Java字節序

http://origin100.iteye.com/blog/267165

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/** * 通信格式轉換 * * Java和一些windows編程語言如c、c++、delphi所寫的網絡程序進行通訊時，需要進行相應的轉換 * 高、低字節之間的轉換 * windows的字節序為低字節開頭 * linux,unix的字節序為高字節開頭 * java則無論平臺變化，都是高字節開頭*/ public class FormatTransfer { /*** 將int轉為低字節在前，高字節在后的byte數組* @param n int* @return byte[]*/ public static byte[] toLH(int n) {byte[] b = new byte[4];b[0] = (byte) (n & 0xff);b[1] = (byte) (n >> 8 & 0xff);b[2] = (byte) (n >> 16 & 0xff);b[3] = (byte) (n >> 24 & 0xff);return b; } /*** 將int轉為高字節在前，低字節在后的byte數組* @param n int* @return byte[]*/ public static byte[] toHH(int n) {byte[] b = new byte[4];b[3] = (byte) (n & 0xff);b[2] = (byte) (n >> 8 & 0xff);b[1] = (byte) (n >> 16 & 0xff);b[0] = (byte) (n >> 24 & 0xff);return b; } /*** 將short轉為低字節在前，高字節在后的byte數組* @param n short* @return byte[]*/ public static byte[] toLH(short n) {byte[] b = new byte[2];b[0] = (byte) (n & 0xff);b[1] = (byte) (n >> 8 & 0xff);return b; } /*** 將short轉為高字節在前，低字節在后的byte數組* @param n short* @return byte[]*/ public static byte[] toHH(short n) {byte[] b = new byte[2];b[1] = (byte) (n & 0xff);b[0] = (byte) (n >> 8 & 0xff);return b; } /*** 將將int轉為高字節在前，低字節在后的byte數組 public static byte[] toHH(int number) {int temp = number;byte[] b = new byte[4];for (int i = b.length - 1; i > -1; i--) {b = new Integer(temp & 0xff).byteValue();temp = temp >> 8;}return b; } public static byte[] IntToByteArray(int i) {byte[] abyte0 = new byte[4];abyte0[3] = (byte) (0xff & i);abyte0[2] = (byte) ((0xff00 & i) >> 8);abyte0[1] = (byte) ((0xff0000 & i) >> 16);abyte0[0] = (byte) ((0xff000000 & i) >> 24);return abyte0; } */ /*** 將float轉為低字節在前，高字節在后的byte數組*/ public static byte[] toLH(float f) {return toLH(Float.floatToRawIntBits(f)); } /*** 將float轉為高字節在前，低字節在后的byte數組*/ public static byte[] toHH(float f) {return toHH(Float.floatToRawIntBits(f)); } /*** 將String轉為byte數組*/ public static byte[] stringToBytes(String s, int length) {while (s.getBytes().length < length) {s += " ";}return s.getBytes(); } /*** 將字節數組轉換為String* @param b byte[]* @return String*/ public static String bytesToString(byte[] b) {StringBuffer result = new StringBuffer("");int length = b.length;for (int i=0; i<length; i++) {result.append((char)(b & 0xff));}return result.toString(); } /*** 將字符串轉換為byte數組* @param s String* @return byte[]*/ public static byte[] stringToBytes(String s) {return s.getBytes(); } /*** 將高字節數組轉換為int* @param b byte[]* @return int*/ public static int hBytesToInt(byte[] b) {int s = 0;for (int i = 0; i < 3; i++) {if (b >= 0) {s = s + b;} else {s = s + 256 + b;}s = s * 256;}if (b[3] >= 0) {s = s + b[3];} else {s = s + 256 + b[3];}return s; } /*** 將低字節數組轉換為int* @param b byte[]* @return int*/ public static int lBytesToInt(byte[] b) {int s = 0;for (int i = 0; i < 3; i++) {if (b[3-i] >= 0) {s = s + b[3-i];} else {s = s + 256 + b[3-i];}s = s * 256;}if (b[0] >= 0) {s = s + b[0];} else {s = s + 256 + b[0];}return s; } /*** 高字節數組到short的轉換* @param b byte[]* @return short*/ public static short hBytesToShort(byte[] b) {int s = 0;if (b[0] >= 0) {s = s + b[0];} else {s = s + 256 + b[0];}s = s * 256;if (b[1] >= 0) {s = s + b[1];} else {s = s + 256 + b[1];}short result = (short)s;return result; } /*** 低字節數組到short的轉換* @param b byte[]* @return short*/ public static short lBytesToShort(byte[] b) {int s = 0;if (b[1] >= 0) {s = s + b[1];} else {s = s + 256 + b[1];}s = s * 256;if (b[0] >= 0) {s = s + b[0];} else {s = s + 256 + b[0];}short result = (short)s;return result; } /*** 高字節數組轉換為float* @param b byte[]* @return float*/ public static float hBytesToFloat(byte[] b) {int i = 0;Float F = new Float(0.0);i = ((((b[0]&0xff)<<8 | (b[1]&0xff))<<8) | (b[2]&0xff))<<8 | (b[3]&0xff);return F.intBitsToFloat(i); } /*** 低字節數組轉換為float* @param b byte[]* @return float*/ public static float lBytesToFloat(byte[] b) {int i = 0;Float F = new Float(0.0);i = ((((b[3]&0xff)<<8 | (b[2]&0xff))<<8) | (b[1]&0xff))<<8 | (b[0]&0xff);return F.intBitsToFloat(i); } /*** 將byte數組中的元素倒序排列*/ public static byte[] bytesReverseOrder(byte[] b) {int length = b.length;byte[] result = new byte[length];for(int i=0; i<length; i++) {result[length-i-1] = b;}return result; } /*** 打印byte數組*/ public static void printBytes(byte[] bb) {int length = bb.length;for (int i=0; i<length; i++) {System.out.print(bb + " ");}System.out.println(""); } public static void logBytes(byte[] bb) {int length = bb.length;String out = "";for (int i=0; i<length; i++) {out = out + bb + " ";} } /*** 將int類型的值轉換為字節序顛倒過來對應的int值* @param i int* @return int*/ public static int reverseInt(int i) {int result = FormatTransfer.hBytesToInt(FormatTransfer.toLH(i));return result; } /*** 將short類型的值轉換為字節序顛倒過來對應的short值* @param s short* @return short*/ public static short reverseShort(short s) {short result = FormatTransfer.hBytesToShort(FormatTransfer.toLH(s));return result; } /*** 將float類型的值轉換為字節序顛倒過來對應的float值* @param f float* @return float*/ public static float reverseFloat(float f) {float result = FormatTransfer.hBytesToFloat(FormatTransfer.toLH(f));return result; } }

