Activity与Intent通信机制

1、使用Intent对象来指定一个Activity,并通过startActivity或startActivityForResult方法启动该Activity.以及在Activity之间传递数据：

public class MainActivity extends Activity {  
        private Button btn1,btn2;  
        @Override  
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            LinearLayout view = new LinearLayout(this);  
            view.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
              
            btn1 = new Button(this);  
            btn1.setId(1);  
            btn1.setText("使用类名开启另一个Activity");  
            btn1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
      
            btn2 = new Button(this);  
            btn2.setId(2);  
            btn2.setText("使用action开启另一个Activity");  
            btn2.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
              
            view.addView(btn1);  
            view.addView(btn2);  
            setContentView(view);  
              
            btn1.setOnClickListener(listener);  
            btn2.setOnClickListener(listener);  
        }  
          
        private View.OnClickListener listener = new OnClickListener() {  
            @Override  
            public void onClick(View view) {  
                Intent intent = new Intent();  
                switch (view.getId()) {  
                case 1:  
                    intent.setClass(MainActivity.this, ResultActivity.class);  
                    intent.putExtra("name", "JAVA");  
                    startActivityForResult(intent, 222);  
                    break;  
                case 2:  
                    intent.setAction("forResult");  
                    MyData myData = new MyData();  
                    //使用putExtra传递自定义对象时，该对象必须实现序列化，该类中所有成员属性也必须实现序列化接口   
                    intent.putExtra("data", myData);  
                    startActivity(intent);  
                    break;  
                default:  
                    break;  
                }  
            }  
        };  
      
        @Override  
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {  
            //requestCode是请求码，即startActivityForResult(intent, 222)中的第二个参数   
            //resultCode是结果码，即setResult(333)中设置的数字   
            switch (requestCode) {  
            case 222:  
                if(resultCode == 333){  
                    Toast.makeText(this, "无结果返回...", Toast.LENGTH_LONG).show();  
                } else if(resultCode == 444){  
                    Toast.makeText(this, data.getStringExtra("result"), Toast.LENGTH_LONG).show();  
                }  
                break;  
            default:  
                break;  
            }  
        }  
    }

    public class ResultActivity extends Activity {  
        private Button btn1 , btn2;  
        private TextView tv;  
        private Intent intent;  
        @Override  
        protected void onCreate(Bundle savedInstanceState) {  
            // TODO Auto-generated method stub   
            super.onCreate(savedInstanceState);  
              
            intent = getIntent();  
              
            LinearLayout view = new LinearLayout(this);  
            view.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,  
                    LayoutParams.FILL_PARENT));  
              
            tv = new TextView(this);  
            tv.setText("name is "+intent.getStringExtra("name"));  
            tv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,  
                    LayoutParams.WRAP_CONTENT));  
              
            btn1 = new Button(this);  
            btn1.setId(1);  
            btn1.setText("Back1");  
            btn1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,  
                    LayoutParams.WRAP_CONTENT));  
              
            btn2 = new Button(this);  
            btn2.setId(2);  
            btn2.setText("Back2");  
            btn2.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,  
                    LayoutParams.WRAP_CONTENT));  
              
            view.addView(tv);  
            view.addView(btn1);  
            view.addView(btn2);  
              
            btn1.setOnClickListener(listener);  
            btn2.setOnClickListener(listener);  
            setContentView(view);  
        }  
      
        private View.OnClickListener listener = new OnClickListener() {  
            @Override  
            public void onClick(View view) {  
                switch (view.getId()) {  
                case 1:  
                    setResult(333);  
                    break;  
                case 2:  
                    intent.putExtra("result", "带结果返回");  
                    setResult(444, intent);  
                    break;  
                default:  
                    break;  
                }  
                ResultActivity.this.finish();  
            }  
        };  
      
    }  

    public class Result2Activity extends Activity {  
        @Override  
        protected void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
            MyData data = (MyData)getIntent().getSerializableExtra("data");  
            setTitle(data.value);  
        }  
    }  

public class MyData implements Serializable {  
    public String value = "this is test";  
}  

2、Intent指定Activity的方式

2.1 直接使用Class
   

intent.setClass(MainActivity.this, ResultActivity.class);

<activity Android:name=".ResultActivity"></activity>

2.2 使用Action
   

intent.setAction("forResult");
<activity android:name=".Result2Activity">
     <intent-filter>
           <action android:name="forResult"></action>
           <category android:name="android.intent.category.DEFAULT"></category>
     </intent-filter>
</activity>

    2.3 使用包名
  

 ComponentName cn = new ComponentName(MainActivity.this, "com.zj.activity.another.ActivityA");
intent.setComponent(cn);

<activity android:name=".another.ActivityA"></activity>