Android入门练习———基于Bundle的消息传递

客官°小女子只卖身不卖艺 2022-02-02 09:31 208阅读 0赞

**Activity之间传递数据**  
数据的附加有两种方式：

*  一种是直接intent.putExtra();
 *  另一种是先bundle.putXxx（），然后再调用Intent.putExtras(Bundle)添加bundle
 *  其实两种的本质是一样的

从Activity返回数据

*  startActivity新启动的Activity与原Activity相互独立，在关闭时不会返回任何信息。当需要返回数据时，可以使用startActivityForResult（）方法启动一个Activity，新启动的Activity可以在关闭时给原Activity返回数据
 *  setResult（）方法时专门用于向上一个活动返回数据

--------------------

**实例1**  
效果：  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTQ1OTI2_size_16_color_FFFFFF_t_70][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTQ1OTI2_size_16_color_FFFFFF_t_70 1][]

1 activity\_main.xml  
2 otheractivity.xml  
3 tri\_activity.xml  
4 MainActivity.java  
5 SecondActivity.java  
6 TriActivity.java

1 activity\_main.xml

2 otheractivity.xml

3 tri\_activity.xml  
/  
4 MainActivity.java

public class MainActivity extends Activity { 
    	private Button btn1;
    	private Button btn2;
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    		btn1=(Button) findViewById(R.id.button1);
    		btn2=(Button) findViewById(R.id.button2);
    		
    		btn1.setOnClickListener(new OnClickListener() { 
    			
    			@Override
    			public void onClick(View v) { 
    				// TODO Auto-generated method stub
    				Intent intent=new Intent();
    				intent.setClass(MainActivity.this, SecondActivity.class);
    				intent.putExtra("myintro", "我是一个Android程序");
    				intent.putExtra("myNum", 50);
    				//putExtra("A",B)中，AB为键值对，第一个参数为键名，第二个参数为键对应的值。
    				//表示追加到Bundle中相应的值。
    				//如果想取出Intent对象中的这些值，需要在另一个Activity中用getXXXXXExtra方法，
    				//注意需要使用对应类型的方法，参数为键名
    				startActivity(intent);
    			}
    		});
    		
    		btn2.setOnClickListener(new OnClickListener() { 
    			
    			@Override
    			public void onClick(View v) { 
    				// TODO Auto-generated method stub
    				Bundle bundle=new Bundle();   //利用Bundle类来传递数据
    				bundle.putString("bundle_s", "通过Bundle传递数据");
    				bundle.putInt("b_num", 30);
    				Intent intent=new Intent();
    				intent.setClass(MainActivity.this, TriActivity.class);
    				intent.putExtras(bundle);//直接将Bundle对象参数传递给intent
    				startActivity(intent);
    				
    			}
    		});
    	}
    }

5 SecondActivity.java

public class SecondActivity extends Activity{ 
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		// TODO Auto-generated method stub
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.otheractivity);
    		Intent intent=getIntent();
    		String str=intent.getStringExtra("myintro");
    		Integer integer=intent.getIntExtra("myNum",0);//defult是0 若没有传值则默认0
    		Toast.makeText(this, str, Toast.LENGTH_LONG).show();
    		Toast.makeText(this, integer+"", Toast.LENGTH_LONG).show();
    	}
    }

6 TriActivity.java

public class TriActivity extends Activity{ 
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		// TODO Auto-generated method stub
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.tri_activity);
    		Bundle bundle=getIntent().getExtras();//获取从Intent中传过来的Bundle对象
    		String str=bundle.getString("bundle_s");
    		Integer integer=bundle.getInt("b_num");
    		Toast.makeText(this, str, Toast.LENGTH_LONG).show();
    		Toast.makeText(this, integer+"", Toast.LENGTH_LONG).show();
    	}
    
    }

--------------------

**实例2**

效果图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTQ1OTI2_size_16_color_FFFFFF_t_70 2][]

1 activity\_main.xml  
2 activity\_info.xml  
3 MyCar.java  
4 CarInfo.java  
5 MainActivity.java

1 activity\_main.xml

2 activity\_info.xml

3 MyCar.java

public class MyCar implements Serializable{ //若要传递对象，需要实现Serializable接口
    	private String name;  
    	private String color;  
    	public String getName() {   
    	        return name;  
    	    }  
    	public void setName(String name) {   
    	        this.name = name;  
    	    }  
    	public String getColor() {   
    	        return color;  
    	        }  
    	public void setColor(String color) {   
    	        this.color = color;  
    	    }  
    }

