HarmonyOs开发之———使用HTTP访问网络资源
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HarmonyOS 网络开发入门:使用 HTTP 访问网络资源
HarmonyOS 作为新一代智能终端操作系统,提供了丰富的网络 API 支持。本文将详细介绍如何在 HarmonyOS 应用中使用 HTTP 协议访问网络资源,包含完整的开发流程和示例代码。
一、网络权限配置
在使用 HTTP 网络请求前,需要在应用配置文件中声明网络访问权限。打开项目中的config.json文件,添加以下权限声明:
{"module": {"reqPermissions": [{"name": "ohos.permission.INTERNET","reason": "需要访问网络获取数据","usedScene": {"ability": ["com.example.myapplication.MainAbility"],"when": "always"}}]}
}
二、使用 HttpURLConnection 进行 HTTP 请求
HarmonyOS 提供了标准 Java API 兼容的HttpURLConnection类,以下是使用该类进行 GET 和 POST 请求的示例:
import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.eventhandler.EventHandler;
import ohos.eventhandler.EventRunner;
import ohos.eventhandler.InnerEvent;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;public class NetworkAbility extends Ability {private static final int MSG_SUCCESS = 1;private static final int MSG_ERROR = 2;private EventHandler mainHandler;@Overridepublic void onStart(Intent intent) {super.onStart(intent);// 创建主线程的EventHandler用于UI更新mainHandler = new EventHandler(EventRunner.getMainEventRunner()) {@Overrideprotected void processEvent(InnerEvent event) {super.processEvent(event);switch (event.eventId) {case MSG_SUCCESS:String result = (String) event.object;// 处理成功返回的数据break;case MSG_ERROR:String errorMsg = (String) event.object;// 处理错误信息break;}}};// 示例:发起GET请求getRequest("https://api.example.com/data");// 示例:发起POST请求Map<String, String> params = new HashMap<>();params.put("username", "test");params.put("password", "123456");postRequest("https://api.example.com/login", params);}/*** 发起GET请求*/private void getRequest(String urlStr) {new Thread(() -> {HttpURLConnection connection = null;BufferedReader reader = null;try {URL url = new URL(urlStr);connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(5000);connection.setReadTimeout(5000);int responseCode = connection.getResponseCode();if (responseCode == HttpURLConnection.HTTP_OK) {InputStream inputStream = connection.getInputStream();reader = new BufferedReader(new InputStreamReader(inputStream));StringBuilder response = new StringBuilder();String line;while ((line = reader.readLine()) != null) {response.append(line);}// 发送成功消息到主线程mainHandler.sendEvent(InnerEvent.get(MSG_SUCCESS, response.toString()));} else {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "HTTP错误: " + responseCode));}} catch (Exception e) {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "请求异常: " + e.getMessage()));} finally {// 关闭资源if (reader != null) {try {reader.close();} catch (IOException e) {e.printStackTrace();}}if (connection != null) {connection.disconnect();}}}).start();}/*** 发起POST请求*/private void postRequest(String urlStr, Map<String, String> params) {new Thread(() -> {HttpURLConnection connection = null;OutputStream outputStream = null;BufferedReader reader = null;try {URL url = new URL(urlStr);connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("POST");connection.setConnectTimeout(5000);connection.setReadTimeout(5000);connection.setDoOutput(true);connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");// 构建POST参数StringBuilder postData = new StringBuilder();for (Map.Entry<String, String> param : params.entrySet()) {if (postData.length() != 0) postData.append('&');postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));postData.append('=');postData.append(URLEncoder.encode(param.getValue(), "UTF-8"));}byte[] postDataBytes = postData.toString().getBytes("UTF-8");// 写入POST数据outputStream = connection.getOutputStream();outputStream.write(postDataBytes);int responseCode = connection.getResponseCode();if (responseCode == HttpURLConnection.HTTP_OK) {InputStream inputStream = connection.getInputStream();reader = new BufferedReader(new InputStreamReader(inputStream));StringBuilder response = new StringBuilder();String line;while ((line = reader.readLine()) != null) {response.append(line);}mainHandler.sendEvent(InnerEvent.get(MSG_SUCCESS, response.toString()));} else {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "HTTP错误: " + responseCode));}} catch (Exception e) {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "请求异常: " + e.getMessage()));} finally {// 关闭资源if (outputStream != null) {try {outputStream.close();} catch (IOException e) {e.printStackTrace();}}if (reader != null) {try {reader.close();} catch (IOException e) {e.printStackTrace();}}if (connection != null) {connection.disconnect();}}}).start();}
}
三、网络请求注意事项
- 线程管理:HarmonyOS 不允许在主线程中进行网络操作,必须在子线程中执行网络请求。示例中使用了 Thread+EventHandler 的方式,实际开发中也可以使用 AsyncTask 或线程池。
- 异常处理:网络请求可能会因为各种原因失败,如网络中断、服务器错误等,必须进行完善的异常处理。
- 数据解析:接收到的网络数据通常需要解析,常见的格式有 JSON、XML 等。可以使用 GSON、FastJSON 等库进行 JSON 数据解析。
- HTTPS 支持:如果需要访问 HTTPS 资源,还需要处理 SSL 证书验证等问题。
四、使用 OkHttp 库简化网络请求
除了标准的 HttpURLConnection,也可以使用第三方库 OkHttp 来简化网络请求。首先需要在build.gradle中添加依赖:
dependencies {implementation 'com.squareup.okhttp3:okhttp:4.9.1'}
以下是使用 OkHttp 的示例代码:
// 在Ability中调用
public void fetchData() {OkHttpUtil.get("https://api.example.com/data", new Callback() {@Overridepublic void onFailure(Call call, IOException e) {// 处理失败mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "请求失败: " + e.getMessage()));}@Overridepublic void onResponse(Call call, Response response) throws IOException {if (response.isSuccessful()) {String responseData = response.body().string();// 发送成功消息到主线程mainHandler.sendEvent(InnerEvent.get(MSG_SUCCESS, responseData));} else {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "响应错误: " + response.code()));}}});
}
使用 OkHttp 发起请求的示例:
// 在Ability中调用
public void fetchData() {OkHttpUtil.get("https://api.example.com/data", new Callback() {@Overridepublic void onFailure(Call call, IOException e) {// 处理失败mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "请求失败: " + e.getMessage()));}@Overridepublic void onResponse(Call call, Response response) throws IOException {if (response.isSuccessful()) {String responseData = response.body().string();// 发送成功消息到主线程mainHandler.sendEvent(InnerEvent.get(MSG_SUCCESS, responseData));} else {mainHandler.sendEvent(InnerEvent.get(MSG_ERROR, "响应错误: " + response.code()));}}});
}
五、总结
本文介绍了 HarmonyOS 中使用 HTTP 协议访问网络资源的基本方法,包括权限配置、使用 HttpURLConnection 和 OkHttp 进行网络请求的实现。在实际开发中,建议根据项目需求选择合适的网络请求方式,并注意网络请求的线程管理和异常处理,以提供稳定、流畅的用户体验。
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请注意,HarmonyOS的UI框架可能会随着版本的更新而有所变化,因此为了获取最新和最准确的属性说明和用法,建议查阅HarmonyOS的官方文档。
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