public static final String TYPE_JPG = "jpg";
public static final String TYPE_GIF = "gif";
public static final String TYPE_PNG = "png";
public static final String TYPE_BMP = "bmp";
public static final String TYPE_UNKNOWN = "unknown";
/**
* byte数组转换成16进制字符串
* @param src
* @return
*/
public static String bytesToHexString(byte[] src){
StringBuilder stringBuilder = new StringBuilder();
if (src == null || src.length <= 0) {
return null;
}
for (int i = 0; i < src.length; i++) {
int v = src[i] & 0xFF;
String hv = Integer.toHexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
return stringBuilder.toString();
}
/**
* 根据文件流判断图片类型
* @param fis
* @return jpg/png/gif/bmp
*/
public static String getPicType(FileInputStream fis) {
//读取文件的前几个字节来判断图片格式
byte[] b = new byte[4];
try {
fis.read(b, 0, b.length);
String type = bytesToHexString(b).toUpperCase();
if (type.contains("FFD8FF")) {
return TYPE_JPG;
} else if (type.contains("89504E47")) {
return TYPE_PNG;
} else if (type.contains("47494638")) {
return TYPE_GIF;
} else if (type.contains("424D")) {
return TYPE_BMP;
}else{
return TYPE_UNKNOWN;
}
} catch (IOException e) {
e.printStackTrace();
}finally{
if(fis != null){
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
//test code
System.out.println("图片格式1： " + getPicType(new FileInputStream(new File("D:\\3_副本.png"))));
System.out.println("图片格式2： " + getPicType(new FileInputStream(new File("D:\\3.png"))));
java代码判断图片文件格式， 不是根据文件后缀来判断。的相关教程结束。