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java整型數與網絡字節序的 byte[] 數組轉換關系

http://www.cnblogs.com/devinzhang/archive/2012/09/28/2707605.html

工作項目需要在java和c/c++之間進行socket通信，socket通信是以字節流或者字節包進行的，socket發送方須將數據轉換為字節流或者字節包，而接收方則將字節流和字節包再轉換回相應的數據類型。如果發送方和接收方都是同種語言，則一般只涉及到字節序的調整。而對于java和c/c++的通信，則情況就要復雜一些，主要是因為java中沒有unsigned類型，并且java和c在某些數據類型上的長度不一致。
　　本文就是針對這種情況，整理了java數據類型和網絡字節流或字節包(相當于java的byte數組)之間轉換方法。實際上網上這方面的資料不少，但往往不全，甚至有些有錯誤，于是就花了點時間對java整型數和網絡字節序的byte[]之間轉換的各種情況做了一些驗證和整理。整理出來的函數如下：

public class ByteConvert {// 以下 是整型數 和 網絡字節序的 byte[] 數組之間的轉換public static byte[] longToBytes(long n) {byte[] b = new byte[8];b[7] = (byte) (n & 0xff);b[6] = (byte) (n >> 8 & 0xff);b[5] = (byte) (n >> 16 & 0xff);b[4] = (byte) (n >> 24 & 0xff);b[3] = (byte) (n >> 32 & 0xff);b[2] = (byte) (n >> 40 & 0xff);b[1] = (byte) (n >> 48 & 0xff);b[0] = (byte) (n >> 56 & 0xff);return b;}public static void longToBytes( long n, byte[] array, int offset ){array[7+offset] = (byte) (n & 0xff);array[6+offset] = (byte) (n >> 8 & 0xff);array[5+offset] = (byte) (n >> 16 & 0xff);array[4+offset] = (byte) (n >> 24 & 0xff);array[3+offset] = (byte) (n >> 32 & 0xff);array[2+offset] = (byte) (n >> 40 & 0xff);array[1+offset] = (byte) (n >> 48 & 0xff);array[0+offset] = (byte) (n >> 56 & 0xff);}public static long bytesToLong( byte[] array ){return ((((long) array[ 0] & 0xff) << 56)| (((long) array[ 1] & 0xff) << 48)| (((long) array[ 2] & 0xff) << 40)| (((long) array[ 3] & 0xff) << 32)| (((long) array[ 4] & 0xff) << 24)| (((long) array[ 5] & 0xff) << 16)| (((long) array[ 6] & 0xff) << 8) | (((long) array[ 7] & 0xff) << 0)); }public static long bytesToLong( byte[] array, int offset ){return ((((long) array[offset + 0] & 0xff) << 56)| (((long) array[offset + 1] & 0xff) << 48)| (((long) array[offset + 2] & 0xff) << 40)| (((long) array[offset + 3] & 0xff) << 32)| (((long) array[offset + 4] & 0xff) << 24)| (((long) array[offset + 5] & 0xff) << 16)| (((long) array[offset + 6] & 0xff) << 8) | (((long) array[offset + 7] & 0xff) << 0)); }public static byte[] intToBytes(int n) {byte[] b = new byte[4];b[3] = (byte) (n & 0xff);b[2] = (byte) (n >> 8 & 0xff);b[1] = (byte) (n >> 16 & 0xff);b[0] = (byte) (n >> 24 & 0xff);return b;}public static void intToBytes( int n, byte[] array, int offset ){array[3+offset] = (byte) (n & 0xff);array[2+offset] = (byte) (n >> 8 & 0xff);array[1+offset] = (byte) (n >> 16 & 0xff);array[offset] = (byte) (n >> 24 & 0xff);} public static int bytesToInt(byte b[]) {return b[3] & 0xff | (b[2] & 0xff) << 8 | (b[1] & 0xff) << 16| (b[0] & 0xff) << 24;}public static int bytesToInt(byte b[], int offset) {return b[offset+3] & 0xff | (b[offset+2] & 0xff) << 8 | (b[offset+1] & 0xff) << 16| (b[offset] & 0xff) << 24;}public static byte[] uintToBytes( long n ){byte[] b = new byte[4];b[3] = (byte) (n & 0xff);b[2] = (byte) (n >> 8 & 0xff);b[1] = (byte) (n >> 16 & 0xff);b[0] = (byte) (n >> 24 & 0xff);return b;}public static void uintToBytes( long n, byte[] array, int offset ){array[3+offset] = (byte) (n );array[2+offset] = (byte) (n >> 8 & 0xff);array[1+offset] = (byte) (n >> 16 & 0xff);array[offset] = (byte) (n >> 24 & 0xff);}public static long bytesToUint(byte[] array) { return ((long) (array[3] & 0xff)) | ((long) (array[2] & 0xff)) << 8 | ((long) (array[1] & 0xff)) << 16 | ((long) (array[0] & 0xff)) << 24; }public static long bytesToUint(byte[] array, int offset) { return ((long) (array[offset+3] & 0xff)) | ((long) (array[offset+2] & 0xff)) << 8 | ((long) (array[offset+1] & 0xff)) << 16 | ((long) (array[offset] & 0xff)) << 24; }public static byte[] shortToBytes(short n) {byte[] b = new byte[2];b[1] = (byte) ( n & 0xff);b[0] = (byte) ((n >> 8) & 0xff);return b;}public static void shortToBytes(short n, byte[] array, int offset ) { array[offset+1] = (byte) ( n & 0xff);array[offset] = (byte) ((n >> 8) & 0xff);}public static short bytesToShort(byte[] b){return (short)( b[1] & 