看到论坛有人问如何hook接口类参数 我这里总结分享一下

Xposed有时候我们遇上方法调用方法需要传入接口作为参数，由于无法直接 newInstance 生成接口类。一般我们有两种方法

1.靠别人实现---查看是否有接口的实现类
2.靠自己实现---使用动态代理实现接口

代码示例

被 hook的app代码

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onResume() {
        super.onResume();
    }

    public void getData(okhttp3.Callback callback){
        Request.Builder builder = new Request.Builder();
        builder.url("https://www.baidu.com/");
        builder.get();
        ApiClient.getOkHttpClientInstance().newCall(builder.build()).enqueue(callback);
    }

    public static class OkCallBack implements Callback {

        @Override
        public void onFailure(Call call, IOException e) {

        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            LogXUtils.e(response.body().string());
        }
    }
}

hook代码

方案1

已有实现类 OkCallBack 直接使用

 Class cls = XposedHelpers.findClassIfExists("com.huruwo.app.MainActivity$OkCallBack", loadPackageParam.classLoader);
Object callback = XposedHelpers.newInstance(cls);
XposedHelpers.callMethod(activity,"getData", callback);

非常简单 但是有个缺点就是要得到数据 还要hook OkCallBack 的 onResponse 函数

 XposedHelpers.findAndHookMethod(cls, "onResponse", XposedHelpers.findClassIfExists("okhttp3.Callback", loadPackageParam.classLoader), XposedHelpers.findClassIfExists("okhttp3.onResponse", loadPackageParam.classLoader), new XC_MethodHook() {
                                   @Override
                                   protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                                       super.beforeHookedMethod(param);
                                           Object res = args[1];
                                           LogXUtils.e((String) XposedHelpers.callMethod(XposedHelpers.callMethod(res,"body"),"string"));
                                   }

                                   @Override
                                   protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                                       super.afterHookedMethod(param);
                                   }
                               });

方案2 动态代理自己实现接口

Class cls = XposedHelpers.findClassIfExists("okhttp3.Callback", loadPackageParam.classLoader);
                               Object callback =  Proxy.newProxyInstance(loadPackageParam.classLoader, new Class[]{cls}, new InvocationHandler() {
                                   @Override
                                   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                                       //如果不需要 没必要实现
                                       if(method.getName().equals("onResponse")){
                                           Object res = args[1];
                                           LogXUtils.e((String) XposedHelpers.callMethod(XposedHelpers.callMethod(res,"body"),"string"));
                                       }
                                       return null;
                                   }
                               });

                               XposedHelpers.callMethod(activity,"getData", callback);

总结

如果实现方法简单，我更倾向于第二种方案,调用流程清晰。

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