我正在制作一个 android webview 应用程序，我在这里面临一个问题。
我正在尝试在上传之前在网页上预览我的图像
这是我正在使用的 html 和 java script 代码。
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
var preview = $(".upload-preview img");
$(".file").change(function(event){
var input = $(event.currentTarget);
var file = input[0].files[0];
var reader = new FileReader();
reader.onload = function(e){
image_base64 = e.target.result;
preview.attr("src", image_base64);
};
reader.readAsDataURL(file);
});
});
</script>
</head>
<body>
<div class="upload-preview">
<img />
</div>
<input class="file" name="logo" type="file">
</body>
</html>
这里是fiddle
它在几乎所有浏览器(即 Firefox、Chrome 和 IE)上都能正常工作，没有任何错误或警告。这是 Firefox 的快照(显示上传前的预览)
现在，每当我尝试在 android webview 中打开它时，它都不会显示图像预览 它显示类似这样的内容
我不知道出了什么问题，我已启用 javascript 并包含 jquery。从有一天起，它就让我发疯。
这是我的 android webview 代码。
package net.kaosfield.wv1;
import my.functions.MyFunctions;
import android.net.Uri;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.webkit.ValueCallback;
import android.webkit.WebChromeClient;
import android.webkit.WebViewClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.JsResult;
import android.content.Intent;
import com.google.android.gcm.GCMRegistrar;
public class MainActivity extends Activity {
Activity activity = MainActivity.this;
private WebView webView = null;
private ValueCallback<Uri> uploadMessage;
private final static int FILECHOOSER_RESULTCODE = 1;
private static String registrationId = "";
private MyFunctions myFunctions;
@Override
protected void onActivityResult(int requestCode, int resultCode,
Intent intent) {
if (requestCode == FILECHOOSER_RESULTCODE) {
if (uploadMessage == null)
return;
Uri result = intent == null || resultCode != RESULT_OK ? null
: intent.getData();
uploadMessage.onReceiveValue(result);
uploadMessage = null;
}
}
@SuppressLint("SetJavaScriptEnabled")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myFunctions = new MyFunctions(activity);
webView = (WebView) findViewById(R.id.webview);
webView.setInitialScale(myFunctions.setWebViewScale());
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
webView.setWebViewClient(new WebViewClient() {
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if (url.startsWith("net.kaosfield.wv1:")) {
Log.d("wv1", url);
return true;
}
return false;
}
@Override
public void onPageFinished(WebView view, String url) {
Log.d("wv1", "onPageFinished");
String argument = "d.e.f";
view.loadUrl("javascript:alert(window.method(\"" + argument
+ "\"))");
}
});
webView.setWebChromeClient(new WebChromeClient() {
@Override
public boolean onJsAlert(WebView view, String url, String message,
JsResult result) {
if (message.equals("net.kaosfield.wv1")) {
try {
Log.d("wv1", "url: " + url + ", message: " + message);
return true;
} finally {
result.confirm(); // in order not to alert
}
} else {
return false;
}
}
// For Android 3.0+
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback<Uri> uploadMsg) {
uploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
MainActivity.this.startActivityForResult(
Intent.createChooser(i, "File Chooser"),
FILECHOOSER_RESULTCODE);
}
// For Android 3.0+
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback<Uri> uploadMsg,
String acceptType) {
uploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
MainActivity.this.startActivityForResult(
Intent.createChooser(i, "File Browser"),
FILECHOOSER_RESULTCODE);
}
// For Android 4.1
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback<Uri> uploadMsg,
String acceptType, String capture) {
uploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
MainActivity.this.startActivityForResult(
Intent.createChooser(i, "File Chooser"),
MainActivity.FILECHOOSER_RESULTCODE);
}
});
webView.loadUrl("http://blue.genetechz.com/qadir/test.php");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
// Check if the key event was the Back button and if there's history
if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
webView.goBack();
return true;
}
// If it wasn't the Back key or there's no web page history, bubble up
// to the default
// system behavior (probably exit the activity)
return super.onKeyDown(keyCode, event);
}
}
最佳答案
您必须在 onActivityRestult 上进行此更改，因为从库返回的网址不正确:
@Override
protected void onActivityResult(int requestCode, int resultCode,
Intent intent) {
if (requestCode == FILECHOOSER_RESULTCODE) {
if (uploadMessage == null)
return;
Uri result = intent == null || resultCode != RESULT_OK ? null
: intent.getData();
if (result!=null){
String filePath = null;
if ("content".equals(result.getScheme())) {
Cursor cursor = this.getContentResolver().query(result, new String[] { android.provider.MediaStore.Images.ImageColumns.DATA }, null, null, null);
cursor.moveToFirst();
filePath = cursor.getString(0);
cursor.close();
} else {
filePath = result.getPath();
}
Uri myUri = Uri.parse(filePath);
uploadMessage.onReceiveValue(myUri);
} else {
uploadMessage.onReceiveValue(result);
}
uploadMessage = null;
}
}
现在，即使您从图库中选择图像，它也会返回一个 file:/// 格式的 URL。
关于javascript - 上传前 Android webview 中的图像预览不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19947559/