在SD卡中创建文件失败

我将一个下载文件写入SD卡程序。但我不知道为什么创建文件失败。 logcat的打印这样的信息：在SD卡中创建文件失败

11-15 01:22:14.369: I/System.out(385): /mnt/sdcard/ 
11-15 01:22:16.413: I/System.out(385): file------->/mnt/sdcard/test/1.mp3 
11-15 01:22:16.419: I/System.out(385): createSDFile

它捕获错误：

11-15 00:21:29.248: W/dalvikvm(352): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
11-15 00:21:29.259: E/AndroidRuntime(352): FATAL EXCEPTION: main 
11-15 00:21:29.259: E/AndroidRuntime(352): java.lang.NullPointerException 
11-15 00:21:29.259: E/AndroidRuntime(352): at java.io.FileOutputStream.<init>(FileOutputStream.java:97) 
11-15 00:21:29.259: E/AndroidRuntime(352): at java.io.FileOutputStream.<init>(FileOutputStream.java:69) 
11-15 00:21:29.259: E/AndroidRuntime(352): at com.example.Utils.FileUtils.write2SDFromInputStream(FileUtils.java:60) 
11-15 00:21:29.259: E/AndroidRuntime(352): at com.example.Utils.HttpDownload.downloadFile(HttpDownload.java:70)

由于信息，文件已正确创建。我使用fileExplorer check/mnt/sdcard /，并且找不到错误。路径中的“/”有什么问题吗？网络连接权限：

<uses-permission android:name="android.permission.INTERNET"/> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

创建或删除文件的SD卡的权限

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>

调用下载方法：hdl.downloadFile("http://169.254.57.236/test/1.mp3","test/","1.mp3");

文件下载类

package com.example.Utils; 


import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 


import android.os.Environment; 
import android.util.Log; 


public class FileUtils { 
private String SDPATH; 


public FileUtils(){ 
SDPATH = Environment.getExternalStorageDirectory()+"/"; 
} 

//create directory on SD card 
public File createSDDir(String dirName){ 
File dir = new File(SDPATH+dirName); 
dir.mkdirs(); 
return dir; 
} 

//cteate file on SD card： 
public File createSDFile(String dirAndFilename) throws IOException{ 
File file = new File(SDPATH+dirAndFilename); 
file.createNewFile(); 
return file; 
} 

//check the file in SD card is exited or not 
public boolean isFileExist(String fileName){ 
File file = new File(SDPATH + fileName); 
return file.exists(); 
} 


//put InputStream data into SD card 
public File write2SDFromInputStream(String path,String fileName,InputStream in){ 
File file = null; 
OutputStream out = null; 

try { 
createSDDir(path); 
try{ 
file = createSDFile(path+fileName); 
} 

catch(Exception e){ 
System.out.println("createSDFile failed"); 
} 

out = new FileOutputStream(file); 
byte buf[] = new byte[1024*5]; 
int ch = 0; 
while((ch = in.read(buf))!=-1){ 
out.write(buf); 
out.flush(); 
} 

} catch (IOException e) { 

System.out.println("SD write failed！"); 
e.printStackTrace(); 
}finally{ 

if(out!=null) 
try { 
out.close(); 
} catch (IOException e) { 
e.printStackTrace(); 
System.out.println("SD Write inflow closed failure！"); 
} 
} 

return file; 
} 


}

来源

2012-11-15 Li Che

请张贴失败的代码中使用权限了。 – Frank

请发布FileUtils.java的代码？ –

确保您的文件夹“test”也已创建。没有你的代码只是猜测。 – Thommy

检查，如果你添加清单权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

来源

2012-11-15 07:58:30 Mikhaili

没有代码，这几乎是不可能的。但你有没有创建文件？

File f; 
f=new File(Environment.getExternalStorageDirectory() + "/whatever_dic"); 
f.createFile();

来源

2012-11-15 08:01:32

尝试用mkdirs（）

  File sdCardDirectory = Environment 
        .getExternalStorageDirectory(); 
      new File(sdCardDirectory + "/XXX/Wallpapers/").mkdirs(); 
      File image = new File(sdCardDirectory 
        + "/XXX/Wallpapers/Sample" + numberOfImages + ".JPG");

，并在您的清单

  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

来源

2012-11-15 09:07:35

在SD卡中创建文件失败

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