Question

当用户在我的android应用中登录时，我保存服务器以共享偏好返回令牌，并且仅在注销时清除它。但是当我在一段时间后关闭应用时，它需要再次登录。这是我的共享偏好类

        package com.example.narmail.truck30mint.Api.models.UserModels;

        import android.content.Context;
        import android.content.SharedPreferences;

        import com.google.gson.annotations.Expose;
        import com.google.gson.annotations.SerializedName;

        public class User {

          public static   SharedPreferences sharedPreferences;
            Context context;
            @SerializedName("token")
            @Expose
            private static String token;

            /**
             * No args constructor for use in serialization
             *
             */
            public User(Context context) {
                super();
                this.context = context;
                sharedPreferences  = context.getSharedPreferences("user_token",Context.MODE_PRIVATE);
            }

            /**
             *
             * @param //token
             */
          /*  public User(String token) {
                super();
                this.token = token;
            }*/

            public static String getToken() {

                if(sharedPreferences.getString(token,null) != null){
                token = sharedPreferences.getString(token,null);
                };
                return token;
            }

            public void setToken(String token) {
                this.token = token;
                sharedPreferences.edit().putString("token",token).apply();
            }
            public static void removeToken(){
                if(sharedPreferences.contains("token")){
                    SharedPreferences.Editor editor = sharedPreferences.edit();
                    editor.remove("token").commit();
                    token = null;   //Missing this
                    System.out.println("shared preference deleting ");
                }else{
                    System.out.println("not contain key token ");
                }
            }

        }

这是主要活动，用于检查令牌是否存储在共享首选项中

package com.example.narmail.truck30mint.Api.Activities;

        import android.app.Activity;
        import android.content.Context;
        import android.content.Intent;
        import android.location.Location;
        import android.location.LocationListener;
        import android.location.LocationManager;
        import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.Button;

        import com.example.narmail.truck30mint.Api.models.UserModels.User;
        import com.example.narmail.truck30mint.R;

        public class MainActivity extends AppCompatActivity {
            public String token = null;
            private Context context;
            public static Activity activity = null;

        //save the context received via constructor in a local variable

           /* public MainActivity(Context context) {
                this.context = context;
            }*/
            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                User user = new User(getApplicationContext());
                activity = this;
                token = user.getToken();
                System.out.println("in main activity token is "+token);
                if (token != null && !token.equalsIgnoreCase("")) {
                    Intent a = new Intent(MainActivity.this, DashboardActivity.class);
                    startActivity(a);
                }else if(token == null){
                    setContentView(R.layout.activity_main);
                    Button btnNewUser = findViewById(R.id.newUser);
                    Button btnExistingUser = findViewById(R.id.existingUser);

                    btnExistingUser.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            Intent a = new Intent(MainActivity.this, LoginActivity.class);
                            startActivity(a);
                          //  MainActivity.this.finish();
                        }
                    });

                    btnNewUser.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            Intent i = new Intent(MainActivity.this, RegisterActivity.class);
                            startActivity(i);
                           // MainActivity.this.finish();
                        }
                    });
                }



                    // Acquire a reference to the system Location Manager
                    LocationManager locationManager =
                            (LocationManager) getSystemService(Context.LOCATION_SERVICE);
                    // Define a listener that responds to location updates
                    LocationListener locationListener = new LocationListener() {
                        public void onLocationChanged(Location location) {
                            // Called when a new location is found by the network location provider.
                           String lat = Double.toString(location.getLatitude());
                          String  lon = Double.toString(location.getLongitude());
                        }

                        public void onStatusChanged(String provider, int status, Bundle extras) {}
                        public void onProviderEnabled(String provider) {}
                        public void onProviderDisabled(String provider) {}
                    };
                 /*   if(checkPermission(Location,
                            android.Manifest.permission.ACCESS_FINE_LOCATION)){
                        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);

                    }*/
                    // Register the listener with the Location Manager to receive location updates
            }
        }

如果登录成功，我将通过此方法存储共享首选项

 User user= new User(loginContext);
                    user.setToken(token);

Answer 1

在类User的setToken（String token）方法中，尝试使用.commit（）方法代替.apply（）。它将返回布尔值，给出有关登录的确认。不确定，但是应该可以。

Answer 2

我自己解决了这是修改过的user.java文件

    package com.example.narmail.truck30mint.Api.models.UserModels;

    import android.content.Context;
    import android.content.SharedPreferences;

    import com.google.gson.annotations.Expose;
    import com.google.gson.annotations.SerializedName;

    public class User {

      public static   SharedPreferences sharedPreferences;
        Context context;
        @SerializedName("token")
        @Expose
        private static String token;

        /**
         * No args constructor for use in serialization
         *
         */
        public User(Context context) {
            super();
            this.context = context;
            sharedPreferences  = context.getSharedPreferences("user_token",Context.MODE_PRIVATE);
        }

        /**
         *
         * @param //token
         */
       /* public User(String token) {
            super();
            this.token = token;
        }*/

        public static String getToken() {

            if(sharedPreferences.getString("token",null) != null){
            token = sharedPreferences.getString("token",null);
            };
            return token;
        }

        public void setToken(String token) {
            this.token = token;
            sharedPreferences.edit().putString("token",token).commit();
        }
        public static void removeToken(){
            if(sharedPreferences.contains("token")){
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.remove("token").commit();
                token = null;   //Missing this
                System.out.println("shared preference deleting ");
            }else{
                System.out.println("not contain key token ");
            }
        }

    }

应用会在一段时间后自动注销

2 个答案: