第一次点击“java文件存在”在谷歌:

import java.io.*;

public class FileTest {
    public static void main(String args[]) {
        File f = new File(args[0]);
        System.out.println(f + (f.exists()? " is found " : " is missing "));
    }
}

设计这些方法是有特定目的的。我们不能说使用任何人来检查文件是否存在。

isFile():测试由这个抽象路径名表示的文件是否是一个正常的文件。 exists():测试由此抽象路径名表示的文件或目录是否存在。 docs.oracle.com

使用Java 8:

if(Files.exists(Paths.get(filePathString))) { 
    // do something
}

如果使用spring框架，文件路径以classpath开头:

public static boolean fileExists(String sFileName) {
    if (sFileName.startsWith("classpath:")) {
        String path = sFileName.substring("classpath:".length());
        ClassLoader cl = ClassUtils.getDefaultClassLoader();
        URL url = cl != null ? cl.getResource(path) : ClassLoader.getSystemResource(path);
        return (url != null);
    } else {
        Path path = Paths.get(sFileName);
        return Files.exists(path);
    }
}

熟悉Commons FileUtils https://commons.apache.org/proper/commons-io/javadocs/api-2.5/org/apache/commons/io/FileUtils.html也是非常值得的 它有额外的管理文件的方法，通常比JDK更好。

You must use the file class , create a file instance with the path of the file you want to check if existent . After that you must make sure that it is a file and not a directory . Afterwards you can call exist method on that file object referancing your file . Be aware that , file class in java is not representing a file . It actually represents a directory path or a file path , and the abstract path it represents does not have to exist physically on your computer . It is just a representation , that`s why , you can enter a path of a file as an argument while creating file object , and then check if that folder in that path does really exist , with the exists() method .