0xff|(b[0] & 0xff) << 8 ); } public static short bytesToShort(byte[] b, int offset){return (short)( b[offset+1] & 0xff|(b[offset] & 0xff) << 8 ); }public static byte[] ushortToBytes(int n) {byte[] b = new byte[2];b[1] = (byte) ( n & 0xff);b[0] = (byte) ((n >> 8) & 0xff);return b;} public static void ushortToBytes(int n, byte[] array, int offset ) {array[offset+1] = (byte) ( n & 0xff);array[offset] = (byte) ((n >> 8) & 0xff);}public static int bytesToUshort(byte b[]) {return b[1] & 0xff | (b[0] & 0xff) << 8;} public static int bytesToUshort(byte b[], int offset) {return b[offset+1] & 0xff | (b[offset] & 0xff) << 8;} public static byte[] ubyteToBytes( int n ){byte[] b = new byte[1];b[0] = (byte) (n & 0xff);return b;}public static void ubyteToBytes( int n, byte[] array, int offset ){array[0] = (byte) (n & 0xff);}public static int bytesToUbyte( byte[] array ){ return array[0] & 0xff;} public static int bytesToUbyte( byte[] array, int offset ){ return array[offset] & 0xff;} // char 類型、 float、double 類型和 byte[] 數組之間的轉換關系還需繼續研究實現。 }測試程序如下：public class ByteConvertTest {public static String byte2Hex(byte[] buf) {StringBuffer strbuf = new StringBuffer();strbuf.append("{");for (byte b : buf) {if (b == 0) {strbuf.append("00");} else if (b == -1) {strbuf.append("FF");} else {String str = Integer.toHexString(b).toUpperCase();// sb.append(a);if (str.length() == 8) {str = str.substring(6, 8);} else if (str.length() < 2) {str = "0" + str;}strbuf.append(str);}strbuf.append(" ");}strbuf.append("}");return strbuf.toString();} public static byte[] longToBytes(long n) {byte[] b = new byte[8];b[7] = (byte) (n & 0xff);b[6] = (byte) (n >> 8 & 0xff);b[5] = (byte) (n >> 16 & 0xff);b[4] = (byte) (n >> 24 & 0xff);b[3] = (byte) (n >> 32 & 0xff);b[2] = (byte) (n >> 40 & 0xff);b[1] = (byte) (n >> 48 & 0xff);b[0] = (byte) (n >> 56 & 0xff);return b;}public static long bytesToLong( byte[] array ){return ((((long) array[ 0] & 0xff) << 56)| (((long) array[ 1] & 0xff) << 48)| (((long) array[ 2] & 0xff) << 40)| (((long) array[ 3] & 0xff) << 32)| (((long) array[ 4] & 0xff) << 24)| (((long) array[ 5] & 0xff) << 16)| (((long) array[ 6] & 0xff) << 8) | (((long) array[ 7] & 0xff) )); }public static int bytesToInt(byte b[]) {return b[3] & 0xff | (b[2] & 0xff) << 8 | (b[1] & 0xff) << 16| (b[0] & 0xff) << 24;}public static long bytesToUint(byte[] array) { return ((long) (array[3] & 0xff)) | ((long) (array[2] & 0xff)) << 8 | ((long) (array[1] & 0xff)) << 16 | ((long) (array[0] & 0xff)) << 24; }public static byte[] uintToBytes( long n ){byte[] b = new byte[4];b[3] = (byte) (n & 0xff);b[2] = (byte) (n >> 8 & 0xff);b[1] = (byte) (n >> 16 & 0xff);b[0] = (byte) (n >> 24 & 0xff);return b;}public static byte[] shortToBytes(short n) {byte[] b = new byte[2];b[1] = (byte) ( n & 0xff);b[0] = (byte) ((n >> 8) & 0xff);return b;}public static short bytesToShort(byte[] b){return (short)( b[1] & 0xff|(b[0] & 0xff) << 8 ); }static void testShortConvert(){System.out.println("=================== short convert =============");System.out.println("byte2Hex(shortToBytes((short)0x11f2))"+byte2Hex(shortToBytes((short)0x11f2))); System.out.print("println 0x11f2:");System.out.println((short)0x11f2); System.out.println("byte2Hex(shortToBytes((short)0xf1f2))"+byte2Hex(shortToBytes((short)0xf1f2))); System.out.print("println 0xf1f2:");System.out.println((short)0xf1f2); System.out.print("println bytesToShort(shortToBytes((short)0x11f2)):");System.out.println((short)bytesToShort(shortToBytes((short)0x11f2))); System.out.print("println bytesToShort(shortToBytes((short)0xf1f2)):");System.out.println((short)bytesToShort(shortToBytes((short)0xf1f2))); }public static byte[] ushortToBytes(int n) {byte[] b = new byte[2];b[1] = (byte) (n & 0xff);b[0] = (byte) (n >> 8 & 0xff);return b;}public static int bytesToUshort(byte b[]) {return b[1] & 0xff | (b[0] & 0xff) << 8;}static void testUshortConvert(){System.out.println("=================== Ushort