最好用的Java Http客户端Requests

在Java的世界里，HttpClient 是一个功能强大的Http请求库，然而接口非常复杂，设计上遵从正交性，简单的请求也需要写比较多的代码，更不要说隐藏在各种细节里面的高级用法了。

Requests,  是一个模仿python requests 模块来设计的Http lib，拥有简单而灵活的API，在容易使用的同时，又能够满足各种高级定制的使用，可是说是当前最好用的Java Http Client Lib。

简单的请求示例:

String url = ...;  Response<String> resp = Requests.get(url).text();    // post 和其他方法  resp = Requests.post(url).text();  resp = Requests.head(url).text();    //读取Http Response   int statusCode = resp.getStatusCode();  Headers headers = resp.getHeaders();  Cookies cookies = resp.getCookies();  String body = resp.getBody();    //response 返回其他类型  resp = Requests.get(url).text("UTF-8");  // get response as bytes  Response<byte[]> resp1 = Requests.get(url).bytes();  // save response as file   Response<File> resp2 = Requests.get(url).file("/path/to/save/file");    // url 参数:  Map<String, Object> map = new HashMap<>();  map.put("k1", "v1");  map.put("k2", "v2");  Response<String> resp = Requests.get(url).param("key1", "value1").params(map)          //.params(new Parameter(...), new Parameter(...))          .text();    // 请求头  Response<String> resp = Requests.get(url).header("key1", "value1").headers(map)          //.headers(new Header(...), new Header(...))          .text();    // 添加Cookie:  Map<String, Object> cookies = new HashMap<>();  Response<String> resp = Requests.get(url).cookie("key1", "value1").cookies(map)          //.cookies(new Cookie(...), new Cookie(...))          .text();    //  设置 userAgent  Response<String> resp = Requests.get(url).userAgent(userAgent).text();    // 增加请求数据(post, put, patch方法)  // send form-encoded data. x-www-form-urlencoded header will be send automatically  Response<String> resp = Requests.post(url).data(map).text();  // send string data  String str = ...;  resp = Requests.post(url).data(str, "UTF-8").text();  // send from inputStream  InputStream in = ...  resp = Requests.post(url).data(in).text();    // multipart 请求, 用于文件上传:  Response<String> resp = Requests.post(url).data(map).multiPart("ufile", "/path/to/file")          .multiPart(..., ...).text();  请求设置:  //禁止自动重定向  Response<String> resp = Requests.get(url).allowRedirects(false).text();    //超时  // both connec timeout, and socket timeout  Response<String> resp = Requests.get(url).timeout(30_1000).text();  // set connect timeout and socket timeout  resp = Requests.get(url).timeout(30_1000, 30_1000).text();    //禁止使用gzip  Response<String> resp = Requests.get(url).gzip(false).text();    // 不检查https 证书  Response<String> resp = Requests.get(url).verify(false).text();    // Http Basic 验证  Response<String> resp = Requests.get(url).auth("user", "passwd").verify(false).text();    //代理，支持http, https, socks 代理  Response<String> resp = Requests.get("http://www.baidu.com/")          .proxy(Proxy.httpProxy("127.0.0.1", 8080))          .text();  Session. session 可以用来维持http 会话，自动处理cookie, basic auth 等信息:  Session session = Requests.session();  Response<String> resp1 = session.get(url1).text();  Response<String> resp2 = session.get(url2).text();  连接池. 连接池可以用来在多个请求之间复用Http 连接:  ConnectionPool connectionPool = ConnectionPool.custom().verify(false)         .maxPerRoute(20)         .maxTotal(100)         //.proxy(...)         .build();  Response<String> resp1 = Requests.get(url1).connectionPool(connectionPool).text();  Response<String> resp2 = Requests.get(url2).connectionPool(connectionPool).text();  connectionPool.close();