自定义拦截器

public class LoggingInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {

        //首先取到Request
        Request request=chain.request();
        Response response=null;
        Request requestprocess=null;
        if("GET".equals(request.method())){
            String url=request.url().toString()+ "&source=android";
            Request.Builder builder=new Request.Builder();
            builder.get().url(url);

            requestProcess =  builder.build();
            response=chain.proceed(requestprocess);

        }else{
            FormBody.Builder builder=new FormBody.Builder();
            RequestBody requestBody=request.body();
            if (requestBody instanceof FormBody){
                FormBody formBody= (FormBody) requestBody;
                for(int i=0;i<formBody.size();i++){
                   builder.add(formBody.encodedName(i),formBody.encodedValue(i));
                }
                builder.add("source","android");
            }
            requestprocess=request.newBuilder().url(request.url().toString()).post(builder.build()).build();
            response=chain.proceed(requestprocess);
        }
        return response;
    }

}

//添加头

public class UserAgentIntercepter implements Interceptor{
    @Override
    public Response intercept(Chain chain) throws IOException {
        Request request=chain.request().newBuilder()
                .addHeader("key1","value")
                .build();
        return chain.proceed(request);
    }
}