Android之再谈文件操作和SDcard读写

<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

public class FileService {
private Context context;

public FileService(Context context) {
this.context = context;
}
/**
* 以私有文件保存内容
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void saveToSDCard(String filename, String content) throws Exception{
File file = new File(Environment.getExternalStorageDirectory(), filename);
FileOutputStream outStream = new FileOutputStream(file);
outStream.write(content.getBytes());
outStream.close();
}

/**
* 以私有文件保存内容
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void save(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_PRIVATE);
outStream.write(content.getBytes());
outStream.close();
}
/**
* 以追加方式保存内容
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void saveAppend(String filename, String content) throws Exception{// ctrl+shift+y / x
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_APPEND);
outStream.write(content.getBytes());
outStream.close();
}
/**
* 保存内容,注：允许其他应用从该文件中读取内容
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void saveReadable(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_READABLE);
outStream.write(content.getBytes());
outStream.close();
}
/**
* 保存内容,注：允许其他应用往该文件写入内容
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void saveWriteable(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE);
outStream.write(content.getBytes());
outStream.close();
}
/**
* 保存内容,注：允许其他应用对该文件读和写
* @param filename 文件名称
* @param content 文件内容
* @throws Exception
*/
public void saveRW(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename,
Context.MODE_WORLD_READABLE+ Context.MODE_WORLD_WRITEABLE);
outStream.write(content.getBytes());
outStream.close();
}
/**
* 读取文件内容
* @param filename 文件名称
* @return
* @throws Exception
*/
public String readFile(String filename) throws Exception{
FileInputStream inStream = context.openFileInput(filename);
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
while( (len = inStream.read(buffer))!= -1){
outStream.write(buffer, 0, len);
}
byte[] data = outStream.toByteArray();//得到文件的二进制数据
outStream.close();
inStream.close();
return new String(data);
}
}

public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
private FileService fileService;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

fileService = new FileService(this);

Button button = (Button) this.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
EditText filenameText = (EditText) findViewById(R.id.filename);
EditText contentText = (EditText) findViewById(R.id.filecontent);
String filename = filenameText.getText().toString();
String content = contentText.getText().toString();
try {
//判断sdcard是否存在于手机上，并且可以进行读写访问
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
fileService.saveToSDCard(filename, content);
Toast.makeText(MainActivity.this, R.string.success, 1).show();
}else{
Toast.makeText(MainActivity.this, R.string.sdcarderror, 1).show();
}
} catch (Exception e) {
Log.e(TAG, e.toString());
Toast.makeText(MainActivity.this, R.string.error, 1).show();
}
}
});
}
}