每日一问 | 如何在崩溃时，如何获得logcat信息？

我用的 bugly

 //shell 写日志到本地上传服务端
public static void writeLog(Context context){
        if(isSending) return;
        isSending = true;
        String path = Environment.getExternalStorageDirectory()+"/log/writelog.txt";
        try {
            java.lang.Process p = Runtime.getRuntime().exec("logcat -v time");
            final InputStream is = p.getInputStream();
            new Thread() {
                @Override
                public void run() {
                    long startTime = System.currentTimeMillis();
                    FileOutputStream os = null;
                    try {
                        os = new FileOutputStream(path);
                        int len = 0;
                        byte[] buf = new byte[1024];
                        while (-1 != (len = is.read(buf)) && (System.currentTimeMillis() - startTime < 20000)) {
                            os.write(buf, 0, len);
                            os.flush();
                        }
                    } catch (Exception e) {
                        Log.d("writelog", "read logcat process failed. message: " + e.getMessage());
                    } finally {
                        if (null != os) {
                            try {
                                os.close(); os = null;
                            } catch (IOException e) {
                                // Do nothing
                            }
                        }
                    }
                }
            }.start();
        } catch (Exception e) {
            Log.d("writelog", "open logcat process failed. message: " + e.getMessage());
        }
        Observable.timer(25L, TimeUnit.SECONDS).subscribe(new Consumer<Long>() {
            public final void accept(Long code) {
                isSending = false;
                new SettingHttpTools(context).postLogData(1);
            }
        });
    }

今天刚刚想到的解决方法，可以先初始化一个进程，因为native crash后内存变得不可靠，提前初始化一个Process，然后通过signal（这个之前分享过文章，就用这个即可）机制，在回调的时候调用dumplog方法，亲测非常好用！ 改天还想整理一下发博客呢！没想到洋神这里就有提问了

// logcat 的特殊使用
object Monitor {
    lateinit var process:Process

    fun create(){
        process = ProcessBuilder("logcat", "-v", "process").start()
        Log.i("hello","process ${process.isAlive}")
    }

    fun dumpLog(){
        var reader: BufferedReader? = null
        try {
            reader = BufferedReader(InputStreamReader(process.inputStream))
            var line: String?
            while (reader.readLine().also { line = it } != null) {

                if(line?.contains("runtime") == true) {
                    // 自定义上传日志
                    Log.i("hello", "test is $line")
                }

            }
        } catch (ignored: IOException) {
        } finally {
            if (reader != null) {
                try {
                    reader.close()
                } catch (ignored: IOException) {
                }
            }
        }
    }
}

使用UncaughtExceptionHandler：开发者可以在应用程序中实现UncaughtExceptionHandler接口，捕获未处理的异常信息，并保存到本地文件中。可以在应用程序启动时设置自定义的UncaughtExceptionHandler，将异常信息保存到文件中。

来自gpt

参考下腾讯的xlog 方案

https://developer.android.com/studio/command-line/logcat?hl=zh-cn

哆啦A梦能捕获异常时的log，有人分析一下么