convert =============");System.out.println("byte2Hex(ushortToBytes(0x11f2))"+byte2Hex(ushortToBytes(0x11f2))); System.out.print("println 0x11f2:");System.out.println(0x11f2); System.out.println("byte2Hex(ushortToBytes(0xf1f2))"+byte2Hex(ushortToBytes(0xf1f2))); System.out.print("println 0xf1f2:");System.out.println(0xf1f2); System.out.print("println bytesToUshort(ushortToBytes(0x11f2)):");System.out.println(bytesToUshort(ushortToBytes(0x11f2))); System.out.print("println bytesToUshort(ushortToBytes(0xf1f2)):");System.out.println(bytesToUshort(ushortToBytes(0xf1f2))); }public static byte[] ubyteToBytes( int n ){byte[] b = new byte[1];b[0] = (byte) (n & 0xff);return b;}public static int bytesToUbyte( byte[] array ){ return array[0] & 0xff;} static void testUbyteConvert(){System.out.println("=================== Ubyte convert =============");System.out.println("byte2Hex(ubyteToBytes(0x1112))"+byte2Hex(ubyteToBytes(0x1112))); System.out.print("println 0x1112:");System.out.println(0x1112); System.out.println("byte2Hex(ubyteToBytes(0xf2))"+byte2Hex(ubyteToBytes(0xf2))); System.out.print("println 0xf2:");System.out.println(0xf2); System.out.print("println bytesToUbyte(ubyteToBytes(0x1112)):");System.out.println(bytesToUbyte(ubyteToBytes(0x1112))); System.out.print("println bytesToUbyte(ubyteToBytes(0xf1f2)):");System.out.println(bytesToUbyte(ubyteToBytes(0xf1f2))); }/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stub byte[] array = new byte[4];array[3] = (byte) 0xF4;array[2] = 0x13;array[1] = 0x12;array[0] = 0x11;System.out.println("=================== Integer bytes =============");System.out.println("the bytes is:"+byte2Hex(array) );System.out.print("println bytesToInt :");System.out.println( bytesToInt(array));System.out.printf("printf bytesToInt :%X\n", bytesToInt(array));System.out.println("=================== long bytes =============");byte[] longBytes = new byte[8];longBytes[7] = (byte) 0xf7;longBytes[6] = (byte) 0x16;longBytes[5] = (byte) 0xf5;longBytes[4] = (byte) 0x14;longBytes[3] = (byte) 0xf3;longBytes[2] = (byte) 0x12;longBytes[1] = (byte) 0xf1;longBytes[0] = (byte) 0x10;System.out.println( "the bytes is:"+byte2Hex(longBytes) );System.out.printf("printf bytesToLong:%X\n",bytesToLong(longBytes));System.out.println("=================byte to long ================");byte b = (byte)0xf1;System.out.print("Println the byte:");System.out.println(b);System.out.printf("Printf the byte:%X\n",b);long l = b;System.out.print("Println byte to long:");System.out.println(l);System.out.printf("printf byte to long:%X\n",l);System.out.println("================= uint Bytes ================");byte[] uint = new byte[4];uint[3] = (byte) 0xf3;uint[2] = (byte) 0x12;uint[1] = (byte) 0xf1;uint[0] = (byte) 0xFF;System.out.println( "the bytes is:"+byte2Hex(uint) );System.out.printf("printf bytesToUint:%X\n",bytesToUint(uint));System.out.print("Println bytesToUint:");System.out.println(bytesToUint(uint));System.out.println("byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)):"+byte2Hex(uintToBytes(0x11f2f3f4f5f6f7f8l)));System.out.println("===============Long Integer=============="); System.out.print("println 0x11f2f3f4f5f6f7f8l:");System.out.println(0x11f2f3f4f5f6f7f8l); System.out.printf("Printf 0x11f2f3f4f5f6f7f8l:%X\n",0x11f2f3f4f5f6f7f8l);System.out.println("println byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l))"+byte2Hex(longToBytes(0x11f2f3f4f5f6f7f8l)));// 注意，下面的這行，并不能獲得正確的uint。System.out.printf("printf bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l):%X\n",bytesToUint(longToBytes(0x11f2f3f4f5f6f7f8l)));System.out.println("===============bytesToLong(longToBytes())==============");System.out.println(bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));System.out.printf("%X\n",bytesToLong(longToBytes(0x11f2f3f4f5f6f7f8l)));testShortConvert();testUshortConvert();testUbyteConvert();}}

