java7 NIO2(4) 文件和目录操作API
文件和目录操作API,跟原来FILE IO做了很多改进,我们看看新的API,这个也是NIO操作的基础。
package com.mime; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.nio.charset.Charset; import java.nio.file.DirectoryStream; import java.nio.file.FileSystems; import java.nio.file.Files; import java.nio.file.LinkOption; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.StandardCopyOption; import java.nio.file.StandardOpenOption; import java.nio.file.attribute.FileAttribute; import java.nio.file.attribute.PosixFilePermission; import java.nio.file.attribute.PosixFilePermissions; import java.util.List; import java.util.Set; public class NIO2FileAndDir { /** * @param args */ public static void main(String[] args) { Path path = FileSystems.getDefault().getPath( System.getProperty("user.home"), "www", "pyweb.settings"); // 检查文件是否存在 exist, not exist, or unknown. // !Files.exists(...) is not equivalent to Files.notExists(...) and the // notExists() method is not a complement of the exists() method // 如果应用没有权限访问这个文件,则两者都返回false boolean path_exists = Files.exists(path, new LinkOption[] { LinkOption.NOFOLLOW_LINKS }); boolean path_notexists = Files.notExists(path, new LinkOption[] { LinkOption.NOFOLLOW_LINKS }); System.out.println(path_exists); System.out.println(path_notexists); // 检测文件访问权限 boolean is_readable = Files.isReadable(path); boolean is_writable = Files.isWritable(path); boolean is_executable = Files.isExecutable(path); boolean is_regular = Files.isRegularFile(path, LinkOption.NOFOLLOW_LINKS); if ((is_readable) && (is_writable) && (is_executable) && (is_regular)) { System.out.println("The checked file is accessible!"); } else { System.out.println("The checked file is not accessible!"); } // 检测文件是否指定同一个文件 Path path_1 = FileSystems.getDefault().getPath( System.getProperty("user.home"), "www", "pyweb.settings"); Path path_2 = FileSystems.getDefault().getPath( System.getProperty("user.home"), "www", "django.wsgi"); Path path_3 = FileSystems.getDefault().getPath( System.getProperty("user.home"), "software/../www", "pyweb.settings"); try { boolean is_same_file_12 = Files.isSameFile(path_1, path_2); boolean is_same_file_13 = Files.isSameFile(path_1, path_3); boolean is_same_file_23 = Files.isSameFile(path_2, path_3); System.out.println("is same file 1&2 ? " + is_same_file_12); System.out.println("is same file 1&3 ? " + is_same_file_13); System.out.println("is same file 2&3 ? " + is_same_file_23); } catch (IOException e) { System.err.println(e); } // 检测文件可见行 try { boolean is_hidden = Files.isHidden(path); System.out.println("Is hidden ? " + is_hidden); } catch (IOException e) { System.err.println(e); } // 获取文件系统根目录 Iterable<Path> dirs = FileSystems.getDefault().getRootDirectories(); for (Path name : dirs) { System.out.println(name); } // jdk6的API // File[] roots = File.listRoots(); // for (File root : roots) { // System.out.println(root); // } // 创建新目录 Path newdir = FileSystems.getDefault().getPath("/tmp/aaa"); // try { // Files.createDirectory(newdir); // } catch (IOException e) { // System.err.println(e); // } Set<PosixFilePermission> perms = PosixFilePermissions .fromString("rwxr-x---"); FileAttribute<Set<PosixFilePermission>> attr = PosixFilePermissions .asFileAttribute(perms); try { Files.createDirectory(newdir, attr); } catch (IOException e) { System.err.println(e); } // 创建多级目录,创建bbb目录,在bbb目录下再创建ccc目录等等 Path newdir2 = FileSystems.getDefault().getPath("/tmp/aaa", "/bbb/ccc/ddd"); try { Files.createDirectories(newdir2); } catch (IOException e) { System.err.println(e); } // 列举目录信息 Path newdir3 = FileSystems.getDefault().getPath("/tmp"); try (DirectoryStream<Path> ds = Files.newDirectoryStream(newdir3)) { for (Path file : ds) { System.out.println(file.getFileName()); } } catch (IOException e) { System.err.println(e); } // 通过正则表达式过滤 System.out.println("\nGlob pattern applied:"); try (DirectoryStream<Path> ds = Files.newDirectoryStream(newdir3, "*.