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本篇内容主要讲解“java如何获取图片分辨率”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“java如何获取图片分辨率”吧!
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import java.io.*;
/**
* 快速获取图片的分辨率大小
*/
public class FastImageInfo {
private int height;
private int width;
private String mimeType;
public FastImageInfo(File file) throws IOException {
try (InputStream is = new FileInputStream(file)) {
processStream(is);
}
}
public FastImageInfo(InputStream is) throws IOException {
processStream(is);
}
public FastImageInfo(byte[] bytes) throws IOException {
try (InputStream is = new ByteArrayInputStream(bytes)) {
processStream(is);
}
}
private void processStream(InputStream is) throws IOException {
int c1 = is.read();
int c2 = is.read();
int c3 = is.read();
mimeType = null;
width = height = -1;
if (c1 == 'G' && c2 == 'I' && c3 == 'F') { // GIF
is.skip(3);
width = readInt(is, 2, false);
height = readInt(is, 2, false);
mimeType = "image/gif";
} else if (c1 == 0xFF && c2 == 0xD8) { // JPG
while (c3 == 255) {
int marker = is.read();
int len = readInt(is, 2, true);
if (marker == 192 || marker == 193 || marker == 194) {
is.skip(1);
height = readInt(is, 2, true);
width = readInt(is, 2, true);
mimeType = "image/jpeg";
break;
}
is.skip(len - 2);
c3 = is.read();
}
} else if (c1 == 137 && c2 == 80 && c3 == 78) { // PNG
is.skip(15);
width = readInt(is, 2, true);
is.skip(2);
height = readInt(is, 2, true);
mimeType = "image/png";
} else if (c1 == 66 && c2 == 77) { // BMP
is.skip(15);
width = readInt(is, 2, false);
is.skip(2);
height = readInt(is, 2, false);
mimeType = "image/bmp";
} else if (c1 == 'R' && c2 == 'I' && c3 == 'F') { // WEBP
// byte[] bytes = is.readNBytes(27);
byte[] bytes = new byte[27];
is.read(bytes);
width = ((int) bytes[24] & 0xff) << 8 | ((int) bytes[23] & 0xff);
height = ((int) bytes[26] & 0xff) << 8 | ((int) bytes[25] & 0xff);
mimeType = "image/webp";
} else {
int c4 = is.read();
if ((c1 == 'M' && c2 == 'M' && c3 == 0 && c4 == 42)
|| (c1 == 'I' && c2 == 'I' && c3 == 42 && c4 == 0)) { //TIFF
boolean bigEndian = c1 == 'M';
int ifd = 0;
int entries;
ifd = readInt(is, 4, bigEndian);
is.skip(ifd - 8);
entries = readInt(is, 2, bigEndian);
for (int i = 1; i <= entries; i++) {
int tag = readInt(is, 2, bigEndian);
int fieldType = readInt(is, 2, bigEndian);
int valOffset;
if ((fieldType == 3 || fieldType == 8)) {
valOffset = readInt(is, 2, bigEndian);
is.skip(2);
} else {
valOffset = readInt(is, 4, bigEndian);
}
if (tag == 256) {
width = valOffset;
} else if (tag == 257) {
height = valOffset;
}
if (width != -1 && height != -1) {
mimeType = "image/tiff";
break;
}
}
}
}
if (mimeType == null) {
throw new IOException("Unsupported image type");
}
}
private int readInt(InputStream is, int noOfBytes, boolean bigEndian) throws IOException {
int ret = 0;
int sv = bigEndian ? ((noOfBytes - 1) * 8) : 0;
int cnt = bigEndian ? -8 : 8;
for (int i = 0; i < noOfBytes; i++) {
ret |= is.read() << sv;
sv += cnt;
}
return ret;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
public String getMimeType() {
return mimeType;
}
public void setMimeType(String mimeType) {
this.mimeType = mimeType;
}
@Override
public String toString() {
return "MIME Type : " + mimeType + "\t Width : " + width
+ "\t Height : " + height;
}
}到此，相信大家对“java如何获取图片分辨率”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
