Java IO教程 --- Java删除文件

今天我们将研究Java删除文件和Java删除目录的例子。之前我们学习了如何在 java 中创建文件。

Java删除文件

1. Java File delete() 方法可用于在Java 中删除文件或空目录/文件夹。如果文件被删除，Java 文件删除方法返回 true，如果文件不存在，则返回 false。
2. 如果您试图删除一个目录，它会检查 java File delete() 方法检查它是否为空。如果目录为空，它将被删除，否则delete()方法不执行任何操作并返回 false。所以在这种情况下，我们必须递归删除所有文件，然后删除空目录。
3. 删除非空目录的另一种方法是使用Files.walkFileTree()方法。在这个方法中，我们可以一个一个处理所有文件，对单个文件调用delete方法。

Java删除文件示例

让我们看看java删除文件示例程序。

package com.journaldev.files;

import java.io.File;

public class DeleteFileJava {

    /**
     * This class shows how to delete a File in Java
     * @param args
     */
    public static void main(String[] args) {
        //absolute file name with path
        File file = new File("/Users/pankaj/file.txt");
        if(file.delete()){
            System.out.println("/Users/pankaj/file.txt File deleted");
        }else System.out.println("File /Users/pankaj/file.txt doesn't exist");

        //file name only
        file = new File("file.txt");
        if(file.delete()){
            System.out.println("file.txt File deleted from Project root directory");
        }else System.out.println("File file.txt doesn't exist in the project root directory");

        //relative path
        file = new File("temp/file.txt");
        if(file.delete()){
            System.out.println("temp/file.txt File deleted from Project root directory");
        }else System.out.println("File temp/file.txt doesn't exist in the project root directory");

        //delete empty directory
        file = new File("temp");
        if(file.delete()){
            System.out.println("temp directory deleted from Project root directory");
        }else System.out.println("temp directory doesn't exist or not empty in the project root directory");

        //try to delete directory with files
        file = new File("/Users/pankaj/project");
        if(file.delete()){
            System.out.println("/Users/pankaj/project directory deleted from Project root directory");
        }else System.out.println("/Users/pankaj/project directory doesn't exist or not empty");
    }

}

下面是我们第一次执行上述java删除文件示例程序时的输出。

/Users/pankaj/file.txt File deleted
file.txt File deleted from Project root directory
temp/file.txt File deleted from Project root directory
temp directory deleted from Project root directory
/Users/pankaj/project directory doesn't exist or not empty

请注意，临时目录有 file.txt，它首先被删除，然后目录为空并成功删除，/Users/pankaj/project 不为空，因此未删除。

在同一程序的后续运行中，输出为：

File /Users/pankaj/file.txt doesn't exist
File file.txt doesn't exist in the project root directory
File temp/file.txt doesn't exist in the project root directory
temp directory doesn't exist or not empty in the project root directory
/Users/pankaj/project directory doesn't exist or not empty

请注意，与createNewFile()不同，delete 方法不会抛出 IOException。

Java删除目录

下面是一个简单的程序，显示了如何删除非空目录。如果您的目录仅包含文件，这将起作用。

package com.journaldev.files;

import java.io.File;

public class JavaDeleteDirectory {

    public static void main(String[] args) {
        File dir = new File("/Users/pankaj/log");

        if(dir.isDirectory() == false) {
            System.out.println("Not a directory. Do nothing");
            return;
        }
        File[] listFiles = dir.listFiles();
        for(File file : listFiles){
            System.out.println("Deleting "+file.getName());
            file.delete();
        }
        //now directory is empty, so we can delete it
        System.out.println("Deleting Directory. Success = "+dir.delete());

    }

}

Java递归删除目录

早些时候，我们不得不编写基于递归的代码来删除带有嵌套目录的目录。但是在 Java 7 中，我们可以使用Files 类来做到这一点。下面是您应该用来删除目录的代码。它也负责删除嵌套目录。

package com.journaldev.files;

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;

public class JavaDeleteDirectoryRecursively {

    public static void main(String[] args) throws IOException {

        Path directory = Paths.get("/Users/pankaj/log");
        Files.walkFileTree(directory, new SimpleFileVisitor<Path>() {
           @Override
           public FileVisitResult visitFile(Path file, BasicFileAttributes attributes) throws IOException {
               Files.delete(file); // this will work because it's always a File
               return FileVisitResult.CONTINUE;
           }

           @Override
           public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
               Files.delete(dir); //this will work because Files in the directory are already deleted
               return FileVisitResult.CONTINUE;
           }
        });
    }
}

这就是 java 删除文件和 java 删除目录示例的全部内容。