Android: almacenamiento de archivos SharePreference (1)

1. Introducción básica

• Pertenece a un marco de almacenamiento ligero
• Guardar como clave-valor
• Guardar en el directorio data / data / package name / shared_prefs
• Tipos de datos que se pueden guardar: booleanos, flotantes, ints, longs, strings

Segundo, los pasos

• Obtener objeto SharedPreferences
• Leer datos a través del objeto SharedPreferences
• Almacenar datos a través del objeto SharedPreferences

public class MainActivity extends AppCompatActivity {
    
    
    private String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //取值
        SharedPreferences settings = getSharedPreferences("login", 0);
        String username = settings.getString("username","");
        Long password = settings.getLong("password",0);
        float salary = settings.getFloat("salary",0f);
        Boolean sex = settings.getBoolean("sex",false);
        Log.i(TAG,"--------"+username);
        Log.i(TAG,"--------"+password);
        Log.i(TAG,"--------"+salary);
        Log.i(TAG,"--------"+sex);
    }

    @Override
    protected void onStop(){
    
    
        super.onStop();
        //写值
        Map<String,Object> map = new HashMap<>();
        map.put("username","zhangsan");
        map.put("password",123456l);
        map.put("salary",1234.34f);
        map.put("sex",false);
        //文件名不需要后缀名，默认xml
        savaSharedPreferences("login",map);
    }

    public Boolean savaSharedPreferences(String fileName, Map<String,Object> map){
    
    
    	//获取SharedPreferences对象
        SharedPreferences preferences = getSharedPreferences(fileName,Context.MODE_PRIVATE);
        SharedPreferences.Editor edit = preferences.edit();
        for (Map.Entry<String,Object> entry:map.entrySet()){
    
    
            String key = entry.getKey();
            Object values = entry.getValue();
            if (values instanceof String){
    
    
                edit.putString(key,(String)values);
            } else if(values instanceof Boolean){
    
    
                edit.putBoolean(key,(Boolean)values);
            } else if(values instanceof Long){
    
    
                edit.putLong(key,(Long)values);
            } else if (values instanceof Float){
    
    
                edit.putFloat(key,(Float)values);
            }else if(values instanceof Integer){
    
    
                edit.putInt(key,(Integer)values);
            }
        }
        //提交
        boolean commit = edit.commit();
        return commit;
    }
}

El formato del archivo guardado es el siguiente:

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
    <string name="password">1236</string>
    <boolean name="isRemember" value="true" />
    <boolean name="forget" value="false" />
    <string name="userName">张三</string>
</map>

Tres, caso

Descripción del caso : después de que ingresemos el nombre de usuario y la contraseña, haga clic en Recordar contraseña, luego la contraseña de la cuenta se mostrará de forma predeterminada cuando iniciemos sesión la próxima vez. Si no marca Recordar contraseña, deberá ingresarla usted mismo la próxima vez. te registras

Las representaciones son las siguientes: el

código es el siguiente:

<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="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/editTextuserName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="用户名"
        android:inputType="text" />

    <EditText
        android:id="@+id/editTextPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="密码"
        android:inputType="textPassword" />
    <CheckBox
            android:id="@+id/isRemember"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="记住密码" />
    <Button
        android:id="@+id/btnLogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="登录" />
    <Button
        android:id="@+id/btnRegister"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="注册" />
</LinearLayout>

public class MainActivity extends PreferenceActivity {
    
    
    private String TAG = "MainActivity";
    private EditText edtUserName,edtPassWord;
    private Button btnLogin,btnRegister;
    private CheckBox isRemember;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findView();
        //获取文件数据
        Map<String, ?> map = getSharePreference();
        if (map != null && !map.isEmpty()){
    
    
            String userName = map.get("userName").toString().trim();
            String password = map.get("password").toString().trim();
            Boolean isBeRe = (Boolean) map.get("isRemember");
            Boolean isforget = (Boolean) map.get("forget");
            edtUserName.setText(userName);
            edtPassWord.setText(password);
            isRemember.setChecked(isBeRe);
        }
        //登录点击事件
        btnLogin.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                Map<String,Object> map = new HashMap<>();
                //是否勾选记住密码
                if (isRemember.isChecked()){
    
    
                    map.put("userName",edtUserName.getText().toString());
                    map.put("password",edtPassWord.getText().toString());
                    map.put("isRemember",isRemember.isChecked());
                    savaSharePreference(map);
                }else{
    
    
                    map.put("userName","");
                    map.put("password","");
                    map.put("isRemember",isRemember.isChecked());
                    savaSharePreference(map);
                }
            }
        });
    }

    public void findView(){
    
    
        edtUserName = findViewById(R.id.editTextuserName);
        edtPassWord = findViewById(R.id.editTextPassword);
        btnLogin = findViewById(R.id.btnLogin);
        isRemember = findViewById(R.id.isRemember);
    }

    /**
     * 将数据保存到文件
     * @param map 数据内容
     * @return
     */
    public boolean savaSharePreference(Map<String,Object> map){
    
    
        //获取SharedPreferences对象
        SharedPreferences preferences = getSharedPreferences("login",MODE_PRIVATE);
        SharedPreferences.Editor edit = preferences.edit();
        for (Map.Entry<String,Object> entry:map.entrySet()){
    
    
            String key = entry.getKey();
            Object values = entry.getValue();
            if (values instanceof String){
    
    
                edit.putString(key,(String)values);
            } else if(values instanceof Boolean){
    
    
                edit.putBoolean(key,(Boolean)values);
            } else if(values instanceof Long){
    
    
                edit.putLong(key,(Long)values);
            } else if (values instanceof Float){
    
    
                edit.putFloat(key,(Float)values);
            }else if(values instanceof Integer){
    
    
                edit.putInt(key,(Integer)values);
            }
        }
        boolean flag = edit.commit();
        return flag;
    }

    /*
    获取文件内容
     */
    public Map<String, ?> getSharePreference(){
    
    
        SharedPreferences preferences = getSharedPreferences("login",MODE_PRIVATE);
        Map<String, ?> map = preferences.getAll();
        return map;
    }
}