IO模块-其他操作

copy

File file = new File(getFilesDir(), "test.txt");
File file2 = new File(getFilesDir(), "test2.txt");
try {
    Files.copy(file, file2);
} catch (IOException e) {
    e.printStackTrace();
}

equal

比较两个文件是否相等。

源码：

public static boolean equal(File file1, File file2) throws IOException {
    checkNotNull(file1);
    checkNotNull(file2);
    if (file1 == file2 || file1.equals(file2)) {
      return true;
    }

    /*
     * Some operating systems may return zero as the length for files denoting system-dependent
     * entities such as devices or pipes, in which case we must fall back on comparing the bytes
     * directly.
     */
    long len1 = file1.length();
    long len2 = file2.length();
    if (len1 != 0 && len2 != 0 && len1 != len2) {
      return false;
    }
    return asByteSource(file1).contentEquals(asByteSource(file2));
  }

  public boolean contentEquals(ByteSource other) throws IOException {
    checkNotNull(other);

    byte[] buf1 = createBuffer();
    byte[] buf2 = createBuffer();

    Closer closer = Closer.create();
    try {
      InputStream in1 = closer.register(openStream());
      InputStream in2 = closer.register(other.openStream());
      while (true) {
        int read1 = ByteStreams.read(in1, buf1, 0, buf1.length);
        int read2 = ByteStreams.read(in2, buf2, 0, buf2.length);
        if (read1 != read2 || !Arrays.equals(buf1, buf2)) {
          return false;
        } else if (read1 != buf1.length) {
          return true;
        }
      }
    } catch (Throwable e) {
      throw closer.rethrow(e);
    } finally {
      closer.close();
    }
  }

hash

计算文件的hash值。具体的参考guava源码分析关于hash模块的分析。

map

得到文件的内存映射缓冲区。

touch

创建新文件，或者在文件已经存在的情况下更新文件的时间。

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