Question

正在开发一个需要打印选项的Android应用程序。我使用以下代码在wifi打印机中执行此操作，但它提供Networkonmainthread exception

try {
   Socket sock = new Socket("192.168.199.245", 9100); // ip and port of printer
   PrintWriter oStream = new PrintWriter(sock.getOutputStream());
   oStream.println("\t\t Text to The Printer");
   oStream.println("\n\n\n");
   oStream.close();
   sock.close();
} catch (UnknownHostException e) {
   e.printStackTrace();
} catch (IOException e) {
   e.printStackTrace();
}

有谁知道这是怎么回事？我需要一个用于在打印机打印的示例代码.....谢谢

Answer 1

我的代码正在运行： WifiPrint.java

公共类WifiPrint扩展了Activity {TextView printer_name，   gate_way，printer_port; int port = 9100; WifiManager wifi = null;     android.net.DhcpInfo d; String gateway_ip =“”;

@Override protected void onCreate（Bundle savedInstanceState）{         super.onCreate（savedInstanceState）;         的setContentView（R.layout.activity_wifi_print）; wifi =（WifiManager）   getSystemService（Context.WIFI_SERVICE）; printer_name =（TextView）   findViewById（R.id.textView1）; gate_way =（TextView）   findViewById（R.id.textView2）; printer_port =（TextView）   findViewById（R.id.textView3）;             / * de.lohndirekt.print.IppPrintService svc = new IppPrintService（printerURI）; InputStream stream = new   BufferedInputStream（new FileInputStream（“image.epl”））; DocFlavor的   flavor = DocFlavor.INPUT_STREAM.AUTOSENSE; Doc myDoc = new   SimpleDoc（stream，flavor，null）; DocPrintJob job =   svc.createPrintJob（）; job.print（myDoc，null）; * /

}

@Override public boolean onCreateOptionsMenu（Menu menu）{//   给菜单充气;这会将项目添加到操作栏（如果存在）。         getMenuInflater（）。inflate（R.menu.wifi_print，menu）;返回true;     }

public void wifisettings（View v）{startActivityForResult（new   意图（                 android.provider.Settings.ACTION_WIFI_SETTINGS），0）; }

public void connectSocket（View v）{
                / * Uri filepath = Uri.parse（“android.resource：//”+ getPackageName（）+“/”+ R.raw.pdfsample）; Toast.makeText（this，filepath.getPath（），Toast.LENGTH_LONG）。show（）; * / ClientThread clientThread = new   ClientThread（ “”）;线程clientstartThread = new   螺纹（clientThread）; clientstartThread.start（）; }

public String intToIp（int i）{return（（i＆amp; 0xFF）+“。”+（（i＆gt;＆gt; 8）   ＆安培; 0xFF）+“。” +（（i>＆gt;＆gt; 16）＆amp; 0xFF）                 +“。” +（（i>＆gt;＆gt; 24）＆amp; 0xFF））; }

@Override protected void onActivityResult（int requestCode，int   resultCode，Intent data）{// TODO自动生成的方法存根
  super.onActivityResult(requestCode, resultCode, data);      if
（requestCode == 0）{WifiInfo wifiinfo = wifi.getConnectionInfo（）; d = wifi.getDhcpInfo（）;
      printer_name.setText("Name:" + wifiinfo.getSSID());             gateway_ip =
intToIp（d.gateway）; gate_way.setText（“Printer Ip：”+ gateway_ip）; printer_port.setText（“Port：”+ port）;
  }   }
public File createFileFromInputStream（InputStream inputStream）{
 try{
    File f = new File("/sdcard/testpdf.pdf");
    OutputStream outputStream = new FileOutputStream(f);
    byte buffer[] = new byte[1024];
    int length = 0;

    while((length=inputStream.read(buffer)) > 0) {
      outputStream.write(buffer,0,length);
    }

    outputStream.close();
    inputStream.close();

    return f;
 }catch (IOException e) {
       //Logging exception
 }

 return null;     }
class ClientThread实现Runnable {String filepath =“”; BufferedInputStream bis = null; FileInputStream fis;
  Socket socket;

  public ClientThread(String filename) {          filepath = filename;        }

  @Override       public void run() {             // TODO Auto-generated method
存根尝试{
                InputStream in = getResources（）。openRawResource（R.raw.pdfsample）;                 createFileFromInputStream（IN）;                 文件pdfFile =新文件（“/ sdcard / testpdf.pdf”）;                 byte [] mybytearray = new byte [（int）pdfFile.length（）];                 socket = new Socket（gateway_ip，port）;                 runOnUiThread（new Runnable（）{
                    @覆盖                     public void run（）{                         // TODO自动生成的方法存根                         如果（socket.isConnected（））{                             Toast.makeText（WifiPrint.this，                                     “Socket Connected”，                                     Toast.LENGTH_LONG）.show（）;
                        }
                    }                 }）;
                fis = new FileInputStream（pdfFile）;                 bis = new BufferedInputStream（fis）;                 bis.read（mybytearray，0，mybytearray.length）;                 OutputStream os = socket.getOutputStream（）;                 os.write（mybytearray，0，mybytearray.length）;                 os.flush（）;
          if (bis != null) {
              bis.close();
              os.close();
              socket.close();
              fis.close();

          }
              } catch (final UnknownHostException e) {
          // TODO Auto-generated catch block
          runOnUiThread(new Runnable() {

              @Override
              public void run() {
                  // TODO Auto-generated method stub
                  Toast.makeText(WifiPrint.this,
                          "UnHost Exceptions" + e.getMessage(),
                          Toast.LENGTH_LONG).show();

              }
          });             } catch (final IOException e) {
          // TODO Auto-generated catch block
          runOnUiThread(new Runnable() {

              @Override
              public void run() {
                  // TODO Auto-generated method stub
                  Toast.makeText(WifiPrint.this,
                          "Io Exceptions" + e.getMessage(),
                          Toast.LENGTH_LONG).show();

              }
          });             } finally {
          try {
              if (bis != null) {
                  bis.close();
                  socket.close();
                  fis.close();
              }
          } catch (final IOException e) {
              // TODO Auto-generated catch block
              runOnUiThread(new Runnable() {
                  @Override
                  public void run() {
                      // TODO Auto-generated method stub
                      Toast.makeText(
                              WifiPrint.this,
                              "Io Exeption in Closing Socket"
                                      + e.getMessage(), Toast.LENGTH_LONG)
                              .show();
                  }
              });
          }           }       }
}

}

并在清单文件中添加某些权限：

<uses-feature android:name="android.hardware.wifi" />

Answer 2

只需将此代码粘贴到您的主要活动中即可。

StrictMode.setThreadPolicy(new Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
    StrictMode.setVmPolicy(new VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

如何从Android平板电脑通过wifi打印机打印一个简单的文本

2 个答案: