Android登录仅与列表的最后一个成员一起使用

Question

private String usernameApi;
private String passwordApi;
private EditText usernameet;
private EditText passwordet;
private Button login_btn;
private List<User> users = new ArrayList<User>();

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

    usernameet = findViewById(R.id.username_etext);
    passwordet = findViewById(R.id.password_etext);
    login_btn = findViewById(R.id.login_btn);

    getRetrofitArray();
}

从Restful服务获取JSONArray的方法

void getRetrofitArray() {
    String BASE_URL = 

"http://192.168.0.18:8080/";
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    RestAPI service = retrofit.create(RestAPI.class);

    Call<JsonArray> jsonCall = service.getUsers();

    jsonCall.enqueue(new Callback<JsonArray>() {
        @Override
        public void onResponse(Call<JsonArray> call, Response<JsonArray> response) {

                String userData = response.body().toString();
                Log.i("onResponse", userData);                                       
                Type listType = new TypeToken<List<User>>() {}.getType();
                List<User> users = new Gson().fromJson(userData, listType);
                Log.i("onResponse", users.toString());

                for(int i = 0; i < users.size(); i++) {
                    usernameApi = users.get(i).getUsername();
                    passwordApi = users.get(i).getPassword();
                }


            login_btn.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            login(usernameet.getText().toString(), passwordet.getText().toString());
                        }
                    });



        }

        @Override
        public void onFailure(Call<JsonArray> call, Throwable t) {

        }
    });
}

最后是登录方法

public void login(String usernameInput, String passwordInput) {

    if ((usernameInput.equals(usernameApi)) && (passwordInput.equals(passwordApi))) {
        Intent i = new Intent(this, PostsActivity.class);
        startActivity(i);
        finish();
    }else{
        login_btn.setEnabled(false);
    }

}    

来自回复的userData是[{“id”：1，“name”：“Radovan”，“username”：“1”，“password”：“1”，“photo”：“slika”}， { “ID”：2， “名”： “米洛”， “用户名”： “2”， “密码”： “2”， “照片”： “SLIKA”}， { “ID”：3 “名称”： “Zivan”， “用户名”： “3”， “密码”： “3”， “照片”： “SLIKA”}]

Answer 1

定义此变量：

private List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();

试试这段代码：

private String usernameApi;
private String passwordApi;
private EditText usernameet;
private EditText passwordet;
private Button login_btn;
private List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();

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

    usernameet = findViewById(R.id.username_etext);
    passwordet = findViewById(R.id.password_etext);
    login_btn = findViewById(R.id.login_btn);
    login_btn.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        login(usernameet.getText().toString(), passwordet.getText().toString());
                    }
                });
    getRetrofitArray();
}

和

void getRetrofitArray() {
    String BASE_URL = "http://192.168.0.18:8080/";
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    RestAPI service = retrofit.create(RestAPI.class);

    Call<JsonArray> jsonCall = service.getUsers();

    jsonCall.enqueue(new Callback<JsonArray>() {
        @Override
        public void onResponse(Call<JsonArray> call, Response<JsonArray> response) {

                String userData = response.body().toString();
                listOfMaps = new ArrayList<Map<String, String>>();
                JSONArray temp = new JSONArray(userData);

        for (int i = 0; i < temp.length(); i++) {
            JSONObject row = (JSONObject) temp.get(i);
            int id = row.getInt("id");
            String name = row.getString("name");
            String username = row.getString("username");
            String password = row.getString("password");
            String photo = row.getString("photo");

            HashMap<String, String> user_exist = new HashMap<String, String>();
            user_exist.put("id",String.valueOf("id"));
            user_exist.put("name",name);
            user_exist.put("username",username);
            user_exist.put("password",password);
            user_exist.put("photo",photo);
            listOfMaps.add(user_exist);

        }





        }

        @Override
        public void onFailure(Call<JsonArray> call, Throwable t) {

        }
    });
}

功能：

public void login(String usernameInput, String passwordInput) {
        boolean exist = false;
        try{
            for(int i=0; i<= listOfMaps.size(); i++){
                if(listOfMaps.get(i).get("username").equals(usernameInput) && listOfMaps.get(i).get("password").equals(passwordInput)){
                    exist = true;

                    // save in shared preferences
                    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
                    SharedPreferences.Editor editor = sharedPreferences.edit();
                    editor.putString("username", listOfMaps.get(i).get("username"));
                    editor.putString("password", listOfMaps.get(i).get("password"));
                    editor.putString("id", listOfMaps.get(i).get("id") );
                    editor.putString("photo", listOfMaps.get(i).get("photo") );
                    editor.commit();

                    break;
                }
            }
        }catch (Exception ex){
            ex.printStackTrace();
        }
        if(exist){
            Intent i = new Intent(this, PostsActivity.class);
            startActivity(i);
            finish();
        }else {
            login_btn.setEnabled(false);
        }
    }

要检索其他活动中的数据，请在PostsActivity中尝试此代码：

SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(PostsActivity.this);
    String username = sp.getString("id_user", "");
    String password = sp.getString("password", "");
    String id = sp.getString("id", "");
    String photo = sp.getString("photo", "");