bradleyross.j2ee.servlets

Class ShowSchema

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

bradleyross.j2ee.servlets.ShowSchema

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

public class ShowSchema
extends HttpServlet

Servlet for showing database schema information using DatabaseMetaData.

This was an earlier attempt to do an autodocumenter for database schemas. There was a later version that also listed indices and foreign keys and used better formatting, and I'm trying to locate it.

It should be noted that SQL Server does not have a BOOLEAN type but uses an integer value instead for result sets containing boolean data. A value of 0 indicates false while a value of 1 indicates true.

The servlet uses the init parameters class, system, and account.

• class is the name of the class that is a subclass of DatabaseProperties that serves to connect the databases.
• system is the identifier for the database to be used.
• account is the name of the account to be used.

Author:

Bradley Ross

See Also:

DatabaseMetaData.getCrossReference(String, String, String, String, String, String), DatabaseMetaData.getIndexInfo(String, String, String, boolean, boolean), DatabaseMetaData.getTables(String, String, String, String[]), DatabaseMetaData.getImportedKeys(String, String, String), DatabaseMetaData.getExportedKeys(String, String, String), Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected String	databaseAccount Name of account to be used for database connection.
protected Class<?>	databaseClass Class for handling database.
protected String	databaseClassName Name of class for handling database.
protected String	databaseDescription Description of database.
protected String	databaseSystem Name of system for database connection.
protected Vector<String>	errorMessages List of warning or error messages generated by this application.
protected Vector<String>	infoMessages List of informative messages generated by this application.
protected boolean	isValid True if servlet was correctly instantiated.
(package private) Logger	log
(package private) ExceptionHelper	logger

Constructor Summary

Constructors

Constructor and Description
ShowSchema() Default constructor.
ShowSchema(String className, String system, String account) Constructor to allow the methods to be used by a stand-alone application.

Method Summary

Methods

Modifier and Type	Method and Description
String	buildErrorMessage(String title, String message) Generates an error message for the application.
protected DatabaseProperties	getData() Obtain a connection to the database based on the initialization parameters for the servlet.
void	init(ServletConfig configIn) Initializes object for use with servlets.
protected boolean	isIncluded(DatabaseProperties data, String catalog, String schema, String item) Determines whether an item in the database is to be included in the reports.
protected void	ProblemFound(Exception e, GenericPrinter output, String message) Place error message on web page if exception is encountered.
protected void	processDatabaseInformation(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate a page containing information about the database system.
protected void	processDescribeTable(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate a web page describing the layout of a table.
protected void	processListProcedures(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate the list of procedures in the database.
protected void	processListTables(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate the list of tables in the database.
protected void	processListViews(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate the list of views in the database.
protected void	processRootPage(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate the root page for schema information for the database.
protected void	processUDTInformation(DatabaseProperties data, GenericPrinter output, HttpServletRequest req, HttpServletResponse res) Generate the list of user defined types for the database system.
void	service(HttpServletRequest req, HttpServletResponse res) This is the method that is executed each time a request is made for the web page.
protected int	showResultSet(GenericPrinter output, ResultSet rs) Displays a result set as an HTML table.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

Logger log

logger

ExceptionHelper logger

isValid

protected boolean isValid

True if servlet was correctly instantiated.

databaseClassName

protected String databaseClassName

Name of class for handling database.

databaseClass

protected Class<?> databaseClass

Class for handling database.

databaseSystem

protected String databaseSystem

Name of system for database connection.

databaseDescription

protected String databaseDescription

Description of database.

databaseAccount

protected String databaseAccount

Name of account to be used for database connection.

errorMessages

protected Vector<String> errorMessages

List of warning or error messages generated by this application.

infoMessages

protected Vector<String> infoMessages

List of informative messages generated by this application.

Constructor Detail

ShowSchema

public ShowSchema()

Default constructor.

The default constructor is used by the Tomcat application server when setting up the servlet. The default constructor must be explicitly defined since there is an explicit constructor for the class.

ShowSchema

public ShowSchema(String className,
          String system,
          String account)

Constructor to allow the methods to be used by a stand-alone application.

Parameters:

className - Name of class for defining database connections.

system - Database system for which connection is to be made.

account - Account name to be used in connecting to the database.

Method Detail

buildErrorMessage

public String buildErrorMessage(String title,
                       String message)

Generates an error message for the application.

Parameters:

title - Text to appear in title

message - Text to appear in body of message

Returns:

HTML page

isIncluded

protected boolean isIncluded(DatabaseProperties data,
                 String catalog,
                 String schema,
                 String item)

Determines whether an item in the database is to be included in the reports.

