MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Instrukcja Użytkownika Pobierz pdf (Strona 18)

18 CHAPTER 30 Extending ColdFusion with CFX

Listing 30.3 shows how these objects can be used together to create the <CFX_DatabaseMetaData>

tag. This is a relatively long listing, but it you look at it part by part you’ll see that the code is really

quite simple and straightforward. To a large extent, you will ﬁnd examples in the Java SDK docu-

mentation that contain lines quite similar to many of the lines in this listing.

Listing 30.3 DatabaseMetaData.java—Using Functionality from the java.sql Package in a CFX Tag

import com.allaire.cfx.* ;

import java.sql.* ;

public class DatabaseMetaData implements CustomTag

{

// Constant string for error messages

final String msgError = “Error occurred in a <CFX_DATABASEMETADATA> tag. “;

// This gets called each time the tag is used in a ColdFusion page

public void processRequest( Request request, Response response )

throws Exception

{

// Obtain the values for the tag’s attributes, and throw exceptions

// if any of the required attributes have not been provided.

String strAction = getTagAttr(“ACTION”, request);

String userName = getTagAttr(“USERNAME”, request);

String password = getTagAttr(“PASSWORD”, request);

String driver = getTagAttr(“DRIVER”, request);

String connect = getTagAttr(“CONNECT”, request);

String strQueryName = getTagAttr(“NAME”, request);

// These are optional attributes

String DBCatalog = getTagAttr(“DBCATALOG”, request, null);

String DBSchema = getTagAttr(“DBSCHEMA”, request, null);

String DBTableName = getTagAttr(“DBTABLENAME”, request, “%”);

String DBColumnName = getTagAttr(“DBCOLUMNNAME”, request, “%”);

String DBProcedureName = getTagAttr(“DBPROCEDURENAME”, request, “%”);

// For the DBTableName attribute, consider an empty string to mean null

//if (DBTableName.equals(“”)) DBTableName = null;

// Load the specified database driver

Class.forName(driver).newInstance();

// Attempt to connect to the data source

Connection conn = DriverManager.getConnection(connect, userName, password);

// Get the metadata object from the database connection

java.sql.DatabaseMetaData dbmd = conn.getMetaData();

// This ResultSet will be returned to ColdFusion as a query object

ResultSet rs = null;

// Handle ACTION=”GetTables” (user wants a list of tables)

if ( strAction.equalsIgnoreCase(“GetTables”) ) {

String[] types = {“TABLE”};

rs = dbmd.getTables(DBCatalog, DBSchema, DBTableName, types);

// Handle ACTION=”GetViews” (user wants a list of views)

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MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Instrukcja Użytkownika Strona 18

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