如何获得对象列表与post请求改造2.1.0与android

我是Android编程新手，使用Retrofit。

我看到很多例子来改造库，使GET请求，传递参数和把所有的对象在一个页面上的PHP。这是可能的，做同样的事情与POST ?我想把所有的数据(JSON对象)从我的webservice，通过POST传递参数，但我不能做实现。

有没有人做过或有一个例子来帮助我?

研究文档并查看这里的stackoverflow中的示例，我可以制作下面的示例，但只返回第一个对象。

依赖性:

compile 'com.squareup.retrofit2:retrofit:2.1.0'
compile 'com.squareup.retrofit2:converter-gson:2.1.0'

MainActivity(按钮内部):

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("http://192.168.101.36/json/")
            .addConverterFactory(GsonConverterFactory.create())
            .build();
    ApiService apiService = retrofit.create(ApiService.class);
    Call<User> call = apiService.validateUser(inputEmail.getText().toString(), inputSenha.getText().toString());
    call.enqueue(new Callback<User>() {
        @Override
        public void onResponse(Call<User> call, Response<User> response) {
            //Verifica se houve a conexão com sucesso ao webservice
            if (!response.isSuccessful()) {
                textView.setText("ERROR onResponde: " + response.code());
            } else {
                //requisição retona os dados com sucesso
                String email = response.body().getEmail();
                String senha = response.body().getPassword();
                textView.append("email: " + email + " - password: " + senha + "'n");
            }
        }
        @Override
        public void onFailure(Call<User> call, Throwable t) {
            t.printStackTrace();
            textView.setText(t.getMessage());
        }
    });

接口:

public interface ApiService {
   @FormUrlEncoded
   @POST("index.php") 
   Call<User> validateUser(
        @Field("username") String username,
        @Field("password") String password
   );
}

类用户:

public class User {
private String  username, email, password;
public String getUsername(){
    return this.username;
}
public String getPassword(){
    return this.password;
}
public String getEmail(){
    return this.email;
}
}

index . php:

$email = $_POST['username'];
$senha = $_POST['password'];
if ($email == "manoelps@live.com") {
  echo '
  {
    "email":"' . $email . '",
    "password":"' . $senha . '"
  },
  {
    "email":"myemail@live.com",
    "password":"654321"
  },
  {
    "email":"joselito@joselito.com",
    "password":"123456"
  }
  ';
} else {
  echo '
  {
    "email":"otheremail@otheremail.com",
    "password":"987654"
  },
  {
    "email":"otheremail@otheremail.com",
    "password":"987654"
  },
  {
    "email":"otheremail@otheremail.com",
    "password":"987654"
  }
  ';
}

如果我使用作为对象数组在应用程序中发生错误:

[{
"email":"manoelps@live.com",
"password":"123456"
},
{
"email":"manoelps@live.com",
"password":"123456"
}]