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。