鸿蒙开发实战系列之三：网络请求(原生+ Retrofit)

linhy
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鸿蒙开发实战系列之一：鸿蒙开发实战系列之一：圆角

鸿蒙开发实战系列之二：鸿蒙开发实战系列之二：事件总线EventBus/RxBus

前言

过了一个漫长的中秋+国庆假期，大家伙的鸿蒙内功修炼的怎么样了？难道像小蒙一样，都在吃吃喝喝中度过么，哎，罪过罪过，对不起那些鸡鸭鱼肉啊，赶紧回来写篇文章收收心，让我们一起看看，在鸿蒙中如何发送网络请求吧。

本文会从Java原生访问入手，进而再使用Retrofit访问网络，可以满足绝大部分开发者对于鸿蒙网络访问方面的代码需求，开始之前需要先做一下基础配置。

鸿蒙系统网络访问基础配置

1、跟Android类似，要访问网络，我们首先要配置网络访问权限，在config.json的"module"节点最后，添加上网络权限代码
"reqPermissions": [
      {
        "reason": "",
        "name": "ohos.permission.INTERNET"
      }
    ]
2、配置网络明文访问白名单
"deviceConfig": {
    "default": {
      "network": {
        "usesCleartext": true,
        "securityConfig": {
          "domainSettings": {
            "cleartextPermitted": true,
            "domains": [
              {
                "subDomains": true,
                "name": "www.baidu.com"
              }
            ]
          }
        }
      }
    }
  }

其中的name即为可以直接http访问的域名，如果全是https链接则可以做该不配置，**切记域名是不带http://的**，**切记域名是不带http://的**，**切记域名是不带http://的**，重要的事说三遍。

Java原生访问网络

由于鸿蒙系统支持Java开发，所以我们可以直接使用Java原生的Api来进行网络访问 该方式使用了java的url.openConnection() Api来获取网络数据

HttpDemo.java

package com.example.demo.classone;

import javax.net.ssl.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.SecureRandom;

public class HttpDemo {
    /**
     *访问url，获取内容
     * @param urlStr
     * @return
     */
    public static String httpGet(String urlStr){
        StringBuilder sb = new StringBuilder();
        try{
            //添加https信任
            SSLContext sslcontext = SSLContext.getInstance("SSL");//第一个参数为协议,第二个参数为提供者(可以缺省)
            TrustManager[] tm = {new HttpX509TrustManager()};
            sslcontext.init(null, tm, new SecureRandom());
            HostnameVerifier ignoreHostnameVerifier = new HostnameVerifier() {
                public boolean verify(String s, SSLSession sslsession) {
                    System.out.println("WARNING: Hostname is not matched for cert.");
                    return true;
                }
            };
            HttpsURLConnection.setDefaultHostnameVerifier(ignoreHostnameVerifier);
            HttpsURLConnection.setDefaultSSLSocketFactory(sslcontext.getSocketFactory());
            URL url = new URL(urlStr);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setReadTimeout(10000);
            connection.setConnectTimeout(10000);
            connection.connect();
            int code = connection.getResponseCode();
            if (code == HttpURLConnection.HTTP_OK) {
                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String temp;
                while ((temp = reader.readLine()) != null) {
                    sb.append(temp);
                }
                reader.close();
            }
            connection.disconnect();
        } catch (Exception e) {
            e.printStackTrace();
            return e.getMessage();
        }
        return sb.toString();
    }
}

HttpX509TrustManager.java

package com.example.demo.classone;
import javax.net.ssl.X509TrustManager;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class HttpX509TrustManager implements 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 null;
    }
}

最后是测试是否能够正确访问的代码，注意网络访问是耗时操作要放线程里面执行

new Thread(new Runnable() {
        @Override
        public void run() {
            String result = HttpDemo.httpGet("http://www.baidu.com");
            HiLog.warn(new HiLogLabel(HiLog.LOG_APP, 0, "===demo==="), "网页返回结果："+result);
        }
    }).start();

采用Retrofit访问网络

在模块的build.gradle里添加Retrofit库的引用，我这边采用的是retrofit2的2.5.0版本做示例

implementation 'com.squareup.retrofit2:retrofit:2.5.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
    implementation 'io.reactivex.rxjava3:rxjava:3.0.4'

新建ApiManager类用来管理获取OkHttpClient，SSLSocketClient用来提供https支持，ApiResponseConverterFactory是Retrofit的转换器，将请求结果转成String输出

ApiManager.java

package com.example.demo.classone;

import com.example.demo.DemoAbilityPackage;
import ohos.app.Environment;
import okhttp3.*;
import retrofit2.Retrofit;

import java.io.File;
import java.util.concurrent.TimeUnit;