When dealing with SQLServer, dbo.dtproperties was showing up on the list of tables even though it was a system table. The other system tables weren't appearing.

Parameters:

data - Object describing data connection

catalog - Name of catalog for item in database

schema - Name of schema for item in database

item - Name of item in database

Returns:

True if item is to be included in report

getData

protected DatabaseProperties getData()

Obtain a connection to the database based on the initialization parameters for the servlet.

Returns:

Database connection information

See Also:

databaseAccount, databaseSystem, databaseClassName

init

public void init(ServletConfig configIn)
          throws ServletException

Initializes object for use with servlets.

The following servlet configuration items are used.

• class - Subclass of DatabaseProperties that is used to connect with the database.
• system
• account

Specified by:

init in interface Servlet

Overrides:

init in class GenericServlet

Parameters:

configIn - Servlet configuration object

Throws:

ServletException

ProblemFound

protected void ProblemFound(Exception e,
                GenericPrinter output,
                String message)

Place error message on web page if exception is encountered.

Parameters:

e - Exception

output - Output device for servlet writer

service

public void service(HttpServletRequest req,
           HttpServletResponse res)
             throws IOException

This is the method that is executed each time a request is made for the web page.

Overrides:

service in class HttpServlet

Parameters:

req - Request information

res - Response information

Throws:

IOException

processRootPage

protected void processRootPage(DatabaseProperties data,
                   GenericPrinter output,
                   HttpServletRequest req,
                   HttpServletResponse res)
                        throws IOException

Generate the root page for schema information for the database.

Parameters:

data - Object describing database connection

output - Object for writing web page

req - HTTP request information

res - HTTP response information

Throws:

IOException

processListTables

protected void processListTables(DatabaseProperties data,
                     GenericPrinter output,
                     HttpServletRequest req,
                     HttpServletResponse res)
                          throws IOException

Generate the list of tables in the database.

Parameters:

data - Object describing database connection

output - Object for writing web page

req - HTTP request information

res - HTTP response information

Throws:

IOException

processListViews

protected void processListViews(DatabaseProperties data,
                    GenericPrinter output,
                    HttpServletRequest req,
                    HttpServletResponse res)
                         throws IOException

Generate the list of views in the database.

Parameters:

data - Object describing database connection

output - Object for writing web page

req - HTTP request information

res - HTTP response information

Throws:

IOException

processListProcedures

protected void processListProcedures(DatabaseProperties data,
                         GenericPrinter output,
                         HttpServletRequest req,
                         HttpServletResponse res)
                              throws IOException

Generate the list of procedures in the database.

Parameters:

data - Object containing database connection information

output - Object for writing web page

req - HTTP request information

res - HTTP response information

Throws:

IOException

See Also:

DatabaseMetaData.getProcedures(String, String, String)

processUDTInformation

protected void processUDTInformation(DatabaseProperties data,
                         GenericPrinter output,
                         HttpServletRequest req,
                         HttpServletResponse res)
                              throws IOException

Generate the list of user defined types for the database system.

Needs to have code for User Defined Types inserted.

Parameters:

data - Database connection information

output - GenericPrinter object to which material is sent

req - HTTP request object

res - HTTP response object

Throws:

IOException

See Also:

DatabaseMetaData.getUDTs(String, String, String, int[])

processDatabaseInformation

protected void processDatabaseInformation(DatabaseProperties data,
                              GenericPrinter output,
                              HttpServletRequest req,
                              HttpServletResponse res)
                                   throws IOException

Generate a page containing information about the database system.

Parameters:

data - Object containing database connection information

output - Object for writing web page

req - HTTP request information

res - HTTP response information

Throws:

IOException

See Also:

DatabaseMetaData

processDescribeTable

protected void processDescribeTable(DatabaseProperties data,
                        GenericPrinter output,
                        HttpServletRequest req,
                        HttpServletResponse res)
                             throws IOException

Generate a web page describing the layout of a table.

Parameters:

data - Database connection data object

output - GenericPrinter object to which information is sent

req - HTTP request object

res - HTTP response object

Throws:

IOException

See Also:

DatabaseMetaData.getTables(String, String, String, String[]), DatabaseMetaData.getColumns(String, String, String, String), DatabaseMetaData.getIndexInfo(String, String, String, boolean, boolean), DatabaseMetaData.getExportedKeys(String, String, String), DatabaseMetaData.getImportedKeys(String, String, String)

showResultSet

protected int showResultSet(GenericPrinter output,
                ResultSet rs)

Displays a result set as an HTML table.

Parameters:

output - Object for printing to HTML page

rs - Result set to be processed

Returns:

number of rows