扩展Lucene的索引文件存储

IndexWriter idx_writer = new IndexWriter(“D:/lucene_idx”,new StandardAnalyzer(),false);

package dlog.common.search;

import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.IOUtils;
import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystemException;
import org.apache.commons.vfs.FileSystemManager;
import org.apache.commons.vfs.RandomAccessContent;
import org.apache.commons.vfs.VFS;
import org.apache.commons.vfs.util.RandomAccessMode;
import org.apache.lucene.store.BufferedIndexInput;
import org.apache.lucene.store.BufferedIndexOutput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.Lock;

/**
* 扩展Lucene索引的存储,使用commons-vfs做为lucene的存储引擎
* @author Winter Lau
* @email javayou@gmail.com
* @home /javayou
*/
public class VFSDirectory extends Directory {
private FileSystemManager fileManager;
 private FileObject directory;
 private FileObject locker;

public VFSDirectory(String repository_uri, String lock_uri) throws IOException {
 this.fileManager = VFS.getManager();
 this.directory = fileManager.resolveFile(repository_uri);
 if(!directory.exists())
 directory.createFolder();
 this.locker = fileManager.resolveFile(lock_uri);
 if(!locker.exists())
locker.createFolder();
}

@Override
public void close() throws IOException {
directory.close();
}

protected void finalize() throws IOException {
close(); // close the directory
}

@Override
public IndexOutput createOutput(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
return new VFSIndexOutput(file);
}

@Override
public IndexInput openInput(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
return new VFSIndexInput(file);
}

@Override
public void deleteFile(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
//System.out.println(file.getName().getFriendlyURI());
if(!file.delete())
throw new IOException("Cannot delete " + file);
}

@Override
public boolean fileExists(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
return file.exists();
}

@Override
public long fileLength(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
return file.getContent().getSize();
}

@Override
public long fileModified(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
return file.getContent().getLastModifiedTime();
}

@Override
public String[] list()throws IOException {
List names = new ArrayList();
FileObject[] files = directory.getChildren();

for(int i=0;i

@Override
public Lock makeLock(String name) {

final StringBuffer buf = getLockPrefix();
buf.append("-");
buf.append(name);

try{

final FileObject lockFile = this.fileManager.resolveFile(locker, buf.toString());

return new Lock() {
public boolean obtain() throws IOException {
lockFile.createFile();
return lockFile.exists();
}

public void release() {
try {
lockFile.delete();
} catch (FileSystemException e) {
throw new RuntimeException("Cannot release lock : " + buf.toString(), e);
}
}

public boolean isLocked() {
try {
return lockFile.exists();
} catch (FileSystemException e) {
throw new RuntimeException("Cannot check locking status : " + buf.toString(), e);
}
}

public String toString() {
return "Lock@" + lockFile;
}
};
} catch (IOException e){
throw new RuntimeException("Request lock failed : " + buf.toString(), e);
}
}

private static MessageDigest DIGESTER;

/**
* So we can do some byte-to-hexchar conversion below
*/
static char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

static {
try {
DIGESTER = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e.toString(), e);
}
}

private StringBuffer getLockPrefix() {

String dirName; // name to be hashed

try {
dirName = directory.getURL().toString();
} catch (IOException e) {
throw new RuntimeException(e.toString(), e);
}

byte digest[];

synchronized (DIGESTER) {
digest = DIGESTER.digest(dirName.getBytes());
}

StringBuffer buf = new StringBuffer();
buf.append("lucene-");
for (int i = 0; i < digest.length; i++) {
int b = digest[i];
buf.append(HEX_DIGITS[(b >> 4) & 0xf]);
buf.append(HEX_DIGITS[b & 0xf]);
}
return buf;
}

@Override
public void renameFile(String name1, String name2) throws IOException {
FileObject file1 = this.fileManager.resolveFile(directory, name1);
FileObject file2 = this.fileManager.resolveFile(directory, name2);
try{
IOUtils.copy(file1.getContent().getInputStream(), file2.getContent().getOutputStream());
}finally{
close(file2);
close(file1);
}
}

@Override
public void touchFile(String name) throws IOException {
FileObject file = this.fileManager.resolveFile(directory, name);
file.getContent().setLastModifiedTime(System.currentTimeMillis());
}

private void close(FileObject file){
if(file!=null){
try{
file.close();
}catch (IOException e) {
throw new RuntimeException("Cannot close input stream: " + e.toString(), e);
}
}
}

private static class VFSIndexInput extends BufferedIndexInput {

private long length;
private RandomAccessContent content;

public VFSIndexInput(FileObject file) throws IOException {
this.content = file.getContent().getRandomAccessContent(RandomAccessMode.READ);
this.length = content.length();
}

@Override
public void close() throws IOException {
this.content.close();
}

@Override
public long length() {
return length;
}

@Override
protected void readInternal(byte[] b, int off, int len) throws IOException {
this.content.readFully(b, off, len);
}

@Override
protected void seekInternal(long position) throws IOException {
this.content.seek(position);
}
}

private static class VFSIndexOutput throws BufferedIndexOutput {

private RandomAccessContent content;

public VFSIndexOutput(FileObject file) throws IOException{
if(!file.exists())
file.createFile();
this.content = file.getContent().getRandomAccessContent(RandomAccessMode.READWRITE);
}

@Override
protected void flushBuffer(byte[] b, int size) throws IOException {
this.content.write(b, 0, size);
}

@Override
public void seek(long pos) throws IOException {
super.seek(pos); //此行代 码非常重要，否则会导致写文件错误
this.content.seek(pos);
}

@Override
public long length() throws IOException {
return this.content.length();
}

@Override
public void close() throws IOException {
super.close();
this.content.close();
}

protected void finalize() throws IOException {
close(); // close the file
}
}
}