Java在服务器下删除文件、删除目录及目录下所有文件失败(file.delete() --> false)

删除文件或者目录失败可能有两个原因：

1. 流没有关闭导致文件被占用，从而删除失败

public String getfilesize(String path,String filename) throws IOException {
  　　String pathString=path+"\"+filename;
  　　f=new File(pathString);
  　　FileInputStream fis=new FileInputStream(f);
  　　String time=String.valueOf(((double)fis.available() / 1024));
  　　fis.close();//当时这里没有关闭
  　　return time.substring(0, time.indexOf(".")+2)+"K";
 }

2. File.delete()用于删除“某个文件或者空目录”！

  重点是删除的对象是文件和空目录，非空目录要进行递归删除

/**
 * @ProjectName: test
 * @Package: com.test.utils
 * @ClassName: DeleteDirectory
 * @Author: luqiming
 * @Description:Java中删除文件、删除目录及目录下所有文件
 * @Date: 2021/1/17 16:15
 * @Version: 1.0
 */
public class DeleteDirectory {

    /**
     * 删除空目录
     * @param dir 将要删除的目录路径
     */
    public static void doDeleteEmptyDir(String dir) {
        boolean success = (new File(dir)).delete();
        if (success) {
            System.out.println("Successfully deleted empty directory: " + dir);
        } else {
            System.out.println("Failed to delete empty directory: " + dir);
        }
    }

    /**
     * 递归删除目录下的所有文件及子目录下所有文件
     * @param dir 将要删除的文件目录
     */
    public static boolean deleteDir(File dir) {
        if (dir.isDirectory()) {
            String[] children = dir.list();
            //递归删除目录中的子目录下
            for (int i=0; i<children.length; i++) {
                boolean success = deleteDir(new File(dir, children[i]));
                if (!success) {
                    return false;
                }
            }
        }
        // 目录此时为空，可以删除
        return dir.delete();
    }

 /**
     *测试
     */
    public static void main(String[] args) {
        doDeleteEmptyDir("new_dir1");
        String newDir2 = "new_dir2";
        boolean success = deleteDir(new File(newDir2));
        if (success) {
            System.out.println("Successfully deleted populated directory: " + newDir2);
        } else {
            System.out.println("Failed to delete populated directory: " + newDir2);
        }     
    }
}