4 CarInfo.java

public class CarInfo extends Activity{ 
    	private MyCar car;
    	private TextView tv;
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		// TODO Auto-generated method stub
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_info);
    		tv=(TextView) findViewById(R.id.tv_info);
    		
    		Intent intent=getIntent();
    		car=(MyCar) intent.getSerializableExtra("car_data");//序列化
    		tv.setText(car.getName()+","+car.getColor());
    		
    	}
    }

5 MainActivity.java

public class MainActivity extends Activity { 
    	private EditText etname,etcolor;
    	private Button btn;
    	private MyCar car;
    	
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    		
    		etname=(EditText) findViewById(R.id.et1);
    		etcolor=(EditText) findViewById(R.id.et2);
    		btn=(Button) findViewById(R.id.btn);
    		
    		btn.setOnClickListener(new OnClickListener() { 
    			
    			@Override
    			public void onClick(View v) { 
    				// TODO Auto-generated method stub
    				car=new MyCar();
    				car.setName(etname.getText().toString());
    				car.setColor(etcolor.getText().toString());
    				Intent intent=new Intent();
    				intent.setClass(MainActivity.this, CarInfo.class);
    				intent.putExtra("car_data", car);//传递对象 很重要
    				startActivity(intent);
    			}
    		});
    		
    	}
    }

--------------------

**实例3**  
**效果：**  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTQ1OTI2_size_16_color_FFFFFF_t_70 3][]  
1 activity\_main.xml  
2 activity02.xml  
3 Activity02.java  
4 MainActivity.java

1 activity\_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" >
    <TextView android:id="@+id/mText01" android:layout_width="match_parent" android:layout_height="wrap_content" />
    <TextView android:id="@+id/mText02" android:layout_width="match_parent" android:layout_height="wrap_content" />
    <Button android:id="@+id/mButton01" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="改变第一行文本的值" />
    <Button android:id="@+id/mButton02" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="改变第二行文本的值" />
    </LinearLayout>

2 activity02.xml

3 Activity02.java

public class Activity02 extends Activity{ 
    	//private int resultCode=100;//在有多个Activity返回时使用
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		// TODO Auto-generated method stub
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity02);
    		Intent mIntent = new Intent();
    		mIntent.putExtra("change01", "1000");
    		mIntent.putExtra("change02", "2000");
    		// 设置结果，并进行传送
    		setResult(RESULT_OK, mIntent);
    		finish();//finish()动作或者back动作后，会回调第一个页面的onActivityResult()方法
    	}
    
    }

4 MainActivity.java

public class MainActivity extends Activity implements OnClickListener { 
    	private TextView mText01;
    	private TextView mText02;
    	private Button button01;
    	private Button button02;
    	private Intent mIntent;
    	private int requestCode;
    	
    	@Override
    	protected void onCreate(Bundle savedInstanceState) { 
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    
    		mText01 = (TextView) findViewById(R.id.mText01);
    		mText02 = (TextView) findViewById(R.id.mText02);
    		button01 = (Button) findViewById(R.id.mButton01);
    		button02 = (Button) findViewById(R.id.mButton02);
    
    		button01.setOnClickListener(this);
    		button02.setOnClickListener(this);
    		mText01.setText("01");
    		mText02.setText("02");
    		
    		mIntent = new Intent();
    		mIntent.setClass(MainActivity.this,	Activity02.class);
    		}
    
    		@Override
    		public void onClick(View v) { 
    			switch (v.getId()) { 
    			case R.id.mButton01:
    				// 请求码的值随便设置，但必须>=0,，用于在之后的回调中判断数据的来源
    				requestCode = 0;
    				startActivityForResult(mIntent, requestCode);
    				break;
    			case R.id.mButton02:
    				requestCode = 2;
    				startActivityForResult(mIntent, requestCode);
    				break;
    			default:
    				break;
    			}
    		}
    
    		// 回调方法，从第二个页面回来的时候会执行这个方法
    		@Override
    		protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    			String change01 = data.getStringExtra("change01");
    			String change02 = data.getStringExtra("change02");
    			// 根据上面发送过去的请求码来区别
    			switch (requestCode) { 
    			case 0:
    				if(resultCode==RESULT_OK){ //判断是哪个返回的
    				mText01.setText(change01);
    				break;}
    			case 2://因为只有一个 所以省略
    				mText02.setText(change02);
    				break;
    			default:
    				break;
    			}
    		}
    	
    }

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