java 7 NIO2（2） Metadata File Attributes
java 7 NIO2新特性支持操作文件的属性，使用NIO2的API操作你自己的文件元数据。
NIO2的属性操作相关类包
我们看下示例代码：
package com.mime;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.file.FileStore;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.AclEntry;
import java.nio.file.attribute.AclEntryPermission;
import java.nio.file.attribute.AclEntryType;
import java.nio.file.attribute.AclFileAttributeView;
import java.nio.file.attribute.BasicFileAttributeView;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.DosFileAttributes;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.FileOwnerAttributeView;
import java.nio.file.attribute.FileStoreAttributeView;
import java.nio.file.attribute.FileTime;
import java.nio.file.attribute.GroupPrincipal;
import java.nio.file.attribute.PosixFileAttributeView;
import java.nio.file.attribute.PosixFileAttributes;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.nio.file.attribute.UserDefinedFileAttributeView;
import java.nio.file.attribute.UserPrincipal;
import java.util.List;
import java.util.Set;
import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
public class NIO2FileAttribute {
public static void main(String[] args) {
FileSystem fs = FileSystems.getDefault();
Set<String> views = fs.supportedFileAttributeViews();
for (String view : views) {
System.out.println(view);
}
/*
* BasicFileAttributeView: This is a view of basic attributes that must
* be supported by all file system implementations. The attribute view
* name is basic. • DosFileAttributeView: This view provides the
* standard four supported attributes on file systems that support the
* DOS attributes. The attribute view name is dos. •
* PosixFileAttributeView: This view extends the basic attribute view
* with attributes supported on file systems that support the POSIX
* (Portable Operating System Interface for Unix) family of standards,
* such as Unix. The attribute view name is posix. •
* FileOwnerAttributeView: This view is supported by any file system
* implementation that supports the concept of a file owner. The
* attribute view name is owner. • AclFileAttributeView: This view
* supports reading or updating a file’s ACL. The NFSv4 ACL model is
* supported. The attribute view name is acl.
* UserDefinedFileAttributeView: This view enables support of metadata
* that is user defined.
*/
for (FileStore store : fs.getFileStores()) {
boolean supported = store
.supportsFileAttributeView(BasicFileAttributeView.class);
System.out.println(store.name() + " ---" + supported);
}
Path path = null;
try {
path = Paths.get(System.getProperty("user.home"), "www",
"pyweb.settings");
FileStore store = Files.getFileStore(path);
boolean supported = store.supportsFileAttributeView("basic");
System.out.println(store.name() + " ---" + supported);
} catch (IOException e) {
System.err.println(e);
}
BasicFileAttributes attr = null;
try {
attr = Files.readAttributes(path, BasicFileAttributes.class);
} catch (IOException e) {
System.err.println(e);
}
System.out.println("File size: " + attr.size());
System.out.println("File creation time: " + attr.creationTime());
System.out.println("File was last accessed at: "
+ attr.lastAccessTime());
System.out.println("File was last modified at: "
+ attr.lastModifiedTime());
System.out.println("Is directory? " + attr.isDirectory());
System.out.println("Is regular file? " + attr.isRegularFile());
System.out.println("Is symbolic link? " + attr.isSymbolicLink());
System.out.println("Is other? " + attr.isOther());
// 只获取某个属性 [view-name:]attribute-name
/**
* Basic attribute names are listed here: lastModifiedTime
* lastAccessTime creationTime size isRegularFile isDirectory
* isSymbolicLink isOther fileKey
**/
try {
long size = (Long) Files.getAttribute(path, "basic:size",
java.nio.file.LinkOption.NOFOLLOW_LINKS);
System.out.println("Size: " + size);
} catch (IOException e) {
System.err.println(e);
}
// Update a Basic Attribute
long time = System.currentTimeMillis();
FileTime fileTime = FileTime.fromMillis(time);
try {
Files.getFileAttributeView(path, BasicFileAttributeView.class)
.setTimes(fileTime, fileTime, fileTime);
} catch (IOException e) {
System.err.println(e);
}
try {
Files.setLastModifiedTime(path, fileTime);
} catch (IOException e) {
System.err.println(e);
}
try {
Files.setAttribute(path, "basic:lastModifiedTime", fileTime,
NOFOLLOW_LINKS);
Files.setAttribute(path, "basic:creationTime", fileTime,
NOFOLLOW_LINKS);
Files.setAttribute(path, "basic:lastAccessTime", fileTime,
NOFOLLOW_LINKS);
} catch (IOException e) {
System.err.println(e);
}
// DosFileAttributeView DOS attributes can be acquired with the
// following names:hidden readonly system archive
DosFileAttributes docattr = null;
