android如何操作sd卡 _Android

【android如何操作sd卡】知识养成了思想,思想同时又在融化知识。这篇文章主要讲述android如何操作sd卡相关的知识，希望能为你提供帮助。

//申明SharedPreferences对象

SharedPreferences mSharedPreferences;
SharedPreferences.Editor mEditor;

mSharedPreferences = getSharedPreferences("user", Context.MODE_PRIVATE);
mEditor = mSharedPreferences.edit();

//在主方法里写一个点击事件保存数据

Button left = (Button) findViewById(R.id.left);

left.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
WriteToSd();
mEditor.putString("user",editText1.getText().toString());
mEditor.putString("passWorld",editText2.getText().toString());
mEditor.commit();
}
});

user = mSharedPreferences.getString("user",null);
passWorld = mSharedPreferences.getString("passWorld",null);
editText1.setText(user);
editText2.setText(passWorld);

//读取文件
private void ReadFromSd(){
String s = Environment.getExternalStorageState();
File root = Environment.getExternalStorageDirectory();
File TargetDir = new File(root,super.getPackageName());
ObjectInputStream ois = null;
if (TargetDir.exists()){
try {
ois = new ObjectInputStream(new FileInputStream(new File(TargetDir+"/liu.txt")));
People people = (People) ois.readObject();
Toast.makeText(getApplication(),people.getUser().toString()+people.getPwd().toString(),Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}finally {
try {
ois.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}else {
Toast.makeText(getApplication(),"false",Toast.LENGTH_SHORT).show();
}
}
写入文件
private void WriteToSd(){
String s = Environment.getExternalStorageState();
ObjectOutputStream oos = null;
if (s.equals(Environment.MEDIA_MOUNTED)){//判断是否有权限,记得在清单文件里声明权限,6.1版本之后的手机可能还是不行
File root = Environment.getExternalStorageDirectory();
File tag = new File(root ,super.getPackageName());
if (!tag.exists()){//判断文件是否存在

tag.mkdir();
}
try {
oos = new ObjectOutputStream(new FileOutputStream(new File(tag,"liu,txt")));
People people = new People("liu","yifan");
oos.writeObject(people);
} catch (IOException e) {
e.printStackTrace();
}
}

< manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jredu.liuyifan.fragmentapplication"> //写在这里面
//两个权限
< uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
< uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>