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Swing Hacks by Chris Adamson, Joshua Marinacci

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172
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Chapter 4, File Choosers
#32 Preview ZIP and JAR Files
HACK
Just like ZipEntryFileProxy, ZipFileProxy wraps a real file object and passes
most method invocations to the superclass. The special code here is in
parse( ), which loops through each entry in the ZIP file, breaks each path-
name into its constituent parts, and builds up a set of nested
HashTables.
Each directory entry is represented by a
HashMap of child filenames. A master
map holds the directory entries. This nested structure is what lets the
ZipEntryFileProxy find its place in the virtual tree of files.
Build a Custom Filesystem View
Now that you have a tree of virtual File objects, you can implement the real
FileSystemView. As shown in Example 4-3, ZipFileSystemView overrides each
of its parent class’s methods, redirecting them to ZIP-specific code if the file
is an instance of a
ZipEntryFileProxy.
String node_name = name;
if(brk != -1) {
node_name = full_name.substring(brk+1);
}
if(ze.isDirectory( )) {
HashMap children = new HashMap( );
hash.put(full_name,children);
}
Map parent_children = (Map)hash.get(parent);
parent_children.put(full_name,"");
}
}
}
Example 4-3. ZipFileSystemView class
public class ZipFileSystemView extends FileSystemView {
public ZipFileSystemView( ) throws IOException { }
public File createNewFolder(File file) { return null; }
public File createFileObject(File dir, String filename) {
if(dir instanceof ZipEntryFileProxy) {
ZipEntryFileProxy zdir = (ZipEntryFileProxy) dir;
return new ZipEntryFileProxy(zdir.zip, zdir.zipfile, filename, dir);
}
return super.createFileObject(dir,filename);
}
Example 4-2. ZipFileProxy class (continued)
Preview ZIP and JAR Files #32
Chapter 4, File Choosers
|
173
HACK
public File getChild(File dir, String filename) {
if(dir instanceof ZipEntryFileProxy) {
ZipEntryFileProxy zdir = (ZipEntryFileProxy) dir;
return new ZipEntryFileProxy(zdir.zip,zdir.zipfile,
dir.getPath( )+filename,dir);
}
return super.getChild(dir,filename);
}
public String getSystemDisplayName(File f) {
if(f instanceof ZipEntryFileProxy) {
return f.getName( );
}
return super.getSystemDisplayName(f);
}
public File getParentDirectory(File dir) {
if(dir instanceof ZipEntryFileProxy) {
return dir.getParentFile( );
}
return super.getParentDirectory(dir);
}
public File[] getFiles(File dir, boolean useFileHiding) {
if(dir.getName( ).endsWith(".zip")) {
ZipFileProxy proxy = new ZipFileProxy(dir);
File[] fs = proxy.getFiles("");
return fs;
}
if(dir instanceof ZipEntryFileProxy) {
return dir.listFiles( );
}
return super.getFiles(dir,useFileHiding);
}
public Boolean isTraversable(File f) {
if(f.getName( ).endsWith(".zip")) {
return new Boolean(true);
}
if(f instanceof ZipEntryFileProxy) {
boolean b = ((ZipEntryFileProxy)f).isDirectory( );
return new Boolean(b);
}
return super.isTraversable(f);
}
}
Example 4-3. ZipFileSystemView class (continued)

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