java - 将根文件夹设置为索引

Question

我这里有这段代码:

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
 *
 * @author Nathan Campos
 */
public class Files extends HttpServlet {
    PrintWriter out = null;              // moved outside doGet() for use in ls()
    @Override
    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html");
        // PrintWriter out = response.getWriter(); would create a copy no accessable in ls()
        out = response.getWriter();   // this uses the out declared outside
        File startDir = new File("C:\\test");
        ls(startDir);
    }

    private void ls(File f) {
        File[] list = f.listFiles();
        if ( list == null ) {
            out.println("Returned null");
                    return; // otherwise the for loop will crash
        }
        for(File file : list) {
            if(file.isDirectory()) {
                ls(file);
            } else {
                out.println("<a href='+file.toURL()+'>'+file.getName()+'</a>");
            }
        }
    }
}

但我想让它在文件夹 C:\WorkFiles\ServletFiles 上搜索。我怎样才能做到这一点？

更新:当我尝试使用private void ls(File f)(没有static)时，我在浏览器(运行 Tomcat):

java.lang.NullPointerException
    Files.ls(Files.java:30)
    Files.doGet(Files.java:18)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

Answer 1

应从配置中读取您启动的目录。不过你也可以这样调用它:

PrintWriter out = null; // moved outside doGet() for use in ls()

public void doGet(HttpServletRequest request,
                  HttpServletResponse response)
throws ServletException, IOException {
    response.setContentType("text/html");
    out = response.getWriter();

    File startDir = new File("C:\\WorkFiles\\ServletFiles");
    ls( startDir );
}

ls() 中的打印行有问题(不能混合 ' 和 ")，应重写为

out.println("<a href="+file.toURL()+'>'+file.getName()+"</a>");

(假设您不希望在重新渲染的 html 页面中输出而不是标准输出)

注意:已弃用的 file.toURL() 方法会抛出 MalformedURLException

编辑:

由于 listFiles 可能返回 null，因此您还应该添加

File[] list = f.listFiles();
if ( list == null ) return;