activity_main.xml文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
   <TextView 
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:text="请选择："
    android:textSize="35px"
    android:textColor="#00aa00"
     android:id="@+id/t1"/>
   
    <Spinner android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner01"/>
</LinearLayout>

MainActivity.java文件

import android.support.v7.app.ActionBarActivity;  
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;
import android.widget.AdapterView.OnItemSelectedListener;
import android.os.Build;

public class MainActivity extends ActionBarActivity {
    private static String[]m={"A型","B型","AB型","o型","其他"}; 
    private TextView textview;
    private Spinner spinner; 
    private ArrayAdapter<String> adapter;
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		textview=(TextView)findViewById(R.id.t1);
		spinner=(Spinner)findViewById(R.id.spinner01);
		adapter=new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,m);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(new SpinnerSelectdeListener());

	}
	class SpinnerSelectdeListener implements OnItemSelectedListener{

		@Override
		public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
				long arg3) {
			textview.setText("您的血型是"+m[arg2]);

		}

		@Override
		public void onNothingSelected(AdapterView<?> arg0) {
			// TODO Auto-generated method stub

		}

	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {

		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

现在模拟器的效果是这样的

看不出下拉列表啊