Java中如何获取图片文件格式(后缀)

String imgSrc = "/book/en/v2/images/basic-branching-1.png";
String formatName = imgSrc.split("\\.")[1];

    public static List<String> getImageFormat(InputStream srcInputStream) throws IOException {
        List<String> formatNameList = new ArrayList<>();
        // 获取ImageInputStream 对象
        ImageInputStream imageInputStream = ImageIO.createImageInputStream(srcInputStream);
        // 获取ImageReader对象的迭代器
        Iterator<ImageReader> iterator = ImageIO.getImageReaders(imageInputStream);
        // 如果能获得ImageReader对象则说明流中含有图片文件
        while(iterator.hasNext()) {
            // ImageReader对象的getFormatName()方法可以获得图片格式
            formatNameList.add(iterator.next().getFormatName());
        }
        return formatNameList;
    }

package com.flex;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
import org.junit.Test;
public class TestImage {
	@Test
	public void testImageFormat() {
		File img = new File("F:/1518048669186_0ssai3.jpg");
		System.out.println(getImageFormat(img));//JPEG
	}
	@Test
	public void testColorFormat() {
		getImageHex("F:/1518048669186_0ssai3.jpg");
		System.out.println("image.text长度：" + new File("F:/image.txt").length());
	}
	/*
	 * 获得图片的格式，例如：JPEG、GIF等
	 */
	public String getImageFormat(Object obj) {
		try {
			ImageInputStream iis = ImageIO.createImageInputStream(obj);
			Iterator<ImageReader> iterator = ImageIO.getImageReaders(iis);
			while (iterator.hasNext()) {
				ImageReader reader = (ImageReader) iterator.next();
				return reader.getFormatName();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}
	/*
	 * 图片转十六进制
	 */
	public void getImageHex(String path) {
		try {
			Long start = System.currentTimeMillis();
			FileInputStream fis = new FileInputStream(path);
			java.io.ByteArrayOutputStream bos = new java.io.ByteArrayOutputStream();
			byte[] buff = new byte[1024];
			int len = 0;
			while ((len = fis.read(buff)) != -1) {
				bos.write(buff, 0, len);
			}
			// 得到图片的字节数组
			byte[] result = bos.toByteArray();
			// 字节数组转成十六进制
			String str = byte2HexStr(result);
			// 将十六进制串保存到txt文件中
			PrintWriter pw = new PrintWriter(new FileWriter("F:/image.txt"));
			pw.println(str);
			pw.close();
			Long end = System.currentTimeMillis();
			System.out.println("图片转十六进制花费时间：" + (end - start));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	/*
	 * 实现字节数组向十六进制的转换方法
	 */
	public static String byte2HexStr(byte[] b) {
		String hs = "";
		String stmp = "";
		for (int n = 0; n < b.length; n++) {
			stmp = (Integer.toHexString(b[n] & 0XFF));
			if (stmp.length() == 1)
				hs = hs + "0" + stmp;
			else
				hs = hs + stmp;
		}
		return hs.toUpperCase();
	}
}