原生webview拦截弹框
SystemWebChromeClient.java
webview通过拦截alert，confirm，prompt等浏览器弹出框并截取弹出框中的数据达到接收数据的目的。以下粘帖部分代码 。
重点解释onJsPrompt。
......
/**
* Tell the client to display a javascript alert dialog.
*/
@Override
public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
dialogsHelper.showAlert(message, new CordovaDialogsHelper.Result() {
@Override public void gotResult(boolean success, String value) {
if (success) {
result.confirm();
} else {
result.cancel();
}
}
});
return true;
}
/**
* Tell the client to display a confirm dialog to the user.
*/
@Override
public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {
dialogsHelper.showConfirm(message, new CordovaDialogsHelper.Result() {
@Override
public void gotResult(boolean success, String value) {
if (success) {
result.confirm();
} else {
result.cancel();
}
}
});
return true;
}
/**
* Tell the client to display a prompt dialog to the user.
* If the client returns true, WebView will assume that the client will
* handle the prompt dialog and call the appropriate JsPromptResult method.
*
* Since we are hacking prompts for our own purposes, we should not be using them for
* this purpose, perhaps we should hack console.log to do this instead!
* 参数含义：
view:webview
origin:网页请求源(网页所属的域名)
message:显示在prompt对话框的内容
defaultValue：显示在prompt输入框上的内容(cordova中的数据传递都是使用该字段值)
result:A JsResult to confirm that the user hit enter.
return true表示由原生端来处理弹出框，此时webview自带的弹出框效果将被禁止
*/
@Override
public boolean onJsPrompt(WebView view, String origin, String message, String defaultValue, final JsPromptResult result) {
// Unlike the @JavascriptInterface bridge, this method is always called on the UI thread.
//由CordovaBridge.java来处理数据
String handledRet = parentEngine.bridge.promptOnJsPrompt(origin, message, defaultValue);
if (handledRet != null) {
//通知webview弹出框已经被处理，你需要调用result.confirm()或者result.cancel()来处理jsResult,否则会出问题.
result.confirm(handledRet);
} else {
//使用原生API AlertDialog.Builder来构建弹出框见CordovaDialogsHelper.java
dialogsHelper.showPrompt(message, defaultValue, new CordovaDialogsHelper.Result() {
@Override
public void gotResult(boolean success, String value) {
if (success) {
result.confirm(value);
} else {
result.cancel();
}
}
});
}
return true;
}
......
CordovaBridge.java
在上面的onJsPrompt中弹出框数据的由该类负责处理(promptOnJsPrompt)，以下说明该类。
String handledRet = parentEngine.bridge.promptOnJsPrompt(origin, message, defaultValue)
package org.apache.cordova;
import java.security.SecureRandom;
import org.json.JSONArray;
import org.json.JSONException;
/**
* Contains APIs that the JS can call. All functions in here should also have
* an equivalent entry in CordovaChromeClient.java, and be added to
* cordova-js/lib/android/plugin/android/promptbasednativeapi.js
*/
public class CordovaBridge {
private static final String LOG_TAG = "CordovaBridge";
private PluginManager pluginManager;//该类用来负责调用具体插件的exec方法
private NativeToJsMessageQueue jsMessageQueue;//该类用来负责向前端传输数据即传送插件的执行结果
private volatile int expectedBridgeSecret = -1; // written by UI thread, read by JS thread.
public CordovaBridge(PluginManager pluginManager, NativeToJsMessageQueue jsMessageQueue) {
this.pluginManager = pluginManager;
this.jsMessageQueue = jsMessageQueue;
}
//js端传入对应server 和 action 再通过pluginManager执行对应的插件
public String jsExec(int bridgeSecret, String service, String action, String callbackId, String arguments) throws JSONException, IllegalAccessException {
if (!verifySecret("exec()", bridgeSecret)) {
return null;
}
// If the arguments weren't received, send a message back to JS. It will switch bridge modes and try again. See CB-2666.
// We send a message meant specifically for this case. It starts with "@" so no other message can be encoded into the same string.
if (arguments == null) {
return "@Null arguments.";
}
jsMessageQueue.setPaused(true);
try {
// Tell the resourceApi what thread the JS is running on.
