1.源码

    package com.test;        import java.awt.image.BufferedImage;        import java.io.File;        import java.io.IOException;        import java.io.UnsupportedEncodingException;        import java.nio.ByteBuffer;        import java.nio.CharBuffer;        import java.nio.charset.CharacterCodingException;        import java.nio.charset.Charset;        import java.nio.charset.CharsetEncoder;        import java.util.Hashtable;        import javax.imageio.ImageIO;        import com.google.zxing.BinaryBitmap;        import com.google.zxing.DecodeHintType;        import com.google.zxing.LuminanceSource;        import com.google.zxing.MultiFormatReader;        import com.google.zxing.Result;        import com.google.zxing.client.j2se.BufferedImageLuminanceSource;        import com.google.zxing.client.j2se.MatrixToImageWriter;        import com.google.zxing.common.BitMatrix;        import com.google.zxing.common.HybridBinarizer;        import com.google.zxing.qrcode.QRCodeWriter;                public class main {            public static void main(String[] args) {                String filePath = "d:/qr_png.png";                String str = "";                /*               for (int i = 0; i < 2685; i++) {                   str += 1;               }               */                            for (int i = 0; i < 635; i++) {                    str += "赵";                }                                    encode(str, filePath);                decode(filePath);            }                    // qrcode 编码            static void encode(String conent, String filePath) {                Charset charset = Charset.forName("UTF-8");                CharsetEncoder encoder = charset.newEncoder();                byte[] b = null;                try { // Convert a string to ISO-8859-1 bytes in a ByteBuffer                    System.out.println("-------->" + conent.length());                    ByteBuffer bbuf = encoder.encode(CharBuffer.wrap(conent));                    b = bbuf.array();                } catch (CharacterCodingException e) {                    System.out.println(e.getMessage());                }                String data = "";                try {                    data = new String(b, "iso8859-1");                } catch (UnsupportedEncodingException e) {                    System.out.println(e.getMessage());                } // get a byte matrix for the data                BitMatrix matrix = null;                int h = 900;                int w = 800;                com.google.zxing.Writer writer = new QRCodeWriter();                try {                    matrix = writer.encode(data,                            com.google.zxing.BarcodeFormat.QR_CODE, w, h);                } catch (com.google.zxing.WriterException e) {                    System.out.println(e.getMessage());                }                File file = new File(filePath);                try {                    MatrixToImageWriter.writeToFile(matrix, "PNG", file);                    System.out.println("printing to " + file.getAbsolutePath());                } catch (IOException e) {                    System.out.println(e.getMessage());                }            }                    // qrcode 解码            static void decode(String file) {                try {                    Result result = null;                    BufferedImage image = null;                    image = ImageIO.read(new File(file));                    LuminanceSource source = new BufferedImageLuminanceSource(image);                    BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));                    Hashtable<DecodeHintType, Object> hints = new Hashtable<DecodeHintType, Object>();                    hints.put(DecodeHintType.CHARACTER_SET, "UTF-8");                    result = new MultiFormatReader().decode(bitmap, hints);                    String rtn = result.getText();                    System.out.println(rtn);                    System.out.println(rtn.length());                } catch (Exception ex) {                    System.out.println(ex.toString());                }            }        }  

2.最多2685个字母635个汉字

635个汉字

2685个字母