expose the printer version ,sn and modal to the constants

expose the printer version ,sn and modal to the constants`

README.md

@@ -79,6 +79,16 @@ See examples folder of the source code that you can find a simple example of pri
 
 ## API
 
+### Constants
+| Name | Description|
+|:-----:|:-----------:|
+| Constants | 打印状态常量 |
+| hasPrinter | boolean,是否有打印机 |
+| printerVersion | 打印机固件版本 |
+| printerSerialNo | 打印机序列号 |
+| printerModal | 打印机型号 |
+
+
 ### Printer Status
 
 |  Name | Description |

android/src/main/java/com/sunmi/innerprinter/SunmiInnerPrinterModule.java

@@ -126,6 +126,25 @@ public Map<String, Object> getConstants() {
 
 		constants.put("hasPrinter", hasPrinter());
 
+		try {
+			constants.put("printerVersion", getPrinterVersion());
+		}catch(Exception e){
+			// Log and ignore for it is not the madatory constants.
+			Log.i(TAG, "ERROR: " + e.getMessage());
+		}
+		try{
+			constants.put("printerSerialNo", getPrinterSerialNo());
+		}catch(Exception e){
+			// Log and ignore for it is not the madatory constants.
+			Log.i(TAG, "ERROR: " + e.getMessage());
+		}
+		try{
+			constants.put("printerModal",getPrinterModal());
+		}catch(Exception e){
+			// Log and ignore for it is not the madatory constants.
+			Log.i(TAG, "ERROR: " + e.getMessage());
+		}
+
 		return constants;
 	}
 
@@ -213,48 +232,65 @@ public void  onRaiseException(int code, String msg){
 	@ReactMethod
 	public void getPrinterSerialNo(final Promise p) {
 		try {
-			final IWoyouService printerService = woyouService;
-			String sn = printerService.getPrinterSerialNo();
-			p.resolve(sn);
+			p.resolve(getPrinterSerialNo());
 		}
 		catch (Exception e) {
 			Log.i(TAG, "ERROR: " + e.getMessage());
 			p.reject("" + 0, e.getMessage());
 		}
 	}
+	private String getPrinterSerialNo()throws Exception{
+		final IWoyouService printerService = woyouService;
+		return printerService.getPrinterSerialNo();
+	}
 
 	/**
 	* 获取打印机固件版本号
 	*/
 	@ReactMethod
 	public void getPrinterVersion(final Promise p) {
 		try {
-			final IWoyouService printerService = woyouService;
-			String version = printerService.getPrinterVersion();
-			p.resolve(version);
+			p.resolve(getPrinterVersion());
 		}
 		catch (Exception e) {
 			Log.i(TAG, "ERROR: " + e.getMessage());
 			p.reject("" + 0, e.getMessage());
 		}
 	}
+	private String getPrinterVersion()throws Exception{
+		final IWoyouService printerService = woyouService;
+		return printerService.getPrinterVersion();
+	}
 
 	/**
 	* 获取打印机型号
 	*/
 	 @ReactMethod
 	 public void getPrinterModal(final Promise p){
-		 //Caution: This method is not fully test -- Januslo 2018-08-11
 		 try{
-			 final IWoyouService printerService = woyouService;
-			 String modal = printerService.getPrinterModal();
-			 p.resolve(modal);
+			 p.resolve(getPrinterModal());
 		 }catch(Exception e){
 			 Log.i(TAG, "ERROR: " + e.getMessage());
 			 p.reject("" + 0, e.getMessage());
 		 }
 	 }
 
+	private String getPrinterModal()throws Exception{
+		//Caution: This method is not fully test -- Januslo 2018-08-11
+		final IWoyouService printerService = woyouService;
+		return printerService.getPrinterModal();
+	}
+
+	@ReactMethod
+	public void hasPrinter(final Promise p){
+		try{
+			p.resolve(hasPrinter());
+		}catch(Exception e){
+			Log.i(TAG, "ERROR: " + e.getMessage());
+			p.reject("" + 0, e.getMessage());
+		}
+	}
+
 	/**
 	 * 是否存在打印机服务
 	 * return {boolean}