鸿蒙开发实战系列之三：网络请求(原生+ Retrofit)
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：https://github.com/maolinnan/HarmonyosClass
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…。
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