AsyncHttpClient知识集锦
简介
本文所指的AsyncHttpClient是指基于Netty的一个开源项目，该项目基于Java8编写，用于简化HTTP客户端的开发。该项目还支持WebSocket协议。
要使用该AsyncHttpClient，引入以下Maven依赖：
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<dependency> <groupId>org.asynchttpclient</groupId> <artifactId>async-http-client</artifactId> <version>LATEST_VERSION</version> </dependency> |
代码示例
配置客户端
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AsyncHttpClientConfig cf = new DefaultAsyncHttpClientConfig .Builder() // 设置代理服务器 .setProxyServer(new ProxyServer.Builder("127.0.0.1", 8087)) .build(); // 为客户端提供配置项 AsyncHttpClient http = new DefaultAsyncHttpClient(cf); |
异步GET请求
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ListenableFuture<Response> future = http.prepareGet( "http://ip:port/path" ).execute( new AsyncCompletionHandler<Response>() { @Override public Response onCompleted( Response response ) throws Exception { String resp = response.getResponseBody(); return response; } @Override public void onThrowable( Throwable t ) { // Something wrong happened. } } ); |
ListenableFuture是java.util.concurrent.Future的子类型，你可以使用Java8并发框架提供的任何特性，例如：
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future.get(); // 阻塞等待处理完毕 // 转换为CompletableFuture CompletableFuture<Response> promise = future.toCompletableFuture(); promise.exceptionally(t -> { /* 当错误发生时 */ } ) .thenApply(resp -> { /* 处理请求 */ return resp; }); |
查询参数
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http.preparePost( "http://ip:port/path" ) // 添加请求参数 .addQueryParam( "name", alex ) .addQueryParam( "feature", "0" ) .execute() |
上传文件
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http.preparePost( "http://ip:port/path" ) // 上传多个文件 .addBodyPart( new FilePart( "imageDatas", new ClassPathResource( "alex1.jpg" ).getFile() ) ) .addBodyPart( new FilePart( "imageDatas", new ClassPathResource( "alex2.jpg" ).getFile() ) ) .execute() |
发送JSON请求
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http.preparePost( "http://192.168.0.89:9090/pems/stpush" ) .addHeader( "Content-Type", "application/json; charset=utf-8" ) .setBody( json.getBytes( "utf-8" ) ) .execute().get(); |
响应生命周期控制
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ByteArrayOutputStream bytes = new ByteArrayOutputStream(); String resp = http.prepareGet( "http://www.example.com/" ).execute( new AsyncHandler<String>() { public void onThrowable( Throwable t ) { } public State onBodyPartReceived( HttpResponseBodyPart bodyPart ) throws Exception { // 接收到一个上传文件后 bytes.write( bodyPart.getBodyPartBytes() ); return State.CONTINUE; } public State onStatusReceived( HttpResponseStatus responseStatus ) throws Exception { // 仅仅获得响应码 int statusCode = responseStatus.getStatusCode(); return State.ABORT; } public State onHeadersReceived( HttpHeaders headers ) throws Exception { // 仅仅接收响应头 return State.ABORT; } public String onCompleted() throws Exception { // 给出此回调的返回值 return bytes.toString( "UTF-8" ); } } ).get(); |
WebSocket
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WebSocket websocket = http.prepareGet( "http://wsep" ) .execute( new WebSocketUpgradeHandler.Builder().addWebSocketListener( new WebSocketTextListener() { @Override public void onMessage( String message ) { // 接收到消息时的回调 } @Override public void onOpen( WebSocket websocket ) { // WebSocket打开时的回调 websocket.sendTextMessage( "..." ).sendMessage( "..." ); } @Override public void onClose( WebSocket websocket ) { // 关闭时的回调 } @Override public void onError( Throwable t ) { } } ).build() ).get(); |
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