Question

我正在尝试将每个访问过的URL保存在.txt文件中。它工作正常，但是，每个新的URL都会替换旧的@Override public void onPageStarted(WebView view, String url, Bitmap favicon) { super.onPageStarted(view, url, favicon); // don't hide URLBar on welcome screen // save to history.txt HistoryHelper file = new HistoryHelper(view.getContext()); file.writeToSD(url.toString()); }。

1）如何添加网址（在顶部，不在底部）？

2）如何在每个网址之间添加一行空格？

MainActivity.java

public class HistoryHelper {

    String TAG = "MyFile";
    Context context;

    public HistoryHelper(Context context) {
        this.context = context;
    }

    public Boolean writeToSD(String text) {
        Boolean write_successful = false;
        File root = null;
        try {
            // check for SDcard
            root = Environment.getExternalStorageDirectory();
            Log.i(TAG, "path.." + root.getAbsolutePath());

            // check sdcard permission
            if (root.canWrite()) {
                File fileDir = new File(
                        Environment.getExternalStorageDirectory() + "/AVD/");
                fileDir.mkdirs();

                File file = new File(fileDir, "History.txt");
                FileWriter filewriter = new FileWriter(file);
                BufferedWriter out = new BufferedWriter(filewriter);
                out.write(text);
                out.close();
                write_successful = true;
                Toast.makeText(context, "success!", Toast.LENGTH_LONG).show();
            }
        } catch (IOException e) {
            Log.e("ERROR:---",
                    "Could not write file to SDCard" + e.getMessage());
            write_successful = false;
            Toast.makeText(context, "operation failed!", Toast.LENGTH_LONG)
                    .show();
        }
        return write_successful;
    }
}

HistoryHelper.java

{{1}}

Answer 1

以附加模式打开文件

FileWriter fileWriter = new FileWriter (file,  true) ;

使用BufferedWriter，每次访问URL时都要打开文件。尽量减少磁盘I / O开销。

如何将字符串添加到文本文件？

1 个答案: