Simple use of Retrofit2 network request framework
Common steps:
Step 1: Add dependencies of the Retrofit library
Step 2: Create a class that receives data returned by the server
Step 3: Create an interface for describing network requests
Step 4: Create a Retrofit instance
Step 5: Create a network request interface instance and configure network request parameters
Step 6 : Send a network request (asynchronous/synchronous), which encapsulates the operations of data conversion and thread switching
Step 7: Process the data returned by the server
Example:
Step 1: Add the dependencies of the Retrofit library
implementation 'com.squareup.retrofit2:retrofit:2.6.1'
//实例用到Gson解析，所以要添加此解析器依赖库
implementation 'com.squareup.retrofit2:converter-gson:2.0.2'
Step 2: Create a class that receives the data returned by the server
Here we take Hefeng Weather's city search API as an example.
- view returned data
{
"HeWeather6": [
{
"basic": [
{
"cid": "CN101281002",
"location": "吴川",
"parent_city": "湛江",
"admin_area": "广东",
"cnty": "中国",
"lat": "21.42845345",
"lon": "110.78050995",
"tz": "+8.00",
"type": "city"
}
],
"status": "ok"
}
]
}
- Create a class in AS that receives the data returned by the server.
After creating a new class, press Alt+Insert to select GsonFromat in the editing interface or directly press Alt+S shortcut keys, paste the data in json format in the pop-up box, and automatically generate json after pressing 'ok' Data processing class.
//City.java
public class City {
private List<HeWeather6Bean> HeWeather6;
public List<HeWeather6Bean> getHeWeather6() {
return HeWeather6;
}
public void setHeWeather6(List<HeWeather6Bean> HeWeather6) {
this.HeWeather6 = HeWeather6;
}
public static class HeWeather6Bean {
/**
* basic : [{"cid":"CN101281002","location":"吴川","parent_city":"湛江","admin_area":"广东","cnty":"中国","lat":"21.42845345","lon":"110.78050995","tz":"+8.00","type":"city"}]
* status : ok
*/
private String status;
private List<BasicBean> basic;
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public List<BasicBean> getBasic() {
return basic;
}
public void setBasic(List<BasicBean> basic) {
this.basic = basic;
}
public static class BasicBean {
/**
* cid : CN101281002
* location : 吴川
* parent_city : 湛江
* admin_area : 广东
* cnty : 中国
* lat : 21.42845345
* lon : 110.78050995
* tz : +8.00
* type : city
*/
private String cid;
private String location;
private String parent_city;
private String admin_area;
private String cnty;
private String lat;
private String lon;
private String tz;
private String type;
public String getCid() {
return cid;
}
public void setCid(String cid) {
this.cid = cid;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
public String getParent_city() {
return parent_city;
}
public void setParent_city(String parent_city) {
this.parent_city = parent_city;
}
public String getAdmin_area() {
return admin_area;
}
public void setAdmin_area(String admin_area) {
this.admin_area = admin_area;
}
public String getCnty() {
return cnty;
}
public void setCnty(String cnty) {
this.cnty = cnty;
}
public String getLat() {
return lat;
}
public void setLat(String lat) {
this.lat = lat;
}
public String getLon() {
return lon;
}
public void setLon(String lon) {
this.lon = lon;
}
public String getTz() {
return tz;
}
public void setTz(String tz) {
this.tz = tz;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
}
}
}
Step 3: Create an interface for describing network requests
Parameters must be in the form of annotations, complete Url = baseUrl set by creating a Retrofit instance + fields in the @GET annotation + @Query parameter settings (serve as parameters in the url?)
//此处要请求的Url为：https://search.heweather.net/find?location=CN101281002&key=5126356**可自行去和风官网申请key**7286
//baseUrl：https://search.heweather.net/
//@GET：find
//@Query：请求参数，即？后面的参数，@Query("键名") 键值的类型 形参
public interface GetCity_Interface {
//用GET方式发送请求
@GET("find")
其中返回类型为Call<*>，*是接收数据的类（即上面定义的City类）
// 如果想直接获得Responsebody中的内容，可以定义网络请求返回值为Call<ResponseBody>
public Call<City> getCall(@Query("mode") String mode,
@Query("location") String location,
@Query("key") String key);
}
Step 4: Create a Retrofit instance
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://search.heweather.net/") //设置（部分）Url
.addConverterFactory(GsonConverterFactory.create()) //设置解析器，这里用Gson解析器
.build();
//可拓展 addCallAdapterFactory(RxJavaCallAdapterFactory.create()) // 支持RxJava平台
Step 5: Create a network request interface instance and configure network request parameters
//创建 网络请求接口实例，create（刚创建的网络接口）
GetCity_Interface getCity_interface = retrofit.create(GetCity_Interface.class);
//配置网络请求参数，调用接口定义的getCall()方法
Call<City> call = getCity_interface.getCall(mode[0], cityName, "5126356**可自行去和风官网申请key**7286");
Step 6: Send a network request (asynchronous/synchronous), which encapsulates the operations of data conversion and thread switching
//实例使用enqueue异步请求
call.enqueue(new Callback<City>() {
@Override
public void onResponse(Call<City> call, Response<City> response) {
//请求成功做相应操作
cities = response.body().getHeWeather6().get(0).getBasic();
//此处结合了先前自定义的ListView对返回的数据用列表显示出来
//文章：https://blog.csdn.net/weixin_44565784/article/details/100023739
CityAdater cityAdater = new CityAdater(SearchCity.this, R.layout.city_list_item, cities);
cityListV.setAdapter(cityAdater);
}
@Override
public void onFailure(Call<City> call, Throwable t) {
//请求失败
t.printStackTrace();
}
});
// 发送网络请求（同步）
// Response<Reception> response = call.execute();
// 对返回数据进行处理
// response.body().show();
Step 7: Process the data returned by the server
//即步骤六的 请求成功做相应操作
cities = response.body().getHeWeather6().get(0).getBasic();
//此处结合了先前自定义的ListView对返回的数据用列表显示出来
CityAdater cityAdater = new CityAdater(SearchCity.this, R.layout.city_list_item, cities);
cityListV.setAdapter(cityAdater);
Extended information
- Carson_Ho blogger - very detailed Retrofit 2.0 tutorial - click directly: https://blog.csdn.net/carson_ho/article/details/73732076
- Carson_Ho blogger- Android: Take you in-depth analysis of Retrofit 2.0 source code- click direct: https://blog.csdn.net/carson_ho/article/details/73732115