android需要传一个List<实体> 给服务器，后台框架不同导致传参的方式不同，之前我另一个项目后台是spring的传List比较方便，android我是直接这样调的没问题的：
@POST
Observable<String> postRaw(@Url String url, @Body RequestBody body);然后这个项目后台是struts2，所以按照上面的方式传参是不可以的，并且后台需要进行对list注解：
@Element(User.class)
public List<User> userList;并且android端传数据的时候也需要注意一下，应该这样这样传:
package ****;import java.util.WeakHashMap;
import java.util.concurrent.TimeUnit;import okhttp3.OkHttpClient;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
import retrofit2.converter.gson.GsonConverterFactory;
import ****.ApiConstants;
import ***.ApiService;/*** @author ChenYe* created by on 2018/1/22 0022. 14:14**/public class RestCreator {private RestCreator() {}/*** 参数容器*/private static final class ParamsHolder {private static final WeakHashMap<String, Object> PARAMS = new WeakHashMap<>();}public static WeakHashMap<String, Object> getParams() {return ParamsHolder.PARAMS;}//=============================正常Json请求的Retrofit==========================private static final class OkHttpHolder {/*** 在指定时间内还没有连接到服务器就会报SocketTimeout异常*/private static final int CONN_TIME_OUT = 5;/*** 是连接后在指定时间还没有获取到数据就超时*/private static final int READ_TIME_OUT = 20;private static final OkHttpClient CLIENT = new OkHttpClient.Builder().addInterceptor(new HttpLoggingInterceptor().setLevel( HttpLoggingInterceptor.Level.BODY)).connectTimeout(CONN_TIME_OUT, TimeUnit.SECONDS).readTimeout(READ_TIME_OUT, TimeUnit.SECONDS).build();}private static final class RetrofitHolder {private static final String BASE_URL = ApiConstants.MR_YANG_SERVER;private static final Retrofit RETROFIT = new Retrofit.Builder().baseUrl(BASE_URL).client(OkHttpHolder.CLIENT).addConverterFactory(GsonConverterFactory.create()).addCallAdapterFactory(RxJava2CallAdapterFactory.create()).build();}private static final class ServiceHolder {private static final ApiService SERVICE = RetrofitHolder.RETROFIT.create(ApiService.class);}public static ApiService getService() {return ServiceHolder.SERVICE;}}public interface ApiService{
//定义接口
@FormUrlEncoded
@POST
Observable<BaseResponse<Object>> sendList(@Url String url, @FieldMap Map<String, String> map);
}//代码中调用接口
List<User> list = new ArrayList<>();
list.add(new User("name1", "10"));
list.add(new User("name2", "7"));
list.add(new User("name3", "18"));
Map<String, String> map = new HashMap();
for (int i = 0; i < list.size(); i++) {User user= list.get(i);map.put("userList[" + i + "].name", user.getName());map.put("userList[" + i + "].age", user.getAge());
}//我这里就没有写subscribe()的代码了，望你能看懂。
RestCreator.getService().postRequestWithList("接口名", map);//上面的网络框架用到的依赖:
implementation 'com.squareup.retrofit2:retrofit:2.1.0'
implementation 'com.squareup.retrofit2:converter-gson:2.1.0'
implementation 'com.squareup.okhttp3:logging-interceptor:3.10.0'
implementation 'com.squareup.okhttp3:okhttp:3.10.0'
implementation 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'
implementation 'com.squareup.retrofit2:retrofit:2.4.0'
implementation 'io.reactivex.rxjava2:rxjava:2.1.14'
implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'