Android笔记（四） Activity之间的数据传递

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class LoginActivity extends AppCompatActivity {

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

        Button button = (Button)findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                EditText text = (EditText) findViewById(R.id.username);
                String username = text.getText().toString();
                //使用显示Intent启动另一个Activity
                Intent intent = new Intent(LoginActivity.this,WelcomeActivity.class);
                //使用putExtra(kay,value)的方法将想要传递给下个Activity的内容封装起来
                intent.putExtra("username",username);
                //启动Activity
                startActivity(intent);
            }
        });
    }
}

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

/**
 * Created by LGB on 2015/8/7.
 */
public class WelcomeActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome_activity_layout);
        //获取到启动Activity的Intent
        Intent intent = getIntent();
        //得到启动Intent中封装的数据
        String username = intent.getStringExtra("username");
        TextView text = (TextView)findViewById(R.id.username);
        //将TextView中的文本设置为username
        text.setText(username.toString());
    }
}

<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".LonginActivity">


    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/username"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="32dp"
        android:layout_alignParentEnd="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录"
        android:id="@+id/button"
        android:layout_below="@+id/username"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="用户名称"
        android:id="@+id/username" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="    欢迎光临"
        android:id="@+id/welcome" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.lixyz.loginapp" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".LoginActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".WelcomeActivity">
        </activity>
    </application>

</manifest>