在android中打印现有的pdf文件

Question

大家好，我正在尝试在 android 上构建一个小型示例打印应用程序，但似乎无法打印现有的 pdf。 有很多关于使用画布创建自定义文档的文档，但我已经有了该文档。 基本上，我只想能够读取 pdf 文档并将其作为文件输出流直接发送到要打印的打印机。 任何帮助表示赞赏。

Answer 1

我们可以通过创建自定义PrintDocumentAdapter来简单地实现这一点

文档适配器.java

public class PdfDocumentAdapter extends PrintDocumentAdapter {

Context context = null;
String pathName = "";
public PdfDocumentAdapter(Context ctxt, String pathName) {
    context = ctxt;
    this.pathName = pathName;
}
@Override
public void onLayout(PrintAttributes printAttributes, PrintAttributes printAttributes1, CancellationSignal cancellationSignal, LayoutResultCallback layoutResultCallback, Bundle bundle) {
    if (cancellationSignal.isCanceled()) {
        layoutResultCallback.onLayoutCancelled();
    }
    else {
        PrintDocumentInfo.Builder builder=
                new PrintDocumentInfo.Builder(" file name");
        builder.setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
                .setPageCount(PrintDocumentInfo.PAGE_COUNT_UNKNOWN)
                .build();
        layoutResultCallback.onLayoutFinished(builder.build(),
                !printAttributes1.equals(printAttributes));
    }
}

@Override
public void onWrite(PageRange[] pageRanges, ParcelFileDescriptor parcelFileDescriptor, CancellationSignal cancellationSignal, WriteResultCallback writeResultCallback) {
    InputStream in=null;
    OutputStream out=null;
    try {
        File file = new File(pathName);
        in = new FileInputStream(file);
        out=new FileOutputStream(parcelFileDescriptor.getFileDescriptor());

        byte[] buf=new byte[16384];
        int size;

        while ((size=in.read(buf)) >= 0
                && !cancellationSignal.isCanceled()) {
            out.write(buf, 0, size);
        }

        if (cancellationSignal.isCanceled()) {
            writeResultCallback.onWriteCancelled();
        }
        else {
            writeResultCallback.onWriteFinished(new PageRange[] { PageRange.ALL_PAGES });
        }
    }
    catch (Exception e) {
        writeResultCallback.onWriteFailed(e.getMessage());
        Logger.logError( e);
    }
    finally {
        try {
            in.close();
            out.close();
        }
        catch (IOException e) {
            Logger.logError( e);
        }
    }
}}

现在使用PrintManager调用打印

        PrintManager printManager=(PrintManager) getActivityContext().getSystemService(Context.PRINT_SERVICE);
    try
    {
        PrintDocumentAdapter printAdapter = new PdfDocumentAdapter(Settings.sharedPref.context,filePath );
        }
        printManager.print("Document", printAdapter,new PrintAttributes.Builder().build());
    }
    catch (Exception e)
    {
        Logger.logError(e);
    }

Answer 2

基本上，我只想能够读取 pdf 文档并将其作为文件输出流直接发送到要打印的打印机。

这不是绝对可能的，除非您找到某些特定的打印机为 Android 提供此类 API。

如果您希望使用 Android 打印框架，则需要创建一个可以处理现有 PDF 文件的PrintDocumentAdapter 。 这个示例项目演示了一个这样的PrintDocumentAdapter ，尽管它不是通用的。

Answer 3

对于那些对Karthik Bollisetti的 kotlin 版本感兴趣的人，答案就在这里。

PdfDocumentAdapter重写为这样

class PdfDocumentAdapter(private val pathName: String) : PrintDocumentAdapter() {

override fun onLayout(
    oldAttributes: PrintAttributes?,
    newAttributes: PrintAttributes,
    cancellationSignal: CancellationSignal?,
    callback: LayoutResultCallback,
    bundle: Bundle
) {
    if (cancellationSignal?.isCanceled == true) {
        callback.onLayoutCancelled()
        return
    } else {
        val builder = PrintDocumentInfo.Builder(" file name")
        builder.setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
            .setPageCount(PrintDocumentInfo.PAGE_COUNT_UNKNOWN)
            .build()

        callback.onLayoutFinished(builder.build(), newAttributes == oldAttributes)
    }
}

override fun onWrite(
    pageRanges: Array<out PageRange>,
    destination: ParcelFileDescriptor,
    cancellationSignal: CancellationSignal?,
    callback: WriteResultCallback
) {
    try {
        // copy file from the input stream to the output stream
        FileInputStream(File(pathName)).use { inStream ->
            FileOutputStream(destination.fileDescriptor).use { outStream ->
                inStream.copyTo(outStream)
            }
        }

        if (cancellationSignal?.isCanceled == true) {
            callback.onWriteCancelled()
        } else {
            callback.onWriteFinished(arrayOf(PageRange.ALL_PAGES))
        }

    } catch (e: Exception) {
        callback.onWriteFailed(e.message)
    }
}
}

然后像这样在您的代码中调用 PrintManager

val printManager : PrintManager = requireContext().getSystemService(Context.PRINT_SERVICE) as PrintManager
try {
    val printAdapter = PdfDocumentAdapter(file.absolutePath)
    printManager.print("Document", printAdapter, PrintAttributes.Builder().build())
} catch (e : Exception) {
    Timber.e(e)
}

Answer 4

对于支持 ipp 和 pdf 的打印机用例，您可以使用我的库https://github.com/gmuth/ipp-client-kotlin将 pdf 直接发送到打印机：

Kotlin:
val printer = IppPrinter(URI.create("ipp://myprinter/ipp"))
val job = printer.printJob(File("mydocument.pdf"))
job.waitForTermination()

不涉及打印对话框。