Android activity的回传数据

 package com.example.myact3;

 import android.content.Intent;
 import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.TextView;
 /**
  * Android activity的回传数据
  * @author shaobn
  *
  */
 public class MainActivity extends ActionBarActivity {
     private Button button;
     private TextView tv;
     private static final  int REQUEST = 1;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         button = (Button)this.findViewById(R.id.button1);
         tv = (TextView) this.findViewById(R.id.textView1);
         button.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View arg0) {
                 // TODO Auto-generated method stub
                 Intent intent = new Intent(MainActivity.this,MainActivity2.class);
                 intent.putExtra("text", tv.getText());
                 //此方法发出请求携带自己的自已的请求码，方便回来时验证
                 startActivityForResult(intent,REQUEST);
             }
         });
     }
     //requestCode 请求码，目的是和发出请求的activity的请求码相一致
     //resultCode 响应码，目的是与本activity设置的响应码一致才接收数据。
     //data 第二个页面传递过来的intent对象
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         // TODO Auto-generated method stub
         super.onActivityResult(requestCode, resultCode, data);
         if(resultCode==2){
             if(requestCode==REQUEST){
                 String string = data.getStringExtra("response");
                 this.tv.setText(string);
             }
         }
     }

 }

 package com.example.myact3;

 import android.content.Intent;
 import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.TextView;

 public class MainActivity2 extends ActionBarActivity {
     private TextView tv;
     private Button button;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main_activity2);
         button = (Button) this.findViewById(R.id.button1);
         tv =  (TextView) this.findViewById(R.id.textView1);
         tv.setText("olympic games");
         button.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View arg0) {
                 // TODO Auto-generated method stub
                 Intent intent = new Intent();
                 intent.putExtra("response", tv.getText());
                 //回传给之前获得焦点的activity
                 setResult(2, intent);
                 //结束声明周期
                 finish();
             }
         });

     }
 }

第二个页面的可以new Intent(),那默认使用的就是之前activit的请求码。