如果搜索文件夹说C:\example我需要做什么
然后，我需要浏览每个文件并检查它是否与几个起始字符匹配，以便文件启动
temp****.txt
tempONE.txt
tempTWO.txt
所以如果文件以temp开头并且有一个扩展名.txt我想把那个文件名放到File file = new File("C:/example/temp***.txt);中，这样我就可以在文件中读取，然后循环需要移动到下一个文件来查看是否有如上所述。
你想要的是File.listFiles(FileNameFilter filter)。
这将为您提供所需目录中与某个筛选器匹配的文件列表。
代码看起来类似于：
// your directory
File f = new File("C:\\example");
File[] matchingFiles = f.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.startsWith("temp") && name.endsWith("txt");
}
});
要详细说明this response，Apache IO Utils可能会为您节省一些时间。请考虑以下示例，该示例将递归搜索给定名称的文件：
File file = FileUtils.listFiles(new File("the/desired/root/path"),
new NameFileFilter("filename.ext"),
FileFilterUtils.trueFileFilter()
).iterator().next();
看到：
您提供文件的名称，要搜索的目录的路径，然后让它完成工作。
private static String getPath(String drl, String whereIAm) {
File dir = new File(whereIAm); //StaticMethods.currentPath() + "\\src\\main\\resources\\" +
for(File e : dir.listFiles()) {
if(e.isFile() && e.getName().equals(drl)) {return e.getPath();}
if(e.isDirectory()) {
String idiot = getPath(drl, e.getPath());
if(idiot != null) {return idiot;}
}
}
return null;
}
用法：
//Searches file names (start with "temp" and extension ".txt")
//in the current directory and subdirectories recursively
Path initialPath = Paths.get(".");
PathUtils.searchRegularFilesStartsWith(initialPath, "temp", ".txt").
stream().forEach(System.out::println);
资源：
public final class PathUtils {
private static final String startsWithRegex = "(?<![_ \\-\\p{L}\\d\\[\\]\\(\\) ])";
private static final String endsWithRegex = "(?=[\\.\\n])";
private static final String containsRegex = "%s(?:[^\\/\\\\]*(?=((?i)%s(?!.))))";
public static List<Path> searchRegularFilesStartsWith(final Path initialPath,
final String fileName, final String fileExt) throws IOException {
return searchRegularFiles(initialPath, startsWithRegex + fileName, fileExt);
}
public static List<Path> searchRegularFilesEndsWith(final Path initialPath,
final String fileName, final String fileExt) throws IOException {
return searchRegularFiles(initialPath, fileName + endsWithRegex, fileExt);
}
public static List<Path> searchRegularFilesAll(final Path initialPath) throws IOException {
return searchRegularFiles(initialPath, "", "");
}
public static List<Path> searchRegularFiles(final Path initialPath,
final String fileName, final String fileExt)
throws IOException {
final String regex = String.format(containsRegex, fileName, fileExt);
final Pattern pattern = Pattern.compile(regex);
try (Stream<Path> walk = Files.walk(initialPath.toRealPath())) {
return walk.filter(path -> Files.isRegularFile(path) &&
pattern.matcher(path.toString()).find())
.collect(Collectors.toList());
}
}
private PathUtils() {
}
}
Try开始使用\ txt \ temp \ tempZERO0.txt的正则表达式：
(?<![_ \-\p{L}\d\[\]\(\) ])temp(?:[^\/\\]*(?=((?i)\.txt(?!.))))
Try ends与正确的\ txt \ temp \ ZERO0temp.txt正则表达式：
temp(?=[\\.\\n])(?:[^\/\\]*(?=((?i)\.txt(?!.))))
Try包含\ txt \ temp \ tempZERO0tempZERO0temp.txt的正则表达式：
temp(?:[^\/\\]*(?=((?i)\.txt(?!.))))
