项目中需要用到二维码，二维码的码制是PDF417，在做了一番研究之后发现zxing是个不错的开源工具（代码托管在google上面）。为什么选择zxing，由于其他一些工具比如barcode4j（开源，支持读，好像不支持写，最后维护时间在2010年）、barcode（商业版）都不太适合，所以选择了zxing。

zxing并没有提供直接可以使用的jar文件，而是需要自己通过编译源码，生成需要的jar文件。额外说明，zxing利用maven管理自己的代码，并且默认使用了jdk7，代码中也使用了jdk7的一些新特性，基于这些情况，可以适当调整jdk的版本（如果降低jdk的版本，需要改动少量的源码）。

下面直接贴出读写文件的代码：

ZxingPdfRead

package test;import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URLDecoder;
import java.util.EnumMap;
import java.util.Map;import javax.imageio.ImageIO;import com.google.zxing.BinaryBitmap;
import com.google.zxing.BufferedImageLuminanceSource;
import com.google.zxing.DecodeHintType;
import com.google.zxing.LuminanceSource;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Reader;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;public class ZxingPdfRead {private static Reader barcodeReader = new MultiFormatReader();/*** @param args* @throws IOException*/public static void main(String[] args) throws Exception {File testImage = new File("E:\\work\\all_workspace\\wp_zxing\\barcode4jTest\\src\\test\\helloworld.png");BufferedImage image = ImageIO.read(testImage);LuminanceSource source = new BufferedImageLuminanceSource(image);BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));try {Map<DecodeHintType, Object> hints = new EnumMap<DecodeHintType, Object>(DecodeHintType.class);hints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);Result result = barcodeReader.decode(bitmap, hints);String resultText = result.getText();System.out.println("resultText:" + URLDecoder.decode(resultText, "UTF-8"));} catch (ReaderException ignored) {ignored.printStackTrace();}}
}

ZxingPdfWrite

package test;import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URLEncoder;import javax.imageio.ImageIO;import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.pdf417.PDF417Writer;public class ZxingPdfWrite {private static final int BLACK = 0xff000000;private static final int WHITE = 0xFFFFFFFF;/*** @param args* @throws WriterException*/public static void main(String[] args) throws Exception {// TODO Auto-generated method stubPDF417Writer pdf417Writer = new PDF417Writer();//注意中文乱码问题BitMatrix bitMatrix = pdf417Writer.encode(URLEncoder.encode("我是中国人","UTF-8"),BarcodeFormat.PDF_417, 100, 50);writeToFile(bitMatrix,"png",new File("E:\\work\\all_workspace\\wp_zxing\\barcode4jTest\\src\\test\\helloworld.png"));}public static void writeToFile(BitMatrix matrix, String format, File file)throws IOException {BufferedImage image = toBufferedImage(matrix);ImageIO.write(image, format, file);}public static BufferedImage toBufferedImage(BitMatrix matrix) {int width = matrix.getWidth();int height = matrix.getHeight();BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_ARGB);for (int x = 0; x < width; x++) {for (int y = 0; y < height; y++) {image.setRGB(x, y, matrix.get(x, y) == true ? BLACK : WHITE);}}return image;}}

BufferedImageLuminanceSource.java

/** Copyright 2009 ZXing authors** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/import com.google.zxing.LuminanceSource;import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.awt.geom.AffineTransform;/*** This LuminanceSource implementation is meant for J2SE clients and our blackbox unit tests.** @author dswitkin@google.com (Daniel Switkin)* @author Sean Owen*/
public final class BufferedImageLuminanceSource extends LuminanceSource {private final BufferedImage image;private final int left;private final int top;private int[] rgbData;public BufferedImageLuminanceSource(BufferedImage image) {this(image, 0, 0, image.getWidth(), image.getHeight());}public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width,int height) {super(width, height);int sourceWidth = image.getWidth();int sourceHeight = image.getHeight();if (left + width > sourceWidth || top + height > sourceHeight) {throw new IllegalArgumentException("Crop rectangle does not fit within image data.");}this.image = image;this.left = left;this.top = top;}// These methods use an integer calculation for luminance derived from:// <code>Y = 0.299R + 0.587G + 0.114B</code>@Overridepublic byte[] getRow(int y, byte[] row) {if (y < 0 || y >= getHeight()) {throw new IllegalArgumentException("Requested row is outside the image: " + y);}int width = getWidth();if (row == null || row.length < width) {row = new byte[width];}if (rgbData == null || rgbData.length < width) {rgbData = new int[width];}image.getRGB(left, top + y, width, 1, rgbData, 0, width);for (int x = 0; x < width; x++) {int pixel = rgbData[x];int luminance = (306 * ((pixel >> 16) & 0xFF) +601 * ((pixel >> 8) & 0xFF) +117 * (pixel & 0xFF)) >> 10;row[x] = (byte) luminance;}return row;}@Overridepublic byte[] getMatrix() {int width = getWidth();int height = getHeight();int area = width * height;byte[] matrix = new byte[area];int[] rgb = new int[area];image.getRGB(left, top, width, height, rgb, 0, width);for (int y = 0; y < height; y++) {int offset = y * width;for (int x = 0; x < width; x++) {int pixel = rgb[offset + x];int luminance = (306 * ((pixel >> 16) & 0xFF) +601 * ((pixel >> 8) & 0xFF) +117 * (pixel & 0xFF)) >> 10;matrix[offset + x] = (byte) luminance;}}return matrix;}@Overridepublic boolean isCropSupported() {return true;}@Overridepublic LuminanceSource crop(int left, int top, int width, int height) {return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);}// Can't run AffineTransforms on images of unknown format.@Overridepublic boolean isRotateSupported() {return image.getType() != BufferedImage.TYPE_CUSTOM;}@Overridepublic LuminanceSource rotateCounterClockwise() {if (!isRotateSupported()) {throw new IllegalStateException("Rotate not supported");}int sourceWidth = image.getWidth();int sourceHeight = image.getHeight();// Rotate 90 degrees counterclockwise.AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);// Note width/height are flipped since we are rotating 90 degrees.BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, image.getType());// Draw the original image into rotated, via transformationGraphics2D g = rotatedImage.createGraphics();g.drawImage(image, transform, null);g.dispose();// Maintain the cropped region, but rotate it too.int width = getWidth();return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width),getHeight(), width);}}