我可以使用共享偏好。我可以存储和检索共享首选项文件夹中的数据。但是在注销时我无法将共享首选项设置为null。请指导我如何在登录中维护会话。
LoginActivity.Java:- 这里我正在处理登录表单。在比较电子邮件ID和密码后，数据存储在共享首选项中。我也能够检索数据。但是如何维持会话？
package com.kezinking.nupur.kezinking;
import android.animation.ObjectAnimator;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.Space;
import android.widget.TextView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import static android.R.attr.password;
/**
* Created by Nupur on 8/2/2016.
*/
public class LoginActivity extends AppCompatActivity {
public static final String MY_JSON = "MY_JSON";
private static final String JSON_URL = "http://kezinking.com/AndroidLogin";
EditText input_email, input_password;
Button btn_login, btnContactUs, btnWorkhr, btnDeltime, btnMoneyBack;
TextView link_signup, textViewJSON, txtcheck,value;
private static Boolean flag = false;
public static final String MyPREFERENCES = "MyPrefs" ;
public static final String Name = "nameKey";
public static final String Phone = "phoneKey";
public static final String emailkey = "emailKey";
public static final String UserId = "user_id";
SharedPreferences sharedpreferences;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
btn_login = (Button) findViewById(R.id.btn_login);
link_signup = (TextView) findViewById(R.id.link_signup);
input_email = (EditText) findViewById(R.id.input_email);
input_password = (EditText) findViewById(R.id.input_password);
textViewJSON = (TextView) findViewById(R.id.textViewJSON);
// value=(TextView)findViewById(R.id.value);
txtcheck = (TextView) findViewById(R.id.txtcheck);
value = (TextView) findViewById(R.id.value);
//shared preference folder
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
//onClick Event on login Button
btn_login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
login();
}
});
link_signup.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(LoginActivity.this, SignupActivity.class);
startActivity(intent);
LoginActivity.this.getIntent();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void login() {
if (!validate()) {
onLoginFailed();
return;
} else {
getJSON(JSON_URL);
}
}
public void getJSON(String url) {
class GetJSON extends AsyncTask<String, Void, String> {
ProgressDialog loading;
@Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(LoginActivity.this, "Please Wait...", null, true, true);
}
@Override
protected String doInBackground(String... params) {
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
//String result=null;
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json + "\n");
}
return sb.toString().trim();
} catch (Exception e) {
return null;
}
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
textViewJSON.setText(s);
String jsonString = textViewJSON.getText().toString();
String email = input_email.getText().toString();
String password = input_password.getText().toString();
/** md5(password); // Enrcypting the given password **/
// final String myResult = (email) + (password);
// String value = (String.valueOf(email + password));
// System.out.println(value);
// String value=(input_email.getText().toString()+input_password.getText().toString());
//String input_email = "";
//String input_password = "";
try {
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray result = jsonObject.getJSONArray("result");
//System.out.println("result " + result);
//iterate through json array and check if id is same with your search
//System.out.println("length " + result.length());
for (int i = 0; i < result.length(); i++) {
// System.out.println(i);
JSONObject item = result.getJSONObject(i);
String Email = item.getString("email");
String Password = item.getString("password");
//System.out.println("Email from json "+ Email);
//System.out.println("Password from json " + Password);
if (Email.equals(email) && Password.equals(password)) {
//System.out.println("Email from json"+ Email);
// System.out.println("Password from json" + Password);
String username=item.getString("username");
String userid=item.getString("user_id");
String phone_number=item.getString("con_no");
String emailSaved = item.getString("email");
// System.out.println("Email from json "+ Email);
