安卓和http服务器通信协议

HTTP协议基础

HTTP（HyperText Transfer Protocol）是安卓与服务器通信的核心协议，基于TCP/IP协议栈，采用请求-响应模式,常见方法包括：

• GET：获取资源
• POST：提交数据
• PUT/DELETE：修改/删除资源
• HEAD：获取头信息

安卓中HTTP通信实现

原生HttpURLConnection

// 创建连接
URL url = new URL("https://api.example.com/data");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// 设置超时
conn.setConnectTimeout(5000); // 连接超时5秒
conn.setReadTimeout(10000);   // 读取超时10秒
// 处理响应
int responseCode = conn.getResponseCode();
if (responseCode == 200) {
    InputStream is = conn.getInputStream();
    // 解析输入流...
}

第三方库OkHttp

OkHttpClient client = new OkHttpClient.Builder()
    .connectTimeout(5, TimeUnit.SECONDS)
    .build();
Request request = new Request.Builder()
    .url("https://api.example.com/data")
    .build();
client.newCall(request).enqueue(new Callback() {
    @Override
    public void onFailure(Call call, IOException e) {
        // 处理失败
    }
    @Override
    public void onResponse(Call call, Response response) throws IOException {
        if (response.isSuccessful()) {
            String json = response.body().string();
            // 解析JSON...
        }
    }
});

异步处理方案对比

安全通信实践

1. 强制HTTPS：在network_security_config.xml配置证书锁定

   

   <domain-config cleartextTrafficPermitted="false">
       <domain includeSubdomains="true">api.example.com</domain>
   </domain-config>

2. 证书验证：自定义信任管理器（高风险操作需谨慎）

   

   // 仅用于自签名证书测试环境
   CertificateFactory cf = CertificateFactory.getInstance("X.509");
   InputStream cert = context.getAssets().open("server.crt");
   X509Certificate ca = (X509Certificate) cf.generateCertificate(cert);
   KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
   keyStore.load(null, null);
   keyStore.setCertificateEntry("ca", ca);
   TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
   tmf.init(keyStore);
   SSLContext sslContext = SSLContext.getInstance("TLS");
   sslContext.init(null, tmf.getTrustManagers(), new SecureRandom());

异常处理策略

性能优化技巧

1. 连接复用：OkHttp默认开启连接池，复用TCP连接
2. 压缩优化：启用GZIP压缩（需服务器支持）

   okhttp3.Request request = new okhttp3.Request.Builder()
       .header("Accept-Encoding", "gzip")
       .build();

3. 缓存策略：使用Cache-Control头或本地缓存机制

   // 内存缓存示例（OkHttp）
   int cacheSize = 10  1024  1024; // 10MB
   Cache cache = new Cache(context.getCacheDir(), cacheSize);
   OkHttpClient client = new OkHttpClient.Builder()
       .cache(cache)
       .build();

相关问题与解答

Q1：如何在Retrofit中配置日志拦截器？
A1：添加HttpLoggingInterceptor并设置Level：

HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY); // 打印请求/响应体
Retrofit retrofit = new Retrofit.Builder()
    .client(new OkHttpClient.Builder()
        .addInterceptor(logging)
        .build())
    .baseUrl("https://api.example.com/")
    .addConverterFactory(GsonConverterFactory.create())
    .build();

Q2：处理混合HTTP/HTTPS请求时出现CLEARTEXT_NOT_PERMITTED错误怎么办？
A2：两种解决方案：

1. 网络配置调整：在AndroidManifest.xml中声明明文流量权限

   <application android:usesCleartextTraffic="true">
       ...
   </application>

2. 安全配置豁免：在network_security_config.xml中临时允许特定域名明文访问

   <domain-config cleartextTrafficPermitted="true">
       <domain includeSubdomains="true">legacy-api.example.com</domain>
   </domain-config>