android nfc写入应用程序包名与网址 自动打开应用程序与网址

       安卓手机大部分手机提供了NFC芯片   可以根据NFC传递数据   NFC卡与手机  手机与手机数据等交互  非常好的功能，这篇文章教大家如何向NFC卡或标签写入功能。

       DEMO下载地址http://download.youkuaiyun.com/detail/u012303938/9243233

       用法 ：  点击包名   将NFC标签靠近手机后置摄像头附近即可  

       效果 ： 第一次靠近  将自己的应用程序包名写入nfc标签，第二次靠近    会自动打开自己写入的应该程序。

       注意几点：

       1、清单文件要加上权限  activity使用singleTop启动模式

       2、NFC主要用到  NdfcAdapter与PendingIntent去建立联系

       3、Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);方法去取nfc里的资源

       代码如下：

package com.example.autonfc;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.nfc.FormatException;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.NfcManager;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;


public class MainActivity extends Activity implements OnItemClickListener{
  private List<String> list;
  private NfcAdapter adapters;
  private PendingIntent intent;
  private String packageName;
  private ListView listView1;
  private NdefMessage ndefMessage;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView1=(ListView) findViewById(R.id.listView1);
        list=new ArrayList<String>();
        PackageManager manager=getPackageManager();
        List<PackageInfo> PackageInfos= manager.getInstalledPackages(PackageManager.GET_ACTIVITIES);
        for(PackageInfo info: PackageInfos){
        	list.add(info.applicationInfo.loadLabel(manager)+"\n"+
        			info.packageName);
        }
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this, 
        		android.R.layout.simple_list_item_1, list);
        listView1.setAdapter(adapter);
        listView1.setOnItemClickListener(this);
        
        adapters=NfcAdapter.getDefaultAdapter(this);
		intent=PendingIntent.getActivity(this, 0, new Intent(this,getClass()), 0);
    }

    @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;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

	@Override
	public void onItemClick(AdapterView<?> parent, View view, int position,
			long id) {
		// TODO Auto-generated method stub
		packageName=list.get(position);
		Toast.makeText(this, "选择了"+packageName, Toast.LENGTH_SHORT).show();
		
	}
	@Override
		protected void onResume() {
			// TODO Auto-generated method stub
			super.onResume();
			if(adapters!=null){
				adapters.enableForegroundDispatch(this, intent, null, null);
			}
			
		}
	
	@Override
		protected void onPause() {
			// TODO Auto-generated method stub
			super.onPause();
			if(adapters!=null){
				adapters.disableForegroundDispatch(this);
			}
			
		}
	@Override
		protected void onNewIntent(Intent intent) {
			// TODO Auto-generated method stub
			super.onNewIntent(intent);
			Toast.makeText(this, "执行了", Toast.LENGTH_SHORT).show();
			Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
			if(packageName==null){
				Toast.makeText(this, "请选择包名", Toast.LENGTH_SHORT).show();
				return;
			}
			onWriteNFC(tag);
			
		}
	
	public void onWriteNFC(final Tag tag){
		if(tag==null){
			Toast.makeText(this, "没有找到TAG", Toast.LENGTH_SHORT).show();
			return;
		}
		Toast.makeText(this, "tag有值", Toast.LENGTH_SHORT).show();
		ndefMessage=new NdefMessage(new NdefRecord[]{NdefRecord.createApplicationRecord(packageName)});
		//写入一个网址 
		//ndefMessage=new NdefMessage(new NdefRecord[]{NdefRecord.createUri(Uri.parse("http://www.baidu.com"))});
		
		int size=ndefMessage.toByteArray().length;
	    Toast.makeText(this, "要写入信息的长度"+size, Toast.LENGTH_SHORT).show();
	    Ndef ndef=Ndef.get(tag);
	    
	    if(ndef!=null){
	    	try {
				ndef.connect();
				if(!ndef.isWritable()){
					Toast.makeText(this, "NFC卡不支持写入", Toast.LENGTH_SHORT).show();
					return;
				}
				if(ndef.getMaxSize()<size){
					Toast.makeText(this, "NFC卡内存不够", Toast.LENGTH_SHORT).show();
					return;
				}
				ndef.writeNdefMessage(ndefMessage);
				Toast.makeText(this, "NFC卡写入成功", Toast.LENGTH_SHORT).show();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (FormatException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	    }else{
	    	Toast.makeText(this, "此卡不是ndef格式", Toast.LENGTH_SHORT).show();
	    	new AlertDialog.Builder(this).setTitle("是否格式化成ndef格式，并写入包名")
	    	.setPositiveButton("是", new AlertDialog.OnClickListener() {
				
				@Override
				public void onClick(DialogInterface dialog, int which) {
					// TODO Auto-generated method stub
					NdefFormatable  formatable=NdefFormatable.get(tag);
					if(formatable==null){
						Toast.makeText(MainActivity.this, "此卡不能ndef格式化", 
								Toast.LENGTH_SHORT).show();
					    return;
					}
					try {
						formatable.connect();
						formatable.format(ndefMessage);
						Toast.makeText(MainActivity. this, "NFC卡写入成功", Toast.LENGTH_SHORT).show();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					} catch (FormatException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}).setNegativeButton("否", null).create().show();
	    }
	}
	
}