Java 基礎 byte[]與各種數據類型互相轉換的簡單示例
這里對byte[]類型對long,int,double,float，short,cahr，object,string類型相互轉換的實例，
在socket開發過程中，通常需要將一些具體的值（這些值可能是各種Java類型）轉化為byte[]類型，為此我總結了如下這個示例，貼出來，以便經常翻看：
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public class TestCase { /** * short到字節數組的轉換. */ public static byte[] shortToByte(short number) { int temp = number; byte[] b = new byte[2]; for (int i = 0; i < b.length; i++) { b[i] = new Integer(temp & 0xff).byteValue();// 將最低位保存在最低位 temp = temp >> 8;// 向右移8位 } return b; } /** * 字節數組到short的轉換. */ public static short byteToShort(byte[] b) { short s = 0; short s0 = (short) (b[0] & 0xff);// 最低位 short s1 = (short) (b[1] & 0xff); s1 <<= 8; s = (short) (s0 | s1); return s; } /** * int到字節數組的轉換. */ public static byte[] intToByte(int number) { int temp = number; byte[] b = new byte[4]; for (int i = 0; i < b.length; i++) { b[i] = new Integer(temp & 0xff).byteValue();// 將最低位保存在最低位 temp = temp >> 8;// 向右移8位 } return b; } /** * 字節數組到int的轉換. */ public static int byteToInt(byte[] b) { int s = 0; int s0 = b[0] & 0xff;// 最低位 int s1 = b[1] & 0xff; int s2 = b[2] & 0xff; int s3 = b[3] & 0xff; s3 <<= 24; s2 <<= 16; s1 <<= 8; s = s0 | s1 | s2 | s3; return s; } /** * long類型轉成byte數組 */ public static byte[] longToByte(long number) { long temp = number; byte[] b = new byte[8]; for (int i = 0; i < b.length; i++) { b[i] = new Long(temp & 0xff).byteValue();// 將最低位保存在最低位 temp = temp // >> 8;// 向右移8位 } return b; } /** * 字節數組到long的轉換. */ public static long byteToLong(byte[] b) { long s = 0; long s0 = b[0] & 0xff;// 最低位 long s1 = b[1] & 0xff; long s2 = b[2] & 0xff; long s3 = b[3] & 0xff; long s4 = b[4] & 0xff;// 最低位 long s5 = b[5] & 0xff; long s6 = b[6] & 0xff; long s7 = b[7] & 0xff; // s0不變 s1 <<= 8; s2 <<= 16; s3 <<= 24; s4 <<= 8 * 4; s5 <<= 8 * 5; s6 <<= 8 * 6; s7 <<= 8 * 7; s = s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7; return s; } /** * double到字節數組的轉換. */ public static byte[] doubleToByte(double num) { byte[] b = new byte[8]; long l = Double.doubleToLongBits(num); for (int i = 0; i < 8; i++) { b[i] = new Long(l).byteValue(); l = l >> 8; } return b; } /** * 字節數組到double的轉換. */ public static double getDouble(byte[] b) { long m; m = b[0]; m &= 0xff; m |= ((long) b[1] << 8); m &= 0xffff; m |= ((long) b[2] << 16); m &= 0xffffff; m |= ((long) b[3] << 24); m &= 0xffffffffl; m |= ((long) b[4] << 32); m &= 0xffffffffffl; m |= ((long) b[5] << 40); m &= 0xffffffffffffl; m |= ((long) b[6] << 48); m &= 0xffffffffffffffl; m |= ((long) b[7] << 56); return Double.longBitsToDouble(m); } /** * float到字節數組的轉換. */ public static void floatToByte(float x) { //先用 Float.floatToIntBits(f)轉換成int } /** * 字節數組到float的轉換. */ public static float getFloat(byte[] b) { // 4 bytes int accum = 0; for ( int shiftBy = 0; shiftBy < 4; shiftBy++ ) { accum |= (b[shiftBy] & 0xff) << shiftBy * 8; } return Float.intBitsToFloat(accum); } /** * char到字節數組的轉換. */ public static byte[] charToByte(char c){ byte[] b = new byte[2]; b[0] = (byte) ((c & 0xFF00) >> 8); b[1] = (byte) (c & 0xFF); return b; } /** * 字節數組到char的轉換. */ public static char byteToChar(byte[] b){ char c = (char) (((b[0] & 0xFF) << 8) | (b[1] & 0xFF)); return c; } /** * string到字節數組的轉換. */ public static byte[] stringToByte(String str) throws UnsupportedEncodingException{ return str.getBytes("GBK"); } /** * 字節數組到String的轉換. */ public static String bytesToString(byte[] str) { String keyword = null; try { keyword = new String(str,"GBK"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return keyword; } /** * object到字節數組的轉換 */ @Test public void testObject2ByteArray() throws IOException, ClassNotFoundException { // Object obj = ""; Integer[] obj = { 1, 3, 4 }; // // object to bytearray ByteArrayOutputStream bo = new ByteArrayOutputStream(); ObjectOutputStream oo = new ObjectOutputStream(bo); oo.writeObject(obj); byte[] bytes = bo.toByteArray(); bo.close(); oo.close(); System.out.println(Arrays.toString(bytes)); Integer[] intArr = (Integer[]) testByteArray2Object(bytes); System.out.println(Arrays.asList(intArr)); byte[] b2 = intToByte(123); System.out.println(Arrays.toString(b2)); int a = byteToInt(b2); System.out.println(a); } /** * 字節數組到object的轉換. */ private Object testByteArray2Object(byte[] bytes) throws IOException, ClassNotFoundException { // byte[] bytes = null; Object obj; // bytearray to object ByteArrayInputStream bi = new ByteArrayInputStream(bytes); ObjectInputStream oi = new ObjectInputStream(bi); obj = oi.readObject(); bi.close(); oi.close(); System.out.println(obj); return obj; } } |
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