[移动开发]android文件存储和SharedPreferences存储实例

该实例为课程作业，请尊重劳动成果。

演示

【文件存储】中查看设备保存的文件：

目录

activity_main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#E6E6E6"
    android:orientation="vertical"
    android:padding="10dp"
    tools:context=".MainActivity">

    <ImageView
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:layout_centerHorizontal="true"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="30dp"
        android:src="@drawable/head" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:background="@android:color/white"
        android:orientation="horizontal">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="账号:"
            android:textColor="#000"
            android:textSize="20sp" />
        <EditText
            android:id="@+id/et_account"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:background="@null"
            android:padding="10dp" />
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:background="@android:color/white"
        android:orientation="horizontal">
        <TextView
            android:id="@+id/tv_password"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="密码:"
            android:textColor="#000"
            android:textSize="20sp" />
        <EditText
            android:id="@+id/et_password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:background="@null"
            android:inputType="textPassword"
            android:padding="10dp" />
    </LinearLayout>
    <Button
        android:id="@+id/btn_login"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="25dp"
        android:background="#3C8DC4"
        android:text="登录"
        android:textColor="@android:color/white"
        android:textSize="20sp" />


</LinearLayout>

MainActivity

/**
 * 文件存储和SharedPreferences存储实例
 */
public class MainActivity extends AppCompatActivity {
    private EditText et_account, et_password; //账号输入框、密码输入框
    private Button loginBtn; //登录按钮

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        et_account = findViewById(R.id.et_account);
        et_password = findViewById(R.id.et_password);
        loginBtn = findViewById(R.id.btn_login);
        //点击监听事件
        loginBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                switch (view.getId()) {
                    case R.id.btn_login:
                        //当点击登录按钮时，获取界面上输入的 QQ 账号和密码
                        String account = et_account.getText().toString().trim();
                        String password = et_password.getText().toString();
                        //检验输入的账号和密码是否为空
                        if (TextUtils.isEmpty(account)) {
                            Toast.makeText(getApplicationContext(), "请输入 QQ 账号", Toast.LENGTH_SHORT).show();
                            return;
                        }
                        if (TextUtils.isEmpty(password)) {
                            Toast.makeText(getApplicationContext(), "请输入密码", Toast.LENGTH_SHORT).show();
                            return;
                        }
                        //文件存储
                        //saveOfFile(account,password);

                        //SharedPreferences存储
                        saveOfSharedPreferences(account,password);
                        break;

                }
            }
        });
    }

    //SharedPreferences存储
    private void saveOfSharedPreferences(String account, String password) {
        //获取 QQ 账号和密码信息
        SharedPreferences userInfo=SPSaveQQ.getUserInfo(getApplicationContext());
        if (userInfo.getString("username", "") != null&&userInfo.getString("pwd", "") != null) {
            String username = userInfo.getString("username", "");//读取账号
            String pwd = userInfo.getString("pwd", "");//读取密码
            Log.i("user", "读取用户信息");
            Log.i("user", "username:" + username + "， pwd:" + pwd);
            if (username.equals(account) && pwd.equals(password)) {
                Toast.makeText(getApplicationContext(), username+"登录成功!", Toast.LENGTH_SHORT).show();
            }else {
                Log.i("user", "用户或密码错误！");
                //保存用户信息
                boolean isSaveSuccess = SPSaveQQ.saveUserInfo(getApplicationContext(), account, password);
                if (isSaveSuccess) {
                    Toast.makeText(getApplicationContext(), "保存成功!", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(getApplicationContext(), "保存失败!", Toast.LENGTH_SHORT).show();
                }
            }
        }else{
            //保存用户信息
            boolean isSaveSuccess = SPSaveQQ.saveUserInfo(getApplicationContext(), account, password);
            if (isSaveSuccess) {
                Toast.makeText(getApplicationContext(), "保存成功!", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(getApplicationContext(), "保存失败!", Toast.LENGTH_SHORT).show();
            }
        }
    }

    //文件存储
    private void saveOfFile(String account, String password) {
        //获取 QQ 账号和密码信息
        Map<String, String> userInfo = FileSaveQQ.getUserInfo(getApplicationContext());
        if (userInfo != null) {
            //将获取的账号显示到界面上
            et_account.setText(userInfo.get("account"));
            //将获取的密码显示到界面上
            et_password.setText(userInfo.get("password"));
            Toast.makeText(getApplicationContext(), userInfo.get("account")+"登录成功!", Toast.LENGTH_SHORT).show();
        }else{
            //保存用户信息
            boolean isSaveSuccess = FileSaveQQ.saveUserInfo(getApplicationContext(), account, password);
            if (isSaveSuccess) {
                Toast.makeText(getApplicationContext(), "保存成功!", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(getApplicationContext(), "保存失败!", Toast.LENGTH_SHORT).show();
            }
        }
    }

}

FileSaveQQ

/**
 * 实现 QQ 账号与密码的文件存取与读取功能
 */
public class FileSaveQQ {
    /**
     * 保存用户信息
     * @param context
     * @param account 账号
     * @param password 密码
     * @return
     */
    public static boolean saveUserInfo(Context context, String account, String password) {
        //文件的输出流对象
        FileOutputStream fos = null;
        try {
            //获取文件的输出流对象 fos,该文件只能被当前程序读写
            fos = context.openFileOutput("user.txt",
                    Context.MODE_PRIVATE);
            //将数据转换为字节码的形式写入 user.txt 文件中
            fos.write((account + ":" + password).getBytes());
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }finally {
            try {
                if(fos != null){
                    fos.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 从 user.txt 文件中获取存储的用户信息
     * @param context
     * @return
     */
    public static Map<String, String> getUserInfo(Context context) {
        String content = "";
        //文件的输入流对象
        FileInputStream fis = null;
        try {
            //获取文件的输入流对象 fis
            fis = context.openFileInput("user.txt");
            //将输入流对象中的数据转换为字节码的形式
            byte[] buffer = new byte[fis.available()];
            //通过 read()方法读取字节码中的数据
            fis.read(buffer);
            //将获取的字节码转换为字符串
            content = new String(buffer);
            Map<String, String> userMap = new HashMap<String, String>();
            String[] infos = content.split(":");
            //放入账号密码
            userMap.put("account", infos[0]);
            userMap.put("password", infos[1]);
            Log.i("user", "读取用户信息");
            Log.i("user", "account:" + infos[0] + "， password:" + infos[1]);
            return userMap;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            try {
                if (fis != null) {
                    fis.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

SPSaveQQ

/**
 * 实现 QQ 账号与密码SharedPreferences的存取与读取功能
 */
public class SPSaveQQ {
    /**
     * 保存用户信息
     */
    public static boolean saveUserInfo(Context context, String account, String password){
        SharedPreferences sharedPreferences = null;
        try {
            sharedPreferences = context.getSharedPreferences("user", Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = sharedPreferences.edit();//获取编辑器
            editor.putString("username", account);
            editor.putString("pwd", password);
            editor.commit();//提交修改
            return true;
        }catch (Exception e){
            e.printStackTrace();
            return false;
        }finally {
            if(sharedPreferences != null){
                return true;
            }
            return false;
        }
    }
    
    /**
     * 读取用户信息
     */
    public static SharedPreferences getUserInfo(Context context){
        SharedPreferences userInfo = context.getSharedPreferences("user", Context.MODE_PRIVATE);
        return userInfo;
    }
}

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