使用Java查找文件夹中的文件

Question

如果搜索文件夹说我需要做什么 C:\example

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一个File file = new File("C:/example/temp***.txt);所以我可以在文件中读取,然后循环需要移动到下一个文件以检查它是否满足如上.

Answer 1

你想要的是什么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");
    }
});

Answer 2

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");
  }
});

Answer 3

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"));

Answer 4

看看java.io.File.list() 和 FilenameFilter。

Answer 5

考虑 Apache Commons IO，它有一个名为FileUtils的类，该类的listFiles方法可能对您的情况非常有用。

Answer 6

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recursive、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：

 /**
 * 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();
}