如何在Android应用程序中的活动之间传递数据？

我有一个场景，在通过登录页面登录后，每个

活动上都会有一个注销
按钮

单击“注销”

，我将传递要注销的已登录用户的会话id。有谁能指导我如何让所有

活动都能使用
会话id

此情况的任何替代方法都是将会话id传递给用于启动活动的
Intent
中的注销活动：

Intent intent = new Intent(getBaseContext(), SignoutActivity.class);
intent.putExtra("EXTRA_SESSION_ID", sessionId);
startActivity(intent);

String sessionId = getIntent().getStringExtra("EXTRA_SESSION_ID");

  if (getIntent().getExtras() != null) {
      String value = getIntent().getStringExtra("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }

  if (getIntent().getExtras() != null) {
      Bundle bundle = getIntent().getStringExtra("bundle_key");    
      String value = bundle.getString("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }

在下一个活动中访问该意图：

Intent intent = new Intent(getBaseContext(), SignoutActivity.class);
intent.putExtra("EXTRA_SESSION_ID", sessionId);
startActivity(intent);

String sessionId = getIntent().getStringExtra("EXTRA_SESSION_ID");

  if (getIntent().getExtras() != null) {
      String value = getIntent().getStringExtra("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }

  if (getIntent().getExtras() != null) {
      Bundle bundle = getIntent().getStringExtra("bundle_key");    
      String value = bundle.getString("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }

for Intents提供了更多信息（请参阅标题为“额外服务”的部分）。
尝试执行以下操作：

IntentHelper.createYourSpecialIntent(getIntent()).putExtra("YOUR_FIELD_NAME", fieldValueToSave);

创建一个简单的“helper”类（工厂供您选择），如下所示：

import android.content.Intent;

public class IntentHelper {
    public static final Intent createYourSpecialIntent(Intent src) {
          return new Intent("YourSpecialIntent").addCategory("YourSpecialCategory").putExtras(src);
    }
}

IntentHelper.createYourSpecialIntent(getIntent());

这将是你想要的工厂。每当您需要一个新的意图时，请在intentelper中创建一个静态工厂方法。要创建一个新的意图，您应该这样说：

import android.content.Intent;

public class IntentHelper {
    public static final Intent createYourSpecialIntent(Intent src) {
          return new Intent("YourSpecialIntent").addCategory("YourSpecialCategory").putExtras(src);
    }
}

IntentHelper.createYourSpecialIntent(getIntent());

在你的活动中。当您想在“会话”中“保存”某些数据时，只需使用以下命令：

IntentHelper.createYourSpecialIntent(getIntent()).putExtra("YOUR_FIELD_NAME", fieldValueToSave);

并发送此意图。在目标活动中，您的字段将可用为：

getIntent().getStringExtra("YOUR_FIELD_NAME");

所以现在我们可以像旧会话一样使用意图（比如在servlet或中）。
正如Erich所指出的，传递额外内容是一种很好的方法

不过，对象是另一种方式，当跨多个活动处理同一状态（而不是必须到处获取/放置）或比原语和字符串更复杂的对象时，有时更容易处理

您可以扩展应用程序，然后在其中设置/获取您想要的任何内容，并使用从任何活动（在同一应用程序中）访问它

还请记住，您可能看到的其他方法，如静力学，可能会有问题，因为它们都是静态的。应用程序也有助于解决这个问题。
更新了注意我提到的使用。它有一个简单的API，可以跨应用程序的活动进行访问。但这是一个笨拙的解决方案，如果您传递敏感数据，则会带来安全风险。最好使用意图。它有一个广泛的重载方法列表，可用于在活动之间更好地传输许多不同的数据类型。看一看。这很好地展示了putExtra的使用

在活动之间传递数据时，我首选的方法是为相关活动创建一个静态方法，其中包括启动意图所需的参数。这样就可以方便地设置和检索参数。所以它可以看起来像这样

public class MyActivity extends Activity {
    public static final String ARG_PARAM1 = "arg_param1";
...
public static getIntent(Activity from, String param1, Long param2...) {
    Intent intent = new Intent(from, MyActivity.class);
        intent.putExtra(ARG_PARAM1, param1);
        intent.putExtra(ARG_PARAM2, param2);
        return intent;
}

....
// Use it like this.
startActivity(MyActvitiy.getIntent(FromActivity.this, varA, varB, ...));
...

