URL请求返回byte

// 打开和URL之间的连接
URLConnection connection = new URL(url).openConnection();
// 设置通用的请求属性
connection.setRequestProperty(“accept”, “/“);
connection.setRequestProperty(“connection”, “Keep-Alive”);
connection.setRequestProperty(“user-agent”, “Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;91TouBaV1)”);
//获取长度the content length of the resource that this connection’s URL references,
// -1 if the content length is not known, or if the content length is greater than Integer.MAX_VALUE.
int bLen = connection.getContentLength();
// 建立实际的连接
InputStream raw = connection.getInputStream();
BufferedInputStream in = new BufferedInputStream(raw);
byte[] buffer = new byte[bLen];
OutputStream out = response.getOutputStream();
while ((tLen = in.read(buffer,0,bLen)) > 0) {
out.write(buffer,0,bLen);
}
in.close();
raw.close();

### 使用 ByteBuddy 获取请求返回的信息 为了实现通过 ByteBuddy 动态代理来获取 HTTP 请求的响应信息,在 Java 中可以利用 `HttpURLConnection` 类发送 HTTP 请求并拦截其方法调用来捕获响应数据[^1]。 下面是一个简单的例子,展示如何使用 ByteBuddy 创建动态代理类,并从中提取 HTTP 响应的内容: ```java import net.bytebuddy.ByteBuddy; import net.bytebuddy.agent.ByteBuddyAgent; import net.bytebuddy.dynamic.loading.ClassLoadingStrategy; import net.bytebuddy.implementation.MethodDelegation; import net.bytebuddy.matcher.ElementMatchers; import java.io.BufferedReader; import java.io.InputStreamReader; import java.lang.instrument.Instrumentation; import java.net.HttpURLConnection; import java.net.URL; public class HttpResponseInterceptor { static { Instrumentation instrumentation = ByteBuddyAgent.install(); new ByteBuddy() .rebase(HttpURLConnection.class) .method(ElementMatchers.named("getInputStream")) .intercept(MethodDelegation.to(InputStreamInterceptor.class)) .make() .load(ClassLoader.getSystemClassLoader(), ClassLoadingStrategy.Default.INJECTION); } public static void main(String[] args) throws Exception { URL url = new URL("http://example.com"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); int responseCode = connection.getResponseCode(); // This should trigger our interceptor when getInputStream() is called. System.out.println("Response Code : " + responseCode); try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) { String inputLine; StringBuilder content = new StringBuilder(); while ((inputLine = in.readLine()) != null) { content.append(inputLine); } System.out.println(content.toString()); } finally { connection.disconnect(); } } public static class InputStreamInterceptor { @net.bytebuddy.asm.Advice.OnMethodEnter public static Object onEnter(@net.bytebuddy.asm.Advice.This Object thiz, @net.bytebuddy.asm.Advice.AllArguments Object... allArguments) { System.out.println("Intercepted call to getInputStream()"); return null; // Return value not used here but required by signature. } @net.bytebuddy.asm.Advice.OnMethodExit(onThrowable = Throwable.class) public static void onExit(@net.bytebuddy.asm.Advice.Thrown(readonly = true) ? extends Throwable throwable) { if (throwable != null) { System.err.println("Error occurred during interception: " + throwable.getMessage()); } } } } ``` 上述代码展示了如何创建一个自定义工具类 `HttpResponseInterceptor` 来拦截 `HttpURLConnection` 的 `getInputStream()` 方法。当此方法被调用时,会触发预设的日志记录逻辑,从而允许开发者查看每次访问 Web API 后接收到的数据流。 需要注意的是,这段程序依赖于 JVM 附带的字节码操作库——Byte Buddy 和它的 Agent 组件以便能够在运行时修改目标类的行为。此外,对于更复杂的场景可能还需要考虑线程安全性和性能优化等问题[^4]。
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