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Added StopWatch class and a generic type adapter that can exclude fields.

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Konrad Neitzel 2025-04-09 10:19:05 +02:00
parent 547c582dbf
commit 78f78adea7
2 changed files with 264 additions and 0 deletions
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128
core/src/main/java/de/neitzel/core/util/StopWatch.java Normal file
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package de.neitzel.core.util;
import java.time.Duration;
import java.time.Instant;
import java.util.Locale;
/**
* A utility class for measuring elapsed time. The StopWatch can be started, stopped, and queried for the elapsed time in various formats.
*/
public class StopWatch {
/**
* Represents the starting time of the stopwatch. This variable is set when the stopwatch is started and is used to calculate the elapsed
* duration between the start and the stop or the current time.
*/
private Instant startTime;
/**
* Represents the stopping time of the stopwatch. This variable is set when the stopwatch is stopped and is used to calculate the elapsed
* duration between the start and stop times.
*/
private Instant stopTime;
/**
* Starts the stopwatch by recording the current time as the starting time. If the stopwatch was previously stopped or not yet started,
* this method resets the starting time to the current time and clears the stopping time. This method is typically called before measuring
* elapsed time.
*/
public void start() {
this.startTime = Instant.now();
this.stopTime = null;
}
/**
* Stops the stopwatch by recording the current time as the stopping time.
* <p>
* This method should only be called after the stopwatch has been started using the {@code start()} method. If the stopwatch has not been
* started, an {@code IllegalStateException} will be thrown. Once this method is called, the elapsed time can be calculated as the
* duration between the starting and stopping times.
*
* @throws IllegalStateException if the stopwatch has not been started prior to calling this method.
*/
public void stop() {
if (startTime == null) {
throw new IllegalStateException("StopWatch must be started before stopping.");
}
this.stopTime = Instant.now();
}
/**
* Calculates the amount of time elapsed between the stopwatch's starting time and either its stopping time or the current time if the
* stopwatch is still running.
*
* @return the duration representing the elapsed time between the start and end points of the stopwatch.
* @throws IllegalStateException if the stopwatch has not been started before calling this method.
*/
public Duration getUsedTime() {
if (startTime == null) {
throw new IllegalStateException("StopWatch has not been started.");
}
Instant end = (stopTime != null) ? stopTime : Instant.now();
return Duration.between(startTime, end);
}
/**
* Formats the duration of elapsed time measured by the stopwatch into a human-readable string. The formatted output may include days,
* hours, minutes, seconds, and milliseconds, depending on the parameters. The method retrieves the elapsed time via the
* {@code getUsedTime} method and formats it based on the specified flags.
*
* @param includeMillis whether to include milliseconds in the formatted output
* @param includeSeconds whether to include seconds in the formatted output
* @param includeMinutes whether to include minutes in the formatted output
* @param includeHours whether to include hours in the formatted output
* @param includeDays whether to include days in the formatted output
* @return a formatted string representing the elapsed time, including the components specified by the parameters
*/
public String getUsedTimeFormatted(boolean includeMillis, boolean includeSeconds, boolean includeMinutes, boolean includeHours,
boolean includeDays) {
Duration duration = getUsedTime();
long millis = duration.toMillis();
long days = millis / (24 * 60 * 60 * 1000);
millis %= (24 * 60 * 60 * 1000);
long hours = millis / (60 * 60 * 1000);
millis %= (60 * 60 * 1000);
long minutes = millis / (60 * 1000);
millis %= (60 * 1000);
long seconds = millis / 1000;
millis %= 1000;
StringBuilder sb = new StringBuilder();
if (includeDays && days > 0) {
sb.append(days).append("d ");
}
if (includeHours && (hours > 0 || sb.length() > 0)) {
sb.append(hours).append("h ");
}
if (includeMinutes && (minutes > 0 || sb.length() > 0)) {
sb.append(minutes).append("m ");
}
if (includeSeconds && (seconds > 0 || sb.length() > 0)) {
sb.append(seconds);
}
if (includeMillis) {
if (includeSeconds) {
sb.append(String.format(Locale.US, ".%03d", millis));
} else {
sb.append(millis).append("ms");
}
}
String result = sb.toString().trim();
return result.isEmpty() ? "0ms" : result;
}
/**
* Provides a compact and human-readable formatted string representing the elapsed time measured by the stopwatch. The method formats the
* duration using a combination of days, hours, minutes, seconds, and milliseconds. This compact format removes additional verbosity in
* favor of a shorter, more concise representation.