String strEmp = new Gson().toJson(emp);
Intent intent = new Intent(getBaseContext(), YourActivity.class);
intent.putExtra("EMP", strEmp);
startActivity(intent);

Bundle bundle = getIntent().getExtras();
String empStr = bundle.getString("EMP");
            Gson gson = new Gson();
            Type type = new TypeToken<Employee>() {
            }.getType();
            Employee selectedEmp = gson.fromJson(empStr, type);

然后，您可以为预期的活动创建意图，并确保您拥有所有参数。您可以对片段进行调整，以使其适应。上面是一个简单的例子，但你明白了。
在你当前的活动中，创建一个新的
Intent
：

String value="Hello world";
Intent i = new Intent(CurrentActivity.this, NewActivity.class);    
i.putExtra("key",value);
startActivity(i);

然后在新活动中，检索这些值：

Bundle extras = getIntent().getExtras();
if (extras != null) {
    String value = extras.getString("key");
    //The key argument here must match that used in the other activity
}

使用此技术将变量从一个活动传递到另一个活动。
在活动之间传递数据最方便的方法是传递意图。在要从中发送数据的第一个活动中，应添加代码

String str = "My Data"; //Data you want to send
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.putExtra("name",str); //Here you will add the data into intent to pass bw activites
v.getContext().startActivity(intent);

您还应该导入

import android.content.Intent;

然后在下一个Acitvity（SecondActivity）中，您应该使用以下代码从intent检索数据

String name = this.getIntent().getStringExtra("name");

另一种方法是使用存储数据的公共静态字段，即：

public class MyActivity extends Activity {

  public static String SharedString;
  public static SomeObject SharedObject;

//...

活动之间的数据传递主要通过意图对象进行

首先，您必须使用
Bundle
类将数据附加到intent对象。然后使用
startActivity（）
或
startActivityForResult（）
方法调用活动

你可以通过博客文章中的一个例子找到更多关于它的信息。
我最近发布了一个jQuery风格的Android框架，它使所有类似的任务变得更简单。如前所述，
SharedReferences
是实现这一点的一种方法

是作为单例实现的，因此这是一个选项，在Vapor API中，它有一个重载严重的
.put（…）
方法，因此您不必显式地担心正在提交的数据类型，只要支持它。它也很流畅，因此您可以链接调用：

$.prefs(...).put("val1", 123).put("val2", "Hello World!").put("something", 3.34);

它还可以选择自动保存更改，并在后台统一读写过程，因此您不需要像在标准Android中那样显式检索编辑器

或者，您可以使用
意图
。在Vapor API中，您还可以使用可链接的重载
.put（…）
方法：

如其他答案中所述，将其作为额外信息传递。您可以从
活动
中检索额外内容，此外，如果您正在使用，这将自动为您完成，以便您可以使用：

this.extras()

要在切换到的
活动
的另一端检索它们

希望这是一些人感兴趣的：）
你只需在打电话时发送额外信息即可

像这样：

Intent intent = new Intent(getApplicationContext(), SecondActivity.class);
intent.putExtra("Variable name", "Value you want to pass");
startActivity(intent);

现在，在您的
SecondActivity
的
OnCreate
方法中，您可以像这样获取额外的内容

如果您发送的值为长
格式：

long value = getIntent().getLongExtra("Variable name which you sent as an extra", defaultValue(you can give it anything));

String value = getIntent().getStringExtra("Variable name which you sent as an extra");

Boolean value = getIntent().getBooleanExtra("Variable name which you sent as an extra", defaultValue);

如果发送的值是
字符串：

long value = getIntent().getLongExtra("Variable name which you sent as an extra", defaultValue(you can give it anything));

String value = getIntent().getStringExtra("Variable name which you sent as an extra");

Boolean value = getIntent().getBooleanExtra("Variable name which you sent as an extra", defaultValue);

如果发送的值是
布尔值：

long value = getIntent().getLongExtra("Variable name which you sent as an extra", defaultValue(you can give it anything));

String value = getIntent().getStringExtra("Variable name which you sent as an extra");

Boolean value = getIntent().getBooleanExtra("Variable name which you sent as an extra", defaultValue);

我在类中使用静态字段，并获取/设置它们：

比如：

要获取值，请在活动中使用：

Info.ID
Info.NAME

Intent intent = new Intent(getApplicationContext(), ClassName.class);
intent.putExtra("Variable name", "Value you want to pass");
startActivity(intent);

String str= getIntent().getStringExtra("Variable name which you sent as an extra");

要设置值，请执行以下操作：

Info.ID = 5;
Info.NAME = "USER!";

源类：

Intent myIntent = new Intent(this, NewActivity.class);
myIntent.putExtra("firstName", "Your First Name Here");
myIntent.putExtra("lastName", "Your Last Name Here");
startActivity(myIntent)

目标类（新活动类）：

您可以在另一个活动中检索它。两种方式：

int id = getIntent.getIntExtra("id", /* defaltvalue */ 2);

第二种方式是：

Intent i = getIntent();
String name = i.getStringExtra("name");

