通过调用打印适配器生命周期方法,可以将printint打印到PDF中。然而,由于回调是非公共抽象类,并且系统在提供null时抛出段错误,因此需要使用DexMaker来实现它们。我已经实现了这样的webView适配器:
@Override
protected void onPreExecute() {
super.onPreExecute();
printAdapter = webView.createPrintDocumentAdapter();
}
@Override
protected Void doInBackground(Void... voids) {
File file = new File(pdfPath);
if (file.exists()) {
file.delete();
}
try {
file.createNewFile();
// get file descriptor
descriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_WRITE);
// create print attributes
PrintAttributes attributes = new PrintAttributes.Builder()
.setMediaSize(PrintAttributes.MediaSize.ISO_A4)
.setResolution(new PrintAttributes.Resolution("id", PRINT_SERVICE, 300, 300))
.setColorMode(PrintAttributes.COLOR_MODE_COLOR)
.setMinMargins(new PrintAttributes.Margins(0, 0, 0, 0))
.build();
ranges = new PageRange[]{new PageRange(1, numberPages)};
// dexmaker cache folder
cacheFolder = new File(context.getFilesDir() +"/etemp/");
printAdapter.onStart();
printAdapter.onLayout(attributes, attributes, new CancellationSignal(), getLayoutResultCallback(new InvocationHandler() {
@Override
public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
if (method.getName().equals("onLayoutFinished")) {
onLayoutSuccess();
} else {
Log.e(TAG, "Layout failed");
pdfCallback.onPdfFailed();
}
return null;
}
}, cacheFolder), new Bundle());
} catch (IOException e) {
e.printStackTrace();
Log.e(TAG, e != null ? e.getMessage() : "PrintPdfTask unknown error");
}
return null;
}
private void onLayoutSuccess() throws IOException {
PrintDocumentAdapter.WriteResultCallback callback = getWriteResultCallback(new InvocationHandler() {
@Override
public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
if (method.getName().equals("onWriteFinished")) {
pdfCallback.onPdfCreated();
} else {
Log.e(TAG, "Layout failed");
pdfCallback.onPdfFailed();
}
return null;
}
}, cacheFolder);
printAdapter.onWrite(ranges, descriptor, new CancellationSignal(), callback);
}
/**
* Implementation of non public abstract class LayoutResultCallback obtained via DexMaker
* @param invocationHandler
* @param dexCacheDir
* @return LayoutResultCallback
* @throws IOException
*/
public static PrintDocumentAdapter.LayoutResultCallback getLayoutResultCallback(InvocationHandler invocationHandler,
File dexCacheDir) throws IOException {
return ProxyBuilder.forClass(PrintDocumentAdapter.LayoutResultCallback.class)
.dexCache(dexCacheDir)
.handler(invocationHandler)
.build();
}
/**
* Implementation of non public abstract class WriteResultCallback obtained via DexMaker
* @param invocationHandler
* @param dexCacheDir
* @return LayoutResultCallback
* @throws IOException
*/
public static PrintDocumentAdapter.WriteResultCallback getWriteResultCallback(InvocationHandler invocationHandler,
File dexCacheDir) throws IOException {
return ProxyBuilder.forClass(PrintDocumentAdapter.WriteResultCallback.class)
.dexCache(dexCacheDir)
.handler(invocationHandler)
.build();
}
惠普可以直接使用自己的打印机。你不容易,因为你不是惠普。 – CommonsWare
加入CommonsWare和其他受到重视的答案,它不是微不足道的。你可以按照评论中提供的链接[this](http://stackoverflow.com/questions/20005975/hide-android-kitkat-4-4-printing-dialog/31570215#31570215)回答(陈述相同的判决),看看它是否有帮助。 – Onik