Question

我正在尝试将日志数据写入android中的文件，然后再次将文件读入字符串。不幸的是我在阅读文件时遇到错误。

我无法理解存储文件是否存在问题，我也想知道我在读取内容时从android获取文件时是否犯了错误。我在阅读文件内容时遇到错误。请让我知道如何解决从android文件读取的问题。

当我使用以下行检查我的文件存储位置时：

android.util.Log.d("myapp",logFile.toString());

我有以下位置： /storage/emulator/0/yourLog.txt

我正在使用以下代码将日志数据写入文件。

public File writeLogDataToFile(String LogData){

        File logFile = null;
        try {
            logFile = new File(Environment.getExternalStorageDirectory(),
                    "yourLog.txt");
            if (!logFile.exists()) {
                try {
                    logFile.createNewFile();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            try {
                BufferedWriter buf = new BufferedWriter(new FileWriter(logFile,
                        true));
                buf.append(LogData);
                buf.newLine();
                buf.close();
                android.util.Log.d("myapp",logFile.toString());
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
                  e.printStackTrace();
        }

        return logFile;
    }

以下是用于将文件内容读入String的代码：

    /* Step no 4 : Get the Contents of the File */
    private String getContentsOfFile() throws FileNotFoundException {
        File sdcard = Environment.getExternalStorageDirectory();

        //Get the text file
        //File file = new File("sdcard/yourLog.txt");
        File file = new File(Environment.getExternalStorageDirectory(),
                "yourLog.txt");
        android.util.Log.d("myapp",file.toString());
        //Read text from file
        StringBuilder text = new StringBuilder();
        String line=null;
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            while ((line = br.readLine()) != null) {
                text.append(line);
                text.append('\n');
            }
        }
        catch (IOException e) {
            //You'll need to add proper error handling here
        }


        /*
        String content = new Scanner(new File(tempFile)).useDelimiter("\\Z").next();
        System.out.println(content);
        */
        return line;
    }

堆栈追踪：

01-31 15:31:18.695: I/System.out(20748): Step no 3 : Writing the JSONObject to File
01-31 15:31:18.695: I/System.out(20748): Printing the Contents in console wrote to File
01-31 15:31:18.705: D/myapp(20748): /storage/emulated/0/yourLog.txt
01-31 15:31:18.705: I/System.out(20748): Step no 4 : Get the contents of the file
01-31 15:31:18.705: D/myapp(20748): /storage/emulated/0/yourLog.txt
01-31 15:31:18.705: D/AndroidRuntime(20748): Shutting down VM
01-31 15:31:18.705: W/dalvikvm(20748): threadid=1: thread exiting with uncaught exception (group=0x41884ba8)
01-31 15:31:18.705: E/AndroidRuntime(20748): FATAL EXCEPTION: main
01-31 15:31:18.705: E/AndroidRuntime(20748): FATAL EXCEPTION: main
01-31 15:31:18.705: E/AndroidRuntime(20748): Process: com.example.sampleaudit, PID: 20748
01-31 15:31:18.705: E/AndroidRuntime(20748): java.lang.NullPointerException
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.android.internal.os.LoggingPrintStream.println(LoggingPrintStream.java:298)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.example.auditor.LogMessages.getContentsOfFile(LogMessages.java:235)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.example.auditor.LogMessages.createLogMessages(LogMessages.java:78)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.example.sampleaudit.MainActivity$2.onClick(MainActivity.java:111)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.view.View.performClick(View.java:4438)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.view.View$PerformClick.run(View.java:18422)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.os.Handler.handleCallback(Handler.java:733)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.os.Handler.dispatchMessage(Handler.java:95)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.os.Looper.loop(Looper.java:136)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at android.app.ActivityThread.main(ActivityThread.java:5017)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at java.lang.reflect.Method.invokeNative(Native Method)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at java.lang.reflect.Method.invoke(Method.java:515)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
01-31 15:31:18.705: E/AndroidRuntime(20748):    at dalvik.system.NativeStart.main(Native Method)
01-31 15:31:20.195: I/Process(20748): Sending signal. PID: 20748 SIG: 9

Answer 1

将日志写入Android中的文件

    public void writeJsonToFile(String tempJsonString){

        File logFile = null;
        try {
             logFile = new File(Environment.getExternalStorageDirectory(),
                    "yourLog.txt");
            if (!logFile.exists()) {
                try {
                    logFile.createNewFile();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            try {
                BufferedWriter buf = new BufferedWriter(new FileWriter(logFile,
                        true));
                buf.append(tempJsonString);
                buf.newLine();
                buf.close();
                android.util.Log.d("myapp",logFile.toString());
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
                  e.printStackTrace();
        }

    //  return logFile;
    }

从Android中的文件中读取内容：

    private void getContentsOfFile() throws FileNotFoundException {

        File file = new File(Environment.getExternalStorageDirectory(),
                "yourLog.txt");
        android.util.Log.d("myapp",file.toString());
        String output = new Scanner(file).useDelimiter("\\Z").next();
        System.out.println("" + output);

    }

在android中写入文件并从android读取文件

1 个答案: