【怎样基于Okhttp3来实现各种各样的远程调用，表单、JSON、文件、文件流等待】

HTTP客户端工具 okhttp3 form/json/multipart

• 提供表达、json、混合表单、混合表单文件流传输等HTTP请求调用
• 支持自定义配置默认客户端，参数列表如下：

     okhtt3.config.connectTimeout 连接超时，TimeUnit.SECONDSokhtt3.config.readTimeOut 读取超时，TimeUnit.SECONDSokhtt3.config.writeTimeOut 写超时，TimeUnit.SECONDSokhtt3.config.callTimeout 流程超时，TimeUnit.SECONDS

• 写一个组件，第一步首先就是定义功能接口啦

public interface Okhttp3 {String postRequest(OkHttpClient httpClient, RequestBody requestBody, String url, Map<String, String> headers) throws IOException;
}

• 然后就是注入我们自定义的okhttpClient，自定义配置参数如下：

@ConfigurationProperties(prefix = "okhtt3.config")
public class DefaultOkhttp3ClientProperties {private Integer connectTimeout = 2;private Integer readTimeout = 10;private Integer writeTimeout = 10;private Integer callTimeOut = 20;public Integer getConnectTimeout() {return connectTimeout;}public void setConnectTimeout(Integer connectTimeout) {this.connectTimeout = connectTimeout;}public Integer getReadTimeout() {return readTimeout;}public void setReadTimeout(Integer readTimeout) {this.readTimeout = readTimeout;}public Integer getWriteTimeout() {return writeTimeout;}public void setWriteTimeout(Integer writeTimeout) {this.writeTimeout = writeTimeout;}public Integer getCallTimeOut() {return callTimeOut;}public void setCallTimeOut(Integer callTimeOut) {this.callTimeOut = callTimeOut;}
}

• 注入自定义客户端，支持HTTP/HTTPS

@Configuration
@EnableConfigurationProperties(DefaultOkhttp3ClientProperties.class)
public class Okhttp3Configuration {@Beanpublic DefaultOkhttp3 defaultOkhttp3() {return new DefaultOkhttp3();}@Bean@ConditionalOnMissingBeanpublic OkHttpClient okHttpClient(@Autowired DefaultOkhttp3ClientProperties defaultOkhttp3ClientProperties) {X509TrustManager x509TrustManager = trustManager();final SSLContext sslContext;try {sslContext = SSLContext.getInstance("SSL");sslContext.init(null, new TrustManager[]{x509TrustManager}, new java.security.SecureRandom());} catch (Exception e) {throw new RuntimeException(e);}final SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();OkHttpClient.Builder builder = new OkHttpClient.Builder();builder.sslSocketFactory(sslSocketFactory, x509TrustManager);builder.hostnameVerifier((hostname, session) -> true);builder.connectTimeout(defaultOkhttp3ClientProperties.getConnectTimeout(), TimeUnit.SECONDS);builder.readTimeout(defaultOkhttp3ClientProperties.getReadTimeout(), TimeUnit.SECONDS);builder.writeTimeout(defaultOkhttp3ClientProperties.getWriteTimeout(), TimeUnit.SECONDS);builder.callTimeout(defaultOkhttp3ClientProperties.getCallTimeOut(), TimeUnit.SECONDS);return builder.build();}private static X509TrustManager trustManager() {return new X509TrustManager() {@Overridepublic void checkClientTrusted(X509Certificate[] chain, String authType) {}@Overridepublic void checkServerTrusted(X509Certificate[] chain, String authType) {}@Overridepublic X509Certificate[] getAcceptedIssuers() {return new X509Certificate[0];}};}
}

