工作中遇到通過圖片的url獲取圖片base64位的需求。一開始是用網上的方法，通過工具類Toolkit，雖然實現的代碼比較簡短，不過偶爾會遇到圖片轉成base64位不正確的情況，至今不知道為啥。
之后，又去網上搜了通過獲取圖片的二進制流轉換成base64的方式，兩種方式，都是親測有效，通過Toolkit偶爾會出現，轉base64后，展示不完整的問題。所以建議用通過下載二進制流轉換的方式進行轉換。
下面附上代碼：
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.net.HttpURLConnection;
import java.net.URL;
public class ImageUtils {
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;
}
/**
* 通過圖片的url獲取圖片的base64字符串
* @param imgUrl 圖片url
* @return 返回圖片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();
//創建一個Buffer字符串
byte[] buffer = new byte[1024];
//每次讀取的字符串長度，如果為-1，代表全部讀取完畢
int len = 0;
//使用一個輸入流從buffer里把數據讀取出來
while( (len=is.read(buffer)) != -1 ){
//用輸出流往buffer里寫入數據，中間參數代表從哪個位置開始讀，len代表讀取的長度
outStream.write(buffer, 0, len);
}
// 對字節數組Base64編碼
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;
}
}
其中
getBase64ByImgUrl方法為通過Toolkit獲取的方式，至於為啥沒注釋，因為我也看不懂原理，也是抄來的。
image2Base64方法為通過下載二進制流的方式，當然也是抄來的。寫出來是為了總結一下。下次遇到相同的問題，不用到處查了。
附上Base64Util的代碼：
1 import java.io.ByteArrayOutputStream;
2 import java.io.File;
3 import java.io.IOException;
4 import java.util.regex.Matcher;
5 import java.util.regex.Pattern;
6
7 import javax.imageio.stream.FileImageInputStream;
8
9 import sun.misc.BASE64Decoder;
10 import sun.misc.BASE64Encoder;
11
12 public class Base64Util{
13 /**
14 * 字符串轉圖片
15 * @param base64Str
16 * @return
17 */
18 public static byte[] decode(String base64Str){
19 byte[] b = null;
20 BASE64Decoder decoder = new BASE64Decoder();
21 try {
22 b = decoder.decodeBuffer(replaceEnter(base64Str));
23 } catch (IOException e) {
24 e.printStackTrace();
25 }
26 return b;
27 }
28
29 /**
30 * 圖片轉字符串
31 * @param image
32 * @return
33 */
34 public static String encode(byte[] image){
35 BASE64Encoder decoder = new BASE64Encoder();
36 return replaceEnter(decoder.encode(image));
37 }
38
39 public static String encode(String uri){
40 BASE64Encoder encoder = new BASE64Encoder();
41 return replaceEnter(encoder.encode(uri.getBytes()));
42 }
43
44 /**
45 *
46 * @path 圖片路徑
47 * @return
48 */
49
50 public static byte[] imageTobyte(String path){
51 byte[] data = null;
52 FileImageInputStream input = null;
53 try {
54 input = new FileImageInputStream(new File(path));
55 ByteArrayOutputStream output = new ByteArrayOutputStream();
56 byte[] buf = new byte[1024];
57 int numBytesRead = 0;
58 while((numBytesRead = input.read(buf)) != -1){
59 output.write(buf, 0, numBytesRead);
60 }
61 data = output.toByteArray();
62 output.close();
63 input.close();
64
65 } catch (Exception e) {
66 e.printStackTrace();
67 }
68
69 return data;
70 }
71
72
73
74 public static String replaceEnter(String str){
75 String reg ="[\n-\r]";
76 Pattern p = Pattern.compile(reg);
77 Matcher m = p.matcher(str);
78 return m.replaceAll("");
79 }
80
81
82 }