使用Java查找文件夹中的文件
如果搜索文件夹时说使用Java查找文件夹中的文件,java,file,search,for-loop,directory,Java,File,Search,For Loop,Directory,如果搜索文件夹时说C:\example 然后,我需要检查每个文件,看看它是否匹配一些开始字符,以便文件是否开始 temp****.txt tempONE.txt tempTWO.txt 因此,如果文件以temp开头,扩展名为.txt,我想将该文件名放入file file=new file(“C:/example/temp***.txt”);中,这样我就可以读入该文件,然后循环需要移动到下一个文件,以检查它是否符合上述要求。您想要的是 这将为您提供目录中与特定筛选器匹配的文件列表 代码将类似于:
C:\example
然后,我需要检查每个文件,看看它是否匹配一些开始字符,以便文件是否开始
temp****.txt
tempONE.txt
tempTWO.txt
因此,如果文件以temp开头,扩展名为.txt,我想将该文件名放入file file=new file(“C:/example/temp***.txt”);
中,这样我就可以读入该文件,然后循环需要移动到下一个文件,以检查它是否符合上述要求。您想要的是
这将为您提供目录中与特定筛选器匹配的文件列表
代码将类似于:
// 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");
}
});
查看
java.io.File.list()
和FilenameFilter
您可以使用,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");
}
});
以Apache Commons IO为例,它有一个名为的类,该类有一个在您的情况下可能非常有用的方法。Appache Commons IO
FilenameUtils.wildcardMatch
请参阅Apache javadoc。它将通配符与文件名匹配。因此,您可以使用此方法进行比较。用于列出给定目录中的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,您可以使用
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
在当前目录及其子目录中搜索文件
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;
}
}
常用的getTargetFile和printFiles方法用于搜索和打印文件
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);
}
}
}
公共类搜索文件{
//它在dfs中使用
私有映射映射=新的HashMap();
私有文件根;
公共搜索文件(文件根目录){
this.root=根;
}
/**
*列出当前路径上符合条件的文件
*@param目录
*要搜索的目录
*@返回
*合格文件
*/
私有字符串[]GetTargetFile(文件目录){
if(目录==null){
返回null;
}
String[]files=directory.list(新文件名过滤器(){
@凌驾
公共布尔接受(文件目录,字符串名称){
//TODO自动生成的方法存根
返回name.startsWith(“Temp”)和name.endsWith(“.txt”);
}
});
归还文件;
}
/**
*打印所有符合条件的文件
*/
私有void打印文件(字符串[]目标){
for(字符串目标:目标){
系统输出打印项次(目标);
}
}
}
我将演示如何使用递归、bfs和dfs完成工作
递归的:
/**
* 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);
}
/**
* 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();
}
/**
* Search as far as possible along each branch before backtracking
*/
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();
}
/**
*父目录及其子目录中有多少文件
*取决于每个子目录及其子目录中的文件数
*/
私有无效递归(文件路径){
打印文件(getTargetFile(path));
对于(文件:path.listFiles()){
if(file.isDirectory()){
递归(文件);
}
}
if(path.isDirectory()){
打印文件(getTargetFile(path));
}
}
公共静态void main(字符串参数[]){
SearchFiles searcher=新的SearchFiles(新文件(“C:\\example”);
递归(searcher.root);
}
广度优先搜索:
/**
* 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);
}
/**
* 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();
}
/**
* Search as far as possible along each branch before backtracking
*/
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();
}
/**
*在移动到下一级邻居之前,首先搜索节点的邻居
*/
私人银行{
if(root==null){
返回;
}
Queue Queue=new LinkedList();
添加(根);
而(!queue.isEmpty()){
文件节点=queue.remove();
打印文件(getTargetFile(节点));
File[]childs=node.listFiles(新文件过滤器(){
@凌驾
公共布尔接受(文件路径名){
//TODO自动生成的方法存根
if(路径名.isDirectory())
返回true;
返回false;
}
});
if(childs!=null){
用于(文件子项:childs){
添加(子级);
}
}
}
}
公共静态void main(字符串参数[]){
SearchFiles searcher=新的SearchFiles(新文件(“C:\\example”);
searcher.bfs();
}
深度优先搜索:
/**
* 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);
}
/**
* 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();
}
/**
* Search as far as possible along each branch before backtracking
*/
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();
}
/**
*回溯之前,尽可能沿每个分支搜索
*/
私有无效dfs(){
if(root==null){
返回;
}
堆栈=新堆栈();
栈.推(根);
map.put(root.getAbsolutePath(),true);
而(!stack.isEmpty()){
文件节点=stack.peek();
File child=getUnvisitedChild(节点);
if(child!=null){
栈.推(子);
打印文件(getTargetFile(子文件));
map.put(child.getAbsolutePath(),true);
}否则{
stack.pop();
}
}
}
/**
*获取节点的未访问节点
*
*/
私有文件getUnvisitedChild(文件节点){
File[]childs=node.listFiles(新文件过滤器(){
@凌驾
公共布尔接受(文件路径名){
//TODO自动生成的方法存根
if(路径名.isDirectory())
返回true;
返回false;
}
});
if(childs==null){
返回null;
}
用于(文件子项:childs){
if(map.containsKey(child.getAbsolutePath())==false){
map.put(child.getAbsolutePath(),false);
}
if(map.get(child.getAbsolutePath())==false){
返回儿童;
}
}
返回null;
}
公共静态void main(字符串参数[]){
SearchFiles searcher=新的SearchFiles(新文件(“C:\\example”);
searcher.dfs();
}
我知道,这是一个老问题。但为了完整起见,lambda版本
File dir = new File(directory);
File[] files = dir.listFiles((dir1, name) -> name.startsWith("temp") && name.endsWith(".txt"));
详述,Apache IO UTILS可能会节省您一些时间。请考虑下面的示例,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();
见:
- org.apache.commons.io.filefilter.FileFilterUtils