详解Android中使用OkHttp发送HTTP的post请求的方法

http post 和 put 请求可以包含要提交的内容。只需要在创建 request 对象时，通过 post 和 put 方法来指定要提交的内容即可。
http post 请求的基本示例：

public class poststring {
  public static void main(string[] args) throws ioexception {
  okhttpclient client = new okhttpclient();
  mediatype media_type_text = mediatype.parse("text/plain");
  string postbody = "hello world";

  request request = new request.builder()
      .url("http://www.baidu.com")
      .post(requestbody.create(media_type_text, postbody))
      .build();

  response response = client.newcall(request).execute();
  if (!response.issuccessful()) {
    throw new ioexception("服务器端错误: " + response);
  }

  system.out.println(response.body().string());
  }
}

以 string 类型提交内容只适用于内容比较小的情况。当请求内容较大时，应该使用流来提交。

post方式提交流

以流的方式post提交请求体。请求体的内容由流写入产生。这个例子是流直接写入 okio 的bufferedsink。你的程序可能会使用 outputstream ，你可以使用 bufferedsink.outputstream() 来获取。

public static final mediatype media_type_markdown
 = mediatype.parse("text/x-markdown; charset=utf-8");

private final okhttpclient client = new okhttpclient();

public void run() throws exception {
 requestbody requestbody = new requestbody() {
  @override public mediatype contenttype() {
   return media_type_markdown;
  }

  @override public void writeto(bufferedsink sink) throws ioexception {
   sink.writeutf8("numbers\n");
   sink.writeutf8("-------\n");
   for (int i = 2; i <= 997; i++) {
  sink.writeutf8(string.format(" * %s = %s\n", i, factor(i)));
   }
  }

  private string factor(int n) {
   for (int i = 2; i < n; i++) {
  int x = n / i;
  if (x * i == n) return factor(x) + " × " + i;
   }
   return integer.tostring(n);
  }
 };

 request request = new request.builder()
   .url("https://api.github.com/markdown/raw")
   .post(requestbody)
   .build();

 response response = client.newcall(request).execute();
 if (!response.issuccessful()) throw new ioexception("unexpected code " + response);

 system.out.println(response.body().string());
}

post方式提交文件

以文件作为请求体是十分简单的。

public static final mediatype media_type_markdown
 = mediatype.parse("text/x-markdown; charset=utf-8");

private final okhttpclient client = new okhttpclient();

public void run() throws exception {
 file file = new file("readme.md");

 request request = new request.builder()
   .url("https://api.github.com/markdown/raw")
   .post(requestbody.create(media_type_markdown, file))
   .build();

 response response = client.newcall(request).execute();
 if (!response.issuccessful()) throw new ioexception("unexpected code " + response);

 system.out.println(response.body().string());
}

post方式提交表单

使用 formencodingbuilder 来构建和html <form> 标签相同效果的请求体。键值对将使用一种html兼容形式的url编码来进行编码。

private final okhttpclient client = new okhttpclient();

public void run() throws exception {
 requestbody formbody = new formencodingbuilder()
   .add("search", "jurassic park")
   .build();
 request request = new request.builder()
   .url("https://en.wikipedia.org/w/index.php")
   .post(formbody)
   .build();

 response response = client.newcall(request).execute();
 if (!response.issuccessful()) throw new ioexception("unexpected code " + response);

 system.out.println(response.body().string());
}

post方式提交分块请求

multipartbuilder 可以构建复杂的请求体，与html文件上传形式兼容。多块请求体中每块请求都是一个请求体，可以定义自己的请求头。这些请求头可以用来描述这块请求，例如他的 content-disposition 。如果 content-length 和 content-type 可用的话，他们会被自动添加到请求头中。

private static final string imgur_client_id = "...";
private static final mediatype media_type_png = mediatype.parse("image/png");

private final okhttpclient client = new okhttpclient();

public void run() throws exception {
 // use the imgur image upload api as documented at https://api.imgur.com/endpoints/image
 requestbody requestbody = new multipartbuilder()
   .type(multipartbuilder.form)
   .addpart(
     headers.of("content-disposition", "form-data; name=\"title\""),
     requestbody.create(null, "square logo"))
   .addpart(
     headers.of("content-disposition", "form-data; name=\"image\""),
     requestbody.create(media_type_png, new file("website/static/logo-square.png")))
   .build();

 request request = new request.builder()
   .header("authorization", "client-id " + imgur_client_id)
   .url("https://api.imgur.com/3/image")
   .post(requestbody)
   .build();

 response response = client.newcall(request).execute();
 if (!response.issuccessful()) throw new ioexception("unexpected code " + response);

 system.out.println(response.body().string());
}