Android Txt文本读写类源代码

[honeymoose]

Android系统内部提供了一个不错的txt文本读写类，但目前并没有公开提供给标准的SDK，FileUtils类的源代码如下，可以很好的操作Linux下的文本文件。

public class FileUtils
{
public static final int S_IRWXU = 00700;
public static final int S_IRUSR = 00400;
public static final int S_IWUSR = 00200;
public static final int S_IXUSR = 00100;

public static final int S_IRWXG = 00070;
public static final int S_IRGRP = 00040;
public static final int S_IWGRP = 00020;
public static final int S_IXGRP = 00010;

public static final int S_IRWXO = 00007;
public static final int S_IROTH = 00004;
public static final int S_IWOTH = 00002;
public static final int S_IXOTH = 00001;

 public static final class FileStatus {
    public int dev;
    public int ino;
    public int mode;
    public int nlink;
    public int uid;
    public int gid;
    public int rdev;
    public long size;
    public int blksize;
    public long blocks;
    public long atime;
    public long mtime;
    public long ctime;
}


public static native boolean getFileStatus(String path, FileStatus status);

private static final Pattern SAFE_FILENAME_PATTERN = Pattern.compile("[\\w%+,./=_-]+");


public static boolean copyFile(File srcFile, File destFile) {
    boolean result = false;
    try {
        InputStream in = new FileInputStream(srcFile);
        try {
            result = copyToFile(in, destFile);
        } finally  {
            in.close();
        }
    } catch (IOException e) {
        result = false;
    }
    return result;
}


public static boolean copyToFile(InputStream inputStream, File destFile) {
    try {
        if (destFile.exists()) {
            destFile.delete();
        }
        OutputStream out = new FileOutputStream(destFile);
        try {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) >= 0) {
                out.write(buffer, 0, bytesRead);
            }
        } finally {
            out.close();
        }
        return true;
    } catch (IOException e) {
        return false;
    }
}

 public static boolean isFilenameSafe(File file) {
    return SAFE_FILENAME_PATTERN.matcher(file.getPath()).matches();
}


public static String readTextFile(File file, int max, String ellipsis) throws IOException {
    InputStream input = new FileInputStream(file);
    try {
        long size = file.length();
        if (max > 0 || (size > 0 && max == 0)) {  

            if (size > 0 && (max == 0 || size < max)) max = (int) size;
            byte[] data = new byte[max + 1];
            int length = input.read(data);
            if (length <= 0) return "";
            if (length <= max) return new String(data, 0, length);
            if (ellipsis == null) return new String(data, 0, max);
            return new String(data, 0, max) + ellipsis;
        } else if (max < 0) {  // "tail" mode: keep the last N
            int len;
            boolean rolled = false;
            byte[] last = null, data = null;
            do {
                if (last != null) rolled = true;
                byte[] tmp = last; last = data; data = tmp;
                if (data == null) data = new byte[-max];
                len = input.read(data);
            } while (len == data.length);

            if (last == null && len <= 0) return "";
            if (last == null) return new String(data, 0, len);
            if (len > 0) {
                rolled = true;
                System.arraycopy(last, len, last, 0, last.length - len);
                System.arraycopy(data, 0, last, last.length - len, len);
            }
            if (ellipsis == null || !rolled) return new String(last);
            return ellipsis + new String(last);
        } else {  
            ByteArrayOutputStream contents = new ByteArrayOutputStream();
            int len;
            byte[] data = new byte[1024];
            do {
                len = input.read(data);
                if (len > 0) contents.write(data, 0, len);
            } while (len == data.length);
            return contents.toString();
        }
    } finally {
        input.close();
    }
}

}