我有一个用Java编写的Lambda函数,我想从NodeJS调用它。这可能吗?我收到以下错误:
An error occurred during JSON parsing: java.lang.RuntimeException
java.lang.RuntimeException: An error occurred during JSON parsing
Caused by: java.io.UncheckedIOException: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token
at [Source: lambdainternal.util.NativeMemoryAsInputStream@5dc0ff7d; line: 1, column: 1]
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token
at [Source: lambdainternal.util.NativeMemoryAsInputStream@5dc0ff7d; line: 1, column: 1]
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148)
at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:857)
at com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:62)
at com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:11)
at com.fasterxml.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:1511)
at com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:1102)
这是我的Lambda的代码:
public String handleRequest(String input, Context context) {
context.getLogger().log("input: " + input + "\n");
JSONObject obj = new JSONObject(input);
String dest_key = obj.getString("key");
context.getLogger().log("key: " + dest_key + "\n");
...
}
这是我的JavaScript调用上面的Lambda:
const AWS = require('aws-sdk');
const payload = "{\"key\": \"slide.pptx\"}"
AWS.config.loadFromPath('./config.json');
const lambda = new AWS.Lambda({ region: "ap-south-1" });
const params = {
FunctionName : 'slide-builder',
InvocationType : 'RequestResponse',
Payload: payload // I get the same error even without a payload
};
lambda.invoke(params, function(err, data) {
if (err) console.log(err, err.stack);
else console.log(JSON.stringify(data));
});
您有两个选项可以比您拥有的更好。尝试获取String对我来说从未起作用,因为Java Lambda会在您获取之前尝试解释JSON有效内容。
一种选择是消除Lambda尝试对输入对象进行任何解释。就像是:
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
public void handleRequest(InputStream inputStream,
OutputStream outputStream,
Context context) throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
JsonNode jsonNode = objectMapper.readTree(inputStream);
String key= jsonNode.get("key").asText();
// key will now be "slide.pptx"
// create object to return...
MyObject myObject = new MyObject();
// create JSON string
String jsonReturn = objectMapper.writeValueAsString(myObject);
// "return" the string
outputStream.write(jsonReturn .getBytes(Charset.forName("UTF-8")));
}
当您尝试将传入数据转换为所需对象时,您所做的就是避免Java Lambda“有用”。当你有一个完整的对象但是没有做你想做的事情时,这种方法很有效。
另一种选择是创建一个镜像Node对象的对象:
public class KeyObject {
private String key;
public String getKey() {
return key;
}
}
然后让你的处理函数为:
public String handleRequest(KeyObject key, Context context) {
String fileName = key.getKey();
// return as you're doing now.
}
我相信其中任何一个都会做你想要的。
public class LambdaFunctionHandler implements RequestHandler<Map<String,Object>, String> {
public String handleRequest(Map<String,Object> input, Context context) {
context.getLogger().log(input.get("key"));
...
}
}
我对stdunbar的解决方案没什么好运,但这对我有用。