【发布时间】：2014-12-10 11:36:37
【问题描述】：
我想将数据写入 SD 卡，但出现以下错误：打开失败失败：EACCES（权限被拒绝）。 我正在开发的 Android 版本是 jelly bean(4.3)。 我也在清单文件中给予了许可。
这是我的代码：
package com.example.androidsdcard;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
// GUI controls
EditText txtData;
Button btnWriteSDFile;
Button btnReadSDFile;
Button btnClearScreen;
Button btnClose;
File sample=null;
String SDCard_Path="/mnt/extsd";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// bind GUI elements with local controls
txtData = (EditText) findViewById(R.id.txtData);
txtData.setHint("Enter some lines of data here...");
btnWriteSDFile = (Button) findViewById(R.id.btnWriteSDFile);
btnWriteSDFile.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// write on SD card file data in the text box
File storageDir = new File(SDCard_Path);
String sample1 = Environment.getExternalStorageDirectory().getPath();
Toast.makeText(MainActivity.this,sample1, Toast.LENGTH_LONG).show();
if(sample == null)
{
Toast.makeText(MainActivity.this,"Sample == null executed", Toast.LENGTH_LONG).show();
}
else
Toast.makeText(MainActivity.this,"Sample == null skipped", Toast.LENGTH_LONG).show();
if(storageDir.isDirectory())
{
String[] dirList = storageDir.list();
if(dirList==null)
{
Toast.makeText(getBaseContext(),"Failed to detect SD card",Toast.LENGTH_SHORT).show();
return;
}
else
Toast.makeText(getBaseContext(),"SD Card Detected",Toast.LENGTH_SHORT).show();
}
try {
File myFile = new File("/mnt/extsd/MedeQuip.txt");
/* if(myFile.createNewFile()==false)
{
Toast.makeText(getBaseContext(),"Unable to create File'",Toast.LENGTH_SHORT).show();
return;
}
else
Toast.makeText(getBaseContext(),"File Created'",Toast.LENGTH_SHORT).show();
*/ FileOutputStream fOut = new FileOutputStream(myFile);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append(txtData.getText());
myOutWriter.close();
fOut.close();
Toast.makeText(getBaseContext(),"Done writing SD mysdfile.txt'",Toast.LENGTH_SHORT).show();
} catch (Exception e)
{
Toast.makeText(getBaseContext(), e.getMessage(),Toast.LENGTH_SHORT).show();
}
}// onClick
}); // btnWriteSDFile
btnReadSDFile = (Button) findViewById(R.id.btnReadSDFile);
btnReadSDFile.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
// write on SD card file data in the text box
try
{
File myFile = new File(SDCard_Path+"/MedeQuip.txt");
FileInputStream fIn = new FileInputStream(myFile);
BufferedReader myReader = new BufferedReader(
new InputStreamReader(fIn));
String aDataRow = "";
String aBuffer = "";
while ((aDataRow = myReader.readLine()) != null) {
aBuffer += aDataRow + "\n";
}
txtData.setText(aBuffer);
myReader.close();
Toast.makeText(getBaseContext(),"Done reading SD 'MedeQuip.txt'",Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
Toast.makeText(getBaseContext(), e.getMessage(),Toast.LENGTH_SHORT).show();
}
}// onClick
}); // btnReadSDFile
btnClearScreen = (Button) findViewById(R.id.btnClearScreen);
btnClearScreen.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// clear text box
txtData.setText("");
}
}); // btnClearScreen
btnClose = (Button) findViewById(R.id.btnClose);
btnClose.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// clear text box
finish();
}
}); // btnClose
}// onCreate
}// AndSDcard
这是我的 xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="@+id/txtData"
android:layout_width="fill_parent"
android:layout_height="180px"
android:textSize="18sp" />
<Button
android:id="@+id/btnWriteSDFile"
android:layout_width="143px"
android:layout_height="44px"
android:layout_alignParentLeft="true"
android:layout_below="@+id/txtData"
android:layout_marginTop="60dp"
android:text="1. Write SD File" />
<Button
android:id="@+id/btnClearScreen"
android:layout_width="141px"
android:layout_height="42px"
android:layout_alignBaseline="@+id/btnWriteSDFile"
android:layout_alignBottom="@+id/btnWriteSDFile"
android:layout_marginLeft="30dp"
android:layout_toRightOf="@+id/btnWriteSDFile"
android:text="2. Clear Screen" />
<Button
android:id="@+id/btnReadSDFile"
android:layout_width="140px"
android:layout_height="42px"
android:layout_alignTop="@+id/btnWriteSDFile"
android:layout_marginLeft="32dp"
android:layout_toRightOf="@+id/btnClearScreen"
android:text="3. Read SD File" />
<Button
android:id="@+id/btnClose"
android:layout_width="141px"
android:layout_height="43px"
android:layout_alignTop="@+id/btnClearScreen"
android:layout_marginLeft="61dp"
android:layout_toRightOf="@+id/btnReadSDFile"
android:text="4. Close" />
</RelativeLayout>
这是我的清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.androidsdcard"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
</manifest>
【问题讨论】：
-
您在哪里运行应用程序？
标签： java android storage android-sdcard