原文：https://www.jianshu.com/p/0fda3132cf98

Retrofit注解

请求方法

注解代码请求格式

@GET

GET请求

@POST

POST请求

@DELETE

DELETE请求

@HEAD

HEAD请求

@OPTIONS

OPTIONS请求

@PATCH

PATCH请求

请求参数

注解代码说明

@Headers

添加请求头

@Path

替换路径

@Query

替代参数值，通常是结合get请求的

@FormUrlEncoded

用表单数据提交

@Field

替换参数值，是结合post请求的

前提：

Android 系统上面默认所有Http的请求都被阻止了。

需要在androidmanifest.xml的 application标签上加入 android:usesCleartextTraffic="true"

首先引入依赖：Gson可以将Json和基本数据类型之间做转换；Okhtttp用来进行HTTP连接(Retrofit就是建立在OkHttp之上的)；ReJava用来提供一个异步处理的操作。

//Gson库

implementation 'com.google.code.gson:gson:2.8.2'

//Okhttp库

implementation 'com.squareup.okhttp3:okhttp:3.1.2'

//Retrofit库

implementation 'com.squareup.retrofit2:retrofit:2.0.2'implementation'com.squareup.retrofit2:converter-gson:2.0.2' //gson转化

implementation 'com.squareup.retrofit2:adapter-rxjava:2.0.2' //RxJava//RxJava库

implementation 'io.reactivex:rxandroid:1.0.1'

先看下服务端代码，其实就是接收到了连接后返回一个JSON格式的数据：

var http = require('http');var url = require('url');var util = require('util');

http.createServer(function(req, res){

res.writeHead(200, {'Content-Type': 'text/plain'});//解析 url 参数

var params = url.parse(req.url, true).query;

console.log("有连接");

console.log(util.inspect(url.parse(req.url,true)));//发送JSON数据

var jsonobj = {time:0, code:1, data:{song_url:'yangzhilong_tem.mp3', msg:123}};

res.end(JSON.stringify(jsonobj));

}).listen(3000);

先定义一个Bean来表示从服务端获取到的东西：

importjava.util.Map;public classUser {private longtime;private intcode;private Mapdata;public MapgetData() {returndata;

}public intgetCode() {returncode;

}public longgetTime() {returntime;

}

}

定义一个接口来提供服务：

importretrofit2.http.GET;importretrofit2.http.Query;importrx.Observable;public interfaceGetAPI {//设置路径

@GET("create/original")

Observable getUser(@Query("author_id") String author_id, @Query("type") String type, @Query("info") String info);

}

java代码：

packagecom.example.m_evolution;importandroid.support.v7.app.AppCompatActivity;importandroid.os.Bundle;importandroid.util.Log;importcom.example.m_evolution.Bean.User;importcom.example.m_evolution.HttpAPI.GetAPI;importjava.util.concurrent.TimeUnit;importokhttp3.OkHttpClient;importretrofit2.Retrofit;importretrofit2.adapter.rxjava.RxJavaCallAdapterFactory;importretrofit2.converter.gson.GsonConverterFactory;importrx.Subscriber;importrx.android.schedulers.AndroidSchedulers;importrx.schedulers.Schedulers;public class TestActivity extendsAppCompatActivity {

@Overrideprotected voidonCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);

setContentView(R.layout.activity_test);

OkHttpClient okHttpClient= newOkHttpClient().newBuilder()

.connectTimeout(10, TimeUnit.SECONDS)

.readTimeout(30, TimeUnit.SECONDS)

.writeTimeout(10, TimeUnit.SECONDS)

.build();

Retrofit retrofit= newRetrofit.Builder()//设置数据解析器

.addConverterFactory(GsonConverterFactory.create())

.addCallAdapterFactory(RxJavaCallAdapterFactory.create())//设置网络请求的Url地址

.baseUrl("http://172.17.1.96:3000/")

