jdk1.8 Base64Util Illegal base64 character

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jdk1.8 base64的编码转码

实用场景

最近工作上有个需求，需要根据图片的url下载到本地，并且客户端无法访问到url只能接收base64图片码。因此决定采用jdk自带的Base64进行编码转码存储。

小插曲

采用了两个工具类：ImageUtil和Base64Util。ImageUtil用于实际操作。Base64Util用于统一编码格式。

由于jdk1.7和jdk1.8内置的Base64遵守的RFC协议不一致，jdk1.7按照照RFC1521实现的，jdk1.8是按照rfc4648和rfc2045两个协议来实现的。具体可以从类注释中查询到。由于协议的不同可能导致jdk1.8的解码jdk1.7编码的数据时抛出java.lang.IllegalArgumentException: Illegal base64 character a异常.因此需要特别注意保持解码编码的一致性。

jdk7的编码结果包含换行；
jdk8的编码结果不包含换行；
jdk8无法解码包含换行的编码结果;

既然得知上述异常产生的由于,故找到解决方案也很简单。

1. 使用apache common包中的org.apache.commons.codec.binary.Base64类进行编码和解码；
2. 编码之后或解码之前去除换行符；
3. 编码和解码使用相同的jdk版本；

附上代码

ImageUtils

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class ImageUtils {

    /**
     * base64转文件地址
     *
     * @param filePath
     * @param base64
     * @param fileName
     */
    public static void base64ToImg(String filePath, String base64, String fileName) {
        File file = null;
        //创建文件目录
        File dir = new File(filePath);
        if (!dir.exists() && !dir.isDirectory()) {
            dir.mkdirs();
        }
        BufferedOutputStream bos = null;
        java.io.FileOutputStream fos = null;
        try {
            byte[] bytes = Base64Util.decode(base64);
            file = new File(filePath + fileName);
            fos = new java.io.FileOutputStream(file);
            bos = new BufferedOutputStream(fos);
            bos.write(bytes);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (bos != null) {
                try {
                    bos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 通过Toolkit获取base64
     *
     * @param url
     * @return
     * @author caoting
     * @date 2018年11月21日
     */
    public static String getBase64ByImgUrl(String url) {
        String suffix = url.substring(url.lastIndexOf(".") + 1);
        try {
            URL urls = new URL(url);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            Image image = Toolkit.getDefaultToolkit().getImage(urls);
            BufferedImage biOut = toBufferedImage(image);
            ImageIO.write(biOut, suffix, baos);
            String base64Str = Base64Util.encode(baos.toByteArray());
            return base64Str;
        } catch (Exception e) {
            return "";
        }

    }

    public static BufferedImage toBufferedImage(Image image) {
        if (image instanceof BufferedImage) {
            return (BufferedImage) image;
        }
        // This code ensures that all the pixels in the image are loaded
        image = new ImageIcon(image).getImage();
        BufferedImage bimage = null;
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        try {
            int transparency = Transparency.OPAQUE;
            GraphicsDevice gs = ge.getDefaultScreenDevice();
            GraphicsConfiguration gc = gs.getDefaultConfiguration();
            bimage = gc.createCompatibleImage(image.getWidth(null), image.getHeight(null), transparency);
        } catch (HeadlessException e) {
            // The system does not have a screen
        }
        if (bimage == null) {
            // Create a buffered image using the default color model
            int type = BufferedImage.TYPE_INT_RGB;
            bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), type);
        }
        // Copy image to buffered image
        Graphics g = bimage.createGraphics();
        // Paint the image onto the buffered image
        g.drawImage(image, 0, 0, null);
        g.dispose();
        return bimage;
    }

    /**
     * 通过下载二进制流的方式获取base64
     *
     * @param imgUrl 图片url
     * @return 返回图片base64的字符串
     */
    public static String image2Base64(String imgUrl) {

        URL url = null;
        InputStream is = null;
        ByteArrayOutputStream outStream = null;

        HttpURLConnection httpUrl = null;
        try {

            url = new URL(imgUrl);
            httpUrl = (HttpURLConnection) url.openConnection();
            httpUrl.connect();

            httpUrl.getInputStream();
            is = httpUrl.getInputStream();
            outStream = new ByteArrayOutputStream();

            // 创建一个Buffer字符串
            byte[] buffer = new byte[1024];
            // 每次读取的字符串长度，如果为-1，代表全部读取完毕
            int len = 0;
            // 使用一个输入流从buffer里把数据读取出来
            while ((len = is.read(buffer)) != -1) {
                // 用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
                outStream.write(buffer, 0, len);
            }
            // 对字节数组Base64编码
            return Base64Util.encode(outStream.toByteArray());

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (outStream != null) {
                try {
                    outStream.close();

                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (httpUrl != null) {
                httpUrl.disconnect();
            }
        }
        return imgUrl;
    }
}

Base64Util

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.imageio.stream.FileImageInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Base64Util{
    /**
     * 字符串转图片
     * @param base64Str
     * @return
     */
    public static byte[] decode(String base64Str){
        byte[] b = null;
        BASE64Decoder decoder = new BASE64Decoder();
        try {
            b = decoder.decodeBuffer(replaceEnter(base64Str));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return b;
    }

    /**
     * 图片转字符串
     * @param image
     * @return
     */
    public static String encode(byte[] image){
        BASE64Encoder decoder = new BASE64Encoder();
        return replaceEnter(decoder.encode(image));
    }

    public static String encode(String uri){
        BASE64Encoder encoder = new BASE64Encoder();
        return replaceEnter(encoder.encode(uri.getBytes()));
    }

    /**
     *
     * @path    图片路径
     * @return
     */

    public static byte[] imageTobyte(String path){
        byte[] data = null;
        FileImageInputStream input = null;
        try {
            input = new FileImageInputStream(new File(path));
            ByteArrayOutputStream output = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            int numBytesRead = 0;
            while((numBytesRead = input.read(buf)) != -1){
                output.write(buf, 0, numBytesRead);
            }
            data = output.toByteArray();
            output.close();
            input.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return data;
    }

    public static String replaceEnter(String str){
        String reg ="[\n-\r]";
        Pattern p = Pattern.compile(reg);
        Matcher m = p.matcher(str);
        return m.replaceAll("");
    }
}