JAVA生成图片缩略图、JAVA截取图片局部内容

朱雀 2021-05-29 08:44 598阅读 0赞

# JAVA生成图片缩略图、JAVA截取图片局部内容

目前，google已经有了更好的处理JAVA图片的工具，请搜索：Thumbnailator

```
package com.ares.image.test;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;

import javax.imageio.ImageIO;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.ares.slf4j.test.Slf4jUtil;

/**
 * Title: ImageUtil 
 * Description: 使用JDK原生态类生成图片缩略图和裁剪图片 
 * Email: icerainsoft@hotmail.com 
 * @author Ares
 * @date 2014年10月28日 上午10:24:26
 */
public class ImageUtil {

static {
 Slf4jUtil.buildSlf4jUtil().loadSlf4j();
 }
 private Logger log = LoggerFactory.getLogger(getClass());
 
 private static String DEFAULT_PREVFIX = "thumb_";
 private static Boolean DEFAULT_FORCE = false;
 
 /**
 * Title: thumbnailImage
 * Description: 根据图片路径生成缩略图 
 * @param imagePath 原图片路径
 * @param w 缩略图宽
 * @param h 缩略图高
 * @param prevfix 生成缩略图的前缀
 * @param force 是否强制按照宽高生成缩略图(如果为false，则生成最佳比例缩略图)
 */
 public void thumbnailImage(File imgFile, int w, int h, String prevfix, boolean force){
 if(imgFile.exists()){
 try {
 // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
 String types = Arrays.toString(ImageIO.getReaderFormatNames());
 String suffix = null;
 // 获取图片后缀
 if(imgFile.getName().indexOf(".") > -1) {
 suffix = imgFile.getName().substring(imgFile.getName().lastIndexOf(".") + 1);
 }// 类型和图片后缀全部小写，然后判断后缀是否合法
 if(suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()) < 0){
 log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
 return ;
 }
 log.debug("target image's size, width:{}, height:{}.",w,h);
 Image img = ImageIO.read(imgFile);
 if(!force){
 // 根据原图与要求的缩略图比例，找到最合适的缩略图比例
 int width = img.getWidth(null);
 int height = img.getHeight(null);
 if((width*1.0)/w < (height*1.0)/h){
 if(width > w){
 h = Integer.parseInt(new java.text.DecimalFormat("0").format(height * w/(width*1.0)));
 log.debug("change image's height, width:{}, height:{}.",w,h);
 }
 } else {
 if(height > h){
 w = Integer.parseInt(new java.text.DecimalFormat("0").format(width * h/(height*1.0)));
 log.debug("change image's width, width:{}, height:{}.",w,h);
 }
 }
 }
 BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
 Graphics g = bi.getGraphics();
 g.drawImage(img, 0, 0, w, h, Color.LIGHT_GRAY, null);
 g.dispose();
 String p = imgFile.getPath();
 // 将图片保存在原目录并加上前缀
 ImageIO.write(bi, suffix, new File(p.substring(0,p.lastIndexOf(File.separator)) + File.separator + prevfix +imgFile.getName()));
 } catch (IOException e) {
 log.error("generate thumbnail image failed.",e);
 }
 }else{
 log.warn("the image is not exist.");
 }
 }
 
 public void thumbnailImage(String imagePath, int w, int h, String prevfix, boolean force){
 File imgFile = new File(imagePath);
 thumbnailImage(imgFile, w, h, prevfix, force);
 }
 
 public void thumbnailImage(String imagePath, int w, int h, boolean force){
 thumbnailImage(imagePath, w, h, DEFAULT_PREVFIX, force);
 }
 
 public void thumbnailImage(String imagePath, int w, int h){
 thumbnailImage(imagePath, w, h, DEFAULT_FORCE);
 }
 
 public static void main(String[] args) {
 new ImageUtil().thumbnailImage("imgs/Tulips.jpg", 100, 150);
 }

}
```

效果：（原图是电脑"图片"文件夹下的郁金香图片，大小1024*768，生成的图片为200*150大小，保持4:3的比例）

![img](https://images0.cnblogs.com/blog/311811/201410/281138310031284.jpg)

