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Oracle® Application Development Framework Developer's Guide
10g Release 3 (10.1.3) B25386-01 |
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Oracle® Application Development Framework Developer's Guide
10g Release 3 (10.1.3) B25386-01 |
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Implementing the AbstractAdapter class is optional. It is required only if you want to enable the user to create a data control by dragging and dropping a node onto the Data Control Palette. In this case, the dropped node represents the data source associated with the data control that you are creating. If you do not want this feature, you do not have to implement this class. For example, the CSV data control adapter that ships with JDeveloper does not implement this class because it does not support the drag-and-drop operation. Instead, this adapter displays a wizard to collect information from the user.
The simple CSV adapter implements the AbstractAdapter. When the user drags and drops a node onto the Data Control Palette, JDeveloper checks to see which adapter can handle the type of node that was dropped. You specify the node types that your adapter can handle in the adapter-definition.xml file. This file is used to register your adapter with JDeveloper. See Section 20.7, "Create an XML File to Define Your Adapter" for details about this file.
In your class, you have to implement some methods in the AbstractAdapter class, as described in these sections:
The abstract class oracle.adf.model.adapter.AbstractAdapter is located in the JDEV_HOME/bc4j/lib/adfm.jar file.
Example 20-1 shows an outline of a class that implements the AbstractAdapter class.
Example 20-1 Outline for Class That Implements AbstractAdapter
import oracle.adf.model.adapter.AbstractAdapter;
import oracle.adf.model.adapter.DTContext;
import oracle.adf.model.adapter.AbstractDefinition;
public class MyAdapter extends AbstractAdapter
{
public void initialize(Object sourceObj, DTContext ctx)
{
// you need to implement this method.
// see Section 20.3.4, "Implementing the initialize Method".
}
public boolean invokeUI()
{
// you need to implement this method.
// see Section 20.3.5, "Implementing the invokeUI Method".
}
public AbstractDefinition getDefinition()
{
// you need to implement this method.
// see Section 20.3.6, "Implementing the getDefinition Method".
}
}
Example 20-2 shows the complete source for the SampleDCAdapter class. This is the class that implements AbstractAdapter for the simple CSV adapter. Subsequent sections describe the methods in this class.
Example 20-2 Complete Source for SampleDCAdapter
package oracle.adfinternal.model.adapter.sample;
import java.net.URL;
import oracle.adf.model.adapter.AbstractAdapter;
import oracle.adf.model.adapter.AbstractDefinition;
import oracle.adf.model.adapter.DTContext;
import oracle.ide.Context;
public class SampleDCAdapter extends AbstractAdapter
{
// JDev Context
private Context mJdevCtx = null;
// Source object of data
private Object mSrc = null;
// Source Location
private String mSrcLoc = null;
// data control name
private String mDCName = null;
// data control definition
private AbstractDefinition mDefinition = null;
public SampleDCAdapter()
{
}
/**
* Initializes the adapter from a source object.
* <p>
* The source object can be different thing depending on the context of the
* design time that the adapter is used in. For JDeveloper, the object will
* be a JDeveloper node.
* </p>
* <p>
* Adapter implementations will check the <code>"ctx"</code> parameter to
* get the current design time context. The source object will be used to
* extract the information for the data source.
* </p>
* @param sourceObj Object that contains information about the data source
* that will be used to define the data control.
* @param ctx Current design time context.
*/
public void initialize(Object sourceObj, DTContext ctx)
{
mSrc = sourceObj;
mJdevCtx = (Context) ctx.get(DTContext.JDEV_CONTEXT);
}
/**
* Invlokes the UI at the design time.
* <p>
* This method is a call back from the JDeveloper design time environment to
* the adapters to bring up any UI if required to gather information about
* the data source they represent.
* </p>
*
* @return false if the user cancels the operation. The default retrun value
* is true.
*/
public boolean invokeUI()
{
// First check if this is a JDev environment.
if (mJdevCtx != null && mSrc != null)
{
if (extractDataSourceInfo(mSrc))
{
SampleDCDef def = new SampleDCDef(mSrcLoc,mDCName);
mDefinition = def;
return true;
}
return false;
}
return false;
}
/**
* <p>
* The Definition instance obtained can be used by the ADF design time to
* capture the data control metadata.
*</p>
*
* @return The definition instance describing the data control design time.
*/
public AbstractDefinition getDefinition()
{
return mDefinition;
}
/**
* @param source the data source object.
* @return false if data type is unknown.
*/
public boolean canCreateDataControl(Object source)
{
return extractDataSourceInfo(source);
}
/**
* Extracts information from a data source. This method extracts name
* from the object.
* @param obj the data source object.
*/
private boolean extractDataSourceInfo(Object obj)
{
mDCName = "SampleDC";
// See if the node dropped is a text node of CSV type.
// We will assume that the CSV data file must end with .csv
if (obj instanceof oracle.ide.model.TextNode)
{
oracle.ide.model.TextNode tn = (oracle.ide.model.TextNode) obj;
URL url = tn.getURL();
String loc = url.getFile();
// Check if the file has a matching extension
if (loc.endsWith(".csv"))
{
mSrcLoc = loc;
String path = url.getPath();
int index = path.lastIndexOf('/');
if (index != -1)
{
String fileName = path.substring(index+1);
int dotIndex = fileName.lastIndexOf('.');
mDCName = fileName.substring(0,dotIndex);
}
return true;
}
}
return false;
}
}
The framework calls the initialize method when the user drags and drops a node onto the Data Control Palette. The method has the following signature:
The sourceObj parameter specifies the node that was dropped. You can check this to ensure that the node type is something your adapter can handle.
The ctx parameter specifies the design time context. The package path for DTContext is oracle.adf.model.adapter.DTContext.
In the initialize method, you should perform these tasks:
check if the source node is something that you support
if you support the node, then extract all the information that you need to create a data control instance from the source node. If the information is not sufficient to create a data control instance, you can display some UI in the invokeUI method to get the user to enter the required information.
For the simple CSV adapter, the initialize method simply sets some class variables. These class variables are checked later in the invokeUI method.
This method enables you to display any UI to collect information from the user about the dropped data source. The method has the following signature in the AbstractAdapter:
The method should return false if the user cancels the operation in the UI. This means that the data control is not created.
The method should return true (which is the default implementation) if the UI was run to collect the information.
The simple CSV adapter uses the initialize method to call extractDataSourceInfo, which performs the following:
checks that the node right-clicked by the user represents a text file and that the filename has a .csv extension
gets the filename of the CSV file
sets the mSrcLoc and mDCName class variables. mSrcLoc points to the location of the CSV file, and mDCName is the name used for the data control. In this case, it is just the name of the CSV file without the .csv extension.
These variables are used by invokeUI to instantiate a SampleDCDef object. The SampleDCDef object, which is another class you have to implement, is described in Section 20.4, "Implement the Data Control Definition Class".
Example 20-6 shows the invokeUI method:
This method returns the definition of the data control that was created from information gathered from the dropped source node. The method has the following signature:
The AbstractDefinition class is the data control definition class that you created. See Section 20.4, "Implement the Data Control Definition Class".
In the simple CSV adapter, the getDefinition method returns the value of the mDefinition class variable, which was set in the invokeUI method. mDefinition refers to the data control definition class that you created (SampleDCDef in the case of the simple CSV adapter).
