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android 框架—网络访问Okhttp

news 2025/9/16 7:14:38

下面给出一份最新、可直接拷贝运行 的 Android OkHttp 基本使用速查表，
覆盖“依赖 → 权限 → 常用 GET/POST/上传 → 同步/异步 → 线程模型 → 踩坑”6 大环节，

依赖 & 权限（一次到位）

依赖

implementation 'com.squareup.okhttp3:okhttp:4.12.0'

权限

<!-- AndroidManifest.xml -->
<uses-permission android:name="android.permission.INTERNET"/>
<!-- Android 9+ 允许 http 明文（开发阶段）-->
<application android:usesCleartextTraffic="true" ... >

全局单例工具类（线程安全）

public final class HttpUtil {private static final OkHttpClient CLIENT = new OkHttpClient.Builder().connectTimeout(10, TimeUnit.SECONDS).readTimeout(20, TimeUnit.SECONDS).writeTimeout(20, TimeUnit.SECONDS).addInterceptor(chain -> {                       // 极简日志拦截器Request req = chain.request();Log.d("OKHTTP", req.method() + " " + req.url());return chain.proceed(req);}).build();public static OkHttpClient client() { return CLIENT; }
}

GET 请求（异步）

public static void getAsync(String url, Callback cb) {Request req = new Request.Builder().url(url).get().build();HttpUtil.client().newCall(req).enqueue(cb);
}/* 使用 */
getAsync("https://api.github.com/users/google", new Callback() {@Override public void onFailure(@NonNull Call call, @NonNull IOException e) {Log.e("OKHTTP", "get error", e);}@Override public void onResponse(@NonNull Call call, @NonNull Response resp) throws IOException {if (resp.isSuccessful()) {String body = resp.body().string();Log.i("OKHTTP", "get body=" + body);}}
});

POST 表单（application/x-www-form-urlencoded）

public static void postFormAsync(String url, Map<String,String> params, Callback cb) {FormBody.Builder fb = new FormBody.Builder();for (Map.Entry<String,String> e : params.entrySet()) fb.add(e.getKey(), e.getValue());Request req = new Request.Builder().url(url).post(fb.build()).build();HttpUtil.client().newCall(req).enqueue(cb);
}

POST JSON（application/json）

public static void postJsonAsync(String url, String json, Callback cb) {RequestBody body = RequestBody.create(json, MediaType.parse("application/json; charset=utf-8"));Request req = new Request.Builder().url(url).post(body).build();HttpUtil.client().newCall(req).enqueue(cb);
}

文件上传（Multipart，带进度）

public static void uploadAsync(String url, File file, Callback cb) {RequestBody fileBody = RequestBody.create(file, MediaType.parse("application/octet-stream"));MultipartBody body = new MultipartBody.Builder().setType(MultipartBody.FORM).addFormDataPart("file", file.getName(), fileBody).addFormDataPart("key", "extra")   // 可继续加字段.build();Request req = new Request.Builder().url(url).post(body).build();HttpUtil.client().newCall(req).enqueue(cb);
}

下载文件（带进度，Kotlin 版更简洁，这里给 Java）

public static void downloadAsync(String url, File saveFile, ProgressListener listener, Callback cb) {Request req = new Request.Builder().url(url).build();OkHttpClient downClient = HttpUtil.client().newBuilder().addNetworkInterceptor(chain -> {Response original = chain.proceed(chain.request());return original.newBuilder().body(new ProgressResponseBody(original.body(), listener)).build();}).build();downClient.newCall(req).enqueue(cb);
}/* 进度回调 */
public interface ProgressListener {void update(long bytesRead, long contentLength, boolean done);
}/* 包装 ResponseBody 计算进度 */
private static class ProgressResponseBody extends ResponseBody {private final ResponseBody delegate;private final ProgressListener listener;ProgressResponseBody(ResponseBody d, ProgressListener l) { delegate = d; listener = l; }@Override public long contentLength() { return delegate.contentLength(); }@Override public MediaType contentType() { return delegate.contentType(); }@Override public BufferedSource source() {return Okio.buffer(new ForwardingSource(delegate.source()) {long total = 0L;@Override public long read(Buffer sink, long byteCount) throws IOException {long bytes = super.read(sink, byteCount);total += (bytes != -1 ? bytes : 0);listener.update(total, contentLength(), bytes == -1);return bytes;}});}
}

同步调用（不推荐主线程，仅给单元测试）

public static String getSync(String url) throws IOException {Request req = new Request.Builder().url(url).get().build();try (Response resp = HttpUtil.client().newCall(req).execute()) {if (!resp.isSuccessful()) throw new IOException("code=" + resp.code());return resp.body().string();}
}

注意事项（面试常问）

所有 onResponse 回调不在主线程，若更新 UI 记得 runOnUiThread() / Handler / LiveData.postValue()。
ResponseBody.string() 只能读一次，再读需要 cache() 或自己缓存。
Android 9+ 默认禁止 HTTP 明文，需在 AndroidManifest.xml 加
android:usesCleartextTraffic="true" 或配置 networkSecurityConfig。
上传/下载大文件用 @Streaming + MultipartBody 边读边写，防止 OOM。