JAVA 截取图片局部内容：

```
package com.ares.image.test;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.ares.slf4j.test.Slf4jUtil;

/**
 * Title: ImageUtil 
 * Description: 
 * Email: icerainsoft@hotmail.com 
 * @author Ares
 * @date 2014年10月28日 上午10:24:26
 */
public class ImageUtil {

static {
 Slf4jUtil.buildSlf4jUtil().loadSlf4j();
 }
 private Logger log = LoggerFactory.getLogger(getClass());
 
 private static String DEFAULT_THUMB_PREVFIX = "thumb_";
 private static String DEFAULT_CUT_PREVFIX = "cut_";
 private static Boolean DEFAULT_FORCE = false;
 
 
 /**
 * Title: cutImage
 * Description: 根据原图与裁切size截取局部图片
 * @param srcImg 源图片
 * @param output 图片输出流
 * @param rect 需要截取部分的坐标和大小
 */
 public void cutImage(File srcImg, OutputStream output, java.awt.Rectangle rect){
 if(srcImg.exists()){
 java.io.FileInputStream fis = null;
 ImageInputStream iis = null;
 try {
 fis = new FileInputStream(srcImg);
 // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
 String types = Arrays.toString(ImageIO.getReaderFormatNames()).replace("]", ",");
 String suffix = null;
 // 获取图片后缀
 if(srcImg.getName().indexOf(".") > -1) {
 suffix = srcImg.getName().substring(srcImg.getName().lastIndexOf(".") + 1);
 }// 类型和图片后缀全部小写，然后判断后缀是否合法
 if(suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()+",") < 0){
 log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
 return ;
 }
 // 将FileInputStream 转换为ImageInputStream
 iis = ImageIO.createImageInputStream(fis);
 // 根据图片类型获取该种类型的ImageReader
 ImageReader reader = ImageIO.getImageReadersBySuffix(suffix).next();
 reader.setInput(iis,true);
 ImageReadParam param = reader.getDefaultReadParam();
 param.setSourceRegion(rect);
 BufferedImage bi = reader.read(0, param);
 ImageIO.write(bi, suffix, output);
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 } finally {
 try {
 if(fis != null) fis.close();
 if(iis != null) iis.close();
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 }else {
 log.warn("the src image is not exist.");
 }
 }
 
 public void cutImage(File srcImg, OutputStream output, int x, int y, int width, int height){
 cutImage(srcImg, output, new java.awt.Rectangle(x, y, width, height));
 }
 
 public void cutImage(File srcImg, String destImgPath, java.awt.Rectangle rect){
 File destImg = new File(destImgPath);
 if(destImg.exists()){
 String p = destImg.getPath();
 try {
 if(!destImg.isDirectory()) p = destImg.getParent();
 if(!p.endsWith(File.separator)) p = p + File.separator;
 cutImage(srcImg, new java.io.FileOutputStream(p + DEFAULT_CUT_PREVFIX + "_" + new java.util.Date().getTime() + "_" + srcImg.getName()), rect);
 } catch (FileNotFoundException e) {
 log.warn("the dest image is not exist.");
 }
 }else log.warn("the dest image folder is not exist.");
 }
 
 public void cutImage(File srcImg, String destImg, int x, int y, int width, int height){
 cutImage(srcImg, destImg, new java.awt.Rectangle(x, y, width, height));
 }
 
 public void cutImage(String srcImg, String destImg, int x, int y, int width, int height){
 cutImage(new File(srcImg), destImg, new java.awt.Rectangle(x, y, width, height));
 }
 /**
 * Title: thumbnailImage
 * Description: 根据图片路径生成缩略图 
 * @param imagePath 原图片路径
 * @param w 缩略图宽
 * @param h 缩略图高
 * @param prevfix 生成缩略图的前缀
 * @param force 是否强制按照宽高生成缩略图(如果为false，则生成最佳比例缩略图)
 */
 public void thumbnailImage(File srcImg, OutputStream output, int w, int h, String prevfix, boolean force){
 if(srcImg.exists()){
 try {
 // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
 String types = Arrays.toString(ImageIO.getReaderFormatNames()).replace("]", ",");
 String suffix = null;
 // 获取图片后缀
 if(srcImg.getName().indexOf(".") > -1) {
 suffix = srcImg.getName().substring(srcImg.getName().lastIndexOf(".") + 1);
 }// 类型和图片后缀全部小写，然后判断后缀是否合法
 if(suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()+",") < 0){
 log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
 return ;
 }
 log.debug("target image's size, width:{}, height:{}.",w,h);
 Image img = ImageIO.read(srcImg);
 // 根据原图与要求的缩略图比例，找到最合适的缩略图比例
 if(!force){
 int width = img.getWidth(null);
 int height = img.getHeight(null);
 if((width*1.0)/w < (height*1.0)/h){
 if(width > w){
 h = Integer.parseInt(new java.text.DecimalFormat("0").format(height * w/(width*1.0)));
 log.debug("change image's height, width:{}, height:{}.",w,h);
 }
 } else {
 if(height > h){
 w = Integer.parseInt(new java.text.DecimalFormat("0").format(width * h/(height*1.0)));
 log.debug("change image's width, width:{}, height:{}.",w,h);
 }
 }
 }
 BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
 Graphics g = bi.getGraphics();
 g.drawImage(img, 0, 0, w, h, Color.LIGHT_GRAY, null);
 g.dispose();
 // 将图片保存在原目录并加上前缀
 ImageIO.write(bi, suffix, output);
 output.close();
 } catch (IOException e) {
 log.error("generate thumbnail image failed.",e);
 }
 }else{
 log.warn("the src image is not exist.");
 }
 }
 public void thumbnailImage(File srcImg, int w, int h, String prevfix, boolean force){
 String p = srcImg.getAbsolutePath();
 try {
 if(!srcImg.isDirectory()) p = srcImg.getParent();
 if(!p.endsWith(File.separator)) p = p + File.separator;
 thumbnailImage(srcImg, new java.io.FileOutputStream(p + prevfix +srcImg.getName()), w, h, prevfix, force);
 } catch (FileNotFoundException e) {
 log.error("the dest image is not exist.",e);
 }
 }
 
 public void thumbnailImage(String imagePath, int w, int h, String prevfix, boolean force){
 File srcImg = new File(imagePath);
 thumbnailImage(srcImg, w, h, prevfix, force);
 }
 
 public void thumbnailImage(String imagePath, int w, int h, boolean force){
 thumbnailImage(imagePath, w, h, DEFAULT_THUMB_PREVFIX, DEFAULT_FORCE);
 }
 
 public void thumbnailImage(String imagePath, int w, int h){
 thumbnailImage(imagePath, w, h, DEFAULT_FORCE);
 }
 
 public static void main(String[] args) {
 new ImageUtil().thumbnailImage("imgs/Tulips.jpg", 150, 100);
 new ImageUtil().cutImage("imgs/Tulips.jpg","imgs", 250, 70, 300, 400);
 }

}
```

效果如下：(使用在上传图片时取缩略图和截图的地方，例如，图像截取并缩略)

![img](/images/20210529/1622277917443.jpg)