摘要：本文主要介绍okhttp3的功能，和我封装的简单工具类，方便大家快速应用于自己的开发环境。

简介

HTTP是现代应用网络的方式。这是我们交换数据和媒体的方式。高效地执行HTTP可以使您的内容加载更快，并节省带宽。

okHttp是一个HTTP客户端，默认情况下是高效的

·HTTP/2支持允许对同一主机的所有请求共享一个套接字。

·连接池减少了请求延迟(如果HTTP/2不可用)。

透明GZIP缩小了下载大小。

响应缓存完全避免重复请求的网络。

• 官网地址：square.github.io/okhttp/

OkHttpUtils工具类

• 该类封装了get,post,put,delete方法
• 未捕捉http请求状态码
• 请求返回结果字符串

public class OkHttpUtils {

    private static final OkHttpClient CLIENT = new OkHttpClient();

    /**
     * GET 请求
     * @param url
     * @param headerMap
     * @return
     * @throws Exception
     */
    public static String get(String url, Map<String,String> headerMap) throws Exception{
        Request.Builder requestBuilder = new Request.Builder().url(url);

        handleRequestHeader(requestBuilder, headerMap);
        return executeRequest(requestBuilder);
    }

    /**
     * POST JSON请求
     * @param url
     * @param jsonStr
     * @param headerMap
     * @return
     * @throws Exception
     */
    public static String postJson(String url, String jsonStr, Map<String,String> headerMap) throws Exception{
        MediaType mediaType = MediaType.parse("application/json; charset=UTF-8");
        Request.Builder requestBuilder = new Request.Builder()
                .url(url)
                .post(RequestBody.create(mediaType,jsonStr));

        handleRequestHeader(requestBuilder, headerMap);
        return executeRequest(requestBuilder);
    }

    /**
     * 上传文件
     * @param url
     * @param file
     * @param headerMap
     * @return
     * @throws Exception
     */
    public static String postFile(String url, File file, Map<String,String> headerMap) throws Exception {
        RequestBody requestBody = new MultipartBody.Builder()
                .setType(MultipartBody.FORM)
                .addFormDataPart("file", file.getName(), RequestBody.create(MediaType.parse("application/octet-stream"), file))
                .build();
        Request.Builder requestBuilder = new Request.Builder()
                .url(url)
                .post(requestBody);

        handleRequestHeader(requestBuilder, headerMap);
        return executeRequest(requestBuilder);
    }

    /**
     * PUT 方法
     * @param url
     * @param jsonStr
     * @param headerMap
     * @return
     * @throws Exception
     */
    public static String putJson(String url, String jsonStr, Map<String,String> headerMap) throws Exception {
        MediaType mediaType = MediaType.parse("application/json; charset=UTF-8");
        Request.Builder requestBuilder = new Request.Builder()
                .url(url)
                .put(RequestBody.create(mediaType,jsonStr));

        handleRequestHeader(requestBuilder, headerMap);
        return executeRequest(requestBuilder);
    }

    /**
     * DELETE 方法
     * @param url
     * @param headerMap
     * @return
     * @throws Exception
     */
    public static String delete(String url, Map<String,String> headerMap) throws Exception {
        Request.Builder requestBuilder = new Request.Builder()
                .url(url)
                .delete();

        handleRequestHeader(requestBuilder, headerMap);
        return executeRequest(requestBuilder);
    }


    /**
     * 真实执行请求
     * @param requestBuilder
     * @return
     * @throws IOException
     */
    private static String executeRequest(Request.Builder requestBuilder) throws IOException {
        try (Response response = CLIENT.newCall(requestBuilder.build()).execute()) {
            if(null != response.body()){
                return response.body().string();
            }
        }
        return null;
    }

    /**
     * 处理请求头
     * @param requestBuilder
     * @param headerMap
     */
    private static void handleRequestHeader(Request.Builder requestBuilder,Map<String,String> headerMap){
        if(null != headerMap && headerMap.size() > 0){
            headerMap.forEach(requestBuilder::header);
        }
    }

}

单元测试

get方法

url后面的参数要自己提前拼接好，headerMap是header中传递的数据

@Test
void get() throws Exception {
    String result = OkHttpUtils.get("http://localhost:8081/index/home?value=123", null);
    log.info(result);
}

postJson方法

url上也可以带参数，jsonStr是对象转为json的字符串，headerMap是header中传递的数据

@Test
void postJson() throws Exception {
    Student student = new Student();
    student.setName("zhangsan");
    String result = OkHttpUtils.postJson("http://localhost:8086/index/addStudent", JSON.toJSONString(student), null);
    log.info(result);
}

postFile

url上也可以带参数，file是文件对象，headerMap是header中传递的数据

@Test
void postFile() throws Exception {
    String result = OkHttpUtils.postFile("http://localhost:8086/index/upload", new File("C:\\Users\\lanzhuo\\Desktop\\测试数据集.csv"), null);
    log.info(result);
}

putJson

和postJson类似

delete

和get类似

Interceptors拦截器使用

拦截器就是在请求执行前可以进行数据的一系列改写操作，可以方便我们统一进行任务管理，官方文档square.github.io/okhttp/feat…

ApiUtils示例

该案例在请求前添加了token

ApiTokenInterceptor 拦截器

@Slf4j
public class ApiTokenInterceptor implements Interceptor {

    @Override
    public Response intercept(Chain chain) throws IOException {

        // 重新构建request，添加了token，实际业务按照大家的token构建算法来
        Request request = chain.request().newBuilder().header("token","abc").build();

        long t1 = System.nanoTime();
        log.info(String.format("Sending request %s on %s%n%s",
                request.url(), chain.connection(), request.headers()));

        Response response = chain.proceed(request);

        long t2 = System.nanoTime();
        log.info(String.format("Received response for %s in %.1fms%n%s",
                response.request().url(), (t2 - t1) / 1e6d, response.headers()));

        return response;
    }
}

ApiUtils 拦截器

封装的方法

public class ApiUtils {

    private static final OkHttpClient CLIENT = new OkHttpClient.Builder()
            .addInterceptor(new ApiTokenInterceptor())
            .build();

    public static String get(String url) throws Exception{
        Request.Builder requestBuilder = new Request.Builder().url(url);

        try (Response response = CLIENT.newCall(requestBuilder.build()).execute()) {
            if(null != response.body()){
                return response.body().string();
            }
        }
        return null;
    }

}

测试用例

@Test
void get() throws Exception {
    String result = ApiUtils.get("http://127.0.0.1:8080/user/info?name=lisi");
    System.out.println(result);
}

结果如下