如何通过 wifi 打印机从 android 平板电脑打印简单的文本

Question

正在开发一个需要打印选项的安卓应用程序。我使用以下代码在 wifi 打印机中执行此操作，但它给出了 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();
}

有人知道怎么做吗？我需要一个在 wifi 打印机中打印的示例代码.....谢谢

Answer 1

我的代码正在运行： WifiPrint.java

公共类 WifiPrint 扩展 Activity { TextView 打印机名称， 网关，打印机端口；国际端口 = 9100； WifiManager wifi = null; android.net.DhcpInfo d;字符串 gateway_ip = "";

@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_wifi_print); wifi = (WifiManager) 获取系统服务（上下文。WIFI_SERVICE）；打印机名称 = (TextView) findViewById(R.id.textView1); gate_way = (TextView) findViewById(R.id.textView2);打印机端口 = (文本视图) findViewById(R.id.textView3); /* de.lohndirekt.print.IppPrintService svc = new IppPrintService(printerURI); InputStream 流 = 新 BufferedInputStream(new FileInputStream("image.epl")); DocFlavor 风味 = DocFlavor.INPUT_STREAM.AUTOSENSE；文档 myDoc = 新 SimpleDoc（流，风味，空）； DocPrintJob 作业 = svc.createPrintJob(); job.print(myDoc, null);*/

}

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

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

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

public String intToIp(int i) { return ((i & 0xFF) + "." + ((i >> 8) & 0xFF) + "." + ((i >> 16) & 0xFF) + "." + ((i >> 24) & 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("打印机IP：" + gateway_ip); 打印机端口.setText("端口：" + 端口);

  }   }

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 = new File("/sdcard/testpdf.pdf"); byte[] mybytearray = new byte[(int) pdfFile.length()]; socket = new Socket(gateway_ip, 端口); runOnUiThread(new Runnable() {
@覆盖 公共无效运行（）{ // TODO 自动生成的方法存根 如果（socket.isConnected（））{ Toast.makeText(WifiPrint.this, "套接字连接", Toast.LENGTH_LONG).show();
}
} });
fis = new FileInputStream(pdfFile); bis = new BufferedInputStream(fis); bis.read(mybytearray, 0, mybytearray.length); 输出流 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..

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