在Android上写入文件问题

Question

我目前正在尝试将当前时间粘贴到Android应用程序的文件中。代码如下所示，但文件未创建。我已经允许我的应用程序通过清单在SD卡上写入。有任何想法吗？

Time today = new Time(Time.getCurrentTimezone()); 
    today.setToNow(); 
    try { 
     File myFile = new File("/sdcard/mysdfile.txt"); 
     myFile.createNewFile(); 
     FileOutputStream fOut = new FileOutputStream(myFile); 
     OutputStreamWriter myOutWriter = 
           new OutputStreamWriter(fOut); 
     SimpleDateFormat dF = new SimpleDateFormat("HHMMSS"); 
     StringBuilder current = new StringBuilder(dF.format(today)); 
     myOutWriter.append(current); 
     myOutWriter.close(); 
     fOut.close(); 

    } 

Answer 1

您应该使用Environment.getExternalStorageDirectory（），而不是硬编码/sdcard/路径。

File file = new File(Environment.getExternalStorageDirectory(), "mysdfile.txt");

我试着运行你的代码，它崩溃由于dF.format(today)。

而不必为此，

Time today = new Time(Time.getCurrentTimezone()); 
today.setToNow(); 

这本

Date today = new Date(); 

此代码的工作我的设备上工作得很好。

Date today = new Date(); 

try { 
    File myFile = new File(Environment.getExternalStorageDirectory(), "mysdfile.txt");    
    myFile.createNewFile(); 

    FileOutputStream fOut = new FileOutputStream(myFile); 
    OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut); 
    SimpleDateFormat dF = new SimpleDateFormat("HHMMSS"); 
    StringBuilder current = new StringBuilder(dF.format(today)); 
    myOutWriter.append(current); 
    myOutWriter.close(); 
    fOut.close(); 
} catch (IOException e) { 
    e.printStackTrace(); 
} 

Answer 2

尝试另一种方式如下，

private BufferedWriter buff = null; 
private File logFile = null; 
logFile = new File ("/sdcard/mysdfile.txt"); 
if (!logFile.exists()) 
{ 
    logFile.createNewFile(); 
} 
buff = new BufferedWriter (new FileWriter (logFile,true)); 
buff.append("Write what you want to store"); 
buff.close(); 

你也需要给<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>权限在AndroidManifest.xml中。