Question

我使用GO语言函数（math.Float32bits）序列化了32位浮点数，它返回对应于IEEE 754二进制表示的浮点数。然后将此数字序列化为32位整数，并作为字节数组读入java脚本。

例如，这是实际数字：

float: 2.8088086
as byte array:  40 33 c3 85
as hex: 0x4033c385

有demo converter显示相同的数字。

我需要从JavaScript中的字节数组中获取相同的浮点数，我不知道该怎么做。

Answer 1

根据您描述的数据：

var buffer = new ArrayBuffer(4);
var bytes = new Uint8Array(buffer);
bytes[0] = 0x40;
bytes[1] = 0x33;
bytes[2] = 0xc3;
bytes[3] = 0x85;

我们可以使用DataView：

将值检索为浮点数

var view = new DataView(buffer);
// If you only had a Uint8Array, you would use bytes.buffer instead of buffer.

console.log(view.getFloat32(0, false));

2.8088085651397705

var buffer = new ArrayBuffer(4);
var bytes = new Uint8Array(buffer);
bytes[0] = 0x40;
bytes[1] = 0x33;
bytes[2] = 0xc3;
bytes[3] = 0x85;    

var view = new DataView(buffer);

console.log(view.getFloat32(0, false));

Answer 2

有点不同的解决方案，如果你不能使用DataView：

formLogin.Close();

Answer 3

我的回答就像@Jeremys 的回答，只是有一些小改动。请现在使用 const/let 和 Float32Array/Float64Array 而不是 DataView。我是这样解决的：

// 0x40a00000 is "5" in float/IEEE-754 32bit.
// You can check this here: https://www.h-schmidt.net/FloatConverter/IEEE754.html
// MSB (Most significant byte) is at highest index
const bytes = [0x00, 0x00, 0xa0, 0x40];
// The buffer is like a raw view into memory.
const buffer = new ArrayBuffer(bytes.length);
// The Uint8Array uses the buffer as its memory.
// This way we can store data byte by byte
const byteArray = new Uint8Array(buffer);
for (let i = 0; i < bytes.length; i++) {
  byteArray[i] = bytes[i];
}

// float array uses the same buffer as memory location
const floatArray = new Float32Array(buffer);

// floatValue is a "number", because a number in javascript is a
// double (IEEE-754 @ 64bit) => it can hold f32 values
const floatValue = floatArray[0];

// prints out "5"
console.log(`${JSON.stringify(bytes)} as f32 is ${floatValue}`);

// double / f64
// const doubleArray = new Float64Array(buffer);
// const doubleValue = doubleArray[0];

在JavaScript

3 个答案: