【Android】設計模式與應用 -「建造者模式」封裝網絡請求

Android設計模式詳細介紹參閱
Android的設計模式-建造者模式

首先，網絡結構封裝的目錄結構爲

建造者模式分爲四種角色：
Product（產品類）
RestService.java

package com.zjn.quickstart.latte_core.net;

import java.util.Map;

import okhttp3.MultipartBody;
import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.http.DELETE;
import retrofit2.http.FieldMap;
import retrofit2.http.FormUrlEncoded;
import retrofit2.http.GET;
import retrofit2.http.Multipart;
import retrofit2.http.POST;
import retrofit2.http.PUT;
import retrofit2.http.Part;
import retrofit2.http.QueryMap;
import retrofit2.http.Streaming;
import retrofit2.http.Url;


public interface RestService {

    @GET
    Call<String> get(@Url String url, @QueryMap Map<String,Object> params);

    @FormUrlEncoded
    @POST
    Call<String> post(@Url String url, @FieldMap Map<String,Object> params);

    @FormUrlEncoded
    @PUT
    Call<String> put(@Url String url, @FieldMap Map<String,Object> params);

    @DELETE
    Call<String> delete(@Url String url, @QueryMap Map<String,Object> params);

    @Streaming
    @GET
    Call<ResponseBody> download(@Url String url, @QueryMap Map<String,Object> params);

    @Multipart
    @POST
    Call<String> upload(@Url String url, @Part MultipartBody.Part file);

}

Builder（抽象建造者）
RestClientBuilder.java

package com.zjn.quickstart.latte_core.net;

import com.zjn.quickstart.latte_core.net.callback.IError;
import com.zjn.quickstart.latte_core.net.callback.IFailure;
import com.zjn.quickstart.latte_core.net.callback.IRequest;
import com.zjn.quickstart.latte_core.net.callback.ISuccess;

import java.util.Map;
import java.util.WeakHashMap;

import okhttp3.MediaType;
import okhttp3.RequestBody;

public class RestClientBuilder {
    private String mUrl;
    private static final Map<String, Object> PARAMS = RestCreator.getParams();
    private IRequest mIRequest;
    private ISuccess mISuccess;
    private IFailure mIFailure;
    private IError mIError;
    private RequestBody mBody;

    RestClientBuilder() {

    }

    public final RestClientBuilder url(String url){
        this.mUrl = url;
        return this;
    }

    public final RestClientBuilder params(Map<String,Object> params){
        PARAMS.putAll(params);
        return this;
    }

    public final RestClientBuilder params(String key,Object value){
        PARAMS.put(key,value);
        return this;
    }

    public final RestClientBuilder raw(String raw){
        this.mBody = RequestBody.create(MediaType.parse("application/json;charset=UTF-8"),raw);
        return this;
    }

    public final RestClientBuilder onRequest(IRequest iRequest){
        this.mIRequest = iRequest;
        return this;
    }
    public final RestClientBuilder success(ISuccess iSuccess){
        this.mISuccess = iSuccess;
        return this;
    }

    public final RestClientBuilder failure(IFailure iFailure){
        this.mIFailure = iFailure;
        return this;
    }

    public final RestClientBuilder error(IError iError){
        this.mIError = iError;
        return this;
    }

    public final RestClient build() {
        return new RestClient(mUrl, PARAMS, mIRequest, mISuccess, mIFailure, mIError, mBody);
    }
}

ConcreteBuilder（具體建造者）
RestClient.java

package com.zjn.quickstart.latte_core.net;


import com.zjn.quickstart.latte_core.net.callback.IError;
import com.zjn.quickstart.latte_core.net.callback.IFailure;
import com.zjn.quickstart.latte_core.net.callback.IRequest;
import com.zjn.quickstart.latte_core.net.callback.ISuccess;
import com.zjn.quickstart.latte_core.net.callback.RequestCallbacks;

import java.util.Map;
import java.util.WeakHashMap;

import okhttp3.RequestBody;
import retrofit2.Call;
import retrofit2.Callback;

public class RestClient {

    private final String URL;
    private static final WeakHashMap<String, Object> PARAMS = RestCreator.getParams();
    private final IRequest REQUEST;
    private final ISuccess SUCCESS;
    private final IFailure FAILURE;
    private final IError ERROR;
    private final RequestBody BODY;


    public RestClient(String url, Map<String, Object> params, IRequest request, ISuccess success, IFailure failure, IError error, RequestBody body) {
        URL = url;
        PARAMS.putAll(PARAMS);
        REQUEST = request;
        SUCCESS = success;
        FAILURE = failure;
        ERROR = error;
        BODY = body;
    }
    //測試方法
    public static RestClientBuilder builder(){
        return new RestClientBuilder();
    }

    private void request(HttpMethod method){
        final RestService service = RestCreator.getRestService();
        Call<String> call = null;

        if(REQUEST != null){
            REQUEST.onRequestStart();
        }

        switch (method){
            case GET:
                call = service.get(URL,PARAMS);
                break;
            case POST:
                call = service.post(URL,PARAMS);
                break;
            case PUT:
                call = service.put(URL,PARAMS);
                break;
            case DELETE:
                call = service.delete(URL,PARAMS);
                break;
            default:
                break;
        }
        if(call!=null){
            call.enqueue(getRequestCallback());
        }
    }

    private Callback<String> getRequestCallback(){
        return new RequestCallbacks(
                REQUEST,
                SUCCESS,
                FAILURE,
                ERROR
        );
    }

    public final void get(){
        request(HttpMethod.GET);
    }

    public final void post(){
        request(HttpMethod.POST);
    }

    public final void put(){
        request(HttpMethod.PUT);
    }

    public final void delete(){
        request(HttpMethod.DELETE);
    }
}

Director（指揮者類）
RestCreator.java

package com.zjn.quickstart.latte_core.net;

import com.zjn.quickstart.latte_core.app.ConfigType;
import com.zjn.quickstart.latte_core.app.Latte;

import java.util.WeakHashMap;
import java.util.concurrent.TimeUnit;

import okhttp3.OkHttpClient;
import retrofit2.Retrofit;
import retrofit2.converter.scalars.ScalarsConverterFactory;;


//java併發編程推薦的單例模式-holder
public class RestCreator {

    private static final class ParamsHolder{
        public static final WeakHashMap<String,Object> PARAMS = new WeakHashMap<>();
    }

    public static WeakHashMap<String,Object> getParams(){
        return ParamsHolder.PARAMS;
    }

    public static RestService getRestService() {
        return RestServiceHolder.REST_SERVICE;
    }
    private static final class RetrofitHolder {
        private static final String BASE_URL = (String) Latte.getConfiguration().get(ConfigType.API_HOST.name());
        //指揮者類：用於組裝
        private static final Retrofit RETROFIT_CLIENT = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .client(OKHttpHolder.OK_HTTP_CLIENT)
                .addConverterFactory(ScalarsConverterFactory.create())
                .build();
    }

    private static final class OKHttpHolder{
        private static final int TIME_OUT = 60;
        private static final OkHttpClient OK_HTTP_CLIENT = new OkHttpClient.Builder()
                .connectTimeout(TIME_OUT, TimeUnit.SECONDS)
                .build();
    }

    private static final class RestServiceHolder{
        private static final RestService REST_SERVICE =
                RetrofitHolder.RETROFIT_CLIENT.create(RestService.class);
    }
}