但我偶然发现了这个问题 – 当我点击选择文件按钮时,文件对话框无法打开.
几天我用Google搜索了这个问题,但我没有找到任何解决方案.看起来有workaround on Java platform,但它不适用于C#.
有人有任何想法如何让它工作？
解决方法 我知道如何使它工作.它的一部分是沼泽标准的“如何绑定虚拟方法”,其中一部分是纯粹的无懈可击的邪恶.首先,我们需要一个“中间人”.由于WebChromeClIEnt未声明openfileChooser()方法,因此我们需要声明一个名为OpenfileWebChromeClIEnt的版本.它声明了一个虚拟的OpenfileChooser方法,并为它提供了一个绑定,以便可以覆盖它：
using System;using AndroID.App;using AndroID.Content;using AndroID.Runtime;using AndroID.OS;using AndroID.Webkit;namespace Scratch.fileUpload{ [Register ("androID/webkit/WebChromeClIEnt",DoNotGenerateAcw=true)] class OpenfileWebChromeClIEnt : WebChromeClIEnt { static IntPtr ID_openfileChooser; [Register ("openfileChooser","(LandroID/webkit/ValueCallback;)V","GetopenfileChooserHandler")] public virtual voID OpenfileChooser (IValueCallback uploadMsg) { if (ID_openfileChooser == IntPtr.Zero) ID_openfileChooser = jnienv.getmethodID (ThresholdClass,"openfileChooser","(LandroID/webkit/ValueCallback;)V"); if (GetType () == ThresholdType) jnienv.CallVoIDMethod (Handle,ID_openfileChooser,new JValue (jnienv.ToJniHandle (uploadMsg))); else jnienv.CallNonvirtualVoIDMethod (Handle,ThresholdClass,new JValue (jnienv.ToJniHandle (uploadMsg))); }#pragma warning disable 0169 static Delegate cb_openfileChooser; static Delegate GetopenfileChooserHandler () { if (cb_openfileChooser == null) cb_openfileChooser = JNINativeWrapper.CreateDelegate ((Action<IntPtr,IntPtr,IntPtr>) n_OpenfileChooser); return cb_openfileChooser; } static voID n_OpenfileChooser (IntPtr jnienv,IntPtr native__this,IntPtr native_uploadMsg) { OpenfileWebChromeClIEnt __this = java.lang.Object.Getobject<OpenfileWebChromeClIEnt> (native__this,JniHandleOwnership.DoNottransfer); var uploadMsg = java.lang.Object.Getobject<IValueCallback> (native_uploadMsg,JniHandleOwnership.DoNottransfer); __this.OpenfileChooser (uploadMsg); }#pragma warning restore 0169 }} 接下来,由于C#缺少匿名内部类,我们需要一个名为MyOpenfileWebChromeClIEnt的显式类：
namespace Scratch.fileUpload { class MyOpenfileWebChromeClIEnt : OpenfileWebChromeClIEnt { Action<IValueCallback> cb; public MyOpenfileWebChromeClIEnt(Action<IValueCallback> cb) { this.cb = cb; } public overrIDe voID OpenfileChooser (IValueCallback uploadMsg) { cb (uploadMsg); } } Activity端口与您引用的博客文章相同,只是它使用MyOpenfileWebChromeClIEnt而不是匿名内部类.我还更新了一些逻辑来显示OnActivityResult()收到的URI：
namespace Scratch.fileUpload { [Activity (Label = "Scratch.fileUpload",MainLauncher = true)] public class Activity1 : Activity { private WebVIEw wv; private IValueCallback mUploadMessage; const int filechooserResultcode = 1; protected overrIDe voID OnCreate (Bundle bundle) { base.OnCreate (bundle); wv = new WebVIEw (this); wv.SetWebVIEwClIEnt(new WebVIEwClIEnt()); wv.SetWebChromeClIEnt(new MyOpenfileWebChromeClIEnt(uploadMsg => { mUploadMessage = uploadMsg; var intent = new Intent (Intent.ActionGetContent); intent.Addcategory(Intent.categoryOpenable); intent.SetType("image/*"); StartActivityForResult(Intent.CreateChooser(intent,"file Chooser"),filechooserResultcode); })); SetHTML(null); SetContentVIEw(wv); } voID SetHTML(string filename) { string HTML = @"<HTML><body><h1>Hello,world!