活动不从NFC_TECH_DISCOVERED-意图过滤器开始

Question

我想通过NFC读取一些信息，并创建意图过滤器以及包含所需技术的xml。意图过滤器应该启动我的ReadActivity，但是当我将该卡放在手机附近时，它不会这样做。 NFC被激活，所以这不应该成为问题。我真的没有看到我的代码出现问题，所以如果有人可以看一下它，并且给我一个正确方向的提示，那将是非常棒的。下面是代码：

的AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.example.johan.nfcreaderforunicard"> 
    <uses-permission android:name="android.permission.NFC" /> 
    <uses-feature android:name="android.hardware.nfc" android:required="true"/> 
    <uses-sdk android:minSdkVersion="10"/> 

    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/apple" 
     android:label="@string/app_name" 
     android:supportsRtl="true" 
     android:theme="@style/Theme.AppCompat.Light.NoActionBar"> 

     <activity android:name=".MainActivity"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 

     <activity android:name=".ReadActivity"> 
      <intent-filter> 
       <action android:name="android.nfc.action.TECH_DISCOVERED"/> 
       <category android:name="android.intent.category.DEFAULT" /> 
      </intent-filter> 
      <meta-data android:name="android.nfc.action.TECH_DISCOVERED" 
       android:resource="@xml/tech"/> 
     </activity> 
</manifest> 

ReadActivity：

import android.nfc.NfcAdapter; 
import android.nfc.Tag; 
import android.nfc.tech.IsoDep; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.widget.TextView; 
import android.content.Intent; 
import android.os.Bundle; 

import java.io.IOException; 

public class ReadActivity extends AppCompatActivity { 

    private final byte[] selectAid = {(byte)90, (byte)95, (byte)-124, (byte)21}; 
    private final byte[] creditPayload = {(byte)108, (byte)1};       

    private byte[] resultOk; 
    private byte[] creditBytes; 

    @Override 
    public void onCreate(Bundle savedInstanceState){ 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.read_view); 
     Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar); 
     setSupportActionBar(myToolbar); 
     if(NfcAdapter.ACTION_TECH_DISCOVERED.equals(getIntent().getAction())){ 
      IsoDep isodep = IsoDep.get((Tag)getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG)); 
      if(isodep != null){ 
       try{ 
        isodep.connect(); 
        resultOk = isodep.transceive(selectAid); 
        if(resultOk[0] == 0){ 
         creditBytes = isodep.transceive(creditPayload); 
        } 
       }catch (IOException e){ 
       } 
      } 
     } 
     float credit = (float)formatCredit(creditBytes); 
     TextView label = (TextView)findViewById(R.id.read_text); 
     label.setText("Dein Guthaben: "+String.valueOf(credit)+"€"); 
    } 

    private double formatCredit(byte[] array) { 
     double credit = (double)(((0xff & array[4]) << 24) + ((0xff & array[3]) << 16) + ((0xff & array[2]) << 8) + (0xff & array[1]))/1000D; 
     return credit; 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu){ 
     MenuInflater inflater = getMenuInflater(); 
     inflater.inflate(R.menu.menu, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem menuItem){ 
     switch(menuItem.getItemId()){ 
      case(R.id.action_settings): 
       Intent startSettings = new Intent(ReadActivity.this, SettingsActivity.class); 
       startActivity(startSettings); 
       return true; 
      case(R.id.about): 
       Intent startAbout = new Intent(ReadActivity.this, AboutActivity.class); 
       startActivity(startAbout); 
       return true; 
      default: 
       return super.onOptionsItemSelected(menuItem); 
     } 
    } 

    @Override 
    public void onBackPressed(){ 
     Intent backToMain = new Intent(getApplicationContext(), MainActivity.class); 
     startActivity(backToMain); 
     finish(); 
    } 
} 

MainActivity：

import android.content.Intent; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar); 
     setSupportActionBar(myToolbar); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu){ 
     MenuInflater inflater = getMenuInflater(); 
     inflater.inflate(R.menu.menu, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem menuItem){ 
     switch(menuItem.getItemId()){ 
      case(R.id.action_settings): 
       Intent startSettings = new Intent(MainActivity.this, SettingsActivity.class); 
       startActivity(startSettings); 
       return true; 
      case(R.id.about): 
       Intent startAbout = new Intent(MainActivity.this, AboutActivity.class); 
       startActivity(startAbout); 
       return true; 
      default: 
       return super.onOptionsItemSelected(menuItem); 
     } 
    } 

    @Override 
    public void onBackPressed(){ 
     finish(); 
    } 
} 

的AboutActivity和SettingsActivity不包含任何东西，所以我没有在这篇文章中加入他们。我真的不知道问题出在哪里。

Answer 1

重新启动手机和NFC设置解决了问题。