java IOUtils下载图片

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;

public class ImgDownload {

    public static void main(String[] args) {
        downloadHttpUrl("https://www.baidu.com/img/bd_logo1.png", "D:/test/", "test.png");
    }

    public static String downloadHttpUrl(String url, String dir, String fileName) {
        try {
            URL httpurl = new URL(url);
            File f = new File(dir + fileName);
            FileUtils.copyURLToFile(httpurl, f);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return dir + fileName;
    }  

    public static FileOutputStream openOutputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canWrite() == false) {
                throw new IOException("File '" + file + "' cannot be written to");
            }
        } else {
            File parent = file.getParentFile();
            if (parent != null && parent.exists() == false) {
                if (parent.mkdirs() == false) {
                    throw new IOException("File '" + file + "' could not be created");
                }
            }
        }
        return new FileOutputStream(file);
    }  

    public static void copyURLToFile(URL source, File destination) throws IOException {
        InputStream input = source.openStream();
        try {
            FileOutputStream output = openOutputStream(destination);
            try {
                IOUtils.copy(input, output);
            } finally {
                IOUtils.closeQuietly(output);
            }
        } finally {
            IOUtils.closeQuietly(input);
        }
    }  

}