add option to pick a random port by passing port 0

Author: fchasen

README.md

@@ -38,7 +38,7 @@ A cross platform component for serving static assets with React Native.
 
 ## Usage
 
-Declare the `StaticServer` with a port or use the default `9999`
+Declare the `StaticServer` with a port or use the default `0` to pick a random available port.
 
 ```javascript
 import StaticServer from 'react-native-static-server';
@@ -64,7 +64,7 @@ import RNFS from 'react-native-fs';
 // create a path you want to write to
 let path = RNFS.DocumentDirectoryPath + '/www';
 
-let server = new StaticServer(8080, path);
+let server = new StaticServer(0, path);
 ```
 
 If the server should only be accessible from within the app, set `localOnly` to `true`

android/src/main/java/com/futurepress/staticserver/FPStaticServerModule.java

@@ -77,8 +77,20 @@ public void start(String _port, String root, Boolean localhost, Promise promise)
     if (_port != null) {
       try {
         port = Integer.parseInt(_port);
+
+        if (port == 0) {
+          try {
+            port = this.findRandomOpenPort();
+          } catch (IOException e) {
+            port = 9999;
+          }
+        }
       } catch(NumberFormatException nfe) {
-        port = 9999;
+        try {
+          port = this.findRandomOpenPort();
+        } catch (IOException e) {
+          port = 9999;
+        }
       }
     }
 
@@ -130,6 +142,18 @@ public void start(String _port, String root, Boolean localhost, Promise promise)
 
   }
 
+  private Integer findRandomOpenPort() throws IOException {
+    try {
+      ServerSocket socket = new ServerSocket(0);
+      int port = socket.getLocalPort();
+      Log.w(LOGTAG, "port:" + port);
+      socket.close();
+      return port;
+    } catch (IOException e) {
+      return 0;
+    }
+  }
+
   @ReactMethod
   public void stop() {
     if (server != null) {

index.js

@@ -5,7 +5,7 @@ import {
 
 const { FPStaticServer } = NativeModules;
 
-const PORT = "9999";
+const PORT = "0";
 const ROOT = null;
 const LOCALHOST = 'http://127.0.0.1:';
 

package.json

@@ -1,7 +1,7 @@
 
 {
   "name": "react-native-static-server",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "repository": "https://github.com/futurepress/react-native-static-server",
   "description": "HTTP static file server for React Native",
   "main": "index.js",