java 流与 byte[] 的互转操作

java 流与 byte[] 的互转操作

1. InputStream -> byte[]

引入 apache.commons.is 包

import org.apache.commons.io.IOUtils;

byte[] bytes = IOUtils.toByteArray(inputStream);

2. byte[] -> InputStream

InputStream inputStream = new ByteArrayInputStream(bytes);

补充知识：byte[]与各种数据类型互相转换示例

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

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)http:// {

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;

}

}

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。