Retrofit2简单实例

Retrofit 是什么呢？Rotrofit是square开发的一个jar,便于客户端与服务器的数据交互。下面通过一个简单的例子，给大家起到一个抛砖引玉的作用.

1 在Android Studio中引入Retrofit2

compile 'com.squareup.retrofit2:retrofit:2.0.2'
    compile 'com.squareup.retrofit2:converter-gson:2.0.2'
           

记得要在AndroidManifest中添加Intent 权限.

2 定义一个Bean，使用Gson完成请求数据与POJO的转换

package com.example.mvgos.retrofit2demo;
public class RepositoryBean {

    String full_name;
    String html_url;

    int contributions;

    @Override
    public String toString() {
        return full_name + " (" + contributions + ")";
    }
}
           

3 定一个Interface，完成Retrofit初始化和封装网络请求涉及的接口

package com.example.mvgos.retrofit2demo;

import java.util.List;

import retrofit2.Call;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.GET;
import retrofit2.http.Path;

public interface GitHubService {
    @GET("orgs/{orgName}/repos")
    Call<List<RepositoryBean>> queryOrgRepos(
            @Path("orgName") String orgName);

  Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build();


}
           

4调用接口完成网络请求

//同步调用，Android中不允许在Main Thread中进行网络请求，这里使用下面的一步请求
 public List<RepositoryBean> getContributorList() throws Exception{
        GitHubService gitHubService = retrofit.create(GitHubService.class);
        Call<List<RepositoryBean>> call = gitHubService.queryOrgRepos("guchuanhangOrganization");
        List<RepositoryBean> result = call.execute().body();
        return result;

    }
    //异步请求
    public void getContributorListA() throws Exception {
        GitHubService gitHubService = retrofit.create(GitHubService.class);

        Call<List<RepositoryBean>> call = gitHubService.queryOrgRepos("guchuanhangOrganization");
        call.enqueue(new Callback<List<RepositoryBean>>() {
            @Override
            public void onResponse(Call<List<RepositoryBean>> call, Response<List<RepositoryBean>> response) {
                List<RepositoryBean> conList=response.body();
            }

            @Override
            public void onFailure(Call<List<RepositoryBean>> call, Throwable t) {
                textView.setText(t.getLocalizedMessage());
            }
        });
    } 
           

5 综合测试

<?xml version="1.0" encoding="utf-8"?>
<!--activity_main.xml-->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.mvgos.retrofit2demo.MainActivity">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Fetch"
        android:id="@+id/button"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="151dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text=""
        android:id="@+id/textView"
        android:layout_above="@+id/button"
        android:layout_alignParentEnd="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:textIsSelectable="false" />

</RelativeLayout>
           

//MainActivity.java
package com.example.mvgos.retrofit2demo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.Arrays;
import java.util.List;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

import static com.example.mvgos.retrofit2demo.GitHubService.retrofit;

public class MainActivity extends AppCompatActivity {
    public List<RepositoryBean> getContributorList() throws Exception{
        GitHubService gitHubService = retrofit.create(GitHubService.class);
        Call<List<RepositoryBean>> call = gitHubService.queryOrgRepos("guchuanhangOrganization");
        List<RepositoryBean> result = call.execute().body();
        return result;

    }
    public void getContributorListA() throws Exception {
        GitHubService gitHubService = retrofit.create(GitHubService.class);

        Call<List<RepositoryBean>> call = gitHubService.queryOrgRepos("guchuanhangOrganization");
        call.enqueue(new Callback<List<RepositoryBean>>() {
            @Override
            public void onResponse(Call<List<RepositoryBean>> call, Response<List<RepositoryBean>> response) {
                List<RepositoryBean> conList=response.body();
//              Type conListType=new TypeToken<List<Contributor>>(){}.getType();
//                Gson gson=new Gson();
//               String resultString= gson.toJson(conList,conListType);
                RepositoryBean[] myArray = conList.toArray(new RepositoryBean[]);
                textView.setText(Arrays.toString(myArray));
            }

            @Override
            public void onFailure(Call<List<RepositoryBean>> call, Throwable t) {
                textView.setText(t.getLocalizedMessage());
            }
        });
    }
    TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                 textView = (TextView) findViewById(R.id.textView);
                try{
                    getContributorListA();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        });
    }
}
           

苦于找不到服务器接口进行测试的同学请参考 github api.

参考地址：https://zeroturnaround.com/rebellabs/getting-started-with-retrofit-2/