Android编程四大组件之Activity用法实例分析

//第一种方式：构造函数，代码少
Intent intent1 =new Intent(this,NewActivity.class);
startActivity(intent1);
//第二种方式：类名形式，灵活，可扩展性强
Intent intent2 =new Intent();
intent2.setClassName(this,"cn.test.activity.NewActivity");
startActivity(intent2);
//第三种方式 ：包名类名形式，可启动其他程序中的Activity
Intent intent3 =new Intent();
intent3.setClassName("cn.test.taskdownloader","cn.test.taskdownloader.MainActivity");
startActivity(intent3);

//传递数据方式一
Intent intent1 =new Intent(this,NewActivity.class);
Bundle bundle=new Bundle();
bundle.putString("data","Test");
intent1.putExtras(bundle);
startActivity(intent1);
//获取意图方式一
Bundle bundle2 =getIntent().getExtras();
Toast.makeText(this,bundle2.getString("data"),0).show();
//传递数据方式二
Intent intent2 =new Intent(this,NewActivity.class);
intent2.putExtra("data","Test2");
startActivity(intent2);
//获取意图方式二
 Toast.makeText(this,getIntent().getStringExtra("data"),0).show();

public class MainActivity extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
  }
  /**
   * 创建Activity获取返回数据
   * @param view
   */
  public void createNew(View view){
    Intent intent1 =new Intent(this,NewActivity.class);
    intent1.putExtra("data","请求数据");
    //打开Activity等待返回
    startActivityForResult(intent1,100);
  }
  /**
   * 重写onActivityResult，关闭Activity就会调用此方法
   */
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    Toast.makeText(this,"requestCode:"+requestCode+",requestCode:"+resultCode+",data"+data.getStringExtra("result"),0).show();
  }
}

public class NewActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.new_activity);
    Toast.makeText(this,getIntent().getStringExtra("data"),0).show();
    //设置返回数据
    Intent data =new Intent();
    data.putExtra("result","返回的数据");
    setResult(200,data);
  }
}