AppLog.java

package com.zegoggles.smssync.utils;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.os.Environment;
import android.text.format.DateFormat;
import android.util.Log;
import android.widget.ScrollView;
import android.widget.TextView;
import com.zegoggles.smssync.App;
import com.zegoggles.smssync.R;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.LineNumberReader;
import java.io.PrintWriter;
import java.util.Date;

import static com.zegoggles.smssync.App.LOCAL_LOGV;
import static com.zegoggles.smssync.App.TAG;

public class AppLog {
    // keep max 32k worth of logs
    static final int MAX_SIZE = 32 * 1024;
    public static final int ID = 1;

    private PrintWriter writer;
    private String dateFormat;

    public AppLog(char[] format) {
        this(App.LOG, format);
    }

    private AppLog(String name, char[] format) {
        for (char c : format) {
            if (c == DateFormat.MONTH) {
                dateFormat = "MM-dd kk:mm";
                break;
            }
            if (c == DateFormat.DATE) {
                dateFormat = "dd-MM kk:mm";
                break;
            }
        }

        if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
            final File logFile = getFile(name);
            if (logFile.isFile() && logFile.exists()) rotate(logFile);

            try {
                writer = new PrintWriter(new FileWriter(logFile, true));
            } catch (IOException e) {
                Log.w(TAG, "error opening app log", e);
            }
        }
    }

    public void append(String s) {
        if (writer != null) {
            StringBuilder sb = new StringBuilder();
            sb.append(format(new Date()))
                    .append(" ").append(s);
            writer.println(sb);
            if (LOCAL_LOGV) Log.v(TAG, "[AppLog]: " + sb);
        }
    }

    public void appendAndClose(String s) {
        append(s);
        close();
    }

    public void close() {
        if (LOCAL_LOGV) Log.v(TAG, "AppLog#close()");
        if (writer != null) writer.close();
    }

    public CharSequence format(Date d) {
        return DateFormat.format(dateFormat, d);
    }

    private void rotate(final File logFile) {
        if (logFile.length() > MAX_SIZE) {
            if (LOCAL_LOGV) Log.v(TAG, "rotating logfile " + logFile);
            new Thread() {
                @Override
                public void run() {
                    try {
                        LineNumberReader r = new LineNumberReader(new FileReader(logFile));

                        while (r.readLine() != null) ;
                        r.close();

                        int keep = Math.round(r.getLineNumber() * 0.3f);
                        if (keep > 0) {
                            r = new LineNumberReader(new FileReader(logFile));

                            while (r.readLine() != null && r.getLineNumber() < keep) ;

                            File newFile = new File(logFile.getAbsolutePath() + ".new");
                            PrintWriter pw = new PrintWriter(new FileWriter(newFile));
                            String line;
                            while ((line = r.readLine()) != null) pw.println(line);

                            pw.close();
                            r.close();

                            if (newFile.renameTo(logFile) && LOCAL_LOGV) {
                                Log.v(TAG, "rotated file, new size = " + logFile.length());
                            }
                        }
                    } catch (IOException e) {
                        Log.e(TAG, "error rotating file " + logFile, e);
                    }
                }
            }.start();
        }
    }

    public static Dialog displayAsDialog(String name, Context context) {
        final int PAD = 5;
        final TextView view = new TextView(context);
        view.setId(ID);

        readLog(name, view);

        final ScrollView sView = new ScrollView(context) {
            {
                addView(view);
                setPadding(PAD, PAD, PAD, PAD);
            }

            @Override
            protected void onLayout(boolean changed, int l, int t, int r, int b) {
                super.onLayout(changed, l, t, r, b);
                scrollTo(0, view.getHeight());
            }
        };

        return new AlertDialog.Builder(context)
                .setCustomTitle(null)
                .setPositiveButton(android.R.string.ok, null)
                .setView(sView)
                .create();
    }

    public static boolean readLog(String name, TextView view) {
        return readLog(getFile(name), view);
    }

    public static boolean readLog(File f, TextView view) {
        StringBuilder text = new StringBuilder();
        if (view != null && f.exists()) {
            BufferedReader br = null;
            try {
                br = new BufferedReader(new FileReader(f));
                String line;
                while ((line = br.readLine()) != null) {
                    text.append(line);
                    text.append('\n');
                }
            } catch (IOException e) {
                Log.e(TAG, "error reading", e);
            } finally {
                if (br != null) {
                    try {
                        br.close();
                    } catch (IOException ignored) {
                    }
                }
            }
            view.setText(text.length() > 0 ? text :
                    view.getContext().getString(R.string.app_log_empty));
        }

        return text.length() > 0;
    }

    static File getFile(String name) {
        return new File(Environment.getExternalStorageDirectory(), name);
    }
}