使用zxing生成二维码去除空白区域方法

通常我们生成二维码需要做以下配置

Map<EncodeHintType, Object> hints = new HashMap<>();
hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);//设置容错率默认为最高
hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");// 字符编码为UTF-8
hints.put(EncodeHintType.MARGIN, 0);//二维码空白区域,最小为0也有白边,只是很小,最小是6像素左右

生成的二维码的空白区域怎么设置都是有

实测试100、1000大小的空白像素如 top:7 right:8 bottom:8 left:7 右边、底部会多一个像素

二维码生成返回的对像 BitMatrix可以直接遍历，可以把它当作一个二维数组，通过BitMatrix.get(x,y)判断是否是一个黑点，然后复制到一个新的二维码对像即可，实例代码如下

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
/**
* Created by zengrenyuan
*/
public class QRCodeImageTest {
private static final Logger LOG = LoggerFactory.getLogger(QRCodeImageTest.class);
public static void main(String[] args) {
String format = "png";// 图像类型
String target = "/data/qrcode.png";
Map<EncodeHintType, Object> hints = new HashMap<>();
hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);//设置容错率默认为最高
hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");// 字符编码为UTF-8
hints.put(EncodeHintType.MARGIN, 0);//二维码空白区域,最小为0也有白边,只是很小,最小是6%左右
try (OutputStream os = new FileOutputStream(target)) {
//二维码的宽
int qrCodeWidth = 1000;
BitMatrix bitMatrix = new MultiFormatWriter()
.encode("https://www.baidu.com", BarcodeFormat.QR_CODE, qrCodeWidth, qrCodeWidth, hints);
int height = bitMatrix.getHeight();
int width = bitMatrix.getWidth();
try (OutputStream os1 = new FileOutputStream("/data/qrcode.png")) {
MatrixToImageWriter.writeToStream(bitMatrix, format, os1);
}
boolean isFirstBlankPoint = false;//是否第一个黑点
int left = 0;//开始的宽
int top = 0;//开始的高
for (int y = 0; y < height; y++) {//从左上角开始读
if (isFirstBlankPoint) {
break;
}
for (int x = 0; x < width; x++) {
if (bitMatrix.get(x, y) && !isFirstBlankPoint) {//如果是一个黑点就会返回true
isFirstBlankPoint = true;
left = x;
top = y;
LOG.info("f x:{} y:{}", x, y);
}
}
}
int right = 0;//右边空白区域
int bottom = 0;//底部空白区域
boolean isRightLastPoint = false;
for (int x = width - 1; x >= 0; x--) {//从右上角开始读
if (isRightLastPoint) {
break;
}
for (int y = 0; y < height; y++) {
if (bitMatrix.get(x, y) && !isRightLastPoint) {//如果是一个黑点就会返回true
isRightLastPoint = true;
right = width - x;
LOG.info("e x:{} y:{} right:{}", x, y, right);
break;
}
}
}
boolean isBottomLastPoint = false;
for (int y = height - 1; y >= 0; y--) {//从左理角开始读
if (isBottomLastPoint) {
break;
}
for (int x = 0; x < width; x++) {
if (bitMatrix.get(x, y) && !isBottomLastPoint) {
isBottomLastPoint = true;
bottom = height - y;
LOG.info("e x:{} y:{} bottom:{}", x, y, bottom);
break;
}
}
}
LOG.info("top:{} right:{} bottom:{} left:{} ", top, right, bottom, left);
//最小的空白区域一个像素
int miniPadding = 1;
//原二维码大小减去上下左右的空白区域
int newWidth = qrCodeWidth - left - right + miniPadding * 2;
int newHeight = qrCodeWidth - top - bottom + miniPadding * 2;
BitMatrix newBitMatrix = new BitMatrix(newWidth, newHeight);
//写二维码点的宽度
int pointSize = 1;
for (int y = miniPadding; y < newHeight; y++) {
for (int x = miniPadding; x < newWidth; x++) {
if (bitMatrix.get(x + left, y + top)) {
newBitMatrix.setRegion(x, y, pointSize, pointSize);
}
}
}
MatrixToImageWriter.writeToStream(newBitMatrix, format, os);
} catch (Exception e) {
LOG.error(null, e);
}
}