java中快速读写图片到BufferedImage对象

java7读取文件到BufferedImage对象

BufferedImage bufferedImage = ImageIO.read(Files.newInputStream(Paths.get(basePath + imageSource)));

java7写入文件到图片对象

ImageIO.write(bufferedImage, "jpg", Files.newOutputStream(Paths.get(fullPath)));

The call to Files.newInputStream will return a ChannelInputStream which (AFAIK) is not buffered. You'll want to wrap it

new BufferedInputStream(Files.newInputStream(...));

So that there are less IO calls to disk, depending on how you use it.

意译：据我所知,调用Files.newInputStream将会返回一些ChannelInputStream对象。如果你想对他进行封装，使用以下代码
new BufferedInputStream(File.newInputStream(Paths.get(fullPath)));
如此一来，磁盘IO的调用频次将会降低，具体看你怎么用了。

工具类：

import lombok.extern.slf4j.Slf4j;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

@Slf4j
public final class GraphUtil {

    /**
     * Encode Image to Base64 String
     * @param image
     * @param type
     * @return
     */
    public static String encodeToString(BufferedImage image, String type) {

        String imageString = null;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();

        try {
            ImageIO.write(image, type, bos);
            byte[] imageBytes = bos.toByteArray();

            BASE64Encoder encoder = new BASE64Encoder();
            imageString = encoder.encode(imageBytes);

            bos.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return imageString;
    }

    /***
     * Decode Base64 String to Image
     * @param imageString
     * @return
     */
    public static BufferedImage decodeToImage(String imageString) {

        BufferedImage image = null;
        byte[] imageByte;
        try {
            BASE64Decoder decoder = new BASE64Decoder();
            imageByte = decoder.decodeBuffer(imageString);
            ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
            image = ImageIO.read(bis);
            bis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return image;
    }

    public static BufferedImage getBufferedImage(String basePath, String imageSource){

        try {
            return ImageIO.read(new BufferedInputStream(Files.newInputStream(Paths.get(basePath, imageSource))));
        } catch (IOException e) {
            log.error("读取图片出错:{}",e);
            return null;
        }
    }
}

参考来源：

https://stackoverflow.com/questions/18522398/fastest-way-to-read-write-images-from-a-file-into-a-bufferedimage