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//byte 与 int 的相互转换

public static byte intToByte(int x) {

return (byte) x;

}

public static int byteToInt(byte b) {

//Java 总是把 byte 当做有符处理；我们可以通过将其和 0xFF 进行二进制与得到它的无符值

return b & 0xFF;

}

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//测试 int 转 byte

int int0 = 234;

byte byte0 = intToByte(int0);

System.out.println("byte0=" + byte0);//byte0=-22

//测试 byte 转 int

int int1 = byteToInt(byte0);

System.out.println("int1=" + int1);//int1=234

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//byte 数组与 int 的相互转换

public static int byteArrayToInt(byte[] b) {

return b[3] & 0xFF |

(b[2] & 0xFF) << 8 |

(b[1] & 0xFF) << 16 |

(b[0] & 0xFF) << 24;

}

public static byte[] intToByteArray(int a) {

return new byte[] {

(byte) ((a >> 24) & 0xFF),

(byte) ((a >> 16) & 0xFF),

(byte) ((a >> 8) & 0xFF),

(byte) (a & 0xFF)

};

}

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//测试 int 转 byte 数组

int int2 = 1417;

byte[] bytesInt = intToByteArray(int2);

System.out.println("bytesInt=" + bytesInt);//bytesInt=[B@de6ced

//测试 byte 数组转 int

int int3 = byteArrayToInt(bytesInt);

System.out.println("int3=" + int3);//int3=1417

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private static ByteBuffer buffer = ByteBuffer.allocate(8);

//byte 数组与 long 的相互转换

public static byte[] longToBytes(long x) {

buffer.putLong(0, x);

return buffer.array();

}

public static long bytesToLong(byte[] bytes) {

buffer.put(bytes, 0, bytes.length);

buffer.flip();//need flip

return buffer.getLong();

}

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//测试 long 转 byte 数组

long long1 = 2223;

byte[] bytesLong = longToBytes(long1);

System.out.println("bytes=" + bytesLong);//bytes=[B@c17164

//测试 byte 数组 转 long

long long2 = bytesToLong(bytesLong);

System.out.println("long2=" + long2);//long2=2223

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import java.nio.ByteBuffer;

public class Test {

private static ByteBuffer buffer = ByteBuffer.allocate(8);

public static void main(String[] args) {

//测试 int 转 byte

int int0 = 234;

byte byte0 = intToByte(int0);

System.out.println("byte0=" + byte0);//byte0=-22

//测试 byte 转 int

int int1 = byteToInt(byte0);

System.out.println("int1=" + int1);//int1=234

//测试 int 转 byte 数组

int int2 = 1417;

byte[] bytesInt = intToByteArray(int2);

System.out.println("bytesInt=" + bytesInt);//bytesInt=[B@de6ced

//测试 byte 数组转 int

int int3 = byteArrayToInt(bytesInt);

System.out.println("int3=" + int3);//int3=1417

//测试 long 转 byte 数组

long long1 = 2223;

byte[] bytesLong = longToBytes(long1);

System.out.println("bytes=" + bytesLong);//bytes=[B@c17164

//测试 byte 数组 转 long

long long2 = bytesToLong(bytesLong);

System.out.println("long2=" + long2);//long2=2223

}

//byte 与 int 的相互转换

public static byte intToByte(int x) {

return (byte) x;

}

public static int byteToInt(byte b) {

//Java 总是把 byte 当做有符处理；我们可以通过将其和 0xFF 进行二进制与得到它的无符值

return b & 0xFF;

}

//byte 数组与 int 的相互转换

public static int byteArrayToInt(byte[] b) {

return b[3] & 0xFF |

(b[2] & 0xFF) << 8 |

(b[1] & 0xFF) << 16 |

(b[0] & 0xFF) << 24;

}

public static byte[] intToByteArray(int a) {

return new byte[] {

(byte) ((a >> 24) & 0xFF),

(byte) ((a >> 16) & 0xFF),

(byte) ((a >> 8) & 0xFF),

(byte) (a & 0xFF)

};

}

//byte 数组与 long 的相互转换

public static byte[] longToBytes(long x) {

buffer.putLong(0, x);

return buffer.array();

}

public static long bytesToLong(byte[] bytes) {

buffer.put(bytes, 0, bytes.length);

buffer.flip();//need flip

return buffer.getLong();

}

}

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byte0=-22

int1=234

bytesInt=[B@de6ced

int3=1417

bytes=[B@c17164

long2=2223