对于java 7及以上版本:

Path path = Paths.get("/your/path/string");
Files.createDirectories(path);

在创建之前检查目录或文件是否存在似乎是不必要的，from createDirectories javadocs:

Creates a directory by creating all nonexistent parent directories first. Unlike the createDirectory method, an exception is not thrown if the directory could not be created because it already exists. The attrs parameter is optional file-attributes to set atomically when creating the nonexistent directories. Each file attribute is identified by its name. If more than one attribute of the same name is included in the array then all but the last occurrence is ignored. If this method fails, then it may do so after creating some, but not all, of the parent directories.

new File("/path/directory").mkdirs();

这里的“directory”是你想要创建/存在的目录的名称。

大约7年后，我会将其更新为Bozho建议的更好的方法。

File theDir = new File("/path/directory");
if (!theDir.exists()){
    theDir.mkdirs();
}

整洁干净:

import java.io.File;

public class RevCreateDirectory {

    public void revCreateDirectory() {
        //To create single directory/folder
        File file = new File("D:\\Directory1");
        if (!file.exists()) {
            if (file.mkdir()) {
                System.out.println("Directory is created!");
            } else {
                System.out.println("Failed to create directory!");
            }
        }
        //To create multiple directories/folders
        File files = new File("D:\\Directory2\\Sub2\\Sub-Sub2");
        if (!files.exists()) {
            if (files.mkdirs()) {
                System.out.println("Multiple directories are created!");
            } else {
                System.out.println("Failed to create multiple directories!");
            }
        }

    }
}

下面的方法可以做你想做的事情，只要确保你检查了mkdir() / mkdirs()的返回值

private void createUserDir(final String dirName) throws IOException {
    final File homeDir = new File(System.getProperty("user.home"));
    final File dir = new File(homeDir, dirName);
    if (!dir.exists() && !dir.mkdirs()) {
        throw new IOException("Unable to create " + dir.getAbsolutePath();
    }
}

对于java 7及以上版本:

Path path = Paths.get("/your/path/string");
Files.createDirectories(path);

在创建之前检查目录或文件是否存在似乎是不必要的，from createDirectories javadocs:

Creates a directory by creating all nonexistent parent directories first. Unlike the createDirectory method, an exception is not thrown if the directory could not be created because it already exists. The attrs parameter is optional file-attributes to set atomically when creating the nonexistent directories. Each file attribute is identified by its name. If more than one attribute of the same name is included in the array then all but the last occurrence is ignored. If this method fails, then it may do so after creating some, but not all, of the parent directories.