简单的文本数据写入文件不需要权限，读写SD卡在4.0版本前需要写权限、在4.0后需要读写权限
布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
tools:context=".MainActivity" > <EditText android:id="@+id/et_number"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:phoneNumber="true"
android:hint="请输入手机号" /> <EditText
android:id="@+id/et_pwd"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:hint="请输入密码"
android:inputType="textPassword" /> <CheckBox android:id="@+id/cb_remerber_pwd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="记住密码" /> <Button android:id="@+id/btn_Login"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="登陆"
/> </LinearLayout>
Manifest.xml添加权限
<!-- 写入外部设备(sdka)的权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
MainActivity：
public class MainActivity extends Activity implements OnClickListener {
private static final String TAG = "MainActivity";
private EditText etNumber;
private EditText etPwd;
private CheckBox cbRemerber;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//获取控件中数据
etNumber = (EditText)findViewById(R.id.et_number);
etPwd=(EditText)findViewById(R.id.et_pwd);
cbRemerber=(CheckBox)findViewById(R.id.cb_remerber_pwd);
Button btnLogin = (Button)findViewById(R.id.btn_Login);
//添加点击事件
btnLogin.setOnClickListener(this);
//获取SD卡数据
Map<String,String> userInfo=UtilsOfSDCard.getUserInfo(this);
if(userInfo!=null){
etNumber.setText(userInfo.get("number"));
etPwd.setText(userInfo.get("pwd"));
}
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//1.取出账号，密码
String Number=etNumber.getText().toString();
String Pwd=etPwd.getText().toString();
//判断是否有值，弹出吐司
if(TextUtils.isEmpty(Number) || TextUtils.isEmpty(Pwd)){
Toast.makeText(this, "请正确数据账号、密码", Toast.LENGTH_SHORT).show();
return;
}
//2.判断cb是否被选中
if(cbRemerber.isChecked()){
Log.i(TAG, "记住密码"+Number+","+Pwd);
boolean isSuccess=UtilsOfSDCard.saveUserInfo(this,Number, Pwd);
if(isSuccess)
Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
else
Toast.makeText(this, "保存失败", Toast.LENGTH_SHORT).show();
}
//3.登陆成功
Toast.makeText(this, "登陆成功", Toast.LENGTH_SHORT).show();
}
}
UtilsOfSDCard类：
public class UtilsOfSDCard {
//保存信息到sd卡
public static boolean saveUserInfo(Context context, String number,String pwd){
try {
//获取SD卡状态
String state=Environment.getExternalStorageState();
//判断SD卡状态
if(!Environment.MEDIA_MOUNTED.equals(state))
{
return false;
}
//动态获取SD卡路径
File sdCardFile = Environment.getExternalStorageDirectory();
File f=new File(sdCardFile,"qqLogin1.txt");
//写入流
FileOutputStream fos=new FileOutputStream(f);
String data=number+"##"+pwd;
fos.write(data.getBytes());
fos.flush();
fos.close();
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
//返回信息
public static Map<String,String> getUserInfo(Context context){
try {
String state=Environment.getExternalStorageState();
if(!Environment.MEDIA_MOUNTED.equals(state))
{
return null;
}
File sdCartFile=Environment.getExternalStorageDirectory();
File f=new File(sdCartFile,"qqLogin1.txt");
BufferedReader br=new BufferedReader(new InputStreamReader(new FileInputStream(f)));
String text=br.readLine();
br.close();
if(!TextUtils.isEmpty(text)){
Map<String,String> userInfoMap=new HashMap<String,String>();
String[] split = text.split("##");
userInfoMap.put("number", split[0]);
userInfoMap.put("pwd", split[1]);
Log.w("UtilsOfSDCard", split[0]+","+split[1]);
return userInfoMap;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
Utils类：
public class Utils {
/*
* 保存用户信息
* */
public static boolean saveUserInfo(String number,String pwd){
try {
String path="/data/data/com.cui.qqlogin/QQLogin.txt";
//写入流
FileOutputStream fs=new FileOutputStream(path);
String data=number+"##"+pwd;
fs.write(data.getBytes());
fs.flush();
fs.close();
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
public static boolean saveUserInfo(Context context, String number,String pwd){
try {
//动态获取文件路径
File filesDir = context.getFilesDir();
File f=new File(filesDir,"QQLogin.txt");
//写入流
FileOutputStream fs=new FileOutputStream(f);
String data=number+"##"+pwd;
fs.write(data.getBytes());
fs.flush();
fs.close();
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
public static Map<String,String> getUserInfo(){
try {
String path="/data/data/com.cui.qqlogin/QQLogin.txt";
//输出流
FileInputStream fis=new FileInputStream(path);
//字符流
BufferedReader reader=new BufferedReader(new InputStreamReader(fis));
String text = reader.readLine();
if(!TextUtils.isEmpty(text)){
String[] split=text.split("##");
Map<String,String> userofMap=new HashMap<String,String>();
userofMap.put("number", split[0]);
userofMap.put("pwd", split[1]);
return userofMap;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
public static Map<String,String> getUserInfo(Context context){
try {
//String path="/data/data/com.cui.qqlogin/QQLogin.txt";
//动态获取文件路径
File filesDir = context.getFilesDir();
File f=new File(filesDir,"QQLogin.txt");
//输出流
FileInputStream fis=new FileInputStream(f);
//字符流
BufferedReader reader=new BufferedReader(new InputStreamReader(fis));
String text = reader.readLine();
reader.close();
if(!TextUtils.isEmpty(text)){
String[] split=text.split("##");
Map<String,String> userofMap=new HashMap<String,String>();
userofMap.put("number", split[0]);
userofMap.put("pwd", split[1]);
return userofMap;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
====================插播快捷键
Ctrl+N 快速新建
Ctrl+H 选中项目中搜索
Ctrl+L 跳转到指定行
Ctrl+F 在文本中查找内容
====================
文件存储地址:
this.getFilesDir(); // /data/data/包名/files
this.getCacheDir(); // /data/data/包名/cache
openFileOutput("aa.txt", 0); /data/data/包名/files/aa.txt
context.getSharedPreferences("cuidemo", context.MODE_PRIVATE); /data/data/包名/shared_prefs/cuidemo.xml
public class UtilsOfSharedPreferences {
//保存信息到sd卡
public static boolean saveUserInfo(Context context, String number,String pwd){
try {
sp=context.getSharedPreferences("cuidemo", context.MODE_PRIVATE);
//获得一个编辑对象
Editor edit = sp.edit();
edit.putString("number", number);
edit.putString("pwd", pwd);
edit.commit();
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
//返回信息
public static Map<String,String> getUserInfo(Context context){
SharedPreferences sp=context.getSharedPreferences("cuidemo", context.MODE_PRIVATE);
String number=sp.getString("number", null);
String pwd=sp.getString("pwd", null);
if(!TextUtils.isEmpty(number)&& !TextUtils.isEmpty(pwd)){
Map<String,String> userInfoMap=new HashMap<String,String>();
userInfoMap.put("number", number);
userInfoMap.put("pwd", pwd);
return userInfoMap;
}
return null;
}
}
权限相关:
1. 私有文件
Context.MODE_PRIVATE
2. 可读文件
Context.MODE_WORLD_READABLE
3. 可写文件
Context.MODE_WORLD_WRITEABLE
4. 可读可写文件.
Context.MODE_WORLD_WRITEABLE+Context.MODE_WORLD_READABLE
权限二进制图解：