您可以使用FilenameFilter，如下所示：
File dir = new File(directory);
File[] matches = dir.listFiles(new FilenameFilter()
{
public boolean accept(File dir, String name)
{
return name.startsWith("temp") && name.endsWith(".txt");
}
});
我知道，这是一个老问题。但仅仅为了完整性，lambda版本。
File dir = new File(directory);
File[] files = dir.listFiles((dir1, name) -> name.startsWith("temp") && name.endsWith(".txt"));
看看java.io.File.list()和FilenameFilter。
列出您给定目录中的Json文件。
import java.io.File;
import java.io.FilenameFilter;
public class ListOutFilesInDir {
public static void main(String[] args) throws Exception {
File[] fileList = getFileList("directory path");
for(File file : fileList) {
System.out.println(file.getName());
}
}
private static File[] getFileList(String dirPath) {
File dir = new File(dirPath);
File[] fileList = dir.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.endsWith(".json");
}
});
return fileList;
}
}
正如@Clarke所说，你可以使用java.io.FilenameFilter按特定条件过滤文件。
作为补充，我想展示如何使用java.io.FilenameFilter搜索当前目录及其子目录中的文件。
常用方法getTargetFiles和printFiles用于搜索文件并打印它们。
public class SearchFiles {
//It's used in dfs
private Map<String, Boolean> map = new HashMap<String, Boolean>();
private File root;
public SearchFiles(File root){
this.root = root;
}
/**
* List eligible files on current path
* @param directory
* The directory to be searched
* @return
* Eligible files
*/
private String[] getTargetFiles(File directory){
if(directory == null){
return null;
}
String[] files = directory.list(new FilenameFilter(){
@Override
public boolean accept(File dir, String name) {
// TODO Auto-generated method stub
return name.startsWith("Temp") && name.endsWith(".txt");
}
});
return files;
}
/**
* Print all eligible files
*/
private void printFiles(String[] targets){
for(String target: targets){
System.out.println(target);
}
}
}
我将演示如何使用递归，bfs和dfs来完成工作。
递归：
/**
* How many files in the parent directory and its subdirectory <br>
* depends on how many files in each subdirectory and their subdirectory
*/
private void recursive(File path){
printFiles(getTargetFiles(path));
for(File file: path.listFiles()){
if(file.isDirectory()){
recursive(file);
}
}
if(path.isDirectory()){
printFiles(getTargetFiles(path));
}
}
public static void main(String args[]){
SearchFiles searcher = new SearchFiles(new File("C:\\example"));
searcher.recursive(searcher.root);
}
广度优先搜索：
/**
* Search the node's neighbors firstly before moving to the next level neighbors
*/
private void bfs(){
if(root == null){
return;
}
Queue<File> queue = new LinkedList<File>();
queue.add(root);
while(!queue.isEmpty()){
File node = queue.remove();
printFiles(getTargetFiles(node));
File[] childs = node.listFiles(new FileFilter(){
@Override
public boolean accept(File pathname) {
// TODO Auto-generated method stub
if(pathname.isDirectory())
return true;
return false;
}
});
if(childs != null){
for(File child: childs){
queue.add(child);
}
}
}
}
public static void main(String args[]){
SearchFiles searcher = new SearchFiles(new File("C:\\example"));
searcher.bfs();
}
深度优先搜索：
/ ** *在回溯之前尽可能沿每个分支搜索* / private void dfs（）{
if(root == null){
return;
}
Stack<File> stack = new Stack<File>();
stack.push(root);
map.put(root.getAbsolutePath(), true);
while(!stack.isEmpty()){
File node = stack.peek();
File child = getUnvisitedChild(node);
if(child != null){
stack.push(child);
printFiles(getTargetFiles(child));
map.put(child.getAbsolutePath(), true);
}else{
stack.pop();
}
}
}
/**
* Get unvisited node of the node
*
*/
private File getUnvisitedChild(File node){
File[] childs = node.listFiles(new FileFilter(){
@Override
public boolean accept(File pathname) {
// TODO Auto-generated method stub
if(pathname.isDirectory())
return true;
return false;
}
});
if(childs == null){
return null;
}
for(File child: childs){
if(map.containsKey(child.getAbsolutePath()) == false){
map.put(child.getAbsolutePath(), false);
}
if(map.get(child.getAbsolutePath()) == false){
return child;
}
}
return null;
}
public static void main(String args[]){
SearchFiles searcher = new SearchFiles(new File("C:\\example"));
searcher.dfs();
}
从Java 1.8开始，您可以使用Files.list来获取流：
Path findFile(Path targetDir, String fileName) throws IOException {
return Files.list(targetDir).filter( (p) -> {
if (Files.isRegularFile(p)) {
return p.getFileName().toString().equals(fileName);
} else {
return false;
}
}).findFirst().orElse(null);
}