CordovaResourceApi.jsThread = Thread.currentThread();
pluginManager.exec(service, action, callbackId, arguments);
String ret = null;
if (!NativeToJsMessageQueue.DISABLE_EXEC_CHAINING) {
ret = jsMessageQueue.popAndEncode(false);
}
return ret;
} catch (Throwable e) {
e.printStackTrace();
return "";
} finally {
jsMessageQueue.setPaused(false);
}
}
//设置native到js的桥接模式 对应cordova.js 模块cordova/android/promptbasednativeapi 中的retrieveJsMessages方法 setNativeToJsBridgeMode
public void jsSetNativeToJsBridgeMode(int bridgeSecret, int value) throws IllegalAccessException {
if (!verifySecret("setNativeToJsBridgeMode()", bridgeSecret)) {
return;
}
jsMessageQueue.setBridgeMode(value);
}
//检索消息 对应cordova.js 模块cordova/android/promptbasednativeapi 中的retrieveJsMessages方法
public String jsRetrieveJsMessages(int bridgeSecret, boolean fromOnlineEvent) throws IllegalAccessException {
if (!verifySecret("retrieveJsMessages()", bridgeSecret)) {
return null;
}
return jsMessageQueue.popAndEncode(fromOnlineEvent);
}
//验证bridgeSecret是否相等,在cordova/exec模块中的init方法初始化native的bridgeSecret
private boolean verifySecret(String action, int bridgeSecret) throws IllegalAccessException {
if (!jsMessageQueue.isBridgeEnabled()) {
if (bridgeSecret == -1) {
LOG.d(LOG_TAG, action + " call made before bridge was enabled.");
} else {
LOG.d(LOG_TAG, "Ignoring " + action + " from previous page load.");
}
return false;
}
// Bridge secret wrong and bridge not due to it being from the previous page.
if (expectedBridgeSecret < 0 || bridgeSecret != expectedBridgeSecret) {
LOG.e(LOG_TAG, "Bridge access attempt with wrong secret token, possibly from malicious code. Disabling exec() bridge!");
clearBridgeSecret();
throw new IllegalAccessException();
}
return true;
}
/** Called on page transitions */
void clearBridgeSecret() {
expectedBridgeSecret = -1;
}
//bridgeSecret是否初始化(桥接模式是否被设置)
public boolean isSecretEstablished() {
return expectedBridgeSecret != -1;
}
/** Called by cordova.js to initialize the bridge. */
int generateBridgeSecret() {
SecureRandom randGen = new SecureRandom();
expectedBridgeSecret = randGen.nextInt(Integer.MAX_VALUE);
return expectedBridgeSecret;
}
public void reset() {
jsMessageQueue.reset();
clearBridgeSecret();
}
//处理cordova.js prompt弹出框数据
public String promptOnJsPrompt(String origin, String message, String defaultValue) {
//执行插件动作
if (defaultValue != null && defaultValue.length() > 3 && defaultValue.startsWith("gap:")) {
JSONArray array;
try {
array = new JSONArray(defaultValue.substring(4));
int bridgeSecret = array.getInt(0);
String service = array.getString(1);
String action = array.getString(2);
String callbackId = array.getString(3);
String r = jsExec(bridgeSecret, service, action, callbackId, message);
return r == null ? "" : r;
} catch (JSONException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return "";
}
// 设置 native->JS 的桥接模式
else if (defaultValue != null && defaultValue.startsWith("gap_bridge_mode:")) {
try {
int bridgeSecret = Integer.parseInt(defaultValue.substring(16));
jsSetNativeToJsBridgeMode(bridgeSecret, Integer.parseInt(message));
} catch (NumberFormatException e){
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return "";
}
// Polling for JavaScript messages js通过轮寻获取原生数据(插件执行结果)
else if (defaultValue != null && defaultValue.startsWith("gap_poll:")) {
int bridgeSecret = Integer.parseInt(defaultValue.substring(9));
try {
String r = jsRetrieveJsMessages(bridgeSecret, "1".equals(message));
return r == null ? "" : r;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return "";
}
//初始化native -> js 桥接模式
else if (defaultValue != null && defaultValue.startsWith("gap_init:")) {
// Protect against random iframes being able to talk through the bridge.
// Trust only pages which the app would have been allowed to navigate to anyway.
if (pluginManager.shouldAllowBridgeAccess(origin)) {
// Enable the bridge
int bridgeMode = Integer.parseInt(defaultValue.substring(9));
jsMessageQueue.setBridgeMode(bridgeMode);
// Tell JS the bridge secret.
int secret = generateBridgeSecret();
return ""+secret;
} else {
LOG.e(LOG_TAG, "gap_init called from restricted origin: " + origin);
}
return "";
}
return null;
}
}