1.1  认识 std.http

std.http 是 Zig 标准库中用于处理 HTTP 相关操作的类库。以我学习新的编程语言的经历来看，编写web程序是最常见的技术场景，所以熟练掌握 HTTP server/client 服务相关的编程知识是比较重要的。

<code>std.http 主要包含以下API:

Client: HTTP client implementation.Server: HTTP server implementation.protocol：headers parse methods.Connection: Connection type (keep_alive, close)ContentEncoding: Content encoding options (compress, deflate, gzip and zstd)Field: Common type for name and valueHeaders: HTTP headersMethod: HTTP methods such as GET and POSTStatus: HTTP status codes (not_found = 404, teapot = 418, etc.)TransferEncoding: Form of encoding used to transfer the body (chunked)Version: Currently HTTP/1.0 and HTTP/1.1

1.2 编写一个HTTP client程序

先创建一个开工项目：

$ mkdir -p httpz

$ cd httpz

$ zig init

$ ls -ls

total 20

4 -rw-r--r-- 1 xiaods xiaods 3879 Jun 3 11:53 build.zig

4 -rw-r--r-- 1 xiaods xiaods 3080 Jun 3 11:50 build.zig.zon

4 drwxr-xr-x 2 xiaods xiaods 4096 Jun 3 13:33 src

4 drwxr-xr-x 6 xiaods xiaods 4096 Jun 3 11:51 zig-cache

4 drwxr-xr-x 4 xiaods xiaods 4096 Jun 3 11:51 zig-out

编辑 src/main.zig，我们将使用 std.heap.GeneralPurposeAllocator，这是一个安全的分配器，可以防止双重释放（double-free）、使用后释放（use-after-free），并且能够检测内存泄漏。

const std = @import("std");

const print = std.debug.print;

const http = std.http;

var gpa = std.heap.GeneralPurposeAllocator(.{}){};

defer _ = gpa.deinit();

const allocator = gpa.allocator();

下一步，为了发送一个请求，我们需要几样东西：

client.open 函数一个从URL解析而来的 std.Uri

下面是我们如何将这些参数组合在一起的方法：

const uri = try std.Uri.parse("http://httpbin.org/headers");

const buf = try allocator.alloc(u8, 1024 * 1024 * 4);

defer allocator.free(buf);

var req = try client.open(.GET, uri, .{

.server_header_buffer = buf,

});

defer req.deinit();

为了真正的发送请求，需要通过send,finish,wait来完成：

try req.send();

try req.finish();

try req.wait();

打印返回的服务器headers 信息：

var iter = req.response.iterateHeaders();

while (iter.next()) |header| {

std.debug.print("Name:{s}, Value:{s}\n", .{ header.name, header.value });

}

try std.testing.expectEqual(req.response.status, .ok);

打印返回的服务端内容：

var rdr = req.reader();

const body = try rdr.readAllAlloc(allocator, 1024 * 1024 * 4);

defer allocator.free(body);

print("Body:\n{s}\n", .{body});

把上面的代码所有内容放在一起，并打印出响应内容：

const std = @import("std");

const print = std.debug.print;

const http = std.http;

pub fn main() !void {

var gpa = std.heap.GeneralPurposeAllocator(.{}){};

defer _ = gpa.deinit();

const allocator = gpa.allocator();

var client = http.Client{ .allocator = allocator };

defer client.deinit();

const uri = try std.Uri.parse("http://httpbin.org/headers");

const buf = try allocator.alloc(u8, 1024 * 1024 * 4);

defer allocator.free(buf);

var req = try client.open(.GET, uri, .{

.server_header_buffer = buf,

});

defer req.deinit();

try req.send();

try req.finish();

try req.wait();

var iter = req.response.iterateHeaders();

while (iter.next()) |header| {

std.debug.print("Name:{s}, Value:{s}\n", .{ header.name, header.value });

}

try std.testing.expectEqual(req.response.status, .ok);

var rdr = req.reader();

const body = try rdr.readAllAlloc(allocator, 1024 * 1024 * 4);

defer allocator.free(body);

print("Body:\n{s}\n", .{body});

}

跑一下：

$ zig build run

Name:Date, Value:Mon, 03 Jun 2024 08:24:19 GMT

Name:Content-Type, Value:application/json

Name:Content-Length, Value:202

Name:Connection, Value:keep-alive

Name:Server, Value:gunicorn/19.9.0

Name:Access-Control-Allow-Origin, Value:*

Name:Access-Control-Allow-Credentials, Value:true

Body:

{

"headers": {

"Accept-Encoding": "gzip, deflate",

"Host": "httpbin.org",

"User-Agent": "zig/0.12.0 (std.http)",

"X-Amzn-Trace-Id": "Root=1-665d7db3-258c846d0fcca0912fadfa8b"

}

}

成功了！我们成功地向服务器发送了一个GET请求并打印出了响应。

GET请求的例子我们看到了，那么如何发起POST请求呢？让我们继续拿例子说话。

准备好发送内容：

const uri = try std.Uri.parse("http://httpbin.org/anything");

const payload =

\\ {

\\ "name": "zig-learning",

\\ "author": "xiaods"

\\ }

;

发送POST 请求：

var buf: [1024]u8 = undefined;

var req = try client.open(.POST, uri, .{ .server_header_buffer = &buf });

defer req.deinit();

req.transfer_encoding = .{ .content_length = payload.len };

try req.send();

var wtr = req.writer();

try wtr.writeAll(payload);

try req.finish();

try req.wait();

try std.testing.expectEqual(req.response.status, .ok);

打印返回内容：

var rdr = req.reader();

const body = try rdr.readAllAlloc(allocator, 1024 * 1024 * 4);

defer allocator.free(body);

print("Body:\n{s}\n", .{body});

完整的Post代码如下：

const std = @import("std");

const print = std.debug.print;

const http = std.http;

pub fn main() !void {

var gpa = std.heap.GeneralPurposeAllocator(.{}){};

defer _ = gpa.deinit();

const allocator = gpa.allocator();

var client = http.Client{ .allocator = allocator };

defer client.deinit();

const uri = try std.Uri.parse("http://httpbin.org/anything");

const payload =

\\ {

\\ "name": "zig-learning",

\\ "author": "xiaods"

\\ }

;

var buf: [1024]u8 = undefined;

var req = try client.open(.POST, uri, .{ .server_header_buffer = &buf });

defer req.deinit();

req.transfer_encoding = .{ .content_length = payload.len };

try req.send();

var wtr = req.writer();

try wtr.writeAll(payload);

try req.finish();

try req.wait();

try std.testing.expectEqual(req.response.status, .ok);

var rdr = req.reader();

const body = try rdr.readAllAlloc(allocator, 1024 * 1024 * 4);

defer allocator.free(body);

print("Body:\n{s}\n", .{body});

}

 运行结果：

$ zig run src/http-post.zig

Body:

{

"args": {},

"data": " {\n \"name\": \"zig-learning\",\n \"author\": \"xiaods\"\n }",

"files": {},

"form": {},

"headers": {

"Accept-Encoding": "gzip, deflate",

"Content-Length": "52",

"Host": "httpbin.org",

"User-Agent": "zig/0.12.0 (std.http)",

"X-Amzn-Trace-Id": "Root=1-665d8114-01b0167844d8d101012e6d6a"

},

"json": {

"author": "xiaods",

"name": "zig-learning"

},

"method": "POST",

"origin": "219.133.170.77",

"url": "http://httpbin.org/anything"

}

请消化消化以上代码，别着急，我们后面继续前行，编写web server