Question

我的代码在content.html（）中获得空指针异常; 因为每次元素内容被赋值为null 虽然我确信该页面包含具有该ID的元素我正在使用 jsoup 来解析Document 我可以检查代码并发现我的错误

public void get_content(String eliment_by,String identification)
{
    try {

        File currentDirectory = new File(new File(".").getAbsolutePath());
        System.out.println(currentDirectory.getCanonicalPath());
        PrintWriter writer = new PrintWriter(currentDirectory.getCanonicalPath()+"/tmp/input.html", "UTF-8");
        writer.println(" ");
        writer.close();
        File input = new File(currentDirectory.getCanonicalPath()+"/tmp/input.html");
        org.jsoup.nodes.Document doc = Jsoup.parse(input, "UTF-8", this.curr_url);
        Element content = doc.getElementById(identification);

        this.current_page_content=content.html();

    } catch (IOException ex) {
        Logger.getLogger(url_looping.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Answer 1

您正在打开文件并为其写入空格字符，然后读取此文件以进行解析。当您使用PrintWriter时，这会清除您的文件。那么这里发生的是首先清除文件，然后尝试解析它。这就是空指针

的原因

如果你想从网址获取，你可以这样做

public void get_content(String eliment_by, String identification) {
    try {

        org.jsoup.nodes.Document doc = Jsoup.connect("http://www.opengurukul.com/vlc/mod/page/view.php?id=523").get();
        Element content = doc.getElementById(identification);

        this.current_page_content = content.html();

    } catch (IOException ex) {
        Logger.getLogger(url_looping.class.getName()).log(Level.SEVERE,
                null, ex);
    }
}

getElementById获取空指针异常

1 个答案: