我试图使用此数据作为参数的Java函数，只接受一个字节作为参数

这与函数接受一个大于2^32-1的整数并没有本质上的区别。

这听起来似乎取决于函数是如何定义和记录的;我认为有三种可能:

It may explicitly document that the function treats the byte as an unsigned value, in which case the function probably should do what you expect but would seem to be implemented wrong. For the integer case, the function would probably declare the parameter as an unsigned integer, but that is not possible for the byte case. It may document that the value for this argument must be greater than (or perhaps equal to) zero, in which case you are misusing the function (passing an out-of-range parameter), expecting it to do more than it was designed to do. With some level of debugging support you might expect the function to throw an exception or fail an assertion. The documentation may say nothing, in which case a negative parameter is, well, a negative parameter and whether that has any meaning depends on what the function does. If this is meaningless then perhaps the function should really be defined/documented as (2). If this is meaningful in an nonobvious manner (e.g. non-negative values are used to index into an array, and negative values are used to index back from the end of the array so -1 means the last element) the documentation should say what it means and I would expect that it isn't what you want it to do anyway.

我试图使用此数据作为参数的Java函数，只接受一个字节作为参数

这与函数接受一个大于2^32-1的整数并没有本质上的区别。

这听起来似乎取决于函数是如何定义和记录的;我认为有三种可能:

It may explicitly document that the function treats the byte as an unsigned value, in which case the function probably should do what you expect but would seem to be implemented wrong. For the integer case, the function would probably declare the parameter as an unsigned integer, but that is not possible for the byte case. It may document that the value for this argument must be greater than (or perhaps equal to) zero, in which case you are misusing the function (passing an out-of-range parameter), expecting it to do more than it was designed to do. With some level of debugging support you might expect the function to throw an exception or fail an assertion. The documentation may say nothing, in which case a negative parameter is, well, a negative parameter and whether that has any meaning depends on what the function does. If this is meaningless then perhaps the function should really be defined/documented as (2). If this is meaningful in an nonobvious manner (e.g. non-negative values are used to index into an array, and negative values are used to index back from the end of the array so -1 means the last element) the documentation should say what it means and I would expect that it isn't what you want it to do anyway.

在Java中没有原始无符号字节。通常的做法是将其转换为更大的类型:

int anUnsignedByte = (int) aSignedByte & 0xff;

如果你有一个函数必须传递一个有符号字节，如果你传递一个无符号字节，你期望它做什么?

为什么不能使用其他数据类型?

通常情况下，您可以使用一个字节作为一个无符号字节简单或不翻译。这完全取决于如何使用。你需要澄清你打算用它做什么。

在好奇netty ByteBuf writeInt和readUnsignedInt方法的明显不对称之后，我碰巧偶然地进入了这个页面。

在阅读了有趣和有教育意义的答案后，我仍然想知道你说的时候调用的是什么函数:

我试图使用这些数据作为参数的Java函数 只接受一个字节作为参数。

不管这么多年过去了，我的50美分如下:

让我们假设您正在调用的方法正在用微量更新一些余额，并且它根据一些定义良好的需求集进行操作。也就是说，它被认为对其预期的行为有正确的实现:

long processMicroPayment(byte amount) {
    this.balance += amount;
    return balance;     
}

Basically, if you supply a positive amount it will be added to the balance, and a negative amount will effectively be subtracted from the balance. Now because it accepts a byte as its parameter the implicit assumption is that it functionally only accepts amounts between -128 and +127. So if you want to use this method to add, say, 130 to the balance, it simply will not produce the result YOU desire, because there is no way within the implementation of this method to represent an amount higher than 127. So passing it 130 will not result in your desired behavior. Note that the method has no way of implementing a (say) AmountOutOfBoundsException because 130 will be 'interpreted' as a negative value that is still obeying the method's contract.

我有以下几个问题:

您是否根据其(隐式或显式)契约使用该方法? 方法是否正确实现? 我还是误解了你的问题吗?

在Java中，原语是有符号的，这与它们在内存/传输中的表示方式无关——一个字节只有8位，是否将其解释为有符号范围取决于您。没有神奇的旗帜说“这是有符号的”或“这是没有符号的”。

由于原语是有符号的，Java编译器将阻止您为字节分配大于+127的值(或小于-128的值)。然而，没有什么可以阻止你向下转换一个int型(或short型)来实现这一点:

int i = 200; // 0000 0000 0000 0000 0000 0000 1100 1000 (200)
byte b = (byte) 200; // 1100 1000 (-56 by Java specification, 200 by convention)

/*
 * Will print a negative int -56 because upcasting byte to int does
 * so called "sign extension" which yields those bits:
 * 1111 1111 1111 1111 1111 1111 1100 1000 (-56)
 *
 * But you could still choose to interpret this as +200.
 */
System.out.println(b); // "-56"

/*
 * Will print a positive int 200 because bitwise AND with 0xFF will
 * zero all the 24 most significant bits that:
 * a) were added during upcasting to int which took place silently
 *    just before evaluating the bitwise AND operator.
 *    So the `b & 0xFF` is equivalent with `((int) b) & 0xFF`.
 * b) were set to 1s because of "sign extension" during the upcasting
 *
 * 1111 1111 1111 1111 1111 1111 1100 1000 (the int)
 * &
 * 0000 0000 0000 0000 0000 0000 1111 1111 (the 0xFF)
 * =======================================
 * 0000 0000 0000 0000 0000 0000 1100 1000 (200)
 */
System.out.println(b & 0xFF); // "200"

/*
 * You would typically do this *within* the method that expected an 
 * unsigned byte and the advantage is you apply `0xFF` only once
 * and than you use the `unsignedByte` variable in all your bitwise
 * operations.
 *
 * You could use any integer type longer than `byte` for the `unsignedByte` variable,
 * i.e. `short`, `int`, `long` and even `char`, but during bitwise operations
 * it would get casted to `int` anyway.
 */
void printUnsignedByte(byte b) {
    int unsignedByte = b & 0xFF;
    System.out.println(unsignedByte); // "200"
}