How can I parse this json log output into a list of my bean?

Question

I'm working with some software which spits out to the following logfile:

{"message":"logger controller initialised","@timestamp":"2018-09-15T09:33:25.709+01:00","logger_name":"com.hidden.controller.LoggerController","thread_name":"JavaFX Application Thread","level":"DEBUG"}
{"message":"parsing history log data to display","@timestamp":"2018-09-15T09:33:25.877+01:00","logger_name":"com.hidden.controller.LoggerController","thread_name":"JavaFX Application Thread","level":"DEBUG"}

When I'm trying to parse this json file using Gson to a LogRowModel[] it is spitting out various errors around the format of the json, for example:

Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $

I am writing my file using logback/logstash json encoder using the following setup:

<configuration>
    <timestamp key="time" datePattern="yyyy-MM-dd'_'HH-mm-ss.SSS"/>
    <appender name="RootSiftAppender" class="ch.qos.logback.classic.sift.SiftingAppender">
        <discriminator>
            <Key>test</Key>
            <DefaultValue>logfile</DefaultValue>
        </discriminator>
        <sift>
            <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
                <File>src\\main\\resources\\${test}.json</File>
                <encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
                    <providers>
                        <message/>
                        <timestamp/>
                        <loggerName/>
                        <threadName/>
                        <logLevel/>
                    </providers>
                </encoder>
                <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
                    <FileNamePattern>${test_name}.%i.json</FileNamePattern>
                    <MinIndex>1</MinIndex>
                    <MaxIndex>100</MaxIndex>
                </rollingPolicy>
                <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
                    <MaxFileSize>50MB</MaxFileSize>
                </triggeringPolicy>
            </appender>
        </sift>
    </appender>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%n %d{HH:mm:ss} %thread %level %logger{0} %msg</pattern>
        </encoder>
    </appender>

    <root level="RootSiftAppender">
        <appender-ref ref="RootSiftAppender"/>
    </root>
    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
    </root>
</configuration>

How can I parse my json file into an array of this:

@Data
@Slf4j
public class LogRowModel {

    @JsonProperty("@timestamp") private final String timestamp;
    @JsonProperty("message") private final String message;
    @JsonProperty("logger_name") private final String logger;
    @JsonProperty("level") private final String level;
    @JsonProperty("thread_name") private final String thread;
}

Here is my current code which is throwing the error (I assume the fault lies with the json format, scratching my head on how to format it better)

Type collectionType = new TypeToken<Collection<LogRowModel>>(){}.getType();
      Collection<LogRowModel> enums = new Gson().fromJson(new FileReader(new File("src/main/resources/logfile.json")), collectionType);

or how can I make my logger output in a much better json array format?

Thanks.

Answer 1

example code of how I achieved what I needed using Gson's JsonStreamParser to process each root node object in turn.

private void buildHistoryData() {
  if (isLogFileEmpty()) return;
  history.clear();

  Gson gson = new GsonBuilder().create();
  try {
    JsonStreamParser parser = new JsonStreamParser(new FileReader(LOG_FILE));
    while (parser.hasNext()) {
      final LogRowModel currentRow = gson.fromJson(parser.next(), LogRowModel.class);
      if (currentFilter == LogFilter.ALL) history.add(currentRow);
      else if (currentRow.getLevel().equalsIgnoreCase(currentFilter.getLevel()))
        history.add(currentRow);
    }
  } catch (Exception ex) {
    ex.printStackTrace();
  }
}