您可以使用
SharedReferences

日志记录。
SharedReferences

SharedPreferences preferences = getSharedPreferences("session",getApplicationContext().MODE_PRIVATE);
Editor editor = preferences.edit();
editor.putString("sessionId", sessionId);
editor.commit();


签出。SharedReferences中的时间获取会话id

SharedPreferences preferences = getSharedPreferences("session", getApplicationContext().MODE_PRIVATE);
String sessionId = preferences.getString("sessionId", null);


如果您没有所需的会话id，请删除SharedReferences：

SharedPreferences settings = context.getSharedPreferences("session", Context.MODE_PRIVATE);
settings.edit().clear().commit();

这是非常有用的，因为有一次您保存了值，然后检索anyw
byte[] bytes = getIntent().getByteArrayExtra("bitmapbytes");
Bitmap bmp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);

Intent intent = new Intent(getBaseContext(), NextActivity.class);
Foo foo = new Foo();
intent.putExtra("foo", foo);
startActivity(intent);

Foo foo = getIntent().getExtras().getParcelable("foo");

 int n= 10;
 Intent in = new Intent(From_Activity.this,To_Activity.class);
 Bundle b1 = new Bundle();
 b1.putInt("integerNumber",n);
 in.putExtras(b1);
 startActivity(in);

 Bundle b2 = getIntent().getExtras();
 int m = 0;
 if(b2 != null)
  {
     m = b2.getInt("integerNumber");
  }

public class HomeIntent extends Intent {

    private static final String ACTION_LOGIN = "action_login";
    private static final String ACTION_LOGOUT = "action_logout";

    private static final String ARG_USERNAME = "arg_username";
    private static final String ARG_PASSWORD = "arg_password";


    public HomeIntent(Context ctx, boolean isLogIn) {
        this(ctx);
        //set action type
        setAction(isLogIn ? ACTION_LOGIN : ACTION_LOGOUT);
    }

    public HomeIntent(Context ctx) {
        super(ctx, HomeActivity.class);
    }

    //This will be needed for receiving data
    public HomeIntent(Intent intent) {
        super(intent);
    }

    public void setData(String userName, String password) {
        putExtra(ARG_USERNAME, userName);
        putExtra(ARG_PASSWORD, password);
    }

    public String getUsername() {
        return getStringExtra(ARG_USERNAME);
    }

    public String getPassword() {
        return getStringExtra(ARG_PASSWORD);
    }

    //To separate the params is for which action, we should create action
    public boolean isActionLogIn() {
        return getAction().equals(ACTION_LOGIN);
    }

    public boolean isActionLogOut() {
        return getAction().equals(ACTION_LOGOUT);
    }
}

public class LoginActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        String username = "phearum";
        String password = "pwd1133";
        final boolean isActionLogin = true;
        //Passing data to HomeActivity
        final HomeIntent homeIntent = new HomeIntent(this, isActionLogin);
        homeIntent.setData(username, password);
        startActivity(homeIntent);

    }
}

public class HomeActivity extends AppCompatActivity {

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

        //This is how we receive the data from LoginActivity
        //Make sure you pass getIntent() to the HomeIntent constructor
        final HomeIntent homeIntent = new HomeIntent(getIntent());
        Log.d("HomeActivity", "Is action login?  " + homeIntent.isActionLogIn());
        Log.d("HomeActivity", "username: " + homeIntent.getUsername());
        Log.d("HomeActivity", "password: " + homeIntent.getPassword());
    }
}

Intent intent = new Intent(getActivity(), SecondActivity.class);
intent.putExtra(Intent.EXTRA_TEXT, "my text");
startActivity(intent);

Intent intent = getIntent();
String myText = intent.getExtras().getString(Intent.EXTRA_TEXT);

static final String EXTRA_STUFF = "com.myPackageName.EXTRA_STUFF";

Intent intent = new Intent(getActivity(), SecondActivity.class);
intent.putExtra(EXTRA_STUFF, "my text");
startActivity(intent);

Intent intent = getIntent();
String myText = intent.getExtras().getString(FirstActivity.EXTRA_STUFF);

 <string name="EXTRA_STUFF">com.myPackageName.MY_NAME</string>

Intent intent = new Intent(getActivity(), SecondActivity.class);
intent.putExtra(getString(R.string.EXTRA_STUFF), "my text");
startActivity(intent);

Intent intent = getIntent();
String myText = intent.getExtras().getString(getString(R.string.EXTRA_STUFF));

