fileaccess.java

j2me的基于http协议的断点续传。支持多线程的断点续传。

/**
 * FileAccess.java
 */
package NetFox;

import java.io.*;
import javax.microedition.io.*;
import javax.microedition.io.file.*;

public class FileAccess 
{
    FileConnection fConn = null;
    OutputStream savedFile = null;
    
    private FileAccess() {
    }
    
    public FileAccess(String sName, long nPos) throws IOException {
        Utility.log("try to create or resume file: [" + sName + "]");
        fConn = Utility.createFileConn(sName);
        if (!fConn.exists()) {
            fConn.create();
        }
        fConn.truncate(nPos + 1);
        savedFile = fConn.openOutputStream(nPos);
    }
    
    public void close() throws Exception {
        if (null != savedFile) savedFile.close();
        if (null != fConn) fConn.close();
    }
    
    public synchronized int write(byte[] b,int nStart,int nLen) {
        int n = -1;
        try {
            savedFile.write(b, nStart, nLen);
            n = nLen;
        } catch(IOException e) {
            Utility.log(e.getMessage());
        }
        
        return n;
    }
}