Previously, I used Python crawlers to grab movie website information as the data source of my website. The pictures contained in it were all network pictures. There would be such a problem:
When the access speed of the original website is relatively slow, the loading time of the website pictures will also become very slow, and if the original website is down, the pictures will not be directly accessible.
The user experience at this time is very bad, so this is optimized:
Each time the backend is started, the task will be opened by default. First, store the unconverted network pictures locally, and then change the picture list in the web page to access local pictures, which solves the problem of slow loading and reduces the coupling with the original website. The specific steps are as follows:
1. Create a folder for saving pictures
My save path: F:\images
2. Create a new createLocalImage class for image conversion
package com.cn.beauty.task;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
public class createLocalImage {
// 需要保存到本地的根路径
private static String basePath = "F:/";
public static void main(String[] args) {
// 网页图片路径
String destUrl = "http://5b0988e595225.cdn.sohucs.com/images/20200215/349bb3cb88b744dcb67f37dba2f71abf.jpeg";
String filePath = createLocalImageMethod(destUrl);
System.out.println("生成的相对文件路径为" + filePath);
}
private static String createLocalImageMethod(String destUrl) {
FileOutputStream fos = null;
BufferedInputStream bis = null;
HttpURLConnection httpUrl = null;
URL url = null;
int BUFFER_SIZE = 1024;
byte[] buf = new byte[BUFFER_SIZE];
int size = 0;
String filePath = "";
try {
System.out.println("原始图片URL为：" + destUrl);
String[] fileNameArray = destUrl.split("\\/");
if (fileNameArray.length > 1) {
String fileName = fileNameArray[fileNameArray.length - 1];
filePath = "images/" + fileName;
File file = new File(basePath + filePath);
if (!file.exists()) {
url = new URL(destUrl);
httpUrl = (HttpURLConnection) url.openConnection();
httpUrl.connect();
bis = new BufferedInputStream(httpUrl.getInputStream());
fos = new FileOutputStream(basePath + filePath);
while ((size = bis.read(buf)) != -1) {
fos.write(buf, 0, size);
}
fos.flush();
}
// 后续对图片进行缩略图处理，见后面代码
}
} catch (IOException e) {
e.printStackTrace();
} catch (ClassCastException e) {
e.printStackTrace();
} finally {
try {
fos.close();
bis.close();
httpUrl.disconnect();
} catch (IOException e) {
} catch (NullPointerException e) {
}
}
return filePath;
}
}
After running, it is found that the image has been successfully generated:
3. Generate thumbnails
If it is the display of the picture list, the original picture is too large or it will affect the loading speed. At this time, we can process the picture as a thumbnail for display.
We use a very powerful image processing tool class: Thumbnails, which supports functions including:
- Scale according to the specified size;
- Scale according to proportion;
- Do not scale according to the scale, specify the size;
- Rotate, watermark, crop;
- Convert image format;
- Output to OutputStream;
- Output to BufferedImage;
The requirement here is relatively simple, only the function of scaling to a specified size is used.
Introduce the corresponding jar package:
<dependency>
<groupId>net.coobird</groupId>
<artifactId>thumbnailator</artifactId>
<version>0.4.8</version>
</dependency>
Add the code implementation of thumbnail generation in the createLocalImage method:
String thumbName = fileName.split("\\.")[0] + "_thumb." + fileName.split("\\.")[1];
String thumbPath = basePath + filePath.replace(fileName, thumbName);
//将要转换出的小图文件
File fo = new File(thumbPath);
if (fo.exists()) {
return thumbPath;
}
// 第一个参数是原始图片的路径，第二个是缩略图的路径
Thumbnails.of(basePath + filePath).size(120, 120).toFile(thumbPath);
System.out.println("生成的缩略图路径为：" + thumbPath);
Run again and find that the thumbnail has been successfully generated:
