Retrofit是目前最流行的HTTP請(qǐng)求工具迟杂。

使用方法：

1.添加依賴:

compile 'com.squareup.retrofit2:retrofit:2.3.0'

2.定義一個(gè)接口，Retrofit會(huì)將該接口轉(zhuǎn)換成為HTTP請(qǐng)求

public interface APIService{
    @GET("api/getUser")
     Call<ResponseBody>  getUserInfo();
}

3.發(fā)起HTTP請(qǐng)求胜臊，獲取結(jié)果

//創(chuàng)建一個(gè)Retrofit客戶端
  Retrofit retrofit = new Retrofit.Builder()
          .baseUrl("XXXXXXXXX")
          .build();

  //得到一個(gè)APIService代理對(duì)象
  APIService apiService = retrofit.create(APIService.class);
//生成一個(gè)HTTP請(qǐng)求
  Call<ResponseBody> userInfo = apiService.getUserInfo();
  //最后馍资，就可以通過studentInfo對(duì)象獲取WebServer內(nèi)容
  //此處有兩種請(qǐng)求方法：同步調(diào)用膀捷，異步調(diào)用
  //這里使用的是異步調(diào)用方法
  userInfo.enqueue(new Callback<ResponseBody>() {
        @Override
        public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
            try {
                Log.i(TAG,response.body().string());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onFailure(Call<ResponseBody> call, Throwable t) {
            Log.i(TAG, "onFailure: "+t);
        }
    });

進(jìn)階

上面方法獲取到的是JSON數(shù)據(jù)，還要經(jīng)過手動(dòng)進(jìn)一步解析才能獲取所需內(nèi)容拿穴，
而Retrofit默認(rèn)只能解碼HTTP bodies到 OkHttp's ResponseBody類型泣洞，要想使
Retrofit支持其他類型轉(zhuǎn)換，必須通過Converters（數(shù)據(jù)轉(zhuǎn)換器）轉(zhuǎn)換默色。

1.添加Gson依賴：

compile 'com.squareup.retrofit2:converter-gson:2.2.0'

2.創(chuàng)建User類

 public class User {

    @SerializedName("userId")
    @Expose
    private String userId;
    @SerializedName("name")
    @Expose
    private String name;
    @SerializedName("age")
    @Expose
    private int age;

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return String.format("id:%s\nname:%s\nage:%d", userId, name, age);
    }
}

3.定義接口修改

public interface APIService{
    @GET("api/getUser")
     Call<User>  getUserInfo();
}

4.發(fā)起HTTP請(qǐng)求修改

//創(chuàng)建一個(gè)Retrofit客戶端
  Retrofit retrofit = new Retrofit.Builder()
          .baseUrl("XXXXXXXXXXX")
          //增加Gson轉(zhuǎn)換
          .addConverterFactory(GsonConverterFactory.create())
          .build();

  //得到一個(gè)APIService代理對(duì)象
  APIService apiService = retrofit.create(APIService.class);
//生成一個(gè)HTTP請(qǐng)求
  Call<User> userInfo = apiService.getUserInfo();
  userInfo.enqueue(new Callback<User>() {
      @Override
      public void onResponse(Call<User> call, Response<User> response) {
          User user = response.body();
          Log.i(TAG, user.toString());
      }

      @Override
      public void onFailure(Call<User> call, Throwable t) {
          Log.i(TAG, "onFailure: " + t);
      }
  });