aws-lambda - 调用 lambda 函数处理程序 java
问题描述
我有一个 lambda 函数,它有一个处理程序,该处理程序又具有多个路由器。每个路由器对应一个 API。
我在 java 中创建了一个 lambda 客户端,需要调用这些 API。要调用这些 API,我需要调用处理程序并将有效负载连同它一起传递给客户端。你们能帮我了解调用处理程序和传递有效负载的语法吗?
解决方案
如果我正确理解了您的问题,我首先创建了一个如下所示的 Lambda:
public class SampleHandler implements RequestStreamHandler {
private static final Logger logger = LogManager.getLogger(SampleHandler.class);
public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
logger.info("handlingRequest");
LambdaLogger lambdaLogger = context.getLogger();
ObjectMapper objectMapper = new ObjectMapper();
String inputString = new BufferedReader(new InputStreamReader(inputStream)).lines().collect(Collectors.joining("\n"));
JsonNode jsonNode = objectMapper.readTree(inputString);
String route = jsonNode.get("route").asText();
RouterResult routerResult = new RouterResult();
switch( route ) {
case "requestTypeA":
RequestTypeA requestTypeA = objectMapper.readValue(inputString, RequestTypeA.class);
routerResult.setResult(handleRequestTypeA(requestTypeA));
break;
case "requestTypeB":
RequestTypeB requestTypeB = objectMapper.readValue(inputString, RequestTypeB.class);
routerResult.setResult(handleRequestTypeB(requestTypeB));
break;
default:
logger.error( "don't know how to handle route of type \"" + route + "\n" );
routerResult.setResult("error");
}
outputStream.write(objectMapper.writeValueAsString(routerResult).getBytes(StandardCharsets.UTF_8));
logger.info("done with run, remaining time in ms is " + context.getRemainingTimeInMillis() );
}
private String handleRequestTypeA(RequestTypeA requestTypeA) {
logger.info("handling requestTypeA, requestTypeA.requestA is " + requestTypeA.getRequestA() );
return "handled requestTypeA";
}
private String handleRequestTypeB(RequestTypeB requestTypeB) {
logger.info("handling requestTypeB, requestTypeB.requestB is " + requestTypeB.getRequestB() );
return "handled requestTypeB";
}
}
与RouterRequest.java
:
public class RouterRequest {
protected String route;
public String getRoute() {
return route;
}
}
和RequestTypeA.java
:
public class RequestTypeA extends RouterRequest {
private String requestA;
public RequestTypeA() {
route = "requestTypeA";
}
public String getRequestA() {
return requestA;
}
public void setRequestA(String requestA) {
this.requestA = requestA;
}
}
和RequestTypeB.java
public class RequestTypeB extends RouterRequest {
private String requestB;
public RequestTypeB() {
route = "requestTypeB";
}
public String getRequestB() {
return requestB;
}
public void setRequestB(String requestB) {
this.requestB = requestB;
}
}
还有一个结果类RouterResult.java
:
public class RouterResult {
private String result;
public String getResult() {
return result;
}
public void setResult(String result) {
this.result = result;
}
@Override
public String toString() {
return "RouterResult{" +
"result='" + result + '\'' +
'}';
}
}
然后,要调用此 Lambda,您将需要一个具有lambda:InvokeFunction
权限的角色。要调用的代码如下所示:
public class RouterRunner {
private static final String AWS_ACCESS_KEY_ID = "<access key>";
private static final String AWS_SECRET_ACCESS_KEY = "<access secret>";
public static void main( String[] argv ) throws IOException {
AWSCredentials credentials = new BasicAWSCredentials( AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY );
AWSLambda lambda = AWSLambdaClientBuilder.standard()
.withRegion(Regions.US_WEST_2)
.withCredentials(new AWSStaticCredentialsProvider(credentials)).build();
RequestTypeA requestTypeA = new RequestTypeA();
requestTypeA.setRequestA("set from the runner, request type A");
ObjectMapper objectMapper = new ObjectMapper();
InvokeRequest invokeRequest = new InvokeRequest()
.withFunctionName("lambda-router")
.withPayload(objectMapper.writeValueAsString(requestTypeA));
invokeRequest.setInvocationType(InvocationType.RequestResponse);
InvokeResult invokeResult = lambda.invoke(invokeRequest);
String resultJSON = new String(invokeResult.getPayload().array(), StandardCharsets.UTF_8);
System.out.println( "result from lambda is " + resultJSON );
RouterResult routerResult = objectMapper.readValue(resultJSON, RouterResult.class);
System.out.println( "result.toString is " + routerResult.toString() );
RequestTypeB requestTypeB = new RequestTypeB();
requestTypeB.setRequestB("set from the runner, request type B");
invokeRequest = new InvokeRequest()
.withFunctionName("lambda-router")
.withPayload(objectMapper.writeValueAsString(requestTypeB));
invokeRequest.setInvocationType(InvocationType.RequestResponse);
invokeResult = lambda.invoke(invokeRequest);
resultJSON = new String(invokeResult.getPayload().array(), StandardCharsets.UTF_8);
System.out.println( "result from lambda is " + resultJSON );
routerResult = objectMapper.readValue(resultJSON, RouterResult.class);
System.out.println( "result.toString is " + routerResult.toString() );
}
}
可能需要对错误处理进行一些改进,我相信您可以提高效率。但这就是总体思路。最终在 Lambda 方面,我将其转换InputStream
为字符串,并根据请求类型中的公共字段将该字符串转换为某种对象。在客户端,我将对象转换为 JSON,将它们发送出去,然后将结果从 JSON 字符串转换回结果对象。
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