</h1><p>input Box:</p><input type=""file"" /><p>URI: " + filename + @"</body></HTML>"; wv.LoadData(HTML,"text/HTML","utf-8"); } protected overrIDe voID OnActivityResult (int requestCode,Result resultCode,Intent data) { base.OnActivityResult (requestCode,resultCode,data); if (requestCode == filechooserResultcode) { if (mUploadMessage == null) return; var result = data == null || resultCode != Result.Ok ? null : data.Data; SetHTML(result.ToString()); mUploadMessage.OnReceiveValue(result); mUploadMessage = null; } } }} 可悲的是,现在是时候采取纯粹的彻头彻尾的邪恶行为了. MyOpenfileWebChromeClIEnt的上述声明的问题在于它不起作用,原因与M0S’博客无法在匿名内部类声明中使用@OverrIDe相同：你构建应用程序的androID.jar不会声明openfileChooser()方法.
构建过程将生成Android Callable Wrappers,其中必须包含有效的Java代码.问题是生成的代码使用@OverrIDe来覆盖方法和接口方法,从而产生MyOpenfileWebChromeClIEnt的AndroID Callable Wrapper：
package scratch.fileupload;public class MyOpenfileWebChromeClIEntextends androID.webkit.WebChromeClIEnt{ static final String __md_methods; static { __md_methods = "n_openfileChooser:(LandroID/webkit/ValueCallback;)V:GetopenfileChooserHandler\n" + ""; mono.androID.Runtime.register ("Scratch.fileUpload.MyOpenfileWebChromeClIEnt,Scratch.fileUpload,Version=1.0.0.0,Culture=neutral,PublicKeyToken=null",MyOpenfileWebChromeClIEnt.class,__md_methods); } @OverrIDe public voID openfileChooser (androID.webkit.ValueCallback p0) { n_openfileChooser (p0); } private native voID n_openfileChooser (androID.webkit.ValueCallback p0); java.util.ArrayList refList; public voID monodroIDAddReference (java.lang.Object obj) { if (refList == null) refList = new java.util.ArrayList (); refList.add (obj); } public voID monodroIDClearReferences () { if (refList != null) refList.clear (); }} 显然,MyOpenfileWebChromeClIEnt.openfileChooser()上的@OverrIDe会产生编译错误,那么我们如何才能使这个工作呢？通过提供我们自己的@OverrIDe注释！
package scratch.fileupload;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.METHOD)@Retention(RetentionPolicy.soURCE)public @interface OverrIDe {} 将上述内容放入名为OverrIDe.java的文件中,将其添加到项目中,并将其Build *** 作设置为AndroIDJavaSource.
生成的项目有效,因为我们在与MyOpenfileWebChromeClIEnt类型相同的包中提供自定义@OverrIDe注释. (这因此要求您知道生成的包名称是什么,并且为每个包提供单独的@OverrIDe注释.)同一包中的类型优先于导入的名称,甚至来自java的名称.lang,所以我们的自定义@OverrIDe注释不仅编译,它还被MyOpenfileWebChromeClIEnt androID可调用包装器使用,优先于java.lang.OverrIDe注释.
我确实说这是纯粹的不朽邪恶,不是吗？
总结以上是内存溢出为你收集整理的c# – Mono for Android,WebView输入字段filechooser不起作用全部内容，希望文章能够帮你解决c# – Mono for Android,WebView输入字段filechooser不起作用所遇到的程序开发问题。
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