java:多字节数据类型数组(double,float,int,long)数组与byte数组的相互转换

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多字节数据类型数组(double,float,int,long)数组数组和byte数组的相互转换都可以基于

java.nio.Buffer

实现.

java.nio.DoubleBuffer

对应double[],

java.nio.FloatBuffer

对应float[],

java.nio.LongBuffer

对应long[],

java.nio.IntBuffer

对应int[]
…

byte[] 转 double[],float[],int[]…

byte[]转double[],float[],int[]…很简单因为ByteBuffer本身就有

asDoubleBuffer,asFloatBuffer,asIntBuffer

等方法，可以将

ByteBuffer

直接转换为

DoubleBuffer,FloatBuffer,IntBuffer

…;
代码实现如下:

public static double[] asDoubleArray(byte[] input){
if(null == input ){
return null;
}
DoubleBuffer buffer = ByteBuffer.wrap(input).asDoubleBuffer();
double[] res = new double[buffer.remaining()];
buffer.get(res);
return res;
}
public static float[] asFloatArray(byte[] input){
if(null == input ){
return null;
}
FloatBuffer buffer = ByteBuffer.wrap(input).asFloatBuffer();
float[] res = new float[buffer.remaining()];
buffer.get(res);
return res;
}
public static int[] asIntArray(byte[] input){
if(null == input ){
return null;
}
IntBuffer buffer = ByteBuffer.wrap(input).asIntBuffer();
int[] res = new int[buffer.remaining()];
buffer.get(res);
return res;
}
public static long[] asLongArray(byte[] input){
if(null == input ){
return null;
}
LongBuffer buffer = ByteBuffer.wrap(input).asLongBuffer();
long[] res = new long[buffer.remaining()];
buffer.get(res);
return res;
}
public static short[] asShortArray(byte[] input){
if(null == input ){
return null;
}
ShortBuffer buffer = ByteBuffer.wrap(input).asShortBuffer();
short[] res = new short[buffer.remaining()];
buffer.get(res);
return res;
}

double[],float[],int[]…转byte[]

反过来，从多字节类型数组(double[],float[],long[]…)转byte[]要稍麻烦一些，因为多字节类型数组对应的Buffer类并没提供

asByteBuffer

这样的方法.所以要自己写些代码进行转换(比如将

DoubleBuffer

转为

ByteBuffer

),实现代码如下：

/**
* {@link DoubleBuffer} TO {@link ByteBuffer}
* @param input
* @return
*/
public static ByteBuffer asByteBuffer(DoubleBuffer input){
if(null == input
20000
){
return null;
}
ByteBuffer buffer = ByteBuffer.allocate(input.capacity()* (Double.SIZE/8));
while(input.hasRemaining()){
buffer.putDouble(input.get());
}
return buffer;
}
/**
* double[] TO byte[]
* @param input
* @return
*/
public static byte[] asByteArray(double[] input){
if(null == input ){
return null;
}
return asByteBuffer(DoubleBuffer.wrap(input)).array();
}
/**
* {@link FloatBuffer} TO {@link ByteBuffer}
* @param input
* @return
*/
public static ByteBuffer asByteBuffer(FloatBuffer input){
if(null == input ){
return null;
}
ByteBuffer buffer = ByteBuffer.allocate(input.capacity()* (Float.SIZE/8));
while(input.hasRemaining()){
buffer.putFloat(input.get());
}
return buffer;
}
/**
* float[] TO byte[]
* @param input
* @return
*/
public static byte[] asByteArray(float[] input){
if(null == input ){
return null;
}
return asByteBuffer(FloatBuffer.wrap(input)).array();
}
/**
* {@link IntBuffer} TO {@link ByteBuffer}
* @param input
* @return
*/
public static ByteBuffer asByteBuffer(IntBuffer input){
if(null == input ){
return null;
}
ByteBuffer buffer = ByteBuffer.allocate(input.capacity()* (Integer.SIZE/8));
while(input.hasRemaining()){
buffer.putInt(input.get());
}
return buffer;
}
/**
* int[] TO byte[]
* @param input
* @return
*/
public static byte[] asByteArray(int[] input){
if(null == input ){
return null;
}
return asByteBuffer(IntBuffer.wrap(input)).array();
}
/**
* {@link LongBuffer} TO {@link ByteBuffer}
* @param input
* @return
*/
public static ByteBuffer asByteBuffer(LongBuffer input){
if(null == input ){
return null;
}
ByteBuffer buffer = ByteBuffer.allocate(input.capacity()* (Long.SIZE/8));
while(input.hasRemaining()){
buffer.putLong(input.get());
}
return buffer;
}
/**
* long[] TO byte[]
* @param input
* @return
*/
public static byte[] asByteArray(long[] input){
if(null == input ){
return null;
}
return asByteBuffer(LongBuffer.wrap(input)).array();
}
/**
* {@link ShortBuffer} TO {@link ByteBuffer}
* @param input
* @return
*/
public static ByteBuffer asByteBuffer(ShortBuffer input){
if(null == input ){
return null;
}
ByteBuffer buffer = ByteBuffer.allocate(input.capacity()* (Short.SIZE/8));
while(input.hasRemaining()){
buffer.putShort(input.get());
}
return buffer;
}
/**
* short[] TO byte[]
* @param input
* @return
*/
public static byte[] asByteArray(short[] input){
if(null == input ){
return null;
}
return asByteBuffer(ShortBuffer.wrap(input)).array();
}