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java中int與byte〔4〕的相互轉換http://www.cnblogs.com/mayola/archive/2011/11/17/2253101.html我們都知道，JAVA中的基本數據類型有int,byte,char,long,float,double...，它們與引用數據類型很不一樣，之所有在如此面向對象的JAVA語言中依然支持這些值類型，就是考慮到性能的原因。現在，同樣是因為考慮到性能，我們需要一種高效的方法使int與byte[]能夠自由的相互轉換，理由就是，我們需要在網絡上傳送數據，而網絡上的數據都是byte數據流，這就需要一個int-> byte[]與byte[] -> int的方法。簡單的方法，我們可以用DataOutputStream與ByteArrayOutputStream來將int轉換成byte[]，方法就是：int i = 0;ByteArrayOutputStream boutput = newByteArrayOutputStream();DataOutputStream doutput = newDataOutputStream(boutput);doutput.writeInt(i);byte[] buf = boutput.toByteArray(); 執行相反的過程我們就可以將byte[]->int，我們要用到DataInputStream與ByteArrayInputStream。byte[] buf = new byte[4];ByteArrayInputStream bintput = newByteArrayInputStream(buf);DataInputStream dintput = new DataInputStream();int i = dintput.readInt();上面的方法可以達到int<->byte[]的轉化，下面還有更加高效的方法，雖然看起來會比較費勁一些，但是性能的提升是顯而易見的。