*
* @return a compact formatted string representing the elapsed time, including days, hours, minutes, seconds, and milliseconds as
* applicable
*/
public String getUsedTimeFormattedCompact() {
return getUsedTimeFormatted(true, true, true, true, true);
}
}

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gson/src/main/java/de/neitzel/gson/adapter/ExcludeFieldsAdapter.java Normal file
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package de.neitzel.gson.adapter;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;
import com.google.gson.TypeAdapter;
import com.google.gson.internal.Streams;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
/**
* A custom {@link TypeAdapter} implementation for selectively excluding specified fields during JSON serialization.
*
* This adapter facilitates both serialization and deserialization of objects while providing functionality to remove specified
* fields from the serialized output. The set of excluded field names is provided during the adapter's initialization.
*
* @param <T> the type of objects that this adapter can serialize and deserialize
*/
public class ExcludeFieldsAdapter<T> extends TypeAdapter<T> {
/**
* The type of objects that this adapter handles for serialization and deserialization.
*
* This is a generic class type parameter representing the class of objects that the
* {@link ExcludeFieldsAdapter} instance is designed to process. It ensures type
* safety and guarantees the compatibility of the adapter with a specific object type.
*/
private final Class<T> type;
/**
* A set containing the names of fields to be excluded during JSON serialization.
*
* This collection is used in the {@link ExcludeFieldsAdapter} to determine which fields should be removed from the
* serialized JSON representation of an object. The fields to be excluded are specified during the initialization
* of the adapter.
*/
private final Set<String> excludedFields;
/**
* An instance of the Gson library used for JSON serialization and deserialization.
*
* This variable holds the Gson object that is utilized to handle the conversion processes within the
* custom serialization and deserialization logic. If not explicitly provided during initialization,
* it can be lazily initialized using a GsonBuilder.
*/
private Gson gson;
/**
* A {@link GsonBuilder} instance used for configuring and creating {@link Gson} objects within the adapter.
*
* This variable serves as a reference to a GsonBuilder that allows customization of the Gson instance,
* including registering custom type adapters, serializers, and deserializers, as well as adjusting serialization policies.
*
* The {@link #gsonBuilder} is primarily utilized when an existing {@link Gson} instance is not directly provided.
* It ensures that the adapter can defer the creation of a Gson object until it is explicitly required.
*/
private GsonBuilder gsonBuilder;
/**
* Creates a new instance of {@code ExcludeFieldsAdapter} for managing the serialization and deserialization
* of objects of the specified {@code type}, while excluding certain fields during serialization.
*
* @param type the class type of the objects to be serialized and deserialized
* @param excludedFields the set of field names to be excluded during serialization
* @param gson the Gson instance to be used for serialization and deserialization
*/
public ExcludeFieldsAdapter(Class<T> type, Set<String> excludedFields, Gson gson) {
this.type = type;
this.excludedFields = new HashSet<>(excludedFields);
this.gsonBuilder = null;
this.gson = gson;
}
/**
* Constructs an instance of {@code ExcludeFieldsAdapter} that selectively excludes specified fields from
* the JSON output based on the configuration provided during initialization.
*
* @param type the class of the type to be serialized and deserialized
* @param excludedFields a set of field names to be excluded from the serialized JSON output
* @param gsonBuilder an instance of {@code GsonBuilder} used to create a custom {@code Gson} instance if needed
*/
public ExcludeFieldsAdapter(Class<T> type, Set<String> excludedFields, GsonBuilder gsonBuilder) {
this.type = type;
this.excludedFields = new HashSet<>(excludedFields);
this.gsonBuilder = gsonBuilder;
this.gson = null;
}
/**
* Lazily initializes and retrieves the {@link Gson} instance. If the instance is null, it creates a new {@link Gson}
* object using the {@link GsonBuilder} provided during the adapter's initialization.
*
* @return the {@link Gson} instance used for serialization and deserialization
*/
private Gson getGson() {
if (gson == null) {
gson = gsonBuilder.create();
}
return gson;
}
/**
* Serializes an object of type {@code T} into JSON format, excluding certain fields specified during the initialization of this adapter.
* The object is first converted into a {@link JsonObject}, then the fields listed in the excluded fields set are removed from the JSON
* representation before writing it to the provided {@link JsonWriter}.
*
* @param out the {@link JsonWriter} to write the serialized JSON data to
* @param value the object of type {@code T} to serialize into JSON
* @throws IOException if an I/O error occurs during writing
*/
@Override
public void write(JsonWriter out, T value) throws IOException {
JsonObject obj = getGson().toJsonTree(value).getAsJsonObject();
for (String field : excludedFields) {
obj.remove(field);
}
Streams.write(obj, out);
}
/**
* Reads a JSON input stream and deserializes it into an object of the specified type.
*
* @param in the {@link JsonReader} to read the JSON input from
* @return an instance of type {@code T} deserialized from the JSON input
* @throws IOException if an error occurs during reading or deserialization
*/
@Override
public T read(JsonReader in) throws IOException {
return getGson().fromJson(in, type);
}
}