android - 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 Canvas 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。感谢您的帮助。

Answer 1

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

PdfDocumentAdapter.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);
    }