// System.out.println("Password from json " + Password);
// System.out.println("username from json " + username);
// System.out.println("userid from json " + userid);
// System.out.println("phone_number from json " + phone_number);
SharedPreferences.Editor editor = sharedpreferences.edit();
// Store data in shared preference
editor.putString(Name, username);
editor.putString(Phone, phone_number);
editor.putString(UserId,userid);
editor.putString(emailkey, emailSaved);
editor.commit();
flag=true;
// Retrieve data from shared Preference folder
SharedPreferences prefs = getSharedPreferences(MyPREFERENCES, MODE_PRIVATE);
String show_name = prefs.getString("Name", username); // getting data-name from shared preference
String show_email=prefs.getString("emailkey", emailSaved); // retrieving data from shared preference folder
// Checking the values are coming correct from shared preference folder or not
System.out.println("Shared_preference-email " + show_email);
System.out.println("Shared_preference-username " + show_name);
// value.setText(restoredText);
onLoginSuccess();
break;
}
}
if(!flag){
onLoginFailed();
}
} catch (JSONException e) {
e.printStackTrace();
}
//here you can show the result
Log.v(this.getClass().getSimpleName(), "email = " + email);
Log.v(this.getClass().getSimpleName(), "password = " + password);
}
}
GetJSON gj = new GetJSON();
gj.execute(url);
}
/** private String md5(String password) {
MessageDigest digest;
try {
digest = MessageDigest.getInstance("MD5");
digest.reset();
digest.update(password.getBytes());
byte[] a = digest.digest();
int len = a.length;
StringBuilder sb = new StringBuilder(len << 1);
for (int i = 0; i < len; i++) {
sb.append(Character.forDigit((a[i] & 0xf0) >> 4, 16));
sb.append(Character.forDigit(a[i] & 0x0f, 16));
}
return sb.toString();
} catch (NoSuchAlgorithmException e)
{ e.printStackTrace(); }
System.out.print(password);
return password;
} **/
@Override
public void onBackPressed() {
// disable going back to the MainActivity
moveTaskToBack(true);
}
public void onLoginSuccess() {
btn_login.setEnabled(true);
if(sharedpreferences!=null){
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
LoginActivity.this.getIntent();
}
else
{
Toast.makeText(getBaseContext(), "Shared preference is null", Toast.LENGTH_LONG).show();
}
// finish();
}
public void onLoginFailed() {
Toast.makeText(getBaseContext(), "Login failed", Toast.LENGTH_LONG).show();
// btn_login.setEnabled(true);
}
public boolean validate() {
boolean valid = true;
String email = input_email.getText().toString();
String password = input_password.getText().toString();
if (email.isEmpty() || !android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches()) {
input_email.setError("enter a valid email address");
valid = false;
} else {
input_email.setError(null);
}
if (password.isEmpty() || password.length() < 4 || password.length() > 10) {
input_password.setError("between 4 and 10 alphanumeric characters");
valid = false;
} else {
input_password.setError(null);
}
return valid;
}
}
共享首选项sharedpreferences是全局变量所以我也可以在其他java类中使用这个变量吗？我想在logout java类中使用它。如何在其他java类中使用它？
如何将用户名和电子邮件设置为某些textview。 例如，如果我的textview是show_customername。然后我想设置show_customername.setText（show_name）; 。 我尝试这样做： -
show_customername.setText(show_name);
但这不起作用。 请指导我维护登录会话。提前致谢。希望我的问题也能帮助别人。
答案 0 :(得分：0)
在共享偏好设置中存储布尔值。 成功登录当您成功登录并在下次发送登录活动的意图之前检查该布尔值是真还是假。如果是，则跳过登录屏幕，否则显示登录界面。如果您在应用程序中有注销选项，则将布尔值设置为false并再次将其保存在共享首选项中。
答案 1 :(得分：0)
您可以像下面这样初始化共享偏好：
假设您在LoginActivity中将Login首选项设置为true。
当您获得LOGIN设置首选项时，如下所示：
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode
Editor editor = pref.edit();
editor.putBoolean("isLogin",true);
editoe.commit();
您正在LogoutActiviy中设置Logout首选项。 每当您获得Logout设置首选项时，如下所示：
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode
Editor editor = pref.edit();
editor.putBoolean("isLogin",false);
editoe.commit();
如果用户是否登录，请检查您的第一页，如下所示：
if(pref.getBoolean("isLogin", false)){
// Condtion gets true if you are login
}else{
// Condtion gets false if you are not login
}
希望它会对你有所帮助。
如需更多参考，您还可以参考以下链接：
答案 2 :(得分：0)
您只需要在Editor类对象上调用这两个方法。
editor.clear();
editor.commit();
如果您需要进一步的帮助，可以回复。祝你好运。