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

妖狐艹你老母 2022-03-18 20:14 320阅读 0赞

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 ){
        
    			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();
    	}