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