* @throws IOException
      */
     public static String readVnfmAdapterInfoFromJson() throws IOException {
-        String fileContent = "";
-
         String fileName = SystemEnvVariablesFactory.getInstance().getAppRoot()
                 + System.getProperty(Constant.FILE_SEPARATOR) + "etc" + System.getProperty(Constant.FILE_SEPARATOR)
                 + "adapterInfo" + System.getProperty(Constant.FILE_SEPARATOR) + VNFMADAPTER2DRIVERMGR;
 
+        return readJson(fileName);
+    }
+
+    public static String readJson(String fileName) throws IOException {
+        String fileContent = "";
+
         try (InputStream ins = new FileInputStream(fileName)){
             try(BufferedInputStream bins = new BufferedInputStream(ins)){
 
 
      * @throws IOException
      */
     public String readVnfmAdapterInfoFromJson() throws IOException {
-        String fileContent = "";
-
         String fileName = SystemEnvVariablesFactory.getInstance().getAppRoot()
                 + System.getProperty(Constant.FILE_SEPARATOR) + "etc" + System.getProperty(Constant.FILE_SEPARATOR)
                 + "adapterInfo" + System.getProperty(Constant.FILE_SEPARATOR) + VNFMADAPTERINFO;
 
-        try (InputStream ins = new FileInputStream(fileName)) {
-            try (BufferedInputStream bins = new BufferedInputStream(ins)){
+
+        return readJson(fileName);
+    }
+
+    public static String readJson(String fileName) throws IOException {
+        String fileContent = "";
+
+        try (InputStream ins = new FileInputStream(fileName)){
+            try(BufferedInputStream bins = new BufferedInputStream(ins)){
 
                 byte[] contentByte = new byte[ins.available()];
                 int num = bins.read(contentByte);
         return fileContent;
     }
 
+
     private static class RegisterVnfmAdapterThread implements Runnable {
 
         private IDriver2MSBManager adapter2MSBMgr = new Driver2MSBManager();
 
 
 package org.onap.vfc.nfvo.vnfm.svnfm.vnfmadapter.service.ai.internalsvc.impl;
 
-import mockit.Mock;
-import mockit.MockUp;
+import java.io.File;
+import java.io.IOException;
+
 import org.junit.Test;
 import org.onap.vfc.nfvo.vnfm.svnfm.vnfmadapter.service.api.internalsvc.impl.VnfmAdapter2DriverMgrService;
 
-import java.io.IOException;
+import junit.framework.Assert;
+import mockit.Mock;
+import mockit.MockUp;
 
 /**
  * Created by QuanZhong on 2017/3/20.
         mgr.register();
         mgr.unregister();
     }
+
+    @Test
+    public void testReadJson() {
+        File file = new File("./demo.json");
+        try {
+            file.createNewFile();
+            String content = VnfmAdapter2DriverMgrService.readJson("./demo.json");
+            Assert.assertEquals(content,  "");
+            file.delete();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
 }
 
 
 package org.onap.vfc.nfvo.vnfm.svnfm.vnfmadapter.service.ai.internalsvc.impl;
 
-import mockit.Mock;
-import mockit.MockUp;
-import net.sf.json.JSONObject;
+import java.io.File;
+import java.io.IOException;
+
 import org.junit.Test;
 import org.onap.vfc.nfvo.vnfm.svnfm.vnfmadapter.service.api.internalsvc.impl.VnfmAdapterMgrService;
-import org.onap.vfc.nfvo.vnfm.svnfm.vnfmadapter.service.process.VnfMgr;
 
-import java.io.IOException;
+import junit.framework.Assert;
+import mockit.Mock;
+import mockit.MockUp;
 
 /**
  * Created by QuanZhong on 2017/3/20.
         mgr.register();
 
     }
+
+
+    @Test
+    public void testReadJson() {
+        File file = new File("./demo.json");
+        try {
+            file.createNewFile();
+            String content = VnfmAdapterMgrService.readJson("./demo.json");
+            Assert.assertEquals(content,  "");
+            file.delete();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
 }