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int -> byte[]privatebyte[] intToByteArray(final int integer) { int byteNum = (40 -Integer.numberOfLeadingZeros (integer < 0 ? ~integer : integer))/ 8; byte[] byteArray = new byte[4];for (int n = 0; n < byteNum; n++) byteArray[3 - n] = (byte) (integer>>> (n * 8));return (byteArray); }byte[] -> intpublic static int byteArrayToInt(byte[] b, int offset) {int value= 0;for (int i = 0; i < 4; i++) {int shift= (4 - 1 - i) * 8;value +=(b[i + offset] & 0x000000FF) << shift;}return value;} ========================================import java.io.*;public class IOTest { public static void main(String[] args) throws Exception {int i = 65535; byte[] b = intToByteArray1(i);for(byte bb : b) {System.out.print(bb + " ");} }public static byte[] intToByteArray1(int i) { byte[] result = new byte[4]; result[0] = (byte)((i >> 24) & 0xFF);result[1] = (byte)((i >> 16) & 0xFF);result[2] = (byte)((i >> 8) & 0xFF); result[3] = (byte)(i & 0xFF);return result; }public static byte[] intToByteArray2(int i) throws Exception {ByteArrayOutputStream buf = new ByteArrayOutputStream(); DataOutputStream out = new DataOutputStream(buf); out.writeInt(i); byte[] b = buf.toByteArray();out.close();buf.close();return b; }

