java 基础 byte[]与各种数据类型互相转换的简单示例
这里对byte[]类型对long,int,double,float，short,cahr，object,string类型相互转换的实例，
在socket开发过程中，通常需要将一些具体的值（这些值可能是各种java类型）转化为byte[]类型，为此我总结了如下这个示例，贴出来，以便经常翻看：
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public class testcase {
/**
* short到字节数组的转换.
*/
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();// 将最低位保存在最低位
temp = temp >> 8;// 向右移8位
}
return b;
}
/**
* 字节数组到short的转换.
*/
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到字节数组的转换.
*/
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();// 将最低位保存在最低位
temp = temp >> 8;// 向右移8位
}
return b;
}
/**
* 字节数组到int的转换.
*/
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类型转成byte数组
*/
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();// 将最低位保存在最低位 temp = temp
// >> 8;// 向右移8位
}
return b;
}
/**
* 字节数组到long的转换.
*/
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不变
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到字节数组的转换.
*/
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;
}
/**
* 字节数组到double的转换.
*/
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到字节数组的转换.
*/
public static void floattobyte(float x) {
//先用 float.floattointbits(f)转换成int
}
/**
* 字节数组到float的转换.
*/
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到字节数组的转换.
*/
public static byte[] chartobyte(char c){
byte[] b = new byte[2];
b[0] = (byte) ((c & 0xff00) >> 8);
b[1] = (byte) (c & 0xff);
return b;
}
/**
* 字节数组到char的转换.
*/
public static char bytetochar(byte[] b){
char c = (char) (((b[0] & 0xff) << 8) | (b[1] & 0xff));
return c;
}
/**
* string到字节数组的转换.
*/
public static byte[] stringtobyte(string str) throws unsupportedencodingexception{
return str.getbytes("gbk");
}
/**
* 字节数组到string的转换.
*/
public static string bytestostring(byte[] str) {
string keyword = null;
try {
keyword = new string(str,"gbk");
} catch (unsupportedencodingexception e) {
e.printstacktrace();
}
return keyword;
}
/**
* object到字节数组的转换
*/
@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);
}
/**
* 字节数组到object的转换.
*/
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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