Java图片与二进制相互转换实现示例讲解
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1、下面是一个完整的代码示例
- 指定文件路径转为二进制
- 将网络图片转为二进制
- base64 转为图片资源
package com.xxx.example.file;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.imageio.ImageIO;
import com.zxtc.syonline.support.common.StringUtil;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class ImageBioChangeUtil {
static BASE64Encoder encoder = new sun.misc.BASE64Encoder();
static BASE64Decoder decoder = new sun.misc.BASE64Decoder();
//从文件路径中获取图片转为二进制
public static String getImageBinary(String filePath){
if(StringUtil.isEmpty(filePath)) {
return null;
}
File f = new File(filePath); //这里gif动态图不可以，虽然在后面也能输出gif格式，但是却不是动图
BufferedImage bi;
try {
bi = ImageIO.read(f);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(bi, "jpg", baos);
byte[] bytes = baos.toByteArray();
return encoder.encodeBuffer(bytes).trim();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
//从URl中获取图片转为二进制
public static String getImageBinaryFromUrl(String urlPath) throws Exception{
if(StringUtil.isEmpty(urlPath)) {
return "";
}
URL url=new URL(urlPath);
HttpURLConnection conn= (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(3000);//超时提示1秒=1000毫秒
InputStream inStream=conn.getInputStream();//获取输出流
byte[] data=readInputStream(inStream);
return encoder.encodeBuffer(data).trim();
}
//readInputStream方法
private static byte[] readInputStream(InputStream inStream) throws Exception{
ByteArrayOutputStream outStream=new ByteArrayOutputStream();
byte[] buffer=new byte[1024];//转换为二进制
int len=0;
while((len =inStream.read(buffer))!=-1){
outStream.write(buffer,0,len);
}
return outStream.toByteArray();
}
//将二进制转为图片
public static void base64StringToImage(String base64String,String outFilePath){
if(StringUtil.isNotEmpty(base64String)&&StringUtil.isNotEmpty(outFilePath)) {
try {
byte[] bytes1 = decoder.decodeBuffer(base64String);
ByteArrayInputStream bais = new ByteArrayInputStream(bytes1);
BufferedImage bi1 =ImageIO.read(bais);
File w2 = new File(outFilePath);//可以是jpg,png格式
if (!w2.exists()) { //文件不存在则创建文件，先创建目录
File dir = new File(w2.getParent());
dir.mkdirs();
w2.createNewFile(); // 创建新文件
}
ImageIO.write(bi1, "jpg", w2);//不管输出什么格式图片，此处不需改动
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
String imageBinary=null;
try {
imageBinary = getImageBinaryFromUrl("");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(imageBinary);
String outFilePath= "E://test//bio//zhh/aa.png";
base64StringToImage(imageBinary,outFilePath);
}
}2、如何判断 base64 图片的格式
//判断图片base64字符串的文件格式
public static String checkImageBase64Format(String base64ImgData) {
byte[] b = Base64Util.decode(base64ImgData);
String type = "";
if (0x424D == ((b[0] & 0xff) << 8 | (b[1] & 0xff))) {
type = "bmp";
} else if (0x8950 == ((b[0] & 0xff) << 8 | (b[1] & 0xff))) {
type = "png";
} else if (0xFFD8 == ((b[0] & 0xff) << 8 | (b[1] & 0xff))) {
type = "jpg";
}
return type;
}3、将网络图片转为 base64 字符串
public static String getUrlImageToBase64(String requestUrl) throws Exception {
ByteArrayOutputStream data = new ByteArrayOutputStream();
try {
// 创建URL
URL url = new URL(requestUrl);
byte[] by = new byte[1024];
// 创建链接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5 * 1000);
InputStream is = conn.getInputStream();
// 将内容读取内存中
int len = -1;
while ((len = is.read(by)) != -1) {
data.write(by, 0, len);
}
// 关闭流
is.close();
} catch (IOException e) {
e.printStackTrace();
}
// 对字节数组Base64编码
Base64.Encoder encoder = Base64.getEncoder();
// return "data:image/" + photoType + ";base64," + encoder.encodeToString(data.toByteArray());
return encoder.encodeToString(data.toByteArray());
}4、将 base64 字符串转为图片输出
public static boolean writeFileFromBase64(String base64String, String path, String fileName) {
if (base64String == null){
return false;
}
try {
byte[] b = Base64Util.decode(base64String);
File file = new File(path);
if(!file.exists()){
makeDir(file);
}
OutputStream out = new FileOutputStream(path + fileName);
out.write(b);
out.flush();
out.close();
return true;
}catch(Exception e){
e.printStackTrace();
return false;
}
}注：该方法的入参，base64 格式文件不得有 文件头部标识信息，否则会转换失败。所以这里我们需要自行判断是否包含有头部信息。
String urlImageToBase64 = "";//这里就是我们图片的base64字符串
if(urlImageToBase64.indexOf(",")>-1) {//包含头信息
System.out.println("包含头部信息");
urlImageToBase64 = urlImageToBase64.substring(urlImageToBase64.indexOf(",")+1);
}5、将文件转为 base64 字符串
public static String readAsBase64FromFile(String filePath) {
InputStream in = null;
byte[] data = null;
try {
in = new FileInputStream(fileName);
data = new byte[in.available()];
in.read(data);
in.close();
} catch(Exception e) {
e.printStackTrace();
return null;
}
return Base64Util.encode(data);
}上面用到了一个 Base64Util.java
package com.xxx.example.util;
public final class Base64Util {
static private final int BASELENGTH = 128;
static private final int LOOKUPLENGTH = 64;
static private final int TWENTYFOURBITGROUP = 24;
static private final int EIGHTBIT = 8;
static private final int SIXTEENBIT = 16;
static private final int FOURBYTE = 4;
static private final int SIGN = -128;
static private final char PAD = '=';
