Java 帮助在Android中获取HTML文件

我正在编写一个程序，在Android中获取一个HTML文件，当我运行它时，我会不断地得到一个强制关闭！我不知道怎么了！以下是一些代码块：

将文件转换为字符串：

  public String getFileAsString(File file){ FileInputStream fis = null;
        BufferedInputStream bis = null;
        DataInputStream dis = null;
        StringBuffer sb = new StringBuffer();
        try {
        fis = new FileInputStream(file);
        bis = new BufferedInputStream(fis);
        dis = new DataInputStream(bis);

        while (dis.available() != 0) {
        sb.append( dis.readLine() +"\n");
        }
        fis.close();
        bis.close();
        dis.close();

        } catch (FileNotFoundException e) {
        e.printStackTrace();
        } catch (IOException e) {
        e.printStackTrace();
        }
        return sb.toString();
        }

Then where the problem might be:

    File htmlfile = null;
                EditText text = (EditText)findViewById(R.id.editText1);
                TextView tv =(TextView)findViewById(R.id.textView2);
                String data;
            URL url = null;
            try {
                url = new URL(text.getText().toString());
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                tv.setText("Invalid URL");
            }
            try {
                download(url,htmlfile);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                tv.setText("Something went wrong try reinstalling the program!");
            }

            data = getFileAsString(htmlfile);
            tv.setText(data);

其他代码：

private static void download(URL input, File output)
    throws IOException {
  InputStream in = input.openStream();
  try {
    OutputStream out = new FileOutputStream(output);
    try {
      copy(in, out);
    } finally {
      out.close();
    }
  } finally {
    in.close();
  }
}

private static void copy(InputStream in, OutputStream out)
    throws IOException {
  byte[] buffer = new byte[1024];
  while (true) {
    int readCount = in.read(buffer);
    if (readCount == -1) {
      break;
    }
    out.write(buffer, 0, readCount);
  }
}


}

日志：

02-26 18:47:43.571: ERROR/AndroidRuntime(275): FATAL EXCEPTION: main
02-26 18:47:43.571: ERROR/AndroidRuntime(275): java.lang.NullPointerException: Argument must not be null
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at java.io.FileInputStream.<init>(FileInputStream.java:78)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at com.apps.blogspot.blogspot.getFileAsString(blogspot.java:40)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at com.apps.blogspot.blogspot.onClick(blogspot.java:83)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.view.View.performClick(View.java:2408)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.view.View$PerformClick.run(View.java:8816)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.os.Handler.handleCallback(Handler.java:587)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.os.Looper.loop(Looper.java:123)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at android.app.ActivityThread.main(ActivityThread.java:4627)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at java.lang.reflect.Method.invokeNative(Native Method)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at java.lang.reflect.Method.invoke(Method.java:521)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at dalvik.system.NativeStart.main(Native Method)
02-26 18:47:43.661: WARN/ActivityManager(38):   Force finishing activity com.apps.blogspot/.blogspot
02-26 18:47:44.261: WARN/ActivityManager(38): Activity pause timeout for HistoryRecord{43e2ec30 com.apps.blogspot/.blogspot}
02-26 18:47:44.901: INFO/ARMAssembler(38): generated scanline__00000077:03515104_00000000_00000000 [ 33 ipp] (47 ins) at [0x360050:0x36010c] in 6934332 ns
02-26 18:47:44.941: INFO/ARMAssembler(38): generated scanline__00000177:03515104_00001001_00000000 [ 91 ipp] (114 ins) at [0x360110:0x3602d8] in 2187014 ns
02-26 18:47:48.831: INFO/Process(275): Sending signal. PID: 275 SIG: 9
02-26 18:47:48.871: INFO/ActivityManager(38): Process com.apps.blogspot (pid 275) has died.
02-26 18:47:48.871: INFO/WindowManager(38): WIN DEATH: Window{43fd01f8 com.apps.blogspot/com.apps.blogspot.blogspot paused=false}
02-26 18:47:48.911: WARN/InputManagerService(38): Got RemoteException sending setActive(false) notification to pid 275 uid 10036
02-26 18:47:55.766: WARN/ActivityManager(38): Activity destroy timeout for HistoryRecord{43e2ec30 com.apps.blogspot/.blogspot}

02-26 18:47:43.571:错误/AndroidRuntime（275）：致命异常：主
02-26 18:47:43.571:错误/AndroidRuntime（275）：java.lang.NullPointerException:参数不能为null
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：在java.io.FileInputStream。（FileInputStream.java:78）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于com.apps.blogspot.blogspot.getFileAsString（blogspot.java:40）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于com.apps.blogspot.blogspot.onClick（blogspot.java:83）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：在android.view.view.performClick（view.java:2408）上
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：在android.view.view$PerformClick.run（view.java:8816）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于android.os.Handler.handleCallback（Handler.java:587）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于android.os.Handler.dispatchMessage（Handler.java:92）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：在android.os.Looper.loop（Looper.java:123）上
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于android.app.ActivityThread.main（ActivityThread.java:4627）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于java.lang.reflect.Method.invokenactive（本机方法）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于java.lang.reflect.Method.invoke（Method.java:521）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:868）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：位于com.android.internal.os.ZygoteInit.main（ZygoteInit.java:626）
02-26 18:47:43.571:ERROR/AndroidRuntime（275）：在dalvik.system.NativeStart.main（本机方法）
02-26 18:47:43.661:WARN/ActivityManager（38）：强制完成活动com.apps.blogspot/.blogspot
02-26 18:47:44.261:WARN/ActivityManager（38）：历史记录{43e2ec30 com.apps.blogspot/.blogspot}的活动暂停超时
02-26 18:47:44.901:INFO/ARMAssembler（38）：在6934332纳秒的[0x360050:0x36010c]处生成扫描线（37英寸）
02-26 18:47:44.941:INFO/ARMAssembler（38）：在2187014纳秒[0x360110:0x3602d8]处生成扫描线
02-26 18:47:48.831：信息/处理（275）：发送信号。PID:275信号：9
02-26 18:47:48.871:INFO/ActivityManager（38）：Process com.apps.blogspot（pid 275）已死亡。
02-26 18:47:48.871:INFO/WindowManager（38）：WIN DEATH:Window{43fd01f8 com.apps.blogspot/com.apps.blogspot.blogspot暂停=false}
02-26 18:47:48.911:WARN/InputManagerService（38）：获取远程异常，向pid 275 uid 10036发送setActive（false）通知
02-26 18:47:55.766:WARN/ActivityManager（38）：历史记录{43e2ec30 com.apps.blogspot/.blogspot}的活动销毁超时

htmlfile

为

null

：您从未为其赋值

下面是您如何从stacktrace中找到它的：

02-26 18:47:43.571: ERROR/AndroidRuntime(275): java.lang.NullPointerException: Argument must not be null
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at java.io.FileInputStream.<init>(FileInputStream.java:78)
02-26 18:47:43.571: ERROR/AndroidRuntime(275):     at com.apps.blogspot.blogspot.getFileAsString(blogspot.java:40)

如果要查找将某个内容分配给

htmlfile

的位置，您只能找到：

File htmlfile = null;

---

非常感谢你。我对这个东西（文件流）相当陌生。谢谢你的帮助！

File htmlfile = null;