將image圖片轉化為Base64字串
阿新 • • 發佈：2019-01-17
base64工具類：
| /** * Base64 工具類 */ public class Base64Util { private static final char last2byte = (char) Integer.parseInt("00000011", 2); private static final char last4byte = (char) Integer.parseInt("00001111", 2); private static final char last6byte = (char) Integer.parseInt("00111111", 2); private static final char lead6byte = (char) Integer.parseInt("11111100", 2); private static final char lead4byte = (char) Integer.parseInt("11110000", 2); private static final char lead2byte = (char) Integer.parseInt("11000000", 2); private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'}; public Base64Util() { } public static String encode(byte[] from) { StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3); int num = 0; char currentByte = 0; int i; for (i = 0; i < from.length; ++i) { for (num %= 8; num < 8; num += 6) { switch (num) { case 0: currentByte = (char) (from[i] & lead6byte); currentByte = (char) (currentByte >>> 2); case 1: case 3: case 5: default: break; case 2: currentByte = (char) (from[i] & last6byte); break; case 4: currentByte = (char) (from[i] & last4byte); currentByte = (char) (currentByte << 2); if (i + 1 < from.length) { currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6); } break; case 6: currentByte = (char) (from[i] & last2byte); currentByte = (char) (currentByte << 4); if (i + 1 < from.length) { currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4); } } to.append(encodeTable[currentByte]); } } if (to.length() % 4 != 0) { for (i = 4 - to.length() % 4; i > 0; --i) { to.append("="); } } return to.toString(); } } |
圖片轉byte工具類：
| import java.io.BufferedInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; /** * 檔案讀取工具類 */ public class FileUtil { /** * 讀取檔案內容，作為字串返回 */ public static String readFileAsString(String filePath) throws IOException { File file = new File(filePath); if (!file.exists()) { throw new FileNotFoundException(filePath); } if (file.length() > 1024 * 1024 * 1024) { throw new IOException("File is too large"); } StringBuilder sb = new StringBuilder((int) (file.length())); // 建立位元組輸入流 FileInputStream fis = new FileInputStream(filePath); // 建立一個長度為10240的Buffer byte[] bbuf = new byte[10240]; // 用於儲存實際讀取的位元組數 int hasRead = 0; while ( (hasRead = fis.read(bbuf)) > 0 ) { sb.append(new String(bbuf, 0, hasRead)); } fis.close(); return sb.toString(); } /** * 根據檔案路徑讀取byte[] 陣列 */ public static byte[] readFileByBytes(String filePath) throws IOException { File file = new File(filePath); if (!file.exists()) { throw new FileNotFoundException(filePath); } else { ByteArrayOutputStream bos = new ByteArrayOutputStream((int) file.length()); BufferedInputStream in = null; try { in = new BufferedInputStream(new FileInputStream(file)); short bufSize = 1024; byte[] buffer = new byte[bufSize]; int len1; while (-1 != (len1 = in.read(buffer, 0, bufSize))) { bos.write(buffer, 0, len1); } byte[] var7 = bos.toByteArray(); return var7; } finally { try { if (in != null) { in.close(); } } catch (IOException var14) { var14.printStackTrace(); } bos.close(); } } } /** * 根據地址獲得資料的位元組流 * @param strUrl 網路連線地址 * @return */ public static byte[] getImageFromNetByUrl(String strUrl){ try { URL url = new URL(strUrl); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5 * 1000); InputStream inStream = conn.getInputStream();//通過輸入流獲取圖片資料 byte[] btImg = readInputStream(inStream);//得到圖片的二進位制資料 return btImg; } catch (Exception e) { e.printStackTrace(); } return null; } /** * 從輸入流中獲取資料 * @param inStream 輸入流 * @return * @throws Exception */ public static byte[] readInputStream(InputStream inStream) throws Exception{ ByteArrayOutputStream outStream = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int len = 0; while( (len=inStream.read(buffer)) != -1 ){ outStream.write(buffer, 0, len); } inStream.close(); return outStream.toByteArray(); } } |
呼叫方法轉化，返回base64字串：
byte[] imgData = FileUtil.getImageFromNetByUrl(filePath);
String imgStr = Base64Util.encode(imgData);
上述是網路請求下的圖片轉base64
本地圖片轉base64的方法：
byte[] imgData = FileUtil.readFileByBytes(filePath);
String imgStr = Base64Util.encode(imgData);
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