{png,jpg,bmp,ini}")) { for (Path file : ds) { System.out.println(file.getFileName()); } } catch (IOException e) { System.err.println(e); } // 创建新文件 Path newfile = FileSystems.getDefault().getPath( "/tmp/SonyEricssonOpen.txt"); Set<PosixFilePermission> perms1 = PosixFilePermissions .fromString("rw-------"); FileAttribute<Set<PosixFilePermission>> attr2 = PosixFilePermissions .asFileAttribute(perms1); try { Files.createFile(newfile, attr2); } catch (IOException e) { System.err.println(e); } // 写小文件 try { byte[] rf_wiki_byte = "test".getBytes("UTF-8"); Files.write(newfile, rf_wiki_byte); } catch (IOException e) { System.err.println(e); } // 读小文件 try { byte[] ballArray = Files.readAllBytes(newfile); System.out.println(ballArray.toString()); } catch (IOException e) { System.out.println(e); } Charset charset = Charset.forName("ISO-8859-1"); try { List<String> lines = Files.readAllLines(newfile, charset); for (String line : lines) { System.out.println(line); } } catch (IOException e) { System.out.println(e); } // 读写文件缓存流操作 String text = "\nVamos Rafa!"; try (BufferedWriter writer = Files.newBufferedWriter(newfile, charset, StandardOpenOption.APPEND)) { writer.write(text); } catch (IOException e) { System.err.println(e); } try (BufferedReader reader = Files.newBufferedReader(newfile, charset)) { String line = null; while ((line = reader.readLine()) != null) { System.out.println(line); } } catch (IOException e) { System.err.println(e); } // 不用缓存的输入输出流 String racquet = "Racquet: Babolat AeroPro Drive GT"; byte data[] = racquet.getBytes(); try (OutputStream outputStream = Files.newOutputStream(newfile)) { outputStream.write(data); } catch (IOException e) { System.err.println(e); } String string = "\nString: Babolat RPM Blast 16"; try (OutputStream outputStream = Files.newOutputStream(newfile, StandardOpenOption.APPEND); BufferedWriter writer = new BufferedWriter( new OutputStreamWriter(outputStream))) { writer.write(string); } catch (IOException e) { System.err.println(e); } int n; try (InputStream in = Files.newInputStream(newfile)) { while ((n = in.read()) != -1) { System.out.print((char) n); } } catch (IOException e) { System.err.println(e); } // 临时目录操作 String tmp_dir_prefix = "nio_"; try { // passing null prefix Path tmp_1 = Files.createTempDirectory(null); System.out.println("TMP: " + tmp_1.toString()); // set a prefix Path tmp_2 = Files.createTempDirectory(tmp_dir_prefix); System.out.println("TMP: " + tmp_2.toString()); // 删除临时目录 Path basedir = FileSystems.getDefault().getPath("/tmp/aaa"); Path tmp_dir = Files.createTempDirectory(basedir, tmp_dir_prefix); File asFile = tmp_dir.toFile(); asFile.deleteOnExit(); } catch (IOException e) { System.err.println(e); } String tmp_file_prefix = "rafa_"; String tmp_file_sufix = ".txt"; try { // passing null prefix/suffix Path tmp_1 = Files.createTempFile(null, null); System.out.println("TMP: " + tmp_1.toString()); // set a prefix and a suffix Path tmp_2 = Files.createTempFile(tmp_file_prefix, tmp_file_sufix); System.out.println("TMP: " + tmp_2.toString()); File asFile = tmp_2.toFile(); asFile.deleteOnExit(); } catch (IOException e) { System.err.println(e); } // 删除文件 try { boolean success = Files.deleteIfExists(newdir2); System.out.println("Delete status: " + success); } catch (IOException | SecurityException e) { System.err.println(e); } // 拷贝文件 Path copy_from = Paths.get("/tmp", "draw_template.txt"); Path copy_to = Paths .get("/tmp/bbb", copy_from.getFileName().toString()); try { Files.copy(copy_from, copy_to); } catch (IOException e) { System.err.println(e); } try (InputStream is = new FileInputStream(copy_from.toFile())) { Files.copy(is, copy_to); } catch (IOException e) { System.err.println(e); } //移动文件 Path movefrom = FileSystems.getDefault().getPath( "C:/rafaelnadal/rafa_2.jpg"); Path moveto = FileSystems.getDefault().getPath( "C:/rafaelnadal/photos/rafa_2.jpg"); try { Files.move(movefrom, moveto, StandardCopyOption.REPLACE_EXISTING); } catch (IOException e) { System.err.println(e); } } }
输出:
true false The checked file is not accessible! is same file 1&2 ? false is same file 1&3 ? true is same file 2&3 ? false Is hidden ? false / java.nio.file.FileAlreadyExistsException: /tmp/aaa .ICE-unix gpg-LOz0cL .org.chromium.Chromium.YKWsQJ hsperfdata_weijianzhongwj kde-weijianzhongwj pulse-qKcxuRTsGUob scim-im-agent-0.3.0.socket-1000@localhost:0.0 scim-helper-manager-socket-weijianzhongwj ksocket-weijianzhongwj virtuoso_Lh2135.ini scim-socket-frontend-weijianzhongwj scim-panel-socket:0-weijianzhongwj .X0-lock pulse-j0jluTvI3Pe6 sni-qt_kaccessibleapp_2026-mEz8Dy .X11-unix akonadi-weijianzhongwj.mjmToI ssh-mfuayNh73d7Q virt_1111 aaa pulse-PKdhtXMmr18n fcitx-socket-:0 Glob pattern applied: [B@cd32e5 test test Vamos Rafa! Racquet: Babolat AeroPro Drive GT String: Babolat RPM Blast 16TMP: /tmp/3892364837850046417 TMP: /tmp/nio_5078970948266789689 TMP: /tmp/7342813580436243519.tmp TMP: /tmp/rafa_47993266069276248.txt Delete status: true java.nio.file.NoSuchFileException: /tmp/draw_template.txt java.io.FileNotFoundException: /tmp/draw_template.txt (没有那个文件或目录) java.nio.file.NoSuchFileException: C:/rafaelnadal/rafa_2.jpg