try {
docattr = Files.readAttributes(path, DosFileAttributes.class);
} catch (IOException e) {
System.err.println(e);
}
System.out.println("Is read only ? " + docattr.isReadOnly());
System.out.println("Is Hidden ? " + docattr.isHidden());
System.out.println("Is archive ? " + docattr.isArchive());
System.out.println("Is system ? " + docattr.isSystem());
// FileOwnerAttributeView
// Set a File Owner Using Files.setOwner() 三种设置文件所有者的方法
UserPrincipal owner = null;
try {
owner = path.getFileSystem().getUserPrincipalLookupService()
.lookupPrincipalByName("apress");
Files.setOwner(path, owner);
} catch (IOException e) {
System.err.println(e);
}
FileOwnerAttributeView foav = Files.getFileAttributeView(path,
FileOwnerAttributeView.class);
try {
owner = path.getFileSystem().getUserPrincipalLookupService()
.lookupPrincipalByName("apress");
foav.setOwner(owner);
} catch (IOException e) {
System.err.println(e);
}
try {
owner = path.getFileSystem().getUserPrincipalLookupService()
.lookupPrincipalByName("apress");
Files.setAttribute(path, "owner:owner", owner, NOFOLLOW_LINKS);
} catch (IOException e) {
System.err.println(e);
}
// 获取文件所有者
try {
String ownerName = foav.getOwner().getName();
System.out.println(ownerName);
} catch (IOException e) {
System.err.println(e);
}
try {
UserPrincipal owner1 = (UserPrincipal) Files.getAttribute(path,
"owner:owner", NOFOLLOW_LINKS);
System.out.println(owner1.getName());
} catch (IOException e) {
System.err.println(e);
}
// POSIX View file owner, group owner, and nine related access
// permissions (read, write, members of the same group, etc.). •group
// permissions
PosixFileAttributes positattr = null;
try {
positattr = Files.readAttributes(path, PosixFileAttributes.class);
} catch (IOException e) {
System.err.println(e);
}
System.out.println("File owner: " + positattr.owner().getName());
System.out.println("File group: " + positattr.group().getName());
System.out.println("File permissions: "
+ positattr.permissions().toString());
// 设置文件访问权限
FileAttribute<Set<PosixFilePermission>> posixattrs = PosixFilePermissions
.asFileAttribute(positattr.permissions());
try {
Files.createFile(path, posixattrs);
} catch (IOException e) {
System.err.println(e);
}
Set<PosixFilePermission> permissions = PosixFilePermissions
.fromString("rw-r--r--");
try {
Files.setPosixFilePermissions(path, permissions);
} catch (IOException e) {
System.err.println(e);
}
// 设置分组用户
try {
GroupPrincipal group = path.getFileSystem()
.getUserPrincipalLookupService()
.lookupPrincipalByGroupName("apressteam");
Files.getFileAttributeView(path, PosixFileAttributeView.class)
.setGroup(group);
} catch (IOException e) {
System.err.println(e);
}
// 查询组用户
try {
GroupPrincipal group = (GroupPrincipal) Files.getAttribute(path,
"posix:group", NOFOLLOW_LINKS);
System.out.println(group.getName());
} catch (IOException e) {
System.err.println(e);
}
// ACL View access control list acl owner
// 查询acl属性
List<AclEntry> acllist = null;
AclFileAttributeView aclview = Files.getFileAttributeView(path,
AclFileAttributeView.class);
try {
acllist = aclview.getAcl();
for (AclEntry aclentry : acllist) {
System.out
.println("++++++++++++++++++++++++++++++++++++++++++++++++++++");
System.out.println("Principal: "
+ aclentry.principal().getName());
System.out.println("Type: " + aclentry.type().toString());
System.out.println("Permissions: "
+ aclentry.permissions().toString());
System.out.println("Flags: " + aclentry.flags().toString());
}
} catch (Exception e) {
System.err.println(e);
}
// 设置ACL属性
try {
// Lookup for the principal
UserPrincipal user = path.getFileSystem()
.getUserPrincipalLookupService()
.lookupPrincipalByName("apress");
// Get the ACL view
AclFileAttributeView view = Files.getFileAttributeView(path,
AclFileAttributeView.class);
// Create a new entry
AclEntry entry = AclEntry
.newBuilder()
.setType(AclEntryType.ALLOW)
.setPrincipal(user)
.setPermissions(AclEntryPermission.READ_DATA,
AclEntryPermission.APPEND_DATA).build();
// read ACL
List<AclEntry> acl = view.getAcl();
// Insert the new entry
acl.add(0, entry);
// rewrite ACL
view.setAcl(acl);
// or, like this
// Files.setAttribute(path, "acl:acl", acl, NOFOLLOW_LINKS);
} catch (IOException e) {
System.err.println(e);
}
// File Store Attributes
// 获取所有的fifilestore的属性信息
FileSystem fs1 = FileSystems.getDefault();
for (FileStore store : fs1.getFileStores()) {
try {
long total_space = store.getTotalSpace() / 1024;
long used_space = (store.getTotalSpace() - store
.getUnallocatedSpace()) / 1024;
long available_space = store.getUsableSpace() / 1024;
boolean is_read_only = store.isReadOnly();
System.out.println("--- " + store.name() + " --- "
+ store.type());
System.out.println("Total space: " + total_space);
