Android/Java - IO 异常 - 似乎无法加载 HTML 资产

Question

    CalendarParse parser = new CalendarParse();
            parser.countSundays(this);  



public class CalendarParse  {

        String calString = "";
        Document cal = null;
        InputStream is = null;


        public void countSundays(Context context)
        {
            AssetManager assMan = context.getAssets();

            try
            {
                System.out.println("Trying");
                InputStream is = assMan.open("assets/brownbear.html");
                if (is == null){
                    Log.i("FAIL","File not found.");
                }
                else{
                    Log.i("SUCCESS","We did it");
                }
               Document cal = Jsoup.parse(is, "utf-8", "ob stuff");
                Element calBlock =  cal.select("table#CalBlock").first();
               Element calRows = calBlock.select("tr").get(0);
              Log.i("SUCCESS","Parsing has occurred");
                System.out.println(calRows.toString());

            }
            catch(IOException e){
                System.out.println("IO Exception at local calendar asset");
            }


        }

brownbear.html在assets文件夹里，这个写进MainActivity。最初它是一个单独的 .java class，但是当它在 Main Activity 之外时，我无法准确地确定 "Context" 如何影响 AssetManager 并且我在故障排除时试图减轻未知数。

如所写，"Trying" 打印出来，没有 Log.i 打印出来（大概是因为我们在

处失败了

InputStream is = assMan.open("assets/brownbear.html");

) "IO Exception at local calendar asset" 总是打印出来。

如果我将该行更改为

assMan.open("brownbear.html");

然后 "SUCCESS" "We did it" 运行，但发生致命异常：

2019-02-01 02:28:06.069 5637-5637/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.myapplication.schedulo, PID: 5637 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapplication.schedulo/com.myapplication.schedulo.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'org.jsoup.select.Elements org.jsoup.nodes.Element.select(java.lang.String)' on a null object reference

我做错了什么？？

Answer 1

Element calBlock =  cal.select("table#CalBlock").first();
Element calRows = calBlock.select("tr").get(0);

NullPointerException 在第二行，因为第一行 (calBlock) 的结果为空。您应该检查为什么选择器 "table#CalBlock" 与您想要的不匹配。尝试分析文档 cal 的 HTML 并检查它是否包含 ID 为 CalBlock 的 <table ...>。您确定您正在解析的页面没有使用 JavaScript 加载一些片段 dynamically/asynchronously 吗？

Android/Java - IO 异常 - 似乎无法加载 HTML 资产

Android/Java - IO Exception - can't seem to load HTML asset

java

android

jsoup

android-assetmanager