javax.sql Package : JDBC 2.0 standard extension API
• Tomcat 3.1 : java servlet API - http://jakarta.apache.org
• A JDBC data source & Driver(Oracle, SQL Server…)
Generating XML from Generating XML from JDBCJDBC
• Create an architecture that allows you to extract data from a JDBC data source
• Serialize the JDBC result set to XML
• Send it to the requesting client, using XSLT as appropriate to create output that targets a particular device
Generating XML from Generating XML from JDBCJDBC
• A simple XML Gateway Architecture for JDBC– JDBC2XML classJDBC2XML class : control access to the JDBC data source
• Execute a SQL statement against the specified JDBC data source• Serialize the returned JDBC result set as XML• Return the XML document to the calling client• Reused by two java servlets
– XMLDataGateway : a generic XML-over-HTTP interface to JDBC data sources for XML –enabled applications
– JDBC2HTML : return JDBC result sets as a HTML to web browsers using the specified XSL stylesheet like a filter
JDBC Data Source
JDBC2XML class
XMLDataGatewayServleet
XSLStylesheet
JDBC2HTMLServlet
XML-enabledApplication Web browser
JDBC
HTTP GET or POST
XML over HTTP
In-process
call
XML serialized resul
tset
HTTP GET or POST
HTMLover HTT
P
XML serialized resul
tsetIn-
process call
XSLT
Delegated to
Creating & Using the Creating & Using the ArchitectureArchitecture
• Develop the JDBC2XML class
• Develop the XMLDataGateway servlet
• Query a JDBC data source using the XMLDataGateway servlet
• Develop the JDBC2HTML servlet
• Write an XSL stylesheet that defines HTML presentation logic for o
ur <resultset/> XML schema
• Query a JDBC data source using the JDBC2HTML servlet
The JDBC2XML ClassThe JDBC2XML Class
package com.jresources.jdbc;
import java.sql.*;import java.util.*;
public class JDBC2XMLJDBC2XML{
public JDBC2XML() {super();
}
Include the functionality
• to query a JDBC Data
source
• to return the Results of
that query as a well-formed
XML document
public String SQLEncode(String content) {return Replace(content, "\'", "\'\'");
}/** * Applies XML encoding rules to special characters */String encodeXML(String sData) {
String[] before = {"&","<",">","\"", "\'"};String[] after = {"&","<",">",""", "'"};
if(sData!=null) {for(int i=0;i<before.length;i++) {
sData = Replace(sData, before[i], after[i]);}
}else {sData="";}return sData;
}
String Replace(String content, String oldWord, String newWord) {
int position = content.indexOf(oldWord);
while (position > -1) {
content = content.substring(0,position) + newWord +
content.substring(position+oldWord.length());
position = content.indexOf(oldWord,position+newWord.length());
}
return content;
}
<?xml version="1.0" encoding="ISO-8859-1"?><resultset>
<metadata><field name="field name goes here" datatype="field's datatype goes here"/>
</metadata>
<records><record>
<field name="field name goes here">field's value goes here
</field></record>
</records></resultset>
String writeXML(ResultSet rs) { StringBuffer strResults = new StringBuffer("<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>\r\n<resultset>\r\n"); try { ResultSetMetaData rsMetadata = rs.getMetaData();
int intFields = rsMetadata.getColumnCount(); strResults.append("<metadata>\r\n"); for(int h =1; h <= intFields; h++) {
strResults.append("<field name=\"" + rsMetadata.getColumnName(h) + "\" datatype=\"" + rsMetadata.getColumnTypeName(h) + "\"/>\r\n");
} strResults.append("</metadata>\r\n<records>\r\n"); while(rs.next()) {
strResults.append("<record>\r\n"); for(int i =1; i <= intFields; i++) {
strResults.append("<field name=\"" + rsMetadata.getColumnName(i) + "\">" + encodeXML(rs.getString(i)) + "</field>\r\n");
} strResults.append("</record>\r\n");
} }catch(Exception e) {} strResults.append("</records>\r\n</resultset>"); return strResults.toString();
}
public String execute(String driver, String url, String uid, String pwd, String sql) {String output = new String();try {
//instantiate and register the JDBC driverClass.forName(driver);//connect to the database and create a statementConnection conn =
DriverManager.getConnection(url, uid, pwd);Statement s = conn.createStatement();ResultSet rs = s.executeQuery(sql);output = writeXML(rs);writeXML(rs);rs.close();conn.close();
}catch(Exception e) {output = "<error>" + encodeXML(e.toString()) + "</error>";
}return output;
}
The XMLDataGateway ServletThe XMLDataGateway Servletpackage com.jresources.jdbc;
import javax.servlet.*;import javax.servlet.http.*;import java.io.*;
public class XMLDataGateway extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response)throws IOException, ServletException {
response.setContentType("text/xml");PrintWriter out = response.getWriter();JDBC2XML searchObj = new JDBC2XML();out.println(searchObj.execute(request.getParameter("driver"), request.getParameter("jdbcurl"), request.getParameter("uid"), request.getParameter("pwd"), request.getParameter("sql")));
}public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
doGet(request, response);}
}
<form action=“/jdbcxml/servlet/XMLDataGateway" method="POSTPOST"><table border="0"><tr> <td align="right"><font face="Arial">JDBC Driver: </font></td> <td><font face="Arial">
<input type="text" size="50" name="driver" value="sun.jdbc.odbc.JdbcOdbcDriver"></td> </tr>
<tr> <td align="right"><font face="Arial">JDBC URL: </font></td> <td><font face="Arial">
<input type="text" size="50" name="jdbcurl" value="jdbc:odbc:northwind"></td> </tr>
<tr> <td align="right"><font face="Arial">Userid:</font></td> <td><font face="Arial"><input type="text" size="50" name="uid"></font></td> </tr><tr> <td align="right"><font face="Arial">password </font></td> <td><font face="Arial"><input type="password" size="50" name="pwd"></font></td> </tr><tr> <td align="right"><font face="Arial">SQL Statement:</font></td> <td><textarea name="sql" rows="10" cols="50"></textarea></td> </tr><tr> <td align="right"><input type="submit"></td> <td> </td> </tr> </table></form>
Using XMLDataGAteway Using XMLDataGAteway from a Web Browserfrom a Web Browser
The JDBC2HTML ServletThe JDBC2HTML Servlet
import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import org.xml.sax.SAXException;import org.apache.xalan.xslt.*;
public class JDBC2HTML extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
String qryDoc;if(request.getPathInfo()==null) {qryDoc = getServletConfig().getServletContext().getRealPath(request.getServletPath());
}else { qryDoc = request.getPathTranslated();}response.setContentType("text/html");PrintWriter out = response.getWriter();JDBC2XML searchObj = new JDBC2XML();String output = searchObj.execute(request.getParameter("driver"), request.getParameter("jdbcurl"), request.getParameter("uid"), request.getParameter("pwd"), request.getParameter("sql"));try {XSLTProcessor processor = XSLTProcessorFactory.getProcessor();processor.process(new XSLTInputSource(new java.io.StringReader(output)), new XSLTInputSource("file:///" + qryDoc), new XSLTResultTarget(out));}catch(SAXException se) {
throw new ServletException(se);//out.println(se.toString()+", " + se.getMessage() + ", " + qryDoc);
}}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
doGet(request, response);
}
}
Writing an XSL stylesheetWriting an XSL stylesheet
<?xml version='1.0'?><xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="/"><xsl:apply-templates/>
</xsl:template>
<xsl:template match="resultset"><html> <head>
<title>A JDBC Resultset in HTML Table Format
</title></head><body>
<h1 align="center">A JDBC Resultset in HTML Table Format
</h1><table border="1" cellspacing="0" cellpadding="5" align="center">
<xsl:apply-templates select="metadata"/><xsl:apply-templates select="//resultset/records"/>
</table></body>
</html></xsl:template>
<xsl:template match="metadata"><tr bgcolor="#FFD700">
<xsl:apply-templates/></tr>
</xsl:template><xsl:template match="metadata/field">
<td><b><xsl:value-of select="@name"/></b></td><xsl:apply-templates/>
</xsl:template><xsl:template match="records">
<xsl:apply-templates/></xsl:template><xsl:template match="record">
<tr><xsl:for-each select="field">
<td><xsl:value-of select="."/></td></xsl:for-each>
</tr></xsl:template>
<xsl:template match="error"><html>
<head><title>
A JDBC Resultset in HTML Table Format</title>
</head><body>
Your request caused the following error: <xsl:value-of select="."/>
</body></html>
</xsl:template></xsl:stylesheet>