• 下面就是我们应对何种复杂业务的实现了，简单的表单请求、JSON请求，到文件上传，接着就是文件流传输等等，针对大文件的传入，直接通过网络流传递，避免内存问题。下面是各种需求的实现

public class DefaultOkhttp3 implements Okhttp3 {@Overridepublic String postRequest(OkHttpClient httpClient, RequestBody requestBody, String url, Map<String, String> headers) throws IOException {Call call = makeRequestCall(httpClient, requestBody, url, headers);return postRequest(call);}public String buildUrlIncludeQueryParams(String url, Map<String, String> queryParams) {HttpUrl.Builder builder = Objects.requireNonNull(HttpUrl.parse(url)).newBuilder();queryParams.forEach(builder::addQueryParameter);return builder.build().toString();}public RequestBody buildJsonRequestBody(String json) {return RequestBody.create(json, MediaType.parse("application/json; charset=utf-8"));}public RequestBody buildFormRequestBody(Map<String, String> formBody) {FormBody.Builder builder = new FormBody.Builder();formBody.forEach(builder::add);return builder.build();}public RequestBody buildMultipartRequestBodyOfFiles(Map<String, String> formBody, Map<String, FilePat> fileMap) {MultipartBody.Builder builder = new MultipartBody.Builder();builder.setType(MultipartBody.FORM);formBody.forEach(builder::addFormDataPart);fileMap.forEach((k, v) -> builder.addFormDataPart(k, v.getFile().getName(), RequestBody.create(v.getFile(), v.getMediaType())));return builder.build();}public RequestBody buildMultipartFilesRequestBody(Map<String, String> formBody, Map<String, MultipartFile> fileMap) {MultipartBody.Builder builder = new MultipartBody.Builder();builder.setType(MultipartBody.FORM);formBody.forEach(builder::addFormDataPart);fileMap.forEach((k, v) -> {try {builder.addFormDataPart(k, v.getName(), RequestBody.create(v.getBytes(), MediaType.get(Objects.requireNonNull(v.getContentType()))));} catch (IOException e) {throw new RuntimeException(e);}});return builder.build();}public RequestBody buildMultipartFilesInputStreamRequestBody(Map<String, String> formBody, Map<String, MultipartFile> fileMap) {MultipartBody.Builder builder = new MultipartBody.Builder();builder.setType(MultipartBody.FORM);formBody.forEach(builder::addFormDataPart);fileMap.forEach((k, v) -> {builder.addFormDataPart(k, v.getOriginalFilename(), new RequestBody() {@NotNull@Overridepublic MediaType contentType() {return MediaType.get(Objects.requireNonNull(v.getContentType()));}@Overridepublic long contentLength() {return v.getSize();}@Overridepublic void writeTo(@NotNull BufferedSink bufferedSink) throws IOException {try (InputStream inputStream = v.getInputStream()) {byte[] buffer = new byte[2048];int len;while ((len = inputStream.read(buffer)) != -1) {bufferedSink.write(buffer, 0, len);bufferedSink.flush();}}}});});return builder.build();}public static class FilePat {private File file;private MediaType mediaType;public File getFile() {return file;}public void setFile(File file) {this.file = file;}public MediaType getMediaType() {return mediaType;}public void setMediaType(MediaType mediaType) {this.mediaType = mediaType;}}private Call makeRequestCall(OkHttpClient httpClient, RequestBody body, String reqUrl, Map<String, String> headers) {Request.Builder reqBuilder = new Request.Builder();reqBuilder.url(reqUrl).post(body);if (headers != null && !headers.isEmpty()) {for (Map.Entry<String, String> entry : headers.entrySet()) {reqBuilder.header(entry.getKey(), entry.getValue());}}return httpClient.newCall(reqBuilder.build());}private String postRequest(Call call) throws IOException {try (Response resp = call.execute()) {ResponseBody rb = resp.body();if (resp.code() != 200) {String msg = null;if (rb != null) {msg = rb.string();}throw new IOException("http code: " + resp.code() + (msg != null ? ",msg:" + msg : ""));}if (rb == null) {throw new IllegalStateException("http response body is null");}return rb.string();}}}