.client(okHttpClient)

.build();//创建网络请求接口的实例

GetAPI mApi = retrofit.create(GetAPI.class);

mApi.getUser("1", "10", "[嘻哈,兴奋]")

.subscribeOn(Schedulers.newThread())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Subscriber() {

@Overridepublic voidonCompleted() {

Log.d("TestActivity", "调用完成");

}

@Overridepublic voidonError(Throwable e) {

Log.d("TestActivity", "请求失败"+e.toString());

}

@Overridepublic voidonNext(User user) {

Log.d("TestActivity", "请求成功");

Log.d("TestActivity", "time:"+user.getTime());

Log.d("TestActivity", "code:"+user.getCode());

Log.d("TestActivity", "song_url:"+user.getData().get("song_url")+"; msg:"+user.getData().get("msg"));

}

});

}

}

客户端结果：

服务端结果：

GET请求：

服务端提供的接口：

客户端：

//获取某用户的信息

@GET("/user/info")

Observable get_user_info(@Header("Authorization")String token, @Query("user_id")String user_id);

public classUserInfoHTTPResult {private long time; //服务器响应时间

private int code; //响应码 0表示正常

private String msg; //错误信息

private Mapdata;public longgetTime() {returntime;

}public intgetCode() {returncode;

}publicString getMsg() {returnmsg;

}publicString getUserName(){return data.get("username");

}publicString getGender(){return data.get("gender");

}publicString getAvatarUrl(){return data.get("avatar");

}

}

httpAPI.get_user_info(MyApp.token_pre+myApp.getUser_token(), user_id)

.subscribeOn(Schedulers.newThread())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Subscriber() {

@Overridepublic voidonCompleted() {

Log.d(TAG,"onCompleted: "+"调用完成");

}

@Overridepublic voidonError(Throwable e) {

Log.d(TAG,"onError: "+"请求失败: "+e.toString());

myApp.MakeToast("网络出错");

}

@Overridepublic voidonNext(UserInfoHTTPResult userInfoHTTPResult) {if(userInfoHTTPResult.getCode()==0){//更新个人信息

myApp.setUser_nickname(userInfoHTTPResult.getUserName());

myApp.setUser_gender(userInfoHTTPResult.getGender());

myApp.setUser_head_url(userInfoHTTPResult.getAvatarUrl());

Log.d(TAG,"onNext: username: "+myApp.getUser_nickname());

Log.d(TAG,"onNext: gender: "+myApp.getUser_gender());

Log.d(TAG,"onNext: avatar: "+myApp.getUser_head_url());

editor.putString("user_nickname",myApp.getUser_nickname());

editor.putString("user_gender",myApp.getUser_gender());

editor.putString("user_head_url", myApp.getUser_head_url());

editor.commit();//修改控件

tv_user_nickname.setText(userInfoHTTPResult.getUserName());if(myApp.getUser_gender().equals("female")){

iv_user_gender.setImageResource(R.drawable.icon_user_gender_female);

}else{

iv_user_gender.setImageResource(R.drawable.icon_user_gender_male);

}

ImageLoader.getInstance().displayImage(MyApp.baseUrl+myApp.getUser_head_url(),iv_user_head);

}

}

});

POST请求：

服务端提供的接口：

注意，最后一个参数avatar表示头像，涉及到文件的上传；

//用户更新信息

@Multipart

@POST("/update/user")

Observable update_user(@Header("Authorization")String token, @Part("user_id") RequestBody user_id, @Part("username")RequestBody user_nickname, @Part("gender")RequestBody gender, @Part MultipartBody.Part part_head);

public classUpdateUserHTTPResult {private long time; //服务器响应时间

private int code; //响应码 0表示正常

private String msg; //错误信息

private Mapdata;public longgetTime() {returntime;

}public intgetCode() {returncode;

}publicString getMsg() {returnmsg;

}publicString getIsok(){return data.get("isok");

