Base64转换图片，图片转换Base64实例
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
/**
* 将网络路径图片转为base64的格式
* @param requestUrl 请求网络路径
* @throws Exception
*/
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
/**
* 将Base64编码的字符串转为文件输出
* @param base64String 字符串
* @param path 输出文件保存路径
* @param fileName 输出文件名称
* @return 是否转换成功
*/
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
/**
* 读入文件转换为Base64编码并返回
* @param filePath 文件路径
* @return base64 的文件
* @throws Exception
*/
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