android开发模式LiveData+ViewModel+Room+Retrofit

最新推荐文章于 2025-05-26 21:56:14 发布

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最新推荐文章于 2025-05-26 21:56:14 发布 · 6.7k 阅读

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#android

本文介绍了在Android开发中如何结合LiveData、ViewModel、Room和Retrofit构建应用程序。首先，文章讨论了如何引入相关依赖。接着，讲解了网络请求工具Retrofit的使用。然后，详细阐述了ViewModel如何初始化并从数据库获取数据，以及如何通过Adapter展示数据。ViewModel通过Repository获取数据，Repository负责网络请求和缓存操作。文中特别提到了MediatorLiveData在处理多个LiveData事件中的作用，以及AbsDataSource对数据源的封装。最后，文章介绍了Room数据库的配置，包括实体类、DAO接口、数据转换类和数据库管理类的创建。通过这种方式，构建了一个完整的Android应用数据管理框架。

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导依赖

implementation 'com.android.support:cardview-v7:26.1.0'
implementation "android.arch.lifecycle:extensions:1.0.0"
implementation "android.arch.persistence.room:runtime:1.0.0"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"

implementation 'com.squareup.okhttp3:logging-interceptor:3.6.0'
implementation 'com.squareup.retrofit2:retrofit:2.3.0'
implementation 'com.squareup.okhttp3:okhttp:3.8.0'

implementation 'com.squareup.retrofit2:converter-gson:2.1.0'
implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.9.24'
implementation 'com.github.bumptech.glide:glide:3.8.0'

testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

1.网络工具类使用Retrofit进行网络请求

package win.canking.mvvmarch.module_essay.net;

import android.arch.lifecycle.LiveData;
import android.arch.lifecycle.MediatorLiveData;
import android.support.annotation.WorkerThread;

import java.io.IOException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.X509TrustManager;

import okhttp3.OkHttpClient;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Call;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import win.canking.mvvmarch.architecture.IRequestApi;
import win.canking.mvvmarch.module_essay.db.entity.ZhihuItemEntity;
import win.canking.mvvmarch.net.NetConstant;

/**
 * Created by changxing on 2017/12/4.
 */

public class NetEngine {
    private Retrofit mRetrofit;
    private volatile NetEngine mInstance;

    private static class Holder {
        static NetEngine netEngine = new NetEngine();
    }


    private NetEngine() {
        mRetrofit = new Retrofit.Builder()
                .baseUrl(NetConstant.URL_BASE)
                .client(getFreeClient())
                .addConverterFactory(GsonConverterFactory.create())
                .build();
    }

    private OkHttpClient getFreeClient() {
        OkHttpClient.Builder builder = new OkHttpClient.Builder();
        X509TrustManager[] trustManager = new X509TrustManager[]{
                new X509TrustManager() {
                    @Override
                    public void checkClientTrusted(X509Certificate[] chain, String authType) throws
                            CertificateException {
                    }

                    @Override
                    public void checkServerTrusted(X509Certificate[] chain, String authType) throws
                            CertificateException {
                    }

                    @Override
                    public X509Certificate[] getAcceptedIssuers() {
                        return new java.security.cert.X509Certificate[]{};
                    }
                }
        };
        try {
            SSLContext sslContext = SSLContext.getInstance("SSL");
            sslContext.init(null, trustManager, new SecureRandom());
            SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
            if (sslSocketFactory != null)
                builder.sslSocketFactory(sslSocketFactory);
            builder.hostnameVerifier(new HostnameVerifier() {
                @Override
                public boolean verify(String hostname, SSLSession session) {
                    return true;
                }
            });
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        }
        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        logging.setLevel(HttpLoggingInterceptor.Level.BODY);
        builder.addInterceptor(logging);
        builder.connectTimeout(20, TimeUnit.SECONDS);
        builder.writeTimeout(20, TimeUnit.SECONDS).readTimeout(20, TimeUnit.SECONDS);
        builder.retryOnConnectionFailure(true);
        return builder.build();
    }

    public static NetEngine getInstance() {
        return Holder.netEngine;
    }

    @WorkerThread
    public <ResultType> LiveData<IRequestApi<ResultType>> getEssay(@EssayWebService.EssayType String type) throws IOException {
        EssayWebService api = mRetrofit.create(EssayWebService.class);

        Call<ZhihuItemEntity> essayCall = api.getZhihuList("latest");
        MediatorLiveData<IRequestApi<ResultType>> result = new MediatorLiveData<>();
        final Response<ZhihuItemEntity> response = essayCall.execute();

        IRequestApi<ResultType> requestApi = new IRequestApi<ResultType>() {
            @Override
            public ResultType getBody() {
                ZhihuItemEntity entity = response.body();
                return (ResultType) entity;
            }

            @Override
            public String getErrorMsg() {
                return response.message();
            }

            @Override
            public boolean isSuccessful() {
                return response.isSuccessful();
            }
        }