System.out.println("Used space: " + used_space);
System.out.println("Available space: " + available_space);
System.out.println("Is read only? " + is_read_only);
} catch (IOException e) {
System.err.println(e);
}
}
// 获取某个文件的fifilestore，再查询filestroe的属性信息
try {
FileStore store = Files.getFileStore(path);
FileStoreAttributeView fsav = store
.getFileStoreAttributeView(FileStoreAttributeView.class);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// User-Defined File Attributes View 用户自定义文件属性
// 检测文件系统是否支持自定义属性
try {
FileStore store = Files.getFileStore(path);
if (!store
.supportsFileAttributeView(UserDefinedFileAttributeView.class)) {
System.out
.println("The user defined attributes are not supported on: "
+ store);
} else {
System.out
.println("The user defined attributes are supported on: "
+ store);
}
} catch (IOException e) {
System.err.println(e);
}
// 设置文件属性
UserDefinedFileAttributeView udfav = Files.getFileAttributeView(path,
UserDefinedFileAttributeView.class);
try {
int written = udfav.write(
"file.description",
Charset.defaultCharset().encode(
"This file contains private information!"));
System.out.println("write user defined file attribute return :"
+ written);
} catch (IOException e) {
System.err.println(e);
}
// 获取文件的所有自定义属性
try {
for (String name : udfav.list()) {
System.out.println(udfav.size(name) + "" + name);
}
} catch (IOException e) {
System.err.println(e);
}
try {
int size = udfav.size("file.description");
ByteBuffer bb = ByteBuffer.allocateDirect(size);
udfav.read("file.description", bb);
bb.flip();
System.out.println(Charset.defaultCharset().decode(bb).toString());
} catch (IOException e) {
System.err.println(e);
}
//删除自定义文件属性
try {
udfav.delete("file.description");
} catch (IOException e) {
System.err.println(e);
}
}
}
在我的文件系统的输出
basic owner user unix dos posix /dev/loop0 ---true proc ---true sysfs ---true none ---true none ---true none ---true udev ---true devpts ---true tmpfs ---true none ---true none ---true none ---true /dev/sda6 ---true binfmt_misc ---true gvfsd-fuse ---true /dev/sda5 ---true rootfs ---true File size: 265 File creation time: 2012-12-29T12:53:35Z File was last accessed at: 2012-12-29T12:53:35Z File was last modified at: 2012-12-29T12:53:35Z Is directory? false Is regular file? true Is symbolic link? false Is other? false Size: 265 Is read only ? false Is Hidden ? false Is archive ? false Is system ? false java.nio.file.attribute.UserPrincipalNotFoundException weijianzhongwj weijianzhongwj File owner: weijianzhongwj java.nio.file.attribute.UserPrincipalNotFoundException java.nio.file.attribute.UserPrincipalNotFoundException File group: weijianzhongwj File permissions: [OWNER_WRITE, OTHERS_READ, GROUP_READ, OWNER_READ] java.nio.file.FileAlreadyExistsException: /home/weijianzhongwj/www/pyweb.settings java.nio.file.attribute.UserPrincipalNotFoundException weijianzhongwj java.lang.NullPointerException java.nio.file.attribute.UserPrincipalNotFoundException --- /dev/loop0 --- ext4 Total space: 29979608 Used space: 17216488 Available space: 11240228 Is read only? false --- proc --- proc Total space: 0 Used space: 0 Available space: 0 Is read only? false --- sysfs --- sysfs Total space: 0 Used space: 0 Available space: 0 Is read only? false --- none --- fusectl Total space: 0 Used space: 0 Available space: 0 Is read only? false --- none --- debugfs Total space: 0 Used space: 0 Available space: 0 Is read only? false --- none --- securityfs Total space: 0 Used space: 0 Available space: 0 Is read only? false --- udev --- devtmpfs Total space: 4063888 Used space: 4 Available space: 4063884 Is read only? false --- devpts --- devpts Total space: 0 Used space: 0 Available space: 0 Is read only? false --- tmpfs --- tmpfs Total space: 1628652 Used space: 892 Available space: 1627760 Is read only? false --- none --- tmpfs Total space: 5120 Used space: 0 Available space: 5120 Is read only? false --- none --- tmpfs Total space: 4071628 Used space: 380 Available space: 4071248 Is read only? false --- none --- tmpfs Total space: 102400 Used space: 8 Available space: 102392 Is read only? false --- /dev/sda6 --- fuseblk Total space: 164089852 Used space: 101256692 Available space: 62833160 Is read only? false --- binfmt_misc --- binfmt_misc Total space: 0 Used space: 0 Available space: 0 Is read only? false --- gvfsd-fuse --- fuse.gvfsd-fuse Total space: 0 Used space: 0 Available space: 0 Is read only? false --- /dev/sda5 --- fuseblk Total space: 102399704 Used space: 81181588 Available space: 21218116 Is read only? false The user defined attributes are supported on: / (rootfs) write user defined file attribute return :39 39file.description This file contains private information!