Using XML for distributedUsing XML for distributed JDBC Applications JDBC Applications
• Rowset Interface– Provide a framework for writing classes that encapsulate a p
ersistent set of rows
• sun.jdbc.rowset.WebRowSet ClassWebRowSet Class– A rowset implementation that can serialize the data, metadat
a, and properties of a JDBC result set to XML– Use the information in the XML document to re-establish the
connection and update the original data source
A distributed JDBC applications usA distributed JDBC applications using WebRowSeting WebRowSet
• WebRowSetFetchServlet class– Provide an interface for fetching a WebRowSet via HTTP GET
or POST
• WebRowSetUpdateservlet class– Used to update the underlying JDBC data source
• WebRowSetHTTPClient application– Used to execute a query against a JDBC data source & return
the WebRowSet– Add a record to the WebRowSet
Fetching a Rowset via HTTPFetching a Rowset via HTTPpackage com.jresources.jdbc;
import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import javax.sql.*;import sun.jdbc.rowset.*;import java.sql.*;
public class WebRowSetFetchServlet extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
. . . . . . . . .(omit)}public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
doGet(request, response);}
}
Performing a Batch Performing a Batch UpdateUpdate
via HTTP via HTTPpackage com.jresources.jdbc;
import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import javax.sql.*;import sun.jdbc.rowset.*;import java.sql.*;
public class WebRowSetUpdateServlet extends HttpServlet{
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.sendError(403);}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/plain");PrintWriter out = response.getWriter();try {
WebRowSet wrs = new WebRowSet();wrs.readXml(request.getReader());wrs.acceptChanges();out.println("The transaction succeeded");
}catch(Exception e) {out.println("The transaction failed with the following error: " + e.getMessage());
}}
Inserting, Updating, Inserting, Updating, DeletingDeleting
data at the Clientdata at the Client• executeSearch() method
– Encapsulate an HTTP GET request to WebRowSetFetchServletWebRowSetFetchServlet
• updateDataSource() method– Encapsulate an HTTP POST request to WebRowSetUpdateSerWebRowSetUpdateSer
vletvlet
• main() method– The application’s entry point
Web Application Web Application Deployment DescriptionDeployment Description
<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2.2.dtd"><web-app> <display-name>Professional XML Databases:
Chapter 16 (JDBC)</display-name> <description>
This web app contains the sample code for Professional XML Databases: Chapter 16 (JDBC)
</description> <servlet> <servlet-name> JDBC2HTML </servlet-name> <servlet-class> com.jresources.jdbc.JDBC2HTML </servlet-class> </servlet> <servlet> <servlet-name> XMLDataGateway </servlet-name> <servlet-class> com.jresources.jdbc.XMLDataGateway </servlet-class>
</servlet> <servlet> <servlet-name> WebRowSetFetchServlet </servlet-name> <servlet-class> com.jresources.jdbc.WebRowSetFetchServlet </servlet-class> </servlet> <servlet> <servlet-name> WebRowSetUpdateServlet </servlet-name> <servlet-class> com.jresources.jdbc.WebRowSetUpdateServlet </servlet-class> </servlet> <servlet-mapping> <servlet-name> JDBC2HTML </servlet-name> <url-pattern> *.xsl </url-pattern> </servlet-mapping></web-app>
Building ApplicationBuilding Application
• Compile the Java Classes– javac -d %myClasspath% -classpath %CLASSPATH% %basepath%javac -d %myClasspath% -classpath %CLASSPATH% %basepath%
\*.java\*.java
• Package the Bytecode into a JAR– jar cvf %jarpath%\jdbcxml.jar -C %myClasspath%\ .jar cvf %jarpath%\jdbcxml.jar -C %myClasspath%\ .
• Package the Application into a WAR– jar cvf %warpath%\jdbcxml.war -C %apppath%\ .jar cvf %warpath%\jdbcxml.war -C %apppath%\ .
SummarySummary
• How can use JDBC and XML to create universal data access gateways for J2EE applications
• How to construct a simple XML gateway architecture for JDBC that allows to execute SQL statements and return the result-set as well-formed XML data structures
• How to build a distributed JDBC application that allows to interact with a JDBC data source over the Internet using HTTP