支持在Java中调用JavaScript，并获取返回值

Author: lemon

.idea/caches/build_file_checksums.ser

@@ -6,16 +6,20 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <title>Page Title</title>
     <meta name="viewport" content="width=device-width, initial-scale=1">
-    <script src="easybridge.js"></script>
     <script type="text/javascript">
 
         document.addEventListener('WebViewJavascriptBridgeReady',
             function () {
                 toast('inject finished');
+                window['easyBridge'].resultBack = function (parameters, callback) {
+                    if (typeof callback == 'function') {
+                        callback(parameters);
+                    }
+                };
             }, false);
 
         function toast(params = 'toast data') {
-            window['easyBridge'].callHandler('toast', 'toast with:'+params+'at '+new Date().toLocaleString());
+            window['easyBridge'].callHandler('toast', 'toast with:' + params + 'at ' + new Date().toLocaleString());
         }
     </script>
 </head>

.idea/inspectionProfiles/Project_Default.xml

@@ -5,8 +5,10 @@ import android.support.v7.app.AppCompatActivity
 import android.os.Bundle
 import android.webkit.WebChromeClient
 import android.webkit.WebView
+import android.widget.Toast
 import easily.tech.easybridge.handler.ToastHandler
 import easily.tech.easybridge.lib.EasyBridgeWebChromeClient
+import easily.tech.easybridge.lib.ResultCallBack
 import easily.tech.easybridge.lib.SecurityPolicyChecker
 import kotlinx.android.synthetic.main.activity_main.*
 
@@ -18,17 +20,16 @@ class MainActivity : AppCompatActivity() {
             WebView.setWebContentsDebuggingEnabled(true)
         }
         setContentView(R.layout.activity_main)
-        webView.webChromeClient = object : EasyBridgeWebChromeClient(webView) {
-            override fun onProgressChanged(view: WebView?, newProgress: Int) {
-                super.onProgressChanged(view, newProgress)
-                val script = String.format("%s.callHandler('toast','current progress:%s')", webView.bridgeName, newProgress)
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-                    webView.evaluateJavascript(script) {
-                    }
-                }
-            }
-        }
         webView.registerHandler(ToastHandler(this))
         webView.loadUrl("file:///android_asset/demo.html")
+        // call JavaScript From Java
+        webView.postDelayed({
+            webView.callHandler("resultBack", "this is the value pass from Java", object : ResultCallBack() {
+                override fun onResult(result: Any?) {
+                    Toast.makeText(this@MainActivity, result?.toString(), Toast.LENGTH_SHORT).show()
+                }
+
+            })
+        }, 5000)
     }
 }

app/src/main/assets/demo.html

@@ -31,16 +31,48 @@
             parameters = args || {};
             parameters = JSON.stringify(parameters);
         }
-        //the name '_easybridge' is an java object that mapping to a javascrip onject,using addJavaInterface in Java code
+        //the name '_easybridge' is an java object that mapping to a javascript onject,using addJavaInterface in Java code
         if (window._easybridge) {
             setTimeout(function () {
+                //the function enqueue is the pubic method from Java Code,using to call Java logic
                 _easybridge.enqueue(handlerName, location.href, parameters, callbackId);
             }, 0);
         } else {
             console.error(bridgeName + ':' + "the mapping object '_easybridge' had not been added any more");
         }
     }
 
+    //the function for Java Code to invoked JavaScript function 
+    function _executeScript(handlerName, parameters, callbackId) {
+        if (!handlerName) {
+            console.error('invalid handlerName from Java code');
+            return;
+        }
+        var handler = window[bridgeName][handlerName];
+        if (!handler) {
+            console.error('the handler with name \'' + handlerName + '\' to be invoked is not existed');
+            return;
+        }
+        try {
+            if (callbackId) {
+                callbackFunc = function (result) {
+                    if (window._easybridge) {
+                        //the method onExecuteJSCallback is a Java Code,using to dispatch result after execute the JavaScript function from Java
+                        _easybridge.onExecuteJSCallback(callbackId, result);
+                    } else {
+                        console.error(bridgeName + ':' + "the mapping object '_easybridge' had not been added any more");
+                    }
+                };
+                handler(parameters, callbackFunc);
+            } else {
+                handler(parameters);
+            }
+        } catch (exception) {
+            console.error(exception);
+        }
+    }
+
+
     //the function for the java code to dispatch the result
     function _dispatchResult(callbackId, result) {
         //find the target callback function and invoke it
@@ -72,7 +104,9 @@
     //init the bridge object
     window[bridgeName] = {
         callHandler: callHandler,
+        _executeScript: _executeScript,
         _dispatchResult: _dispatchResult,
+
     };
     //notify to javascript that the bridge had been init
     var doc = document;

app/src/main/java/easily/tech/easybridge/MainActivity.kt

@@ -2,7 +2,6 @@
 
 import android.os.Build;
 import android.os.Handler;
-import android.os.Message;
 import android.text.TextUtils;
 import android.webkit.JavascriptInterface;
 import android.webkit.ValueCallback;
@@ -32,15 +31,19 @@ private static class CallBackHandler extends Handler {
 
     private static final String JAVA_SCRIPT_PROTOCOL = "javascript:";
     private static final String CALLBACK_FUNCTION = "%s._dispatchResult(\"%s\",\'%s\')";
+    private static final String EXECUTE_SCRIPT = "%s._executeScript(\'%s\',\'%s\',\'%s\')";
 
     private Map<String, BridgeHandler> registerHandlerMap;
+    private Map<String, ResultCallBack> jsCallbackMap;
     private CallBackHandler callBackHandler;
     private SoftReference<WebView> bridgeWebView;
     private String bridgeName;
+    private static long uniqueId = 1;
 
