如何在Java7中递归读取文件?
我知道用Java处理文件目录的ApacheCommons IO库。但是,本文讨论了Java7中的本机支持 是否有人有使用Java 7递归列出/读取目录中文件的经验?使用 (我没有使用它的经验,但我只是在文档中找到了它,它看起来使用起来很简单。)。基本上,您实现了一个访问者,它可以在进入、退出目录和遇到文件时调用。支持确定文件是否为符号链接,以及跟随符号链接的选项(如果愿意)。快速阅读Java如何在Java7中递归读取文件?,java,file-io,java-7,Java,File Io,Java 7,我知道用Java处理文件目录的ApacheCommons IO库。但是,本文讨论了Java7中的本机支持 是否有人有使用Java 7递归列出/读取目录中文件的经验?使用 (我没有使用它的经验,但我只是在文档中找到了它,它看起来使用起来很简单。)。基本上,您实现了一个访问者,它可以在进入、退出目录和遇到文件时调用。支持确定文件是否为符号链接,以及跟随符号链接的选项(如果愿意)。快速阅读JavaPaths是什么可能很有用 在我的系统(Linux/Fedora)上,它运行良好;然而,我只是在测试它的功
Path
s是什么可能很有用
在我的系统(Linux/Fedora)上,它运行良好;然而,我只是在测试它的功能,并玩弄它。我没有强调测试它的性能或任何其他有意义的测量(除了“它工作”)。@EdwinBuck…是的。我不确定您的评论试图解决什么问题。
Files.walkFileTree
返回一个路径
,而路径本身不做任何事情。FileVisitor
可以“漫游”路径并“发现”路径中的文件,可能会跳过不感兴趣的文件或子目录。您的解决方案是所需解决方案的一部分(因为它提供了路径
部分),但是如果没有访问者,您将永远看不到文件
@EdwinBuck文件。walkFileTree
实际上返回“起始文件”,即您传递给它的路径。此外,如果没有FileVisitor
,它是不可用的,因此如果不实现执行实际工作的FileVisitor
,就不可能“使用Files.walkFileTree
”。我链接到的文档中都非常清楚地说明了这一点。我认为这让我的答案足够了。仅链接的答案是重定向,devinb比我更能描述这些问题。你的答案足以找到答案,但实际上没有什么比devinb(修改后的)引用更好的了“我会带你去一个API信息亭,他们会为你提供答案和更多!“@EdwinBuck当一个人问“附近有人钓鱼吗?”时,我宁愿让他去钓鱼学校,也不愿给他一条鱼和一条海豚。”
import static java.nio.file.FileVisitResult.*;
public static class PrintFiles
extends SimpleFileVisitor<Path> {
// Print information about
// each type of file.
@Override
public FileVisitResult visitFile(Path file,
BasicFileAttributes attr) {
if (attr.isSymbolicLink()) {
System.out.format("Symbolic link: %s ", file);
} else if (attr.isRegularFile()) {
System.out.format("Regular file: %s ", file);
} else {
System.out.format("Other: %s ", file);
}
System.out.println("(" + attr.size() + "bytes)");
return CONTINUE;
}
// Print each directory visited.
@Override
public FileVisitResult postVisitDirectory(Path dir,
IOException exc) {
System.out.format("Directory: %s%n", dir);
return CONTINUE;
}
// If there is some error accessing
// the file, let the user know.
// If you don't override this method
// and an error occurs, an IOException
// is thrown.
@Override
public FileVisitResult visitFileFailed(Path file,
IOException exc) {
System.err.println(exc);
return CONTINUE;
}
}
/*
* Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle or the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.io.*;
import java.nio.file.*;
import java.nio.file.attribute.*;
import static java.nio.file.FileVisitResult.*;
import static java.nio.file.FileVisitOption.*;
import java.util.*;
/**
* Sample code that finds files that
* match the specified glob pattern.
* For more information on what
* constitutes a glob pattern, see
* http://docs.oracle.com/javase/javatutorials/tutorial/essential/io/fileOps.html#glob
*
* The file or directories that match
* the pattern are printed to
* standard out. The number of
* matches is also printed.
*
* When executing this application,
* you must put the glob pattern
* in quotes, so the shell will not
* expand any wild cards:
* java Find . -name "*.java"
*/
public class Find {
/**
* A {@code FileVisitor} that finds
* all files that match the
* specified pattern.
*/
public static class Finder
extends SimpleFileVisitor<Path> {
private final PathMatcher matcher;
private int numMatches = 0;
Finder(String pattern) {
matcher =
FileSystems.getDefault()
.getPathMatcher("glob:" + pattern);
}
// Compares the glob pattern against
// the file or directory name.
void find(Path file) {
Path name = file.getFileName();
if (name != null && matcher.matches(name)) {
numMatches++;
System.out.println(file);
}
}
// Prints the total number of
// matches to standard out.
void done() {
System.out.println("Matched: "
+ numMatches);
}
// Invoke the pattern matching
// method on each file.
@Override
public FileVisitResult
visitFile(Path file,
BasicFileAttributes attrs) {
find(file);
return CONTINUE;
}
// Invoke the pattern matching
// method on each directory.
@Override
public FileVisitResult
preVisitDirectory(Path dir,
BasicFileAttributes attrs) {
find(dir);
return CONTINUE;
}
@Override
public FileVisitResult
visitFileFailed(Path file,
IOException exc) {
System.err.println(exc);
return CONTINUE;
}
}
static void usage() {
System.err.println("java Find <path>" +
" -name \"<glob_pattern>\"");
System.exit(-1);
}
public static void main(String[] args)
throws IOException {
if (args.length < 3
|| !args[1].equals("-name"))
usage();
Path startingDir = Paths.get(args[0]);
String pattern = args[2];
Finder finder = new Finder(pattern);
Files.walkFileTree(startingDir, finder);
finder.done();
}
}