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。
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。
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。
下面附上代码:
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; } }
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(""); } }