/**
 * 提供获取Retrofit对象的方法
 */
public class ApiManager {
    private static final String BUSINESS_BASE_HTTP_URL = "http://www.baidu.com";

    private static Retrofit instance;
    private static OkHttpClient mOkHttpClient;

    private ApiManager(){}

    public static Retrofit get(){
        if (instance == null){
            synchronized (ApiManager.class){
                if (instance == null){
                    setClient();
                    instance = new Retrofit.Builder().baseUrl(BUSINESS_BASE_HTTP_URL).
                            addConverterFactory(ApiResponseConverterFactory.create()).client(mOkHttpClient).build();
                }
            }
        }
        return instance;
    }

    private static void setClient(){
        if (mOkHttpClient != null){
            return;
        }
        Cache cache = new Cache(new File(getRootPath(Environment.DIRECTORY_DOCUMENTS),"HttpCache"),1024*1024*100);
        OkHttpClient.Builder builder = new OkHttpClient.Builder()
//                .followRedirects(false)//关闭重定向
//                .addInterceptor(new AppendUrlParamIntercepter())
                .cache(cache)
                .retryOnConnectionFailure(false)
                .sslSocketFactory(SSLSocketClient.getSSLSocketFactory())
                .hostnameVerifier(SSLSocketClient.getHostnameVerifier())
                .readTimeout(8,TimeUnit.SECONDS)
                .writeTimeout(8,TimeUnit.SECONDS)
                .connectTimeout(8, TimeUnit.SECONDS);
//                .protocols(Collections.singletonList(Protocol.HTTP_1_1));
        mOkHttpClient = builder.build();
        mOkHttpClient.dispatcher().setMaxRequests(100);
    }

    private static String getRootPath(String dirs) {
        String path = DemoAbilityPackage.getInstance().getCacheDir() + "/" + dirs;
        File file = new File(path);
        if (!file.exists()) {
            file.mkdirs();
        }
        return path;
    }
}

SSLSocketClient.java

package com.example.demo.classone;
import javax.net.ssl.*;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;

public class SSLSocketClient {

    //获取这个SSLSocketFactory
    public static SSLSocketFactory getSSLSocketFactory() {
        try {
            SSLContext sslContext = SSLContext.getInstance("SSL");
            sslContext.init(null, getTrustManager(), new SecureRandom());
            return sslContext.getSocketFactory();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    //获取TrustManager
    private static TrustManager[] getTrustManager() {
        TrustManager[] trustAllCerts = new TrustManager[]{
                new X509TrustManager() {
                    @Override
                    public void checkClientTrusted(X509Certificate[] chain, String authType) {
                    }

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

                    @Override
                    public X509Certificate[] getAcceptedIssuers() {
                        return new X509Certificate[]{};
                    }
                }
        };
        return trustAllCerts;
    }


    //获取HostnameVerifier
    public static HostnameVerifier getHostnameVerifier() {
        HostnameVerifier hostnameVerifier = new HostnameVerifier() {
            @Override
            public boolean verify(String s, SSLSession sslSession) {
                return true;
            }
        };
        return hostnameVerifier;
    }
}

ApiResponseConverterFactory.java

package com.example.demo.classone;

import okhttp3.RequestBody;
import okhttp3.ResponseBody;
import retrofit2.Converter;
import retrofit2.Retrofit;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

/**
 * BaseResponse的转换器
 */
public class ApiResponseConverterFactory extends Converter.Factory {

    public static Converter.Factory create(){
        return new ApiResponseConverterFactory();
    }

    @Override
    public Converter<ResponseBody, String> responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) {
        return new StringResponseBodyConverter();
    }

    @Override
    public Converter<?, RequestBody> requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
        return null;
    }

    class StringResponseBodyConverter implements Converter<ResponseBody, String> {
        @Override
        public String convert(ResponseBody value) throws IOException {
            String s = value.string();
            return s;
        }
    }
}

开始使用Retrofit书写业务逻辑

BusinessApiManager.java

package com.example.demo.classone;

/**
 * 服务端访问接口管理
 */
public class BusinessApiManager {

    private static BusinessApiService instance;
    public static BusinessApiService get(){
        if (instance == null){
            synchronized (BusinessApiManager.class){
                if (instance == null){
                    instance = ApiManager.get().create(BusinessApiService.class);
                }
            }
        }
        return instance;
    }
}

BusinessApiService.java

package com.example.demo.classone;

import retrofit2.Call;
import retrofit2.http.*;

/**
 * 服务端访问接口
 */
public interface BusinessApiService {
    /**
     * 获取网页信息
     * @param url
     * @return
     */
    @GET()
    Call<String> getHtmlContent(@Url String url);
}

测试Retrofit是否能够正常使用

BusinessApiManager.get().getHtmlContent("https://www.baidu.com").enqueue(new Callback<String>() {
    @Override
    public void onResponse(Call<String> call, Response<String> response) {
        if (!response.isSuccessful() || response.body() == null){
            onFailure(null,null);
            return;
        }
        String result = response.body();
        HiLog.warn(new HiLogLabel(HiLog.LOG_APP, 0, "===demo==="), "网页返回结果："+result);
    }

    @Override
    public void onFailure(Call<String> call, Throwable throwable) {
        HiLog.warn(new HiLogLabel(HiLog.LOG_APP, 0, "===demo==="), "网页访问异常");
    }
});

总结

鸿蒙是基于Java开发的，所有Java原生api都是可以直接在鸿蒙系统上使用的，另外只要和java相关的库都是可以直接引用的，例如在引用retrofit的时候也带入了RxJava。 更多retrofit的使用方式，可以参考retrofit在android系统中的实现，鸿蒙系统基本兼容。

所有相关代码已上传至github：github.com/maolinnan/H…

这是本系列的第三篇，后面还会为大家带来更多的鸿蒙干货，敬请期待......。

如果文章对您有一点启发的话，希望您能点个赞。

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