我正在尝试从文件目录加载图像文件。然后，我想把file对象转换成string对象。不幸的是，我一直收到这个错误消息。我该怎么解决？

java.io.FileNotFoundException: E:\workspace\sesaja\Images (Access is denied)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:120)
at java.io.FileInputStream.<init>(FileInputStream.java:79)
at test.Test1.main(Test1.java:29)

这是我的全部代码

public class Test1 {

     public static void main(String args[]){        

    String s = System.getProperty("user.dir") + System.getProperty("file.separator")+ "Images";
    File f = new File (s);

    FileInputStream fis = null;
    String str = "";

     try {
            fis = new FileInputStream(f);
            int content;
            while ((content = fis.read()) != -1) {
                // convert to char and display it
                str += (char) content;
            }

            System.out.println("After reading file");
            System.out.println(str);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fis != null)
                    fis.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }      
    }           

}