static private final boolean fDebug = false;
static final private byte[] base64Alphabet = new byte[BASELENGTH];
static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];
static {
for (int i = 0; i < BASELENGTH; ++i) {
base64Alphabet[i] = -1;
}
for (int i = 'Z'; i >= 'A'; i--) {
base64Alphabet[i] = (byte) (i - 'A');
}
for (int i = 'z'; i >= 'a'; i--) {
base64Alphabet[i] = (byte) (i - 'a' + 26);
}
for (int i = '9'; i >= '0'; i--) {
base64Alphabet[i] = (byte) (i - '0' + 52);
}
base64Alphabet['+'] = 62;
base64Alphabet['/'] = 63;
for (int i = 0; i <= 25; i++) {
lookUpBase64Alphabet[i] = (char) ('A' + i);
}
for (int i = 26, j = 0; i <= 51; i++, j++) {
lookUpBase64Alphabet[i] = (char) ('a' + j);
}
for (int i = 52, j = 0; i <= 61; i++, j++) {
lookUpBase64Alphabet[i] = (char) ('0' + j);
}
lookUpBase64Alphabet[62] = (char) '+';
lookUpBase64Alphabet[63] = (char) '/';
}
private static boolean isWhiteSpace(char octect) {
return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
}
private static boolean isPad(char octect) {
return (octect == PAD);
}
private static boolean isData(char octect) {
return (octect < BASELENGTH && base64Alphabet[octect] != -1);
}
public static String encode(byte[] binaryData) {
if (binaryData == null) {
return null;
}
int lengthDataBits = binaryData.length * EIGHTBIT;
if (lengthDataBits == 0) {
return "";
}
int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
char encodedData[] = null;
encodedData = new char[numberQuartet * 4];
byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
int encodedIndex = 0;
int dataIndex = 0;
if (fDebug) {
System.out.println("number of triplets = " + numberTriplets);
}
for (int i = 0; i < numberTriplets; i++) {
b1 = binaryData[dataIndex++];
b2 = binaryData[dataIndex++];
b3 = binaryData[dataIndex++];
if (fDebug) {
System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
}
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
if (fDebug) {
System.out.println("val2 = " + val2);
System.out.println("k4 = " + (k << 4));
System.out.println("vak = " + (val2 | (k << 4)));
}
encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
}
// form integral number of 6-bit groups
if (fewerThan24bits == EIGHTBIT) {
b1 = binaryData[dataIndex];
k = (byte) (b1 & 0x03);
if (fDebug) {
System.out.println("b1=" + b1);
System.out.println("b1<<2 = " + (b1 >> 2));
}
byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
encodedData[encodedIndex++] = PAD;
encodedData[encodedIndex++] = PAD;
} else if (fewerThan24bits == SIXTEENBIT) {
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
encodedData[encodedIndex++] = PAD;
}
return new String(encodedData);
}
public static byte[] decode(String encoded) {
if (encoded == null) {
return null;
}
char[] base64Data = encoded.toCharArray();
// remove white spaces
int len = removeWhiteSpace(base64Data);
if (len % FOURBYTE != 0) {
return null;// should be divisible by four
}
int numberQuadruple = (len / FOURBYTE);
if (numberQuadruple == 0) {
return new byte[0];
}
byte decodedData[] = null;
byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
int i = 0;
int encodedIndex = 0;
int dataIndex = 0;
decodedData = new byte[(numberQuadruple) * 3];
for (; i < numberQuadruple - 1; i++) {
if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
|| !isData((d3 = base64Data[dataIndex++])) || !isData((d4 = base64Data[dataIndex++]))) {
return null;
} // if found "no data" just return null
b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];
b3 = base64Alphabet[d3];
b4 = base64Alphabet[d4];
decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
}
if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
return null;// if found "no data" just return null
}
b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];
d3 = base64Data[dataIndex++];
d4 = base64Data[dataIndex++];
if (!isData((d3)) || !isData((d4))) {// Check if they are PAD characters
if (isPad(d3) && isPad(d4)) {
if ((b2 & 0xf) != 0)// last 4 bits should be zero
{
return null;
}
byte[] tmp = new byte[i * 3 + 1];
System.arraycopy(decodedData, 0, tmp, 0, i * 3);
tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
return tmp;
} else if (!isPad(d3) && isPad(d4)) {
b3 = base64Alphabet[d3];
if ((b3 & 0x3) != 0)// last 2 bits should be zero
{
return null;
}
byte[] tmp = new byte[i * 3 + 2];
System.arraycopy(decodedData, 0, tmp, 0, i * 3);
tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
return tmp;
} else {
return null;
}
} else { // No PAD e.g 3cQl
b3 = base64Alphabet[d3];
b4 = base64Alphabet[d4];
decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
}
return decodedData;
}
private static int removeWhiteSpace(char[] data) {
if (data == null) {
return 0;
}
// count characters that's not whitespace
int newSize = 0;
int len = data.length;
for (int i = 0; i < len; i++) {
if (!isWhiteSpace(data[i])) {
data[newSize++] = data[i];
}
}
return newSize;
}
}到此这篇关于Java图片与二进制相互转换实现示例讲解的文章就介绍到这了,更多相关Java图片与二进制转换内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
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