}publicString getAvatar_url(){return data.get("avatar_url");

}

}

RequestBody requestUserID = RequestBody.create(MediaType.parse("multipart/form-data"), user_id);

RequestBody requestUserNickname= RequestBody.create(MediaType.parse("multipart/form-data"), user_nickname);

RequestBody requestGender= RequestBody.create(MediaType.parse("multipart/form-data"), gender);//将头像图片存储为图片

Bitmap bitmap =((BitmapDrawable)iv_user_head.getDrawable()).getBitmap();

ImageUtils.saveImage(bitmap,"temp.png");//创建RequestBody，传入参数："multipart/form-data"，File

File imgFile = new File(Environment.getExternalStorageDirectory(),getString(R.string.app_name)+"/temp.png");

RequestBody fileRequestBody= RequestBody.create(MediaType.parse("multipart/form-data"), imgFile);//创建MultipartBody.Part，用于封装文件数据

MultipartBody.Part requestImgPart = MultipartBody.Part.createFormData("avatar", imgFile.getName(), fileRequestBody);

httpAPI.update_user("Bearer "+myApp.getUser_token(),requestUserID, requestUserNickname, requestGender, requestImgPart)

.subscribeOn(Schedulers.newThread())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Observer() {

@Overridepublic voidonCompleted() {

Log.d(TAG,"onCompleted: ");

dialog_busying.dismiss();

}

@Overridepublic voidonError(Throwable e) {

Log.d(TAG,"onError: "+e.toString());

myApp.MakeToast("网络出错");

dialog_busying.dismiss();

}

@Overridepublic voidonNext(UpdateUserHTTPResult updateUserHTTPResult) {

Log.d(TAG,"onNext: Time "+updateUserHTTPResult.getTime());

Log.d(TAG,"onNext: Code "+updateUserHTTPResult.getCode());

Log.d(TAG,"onNext: Msg "+updateUserHTTPResult.getMsg());

Log.d(TAG,"onNext: Isok "+updateUserHTTPResult.getIsok());

Log.d(TAG,"onNext: Avatar_url "+updateUserHTTPResult.getAvatar_url());if(updateUserHTTPResult.getIsok().equals("true")){ //如果保存成功//更新本地的用户昵称

String user_nickname =et_user_nickname.getText().toString();

myApp.setUser_nickname(user_nickname);

myApp.setUser_head_url(updateUserHTTPResult.getAvatar_url());if (selector_gender == 0) myApp.setUser_gender("male");else if (selector_gender == 1) myApp.setUser_gender("female");

editor.putString("user_nickname", myApp.getUser_nickname());

editor.putString("user_head_url", myApp.getUser_head_url());

editor.putString("user_gender",myApp.getUser_gender());

editor.commit();

myApp.MakeToast("保存成功");

Log.d(TAG,"onNext: 保存成功");

EventBus.getDefault().post("change_user_info");

}else{

myApp.MakeToast("保存失败");

Log.d(TAG,"onNext: 保存失败");

}

dialog_busying.dismiss();

}

});

上面是表单上传数据，如果是要JSON上传数据，则：

interfaceAPIStore {

@Headers({"Content-Type: application/json","Accept: application/json"})//需要添加头

@POST ("vdyweb/ws/rest/Login")

CallgetMessage(@Body RequestBody info); //请求体味RequestBody 类型

PS：这里的数据类型是@Body，与表单不同

public classInfo {

String account;

String password;publicInfo(String account, String password) {this.account =account;this.password =password;

}

}

Info info=new Info("test","123456"); 　　/*** 利用Gson 将对象转json字符串*/Gson gson=newGson();

String obj=gson.toJson(info);

retrofit=newRetrofit.Builder().baseUrl(BASE_LOGIN_URL).build();

RequestBody body=RequestBody.create(okhttp3.MediaType.parse("application/json; charset=utf-8"),obj);