Android---36---读取SD卡内容

来源：互联网发布：数据库笔试题编辑：程序博客网时间：2024/06/04 01:25

1.调用Environment.getExternalStorageState()判断手机上是否插入了SD卡，并且应用程序具有读写SD卡的权限。
Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)

返回值为true代表该应用程序具有读写SD卡的权限。

2.调用Environment的getExternalStorageDirectory()方法来获取外部存储器，也就是SD卡的目录。

3.使用FileInputStream FileOutputStream FileReader FIleWriter 读写SD卡里的文件。

class Utils {public void MyWrite(String data) throws Exception {File sDfile = Environment.getExternalStorageDirectory();File f = new File(sDfile, "demo.txt");FileOutputStream fos = new FileOutputStream(f);fos.write(data.getBytes());fos.flush();fos.close();}public String MyRead() throws Exception {File sdFile = Environment.getExternalStorageDirectory();File f = new File(sdFile, "demo.txt");FileInputStream fis = new FileInputStream(f);StringBuffer sb = new StringBuffer();int len = 0;while ((len = fis.read()) != -1){sb.append((char)len);}return sb.toString();}}public class MainActivity extends Activity {private EditText write;private Button saveButton, readButton;private TextView show;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);show = (TextView) findViewById(R.id.show);write = (EditText) findViewById(R.id.write);saveButton = (Button) findViewById(R.id.save);readButton = (Button) findViewById(R.id.read);final Utils s = new Utils();try {show.setText(s.MyRead());} catch (Exception e1) {// TODO Auto-generated catch blocke1.printStackTrace();} saveButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubtry {s.MyWrite(write.getText().toString());} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}});readButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubtry {show.setText(s.MyRead());} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}});}}

为了读写SD卡上的数据，需要添加权限：

创建于删除的权限：
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

向SD卡中写入的权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

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