模拟QQ登录(记录账号和密码)：

1.文件存储到文件中：

/** * 文件存储 *@author Administrator * */

public class Utils {

/** * 保存用户信息到文件 *@param number *@param password *@return true 成功 */

public static boolean saveUserInfo(String number, String password) {

try {

String path = "/data/data/com.itheima.qqlogin/itheima.txt";

FileOutputStream fos = new FileOutputStream(path);

// 307966990##123123

String data = number + "##" + password;

fos.write(data.getBytes());

fos.flush();

fos.close();

return true;

} catch (Exception e) {

e.printStackTrace();

}

return false;

}

/** * 保存用户信息 *@param number *@param password *@return true 成功 */

public static boolean saveUserInfo(Context context, String number, String password) {

try {

// String path = "/data/data/com.itheima.qqlogin/itheima.txt";

// File filesDir = context.getFilesDir();//存储用户信息到file文件中

File filesDir = context.getCacheDir();//存储用户信息到缓存

File f = new File(filesDir, "itheima.txt");

FileOutputStream fos = new FileOutputStream(f);

// 307966990##123123

String data = number + "##" + password;

fos.write(data.getBytes());

fos.flush();

fos.close();

return true;

} catch (Exception e) {

e.printStackTrace();

}

return false;

}

/** * 返回用户信息(从文件中读取数据) *@return */

public static Map getUserInfo() {

try {

String path = "/data/data/com.itheima.qqlogin/itheima.txt";

FileInputStream fis = new FileInputStream(path);

// 字符流对象(字符缓冲流是高效流)

BufferedReader reader = new BufferedReader(new InputStreamReader(fis));

// 307966990##123123

String text = reader.readLine();

if(!TextUtils.isEmpty(text)) {

String[] split = text.split("##");

Map userInfoMap = new HashMap();

userInfoMap.put("number", split[0]);

userInfoMap.put("password", split[1]);

return userInfoMap;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

/** * 返回用户信息 *@return */

public static Map getUserInfo(Context context) {

try {

// String path = "/data/data/com.itheima28.qqlogin/itheima28.txt";

// File filesDir = context.getFilesDir();

File filesDir = context.getCacheDir();

File f = new File(filesDir, "itheima.txt");

FileInputStream fis = new FileInputStream(f);

// 字符流对象

BufferedReader reader = new BufferedReader(new InputStreamReader(fis));

// 307966990##123123

String text = reader.readLine();

if(!TextUtils.isEmpty(text)) {

String[] split = text.split("##");

Map userInfoMap = new HashMap();

userInfoMap.put("number", split[0]);

userInfoMap.put("password", split[1]);

return userInfoMap;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

2.文件存储到SD卡中：

/** * 保存用户信息到sd卡 *@param number *@param password *@return true 成功 */

public static boolean saveUserInfo(Context context, String number, String password) {

try {

// 判断当前的手机是否有sd卡

String state = Environment.getExternalStorageState();

if(!Environment.MEDIA_MOUNTED.equals(state)) {

// 已经挂载了sd卡

return false;

}

File sdCardFile = Environment.getExternalStorageDirectory();

File file = new File(sdCardFile, "itheima.txt");

FileOutputStream fos = new FileOutputStream(file);

String data = number + "##" + password;

fos.write(data.getBytes());

fos.flush();

fos.close();

return true;

} catch (Exception e) {

e.printStackTrace();

}

return false;

}

/** * 到sd卡获取用户信息 *@return */

public static Map getUserInfo(Context context) {

try {

// 判断当前的手机是否有sd卡

String state = Environment.getExternalStorageState();

if(!Environment.MEDIA_MOUNTED.equals(state)) {

// 已经挂载了sd卡

return null;

}

File sdCardFile = Environment.getExternalStorageDirectory();

File file = new File(sdCardFile, "itheima.txt");

//字符缓冲流(高效流)从SD卡中读文件

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));

String text = br.readLine();

br.close();

if(!TextUtils.isEmpty(text)) {

Map userInfoMap = new HashMap();

String[] split = text.split("##");

userInfoMap.put("number", split[0]);

userInfoMap.put("password", split[1]);

return userInfoMap;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

3.文件存储：用sharedpreferences保存用户信息：

/** * 用sharedpreferences保存用户信息 *@param number *@param password *@return true 成功 */

public static boolean saveUserInfo(Context context, String number, String password) {

try {

// /data/data/包名/shared_prefs/itheima

SharedPreferences sp = context.getSharedPreferences("itheima", Context.MODE_PRIVATE);

// 获得一个编辑对象

Editor edit = sp.edit();

// 存数据

edit.putString("number", number);

edit.putString("password", password);

// 提交, 数据真正存储起来了.

edit.commit();

return true;

} catch (Exception e) {

e.printStackTrace();

}

return false;

}

/** * 到sd卡获取用户信息(存储到一个集合中，然后再返回) *@return */

public static Map getUserInfo(Context context) {

SharedPreferences sp = context.getSharedPreferences("itheima", Context.MODE_PRIVATE);

String number = sp.getString("number", null);

String password = sp.getString("password", null);

if(!TextUtils.isEmpty(number) && !TextUtils.isEmpty(password)) {

Map userInfoMap = new HashMap();

userInfoMap.put("number", number);

userInfoMap.put("password", password);

return userInfoMap;

}

return null;

}

4.实现登录的业务逻辑：

public class MainActivity extends Activity implements OnClickListener {

private static final String TAG = "MainActivity";

private EditText etNumber;

private EditText etPassword;

private CheckBox cbRemerberPWD;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

etNumber = (EditText) findViewById(R.id.et_number);

etPassword = (EditText) findViewById(R.id.et_password);

cbRemerberPWD = (CheckBox) findViewById(R.id.cb_remerber_pwd);

Button btnLogin = (Button) findViewById(R.id.btn_login);

btnLogin.setOnClickListener(this);

// 回显数据

Map userInfoMap = UtilsOfSharedPreferences.getUserInfo(this);

if(userInfoMap != null) {

etNumber.setText(userInfoMap.get("number"));

etPassword.setText(userInfoMap.get("password"));

}

}

@Override

public void onClick(View v) {

// 执行登录的操作

// 1. 取出号码和密码

String number = etNumber.getText().toString();

String password = etPassword.getText().toString();

if(TextUtils.isEmpty(number) || TextUtils.isEmpty(password)) {

// 弹出吐司

Toast.makeText(this, "请正确输入", Toast.LENGTH_SHORT).show();

return;

}

// 2. 判断记住密码是否被选中, 如果被选中, 存起来

if(cbRemerberPWD.isChecked()) {

// 当前需要记住密码

Log.i(TAG, "记住密码: " + number + ", " + password);

boolean isSuccess = UtilsOfSharedPreferences.saveUserInfo(this, number, password);

if(isSuccess) {

Toast.makeText(this, "保存成功", 0).show();

} else {

Toast.makeText(this, "保存失败", 0).show();

}

}

// 3. 登陆成功

Toast.makeText(this, "登录成功", 0).show();

}

5.文件存储：

this.getFilesDir();// /data/data/包名/files.

this.getCacheDir();// /data/data/包名/cache.

SharedPreferences存储路径: /data/data/包名/shared_prefs/.

SD卡： // /mnt/sdcard.