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ByteArrayOutputStream用法

字節數組流：
ByteArrayOutputStream: 可以捕獲內存緩沖區的數據，轉換成字節數組。
ByteArrayoutputStream bout=new ByteArrayOutputStream();
bout.write(int a); bout.write(int b); bout.write(int c);
byte[] buf=bout.toByteArray();//獲取內存緩沖中的數據
for(int i=0;i<=buf.length;i++)
{
System.out.println(buf);
}
bout.close();
注：通過調用reset（）方法可以重新定位。
ByteArrayInputStream: 可以將字節數組轉化為輸入流
ByteArrayInputStream bin=new ByteArrayInputStream(byte[] buf);
int data=0;
while( (b=bin.read())!=-1)
{
System.out.println(b);
}
bin.close();

與DataOutputStream&DataInputStream聯合使用：

ByteArrayOutputStream bout=new ByteArrayOutputStream();
DataOutputStream dos=new DataOutputStream(bout);
String name="suntao";
int age=19;
dos.writeUTF(name);
dos.writeInt(age);
byte[] buf=bout.toByteArray();//獲取內存緩沖區中的數據
dos.close();
bout.close();

ByteArrayInputStream bin=new ByteArrayInputStream(byte[] buf);
DataInputStream dis=new DataInputStream(bin);
String name=dis.readUTF();//從字節數組中讀取
int age=dis.readInt();
dis.close();
bin.close();

注: DataInputStream&DataOutputStream還可以與FileInputStream&FileOutputStream
聯合使用。
其中：
DataInputStream&DataOutputStream關心如何將數據從高層次的形式轉化成低層次的形式.
FileInputStream&FileOutputStream關心如何操作存儲單元以接受和產生數據。

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JAVA里面關于byte數組和String之間的轉換問題

JAVA里面關于byte數組和String之間的轉換問題
　　引自：http://soniccyj.bokee.com/6175850.html
　　JAVA里面關于byte數組和String之間的轉換問題
　　把byte轉化成string，必須經過編碼。
　　例如下面一個例子:
　　import java.io.UnsupportedEncodingException;
　　public class test{
　　public static void main(String g[]) {
　　String s = "12345abcd";
　　byte b[] = s.getBytes();
　　String t = b.toString();
　　System.out.println(t);
　　}
　　}
　　輸出字符串的結果和字符串s不一樣了.
　　經過以下方式轉碼就可以正確轉換了:
　　public class test{
　　public static void main(String g[]) {
　　String s = "12345abcd";
　　byte b[] = s.getBytes();
　　try {
　　String t = new String(b);
　　System.out.print(t);
　　} catch (Exception e) {
　　e.printStackTrace();
　　}
　　}
　　}
　　引自：http://topic.csdn.net/t/20050404/10/3906398.html
　　String str = "String";
　　byte[] byte1 = str.getBytes();
　　String str1 = new String(byte1);
　　byte[] byte2 = str1.getBytes();
　　String str2 = new String(byte2);
　　System.out.println("str<<<" + str);
　　System.out.println("byte1<<<" + byte1);
　　System.out.println("str1<<<" + str1);
　　System.out.println("byte2<<<" + byte2);
　　System.out.println("str2<<<" + str2);
　　-------------------------------------
　　輸出結果
　　str<<<String
　　byte1<<<[B@192d342
　　str1<<<String
　　byte2<<<[B@6b97fd
　　str2<<<String
　　想請教為什么兩個byte輸出的不一樣呢?
　　String str = "String";
　　byte[] byte1 = str.getBytes();
　　String str1 = new String(byte1);
　　byte[] byte2 = str1.getBytes();
　　----------
　　注意byte1是str得到的byte數組，而byte2是另一個字符串str1得到的數組
　　他們本身也是兩個對象
　　直接打印實際上調用的是toString()方法，而toString()的默認實現是打印對象類型+hashCode()
　　[B表示byte數組
　　@表示之后的是地址
　　后面跟著的是hashCode，其實就是其虛擬機地址
　　所以這個結果也就是順理成章了.

最近的項目中要使用到把byte[]類型轉換成String字符串然后通過網絡發送，但發現發現出去的字符串和獲取的字符串雖然是一樣的，但當用String的getBytes()的方法得到的byte[]跟原來的byte[]是不一樣的。

看如下代碼：

bytebytes[] = new byte[] { 50, 0, -1, 28, -24 };

String string = new String(bytes);

byte[] ret = string.getBytes();

查看ret的數據發現是50, 0, -17, -65, -67, 28, -17, -65, -67,發現數據并不是原來的數據。

而使用如下代碼就可以得到原來的數據：

bytebytes[] = new byte[] { 50, 0, -1, 28, -24 };

StringisoString = new String(bytes, "ISO-8859-1");

byte[] isoret = isoString.getBytes("ISO-8859-1");

這是為什么呢？原因是第一種方法默認是用UTF-8編碼來生成String的，用System.getProperty("sun.jnu.encoding")可以得到Android默認編碼是UTF-8。UTF-8是可變長度的編碼，原來的字節數組就被改變了。而ISO8859-1通常叫做Latin-1，Latin-1包括了書寫所有西方歐洲語言不可缺少的附加字符，其中 0~127的字符與ASCII碼相同，它是單字節的編碼方式，這樣第二種方式生成的String里的字節數組就跟原來的字節數組一樣。在new String使用其他編碼如GBK,GB2312的話一樣也會導致字節數組發生變化，因此要想獲取String里單字節數組，就應該使用iso8859-1編碼。

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