     EasyBridge(WebView webView, String bridgeName) {
         this.bridgeName = bridgeName;
         registerHandlerMap = new HashMap<>();
+        jsCallbackMap = new HashMap<>();
         this.bridgeWebView = new SoftReference<>(webView);
         this.callBackHandler = new CallBackHandler();
     }
@@ -84,6 +87,39 @@ public void run() {
         });
     }
 
+    /**
+     * a method using to return the result from the Java Code execute the JavaScript
+     *
+     * @param callbackId the uniqueId for request
+     * @param result     the result from JavaScript
+     */
+    @JavascriptInterface
+    public void onExecuteJSCallback(String callbackId, final String result) {
+        if (jsCallbackMap == null || jsCallbackMap.isEmpty() || TextUtils.isEmpty(callbackId)) {
+            return;
+        }
+        final ResultCallBack resultCallBack = jsCallbackMap.get(callbackId);
+        if (resultCallBack != null) {
+            jsCallbackMap.remove(callbackId);
+            callBackHandler.post(new Runnable() {
+                @Override
+                public void run() {
+                    resultCallBack.onResult(result);
+                }
+            });
+        }
+    }
+
+    void callHandler(String handlerName, String parameters, ResultCallBack resultCallBack) {
+        String callbackId = "";
+        if (resultCallBack != null) {
+            callbackId = "cb_" + (uniqueId++) + System.currentTimeMillis();
+            jsCallbackMap.put(callbackId, resultCallBack);
+        }
+        String executeScript = String.format(EXECUTE_SCRIPT, bridgeName, handlerName, parameters, callbackId);
+        executeScriptInMain(executeScript);
+    }
+
 
     /**
      * if js invoke the java async ,that the result will be returned by execute a script in the bridge
@@ -157,4 +193,13 @@ void clear() {
         }
     }
 
+    void destroy() {
+        if (registerHandlerMap != null) {
+            registerHandlerMap.clear();
+        }
+        if (jsCallbackMap != null) {
+            jsCallbackMap.clear();
+        }
+    }
+
 }

easybridge/src/main/assets/easybridge.js

@@ -62,6 +62,13 @@ public void unregisterHandler(String handlerName) {
         }
     }
 
+    // use to execute JavaScript
+    public void callHandler(String handlerName, String parameters, ResultCallBack resultCallBack) {
+        if (easyBridge != null) {
+            easyBridge.callHandler(handlerName, parameters, resultCallBack);
+        }
+    }
+
     public void clear() {
         if (easyBridge != null) {
             easyBridge.clear();
@@ -79,4 +86,12 @@ public SecurityPolicyChecker getPolicyChecker() {
     public void setPolicyChecker(SecurityPolicyChecker policyChecker) {
         this.policyChecker = policyChecker;
     }
+
+    @Override
+    protected void onDetachedFromWindow() {
+        super.onDetachedFromWindow();
+        if (easyBridge != null) {
+            easyBridge.destroy();
+        }
+    }
 }

easybridge/src/main/java/easily/tech/easybridge/lib/EasyBridge.java

@@ -9,11 +9,14 @@ public abstract class ResultCallBack {
      */
     private String callbackId;
 
-    public ResultCallBack(String callbackId) {
+    public ResultCallBack() {
+    }
+
+    ResultCallBack(String callbackId) {
         this.callbackId = callbackId;
     }
 
-    public String getCallbackId() {
+    String getCallbackId() {
         return callbackId;
     }
 

easybridge/src/main/java/easily/tech/easybridge/lib/EasyBridgeWebView.java

@@ -17,12 +17,12 @@ public static synchronized String readAssetFile(Context context, String path) {
         try {
             inputStream = context.getAssets().open(path);
             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
-            String line = null;
+            String line;
             StringBuilder fileContent = new StringBuilder();
             do {
                 line = bufferedReader.readLine();
                 // ignore the comments string in file
-                if (line != null && !line.matches("^\\s*\\/\\/.*")) {
+                if (line != null && !line.matches("^\\s*//.*")) {
                     fileContent.append(line);
                 }
             } while (line != null);
@@ -35,7 +35,8 @@ public static synchronized String readAssetFile(Context context, String path) {
             if (inputStream != null) {
                 try {
                     inputStream.close();
-                } catch (IOException e) {
+                } catch (IOException exception) {
+                    exception.printStackTrace();
                 }
             }
         }