Eclipse Plug-in Developer Guide (Galileo) - ByteArrayTransfer (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.swt.dnd
Class ByteArrayTransfer


java.lang.Object
  

org.eclipse.swt.dnd.Transfer
      
org.eclipse.swt.dnd.ByteArrayTransfer

Direct Known Subclasses:: EditorInputTransfer, FileTransfer, HTMLTransfer, ImageTransfer, LocalSelectionTransfer, MarkerTransfer, PluginTransfer, ResourceTransfer, RTFTransfer, TextTransfer, URLTransfer

public abstract class ByteArrayTransfer
extends Transfer
extends Transfer

The class ByteArrayTransfer provides a platform specific mechanism for converting a java byte[] to a platform specific representation of the byte array and vice versa.

ByteArrayTransfer is never used directly but is sub-classed by transfer agents that convert between data in a java format such as a String and a platform specific byte array.

If the data you are converting does not map to a byte[], you should sub-class Transfer directly and do your own mapping to a platform data type.

The following snippet shows a subclass of ByteArrayTransfer that transfers data defined by the class MyType.


 public class MyType {
        public String fileName;
        public long fileLength;
        public long lastModified;
 }


 public class MyTypeTransfer extends ByteArrayTransfer {
        
        private static final String MYTYPENAME = "my_type_name";
        private static final int MYTYPEID = registerType(MYTYPENAME);
        private static MyTypeTransfer _instance = new MyTypeTransfer();
 
 private MyTypeTransfer() {}
 
 public static MyTypeTransfer getInstance () {
        return _instance;
 }
 public void javaToNative (Object object, TransferData transferData) {
        if (object == null || !(object instanceof MyType[])) return;
        
        if (isSupportedType(transferData)) {
                MyType[] myTypes = (MyType[]) object;   
                try {
                        // write data to a byte array and then ask super to convert to pMedium
                        ByteArrayOutputStream out = new ByteArrayOutputStream();
                        DataOutputStream writeOut = new DataOutputStream(out);
                        for (int i = 0, length = myTypes.length; i < length;  i++){
                                byte[] buffer = myTypes[i].fileName.getBytes();
                                writeOut.writeInt(buffer.length);
                                writeOut.write(buffer);
                                writeOut.writeLong(myTypes[i].fileLength);
                                writeOut.writeLong(myTypes[i].lastModified);
                        }
                        byte[] buffer = out.toByteArray();
                        writeOut.close();
 
                        super.javaToNative(buffer, transferData);
                        
                } catch (IOException e) {
                }
        }
 }
 public Object nativeToJava(TransferData transferData){ 
 
        if (isSupportedType(transferData)) {
                
                byte[] buffer = (byte[])super.nativeToJava(transferData);
                if (buffer == null) return null;
                
                MyType[] myData = new MyType[0];
                try {
                        ByteArrayInputStream in = new ByteArrayInputStream(buffer);
                        DataInputStream readIn = new DataInputStream(in);
                        while(readIn.available() > 20) {
                                MyType datum = new MyType();
                                int size = readIn.readInt();
                                byte[] name = new byte[size];
                                readIn.read(name);
                                datum.fileName = new String(name);
                                datum.fileLength = readIn.readLong();
                                datum.lastModified = readIn.readLong();
                                MyType[] newMyData = new MyType[myData.length + 1];
                                System.arraycopy(myData, 0, newMyData, 0, myData.length);
                                newMyData[myData.length] = datum;
                                myData = newMyData;
                        }
                        readIn.close();
                } catch (IOException ex) {
                        return null;
                }
                return myData;
        }
 
        return null;
 }
 protected String[] getTypeNames(){
        return new String[]{MYTYPENAME};
 }
 protected int[] getTypeIds(){
        return new int[] {MYTYPEID};
 }
 }

See Also:: Transfer

Constructor Summary

ByteArrayTransfer ()


Method Summary

TransferData[] getSupportedTypes ()
          Returns a list of the platform specific data types that can be converted using this transfer agent.

boolean isSupportedType ( TransferData transferData)
          Returns true if the TransferData data type can be converted using this transfer agent, or false otherwise (including if transferData is null).

protected void javaToNative ( Object object, TransferData transferData)
          This implementation of javaToNative converts a java byte[] to a platform specific representation.

protected Object nativeToJava ( TransferData transferData)
          This implementation of nativeToJava converts a platform specific representation of a byte array to a java byte[].

Methods inherited from class org.eclipse.swt.dnd. Transfer

getTypeIds, getTypeNames, registerType, validate

Methods inherited from class java.lang. Object

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

Constructor Detail

ByteArrayTransfer

public ByteArrayTransfer()

Method Detail

getSupportedTypes

public 
TransferData[] getSupportedTypes()

Description copied from class: Transfer

Returns a list of the platform specific data types that can be converted using this transfer agent.

Only the data type fields of the TransferData objects are filled in.

Specified by:: getSupportedTypes in class Transfer

Returns:: a list of the data types that can be converted using this transfer agent

isSupportedType

public boolean isSupportedType(
TransferData transferData)