java - java - 将jpg文件转换为字节字符串并再次转换回jpg
问题描述
我没有得到我做错了什么。我被编码为字节字符串的同一个 xyz.jpg 文件。现在,当我尝试从相同的字节字符串转换 jpg 文件时,出现错误。
获得异常
java.lang.IllegalArgumentException: Length of Base64 encoded input string is not a multiple of 4.
at let.application.Base64Coder.decode(Base64Coder.java:95)
at let.application.Base64Coder.decode(Base64Coder.java:92)
at let.application.Base64Coder.decode(Base64Coder.java:89)
at let.application.TestImage.main(TestImage.java:29)
我的主要应用
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import javax.imageio.ImageIO;
import org.apache.commons.io.FileUtils;
import sun.misc.BASE64Encoder;
public class TestImage {
public static void main(String[] args) {
try {
String filePath = "c:\\AFS\\FBUMP_IMAGE.jpg";
//Encode
byte[] fileContent = FileUtils.readFileToByteArray(new File(filePath));
BASE64Encoder base64encoder = new BASE64Encoder();
String encodedString = base64encoder.encode(fileContent); // GALC way
System.out.println(encodedString);
// Decode
byte[] bytearray = Base64Coder.decode(encodedString);
BufferedImage imag;
imag = ImageIO.read(new ByteArrayInputStream(bytearray));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
System.out.println(imag);
ImageIO.write(imag, "png", baos);
} catch (Exception e) {
e.printStackTrace();
}
}
}
请注意:Base64Coder.java 已经存在,我必须“必须”使用它来解码。
/**
*
* @author
* Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland, www.source-code.biz
*/
public class Base64Coder {
//The line separator string of the operating system.
private static final String systemLineSeparator = System.getProperty("line.separator");
//Mapping table from 6-bit nibbles to Base64 characters.
private static final char[] map1 = new char[64];
static {
int i=0;
for (char c='A'; c<='Z'; c++) map1[i++] = c;
for (char c='a'; c<='z'; c++) map1[i++] = c;
for (char c='0'; c<='9'; c++) map1[i++] = c;
map1[i++] = '+'; map1[i++] = '/'; }
//Mapping table from Base64 characters to 6-bit nibbles.
private static final byte[] map2 = new byte[128];
static {
for (int i=0; i<map2.length; i++) map2[i] = -1;
for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }
public static String encodeString (String s) {
return new String(encode(s.getBytes())); }
public static String encodeLines (byte[] in) {
return encodeLines(in, 0, in.length, 76, systemLineSeparator); }
public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
int blockLen = (lineLen*3) / 4;
if (blockLen <= 0) throw new IllegalArgumentException();
int lines = (iLen+blockLen-1) / blockLen;
int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length();
StringBuilder buf = new StringBuilder(bufLen);
int ip = 0;
while (ip < iLen) {
int l = Math.min(iLen-ip, blockLen);
buf.append(encode(in, iOff+ip, l));
buf.append(lineSeparator);
ip += l; }
return buf.toString(); }
public static char[] encode (byte[] in) {
return encode(in, 0, in.length); }
public static char[] encode (byte[] in, int iLen) {
return encode(in, 0, iLen); }
public static char[] encode (byte[] in, int iOff, int iLen) {
int oDataLen = (iLen*4+2)/3; // output length without padding
int oLen = ((iLen+2)/3)*4; // output length including padding
char[] out = new char[oLen];
int ip = iOff;
int iEnd = iOff + iLen;
int op = 0;
while (ip < iEnd) {
int i0 = in[ip++] & 0xff;
int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
int o0 = i0 >>> 2;
int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
int o3 = i2 & 0x3F;
out[op++] = map1[o0];
out[op++] = map1[o1];
out[op] = op < oDataLen ? map1[o2] : '='; op++;
out[op] = op < oDataLen ? map1[o3] : '='; op++; }
return out; }
public static String decodeString (String s) {
return new String(decode(s)); }
public static byte[] decodeLines (String s) {
char[] buf = new char[s.length()];
int p = 0;
for (int ip = 0; ip < s.length(); ip++) {
char c = s.charAt(ip);
if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
buf[p++] = c; }
return decode(buf, 0, p); }
public static byte[] decode (String s) {
return decode(s.toCharArray()); }
public static byte[] decode (char[] in) {
return decode(in, 0, in.length); }
public static byte[] decode (char[] in, int iOff, int iLen) {
if (iLen%4 != 0) throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--;
int oLen = (iLen*3) / 4;
byte[] out = new byte[oLen];
int ip = iOff;
int iEnd = iOff + iLen;
int op = 0;
while (ip < iEnd) {
int i0 = in[ip++];
int i1 = in[ip++];
int i2 = ip < iEnd ? in[ip++] : 'A';
int i3 = ip < iEnd ? in[ip++] : 'A';
if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
int b0 = map2[i0];
int b1 = map2[i1];
int b2 = map2[i2];
int b3 = map2[i3];
if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
int o0 = ( b0 <<2) | (b1>>>4);
int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
int o2 = ((b2 & 3)<<6) | b3;
out[op++] = (byte)o0;
if (op<oLen) out[op++] = (byte)o1;
if (op<oLen) out[op++] = (byte)o2; }
return out; }
//Dummy constructor.
private Base64Coder() {}
} // end class Base64Coder
解决方案
以下是工作示例
- 替换
BASE64Encoder
为java.util.Base64
import org.apache.commons.io.FileUtils;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.util.Base64;
public class TestImage {
public static void main(String[] args) {
try {
String filePath = "IMG_20200711.jpg";
//Encode
byte[] fileContent = FileUtils.readFileToByteArray(new File(filePath));
// BASE64Encoder base64encoder = new BASE64Encoder();
String encodedString = Base64.getEncoder().encodeToString(fileContent); // GALC way
System.out.println(encodedString);
// Decode
byte[] bytearray = Base64.getDecoder().decode(encodedString);
BufferedImage imag;
imag = ImageIO.read(new ByteArrayInputStream(bytearray));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
System.out.println("output buffer: " + imag);
String fileExtension = "png";
ImageIO.write(imag, fileExtension, baos);
File file = new File("IMG_20200711_111422_1." + fileExtension);
ImageIO.write(imag, fileExtension, file); // recreates same image with different name
} catch (Exception e) {
e.printStackTrace();
}
}
}
输出:
//truncated since its big string and each image has different values
/9j/4AAQSkZJRgABAQAAAQABAAD ....... 8lQDedSshTqGUuopVmBzSmxPlYVB//Z
output buffer: BufferedImage@6166e06f: type = 5 ColorModel: #pixelBits = 24 numComponents = 3 color space = java.awt.color.ICC_ColorSpace@8b96fde transparency = 1 has alpha = false isAlphaPre = false ByteInterleavedRaster: width = 4032 height = 3024 #numDataElements 3 dataOff[0] = 2
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