如何将 PDF 文件读取为字节数组？

Question

编译运行后显示“没有可用的pdf打印机”，如何解决这个问题？

我在 c:\print.pdf 中创建了一个文件（使用 PHP TCPDF）。而我是 尝试以字节数组的形式读取该文件，以便我可以默默地打印 它不显示任何打印弹出窗口等。

我无法让它工作，任何人都可以指导如何阅读 字节数组中的文件？执行以下操作：

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.print.Doc;
import javax.print.DocFlavor;
import javax.print.DocPrintJob;
import javax.print.PrintException;
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
import javax.print.SimpleDoc;

public class print 
{
    private static Object pdfBytes;

    // Byte array reader 
    public static byte[] getBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);
        long length = file.length();
        if (length > Integer.MAX_VALUE) {}
        byte[] bytes = new byte[(int)length];

        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
               && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }
        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+file.getName());
        }
        is.close();
        return bytes;
    }    

    // Convert Byte array to Object 
    public static Object toObject(byte[] bytes) 
    {
        Object obj = null;
        try {
            ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
            ObjectInputStream ois = new ObjectInputStream (bis);
            obj = ois.readObject();
        } catch (IOException ex) {

        } catch (ClassNotFoundException ex) {

        }
        return obj;
    }

    private static File fl = new File("c:\\print.pdf");    
    public static void main(String argc[])
    {
        DocFlavor flavor = DocFlavor.BYTE_ARRAY.PDF;
        PrintService[] services = 
                PrintServiceLookup.lookupPrintServices(flavor,
                null);
        //Object pdfBytes = null;
        try {
            byte[] abc = getBytesFromFile(fl);
            pdfBytes =toObject(abc);
        } catch (IOException ex) {
            Logger.getLogger(print.class.getName()).log(Level.SEVERE, null, ex);
        }

        if (services.length>0)
        {
            DocPrintJob printJob = services[0].createPrintJob();
            Doc document = new SimpleDoc(pdfBytes,flavor,null);
            try {
                printJob.print(document, null);
            } catch (PrintException ex) {
                Logger.getLogger(print.class.getName()).log(Level.SEVERE, null, ex);
            }
        } else {
            System.out.println("no pdf printer available");

        }
    }

}

我尝试了此操作，它解决了我的静默打印问题： https://gist.github.com/1094612< /a>

Answer 1

以下是如何将文件读入 byte[] 的示例：

// Returns the contents of the file in a byte array.
public static byte[] getBytesFromFile(File file) throws IOException {
    InputStream is = new FileInputStream(file);

    // Get the size of the file
    long length = file.length();

    // You cannot create an array using a long type.
    // It needs to be an int type.
    // Before converting to an int type, check
    // to ensure that file is not larger than Integer.MAX_VALUE.
    if (length > Integer.MAX_VALUE) {
        // File is too large
    }

    // Create the byte array to hold the data
    byte[] bytes = new byte[(int)length];

    // Read in the bytes
    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length
           && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
        offset += numRead;
    }

    // Ensure all the bytes have been read in
    if (offset < bytes.length) {
        throw new IOException("Could not completely read file "+file.getName());
    }

    // Close the input stream and return bytes
    is.close();
    return bytes;
}

Answer 2

import java.io.*;
import java.util.*;
import com.lowagie.text.*;
import com.lowagie.text.pdf.*;

public class ReadPDFFile {
        public static void main(String[] args) throws IOException {
                try {
                        Document document = new Document();
                        document.open();
                        PdfReader reader = new PdfReader("file.pdf");
                        PdfDictionary dictionary = reader.getPageN(1);
                        PRIndirectReference reference = (PRIndirectReference) dictionary
                                        .get(PdfName.CONTENTS);
                        PRStream stream = (PRStream) PdfReader.getPdfObject(reference);
                        byte[] bytes = PdfReader.getStreamBytes(stream);
                        PRTokeniser tokenizer = new PRTokeniser(bytes);
                        StringBuffer buffer = new StringBuffer();
                        while (tokenizer.nextToken()) {
                                if (tokenizer.getTokenType() == PRTokeniser.TK_STRING) {
                                        buffer.append(tokenizer.getStringValue());
                                }
                        }
                        String test = buffer.toString();
                        System.out.println(test);
                } catch (Exception e) {
                }
        }
}

Answer 3

编译并运行后显示“no pdf Printer available”

从我阅读的文档 这里和此处，问题是您尚未配置了解如何使用该 DocFlavour 打印文档的打印服务提供程序。

一种解决方案是找到一个为 PDF 文档实现 PrinterService SPI 的 JAR 文件，并将其添加到类路径中。谷歌搜索将显示示例。 （我不能推荐任何特定的 SP，因为我从未使用过。您需要进行一些调查/测试才能找到适合您的 SP。）