Intent mIntent = new Intent(FirstActivity.this, SecondActivity.class);
mIntent.putExtra("data", data);
startActivity(mIntent);

public class DataHolder {

 private static DataHolder dataHolder;
 private List<Model> dataList;

 public void setDataList(List<Model>dataList) {
    this.dataList = dataList;
 }

 public List<Model> getDataList() {
    return dataList;
 }

 public synchronized static DataHolder getInstance() {
    if (dataHolder == null) {
       dataHolder = new DataHolder();
    }
    return dataHolder;
 }
}

private List<Model> dataList = new ArrayList<>();
DataHolder.getInstance().setDataList(dataList);

private List<Model> dataList = DataHolder.getInstance().getDataList();

SharedPreferences pref = myContexy.getSharedPreferences("Session 
Data",MODE_PRIVATE);
SharedPreferences.Editor edit = pref.edit();
edit.putInt("Session ID", session_id);
edit.commit();

SharedPreferences pref = myContexy.getSharedPreferences("Session Data", MODE_PRIVATE);
session_id = pref.getInt("Session ID", 0);

Intent intent = new Intent(getBaseContext(), YourActivity.class);
intent.putExtra("USER_NAME", "xyz@gmail.com");
startActivity(intent);

String s = getIntent().getStringExtra("USER_NAME");

class Employee{
    private String empId;
    private int age;
    print Double salary;

    getters...
    setters...
}

String strEmp = new Gson().toJson(emp);
Intent intent = new Intent(getBaseContext(), YourActivity.class);
intent.putExtra("EMP", strEmp);
startActivity(intent);

Bundle bundle = getIntent().getExtras();
String empStr = bundle.getString("EMP");
            Gson gson = new Gson();
            Type type = new TypeToken<Employee>() {
            }.getType();
            Employee selectedEmp = gson.fromJson(empStr, type);

public class MainActivity extends AppCompatActivity {

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

    // "Go to Second Activity" button click
    public void onButtonClick(View view) {

        // get the text to pass
        EditText editText = (EditText) findViewById(R.id.editText);
        String textToPass = editText.getText().toString();

        // start the SecondActivity
        Intent intent = new Intent(this, SecondActivity.class);
        intent.putExtra(Intent.EXTRA_TEXT, textToPass);
        startActivity(intent);
    }
}

public class SecondActivity extends AppCompatActivity {

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

        // get the text from MainActivity
        Intent intent = getIntent();
        String text = intent.getStringExtra(Intent.EXTRA_TEXT);

        // use the text in a TextView
        TextView textView = (TextView) findViewById(R.id.textView);
        textView.setText(text);
    }
}

public class MainActivity extends AppCompatActivity {

    private static final int SECOND_ACTIVITY_REQUEST_CODE = 0;

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

    // "Go to Second Activity" button click
    public void onButtonClick(View view) {

        // Start the SecondActivity
        Intent intent = new Intent(this, SecondActivity.class);
        startActivityForResult(intent, SECOND_ACTIVITY_REQUEST_CODE);
    }

    // This method is called when the second activity finishes
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // check that it is the SecondActivity with an OK result
        if (requestCode == SECOND_ACTIVITY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {

                // get String data from Intent
                String returnString = data.getStringExtra(Intent.EXTRA_TEXT);

                // set text view with string
                TextView textView = (TextView) findViewById(R.id.textView);
                textView.setText(returnString);
            }
        }
    }
}

public class SecondActivity extends AppCompatActivity {

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

    // "Send text back" button click
    public void onButtonClick(View view) {

        // get the text from the EditText
        EditText editText = (EditText) findViewById(R.id.editText);
        String stringToPassBack = editText.getText().toString();

        // put the String to pass back into an Intent and close this activity
        Intent intent = new Intent();
        intent.putExtra(Intent.EXTRA_TEXT, stringToPassBack);
        setResult(RESULT_OK, intent);
        finish();
    }
}

Intent intent = new Intent(getApplicationContext(), ClassName.class);
intent.putExtra("Variable name", "Value you want to pass");
startActivity(intent);

String str= getIntent().getStringExtra("Variable name which you sent as an extra");

val intent = Intent(this, SecondActivity::class.java)
intent.putExtra("key", "value")
startActivity(intent)

val value = intent.getStringExtra("key")

companion object {
    val KEY = "key"
}

  String value="xyz";
  Intent intent = new Intent(CurrentActivity.this, NextActivity.class);    
  intent.putExtra("key", value);
  startActivity(intent);

  if (getIntent().getExtras() != null) {
      String value = getIntent().getStringExtra("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }

  String value="xyz";
  Intent intent = new Intent(CurrentActivity.this, NextActivity.class);  
  Bundle bundle = new Bundle();
  bundle.putInt("key", value);  
  intent.putExtra("bundle_key", bundle);
  startActivity(intent);

  if (getIntent().getExtras() != null) {
      Bundle bundle = getIntent().getStringExtra("bundle_key");    
      String value = bundle.getString("key");
      //The key argument must always match that used send and retrive value from one activity to another.
  }