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relay.js-compatible GraphQL servlet
package graphql.servlet;
import com.google.common.io.ByteStreams;
import com.google.common.io.CharStreams;
import graphql.ExecutionResult;
import graphql.introspection.IntrospectionQuery;
import graphql.schema.GraphQLFieldDefinition;
import graphql.servlet.internal.GraphQLRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.AsyncContext;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.*;
import java.util.*;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* @author Andrew Potter
*/
public abstract class AbstractGraphQLHttpServlet extends HttpServlet implements Servlet, GraphQLMBean {
public static final Logger log = LoggerFactory.getLogger(AbstractGraphQLHttpServlet.class);
public static final String APPLICATION_JSON_UTF8 = "application/json;charset=UTF-8";
public static final String APPLICATION_GRAPHQL = "application/graphql";
public static final int STATUS_OK = 200;
public static final int STATUS_BAD_REQUEST = 400;
private static final GraphQLRequest INTROSPECTION_REQUEST = new GraphQLRequest(IntrospectionQuery.INTROSPECTION_QUERY, new HashMap<>(), null);
protected abstract GraphQLQueryInvoker getQueryInvoker();
protected abstract GraphQLInvocationInputFactory getInvocationInputFactory();
protected abstract GraphQLObjectMapper getGraphQLObjectMapper();
private final List listeners;
private final HttpRequestHandler getHandler;
private final HttpRequestHandler postHandler;
private final boolean asyncServletMode;
public AbstractGraphQLHttpServlet() {
this(null, false);
}
public AbstractGraphQLHttpServlet(List listeners, boolean asyncServletMode) {
this.listeners = listeners != null ? new ArrayList<>(listeners) : new ArrayList<>();
this.asyncServletMode = asyncServletMode;
this.getHandler = (request, response) -> {
GraphQLInvocationInputFactory invocationInputFactory = getInvocationInputFactory();
GraphQLObjectMapper graphQLObjectMapper = getGraphQLObjectMapper();
GraphQLQueryInvoker queryInvoker = getQueryInvoker();
String path = request.getPathInfo();
if (path == null) {
path = request.getServletPath();
}
if (path.contentEquals("/schema.json")) {
query(queryInvoker, graphQLObjectMapper, invocationInputFactory.create(INTROSPECTION_REQUEST, request), response);
} else {
String query = request.getParameter("query");
if (query != null) {
if (isBatchedQuery(query)) {
queryBatched(queryInvoker, graphQLObjectMapper, invocationInputFactory.createReadOnly(graphQLObjectMapper.readBatchedGraphQLRequest(query), request), response);
} else {
final Map variables = new HashMap<>();
if (request.getParameter("variables") != null) {
variables.putAll(graphQLObjectMapper.deserializeVariables(request.getParameter("variables")));
}
String operationName = request.getParameter("operationName");
query(queryInvoker, graphQLObjectMapper, invocationInputFactory.createReadOnly(new GraphQLRequest(query, variables, operationName), request), response);
}
} else {
response.setStatus(STATUS_BAD_REQUEST);
log.info("Bad GET request: path was not \"/schema.json\" or no query variable named \"query\" given");
}
}
};
this.postHandler = (request, response) -> {
GraphQLInvocationInputFactory invocationInputFactory = getInvocationInputFactory();
GraphQLObjectMapper graphQLObjectMapper = getGraphQLObjectMapper();
GraphQLQueryInvoker queryInvoker = getQueryInvoker();
try {
if (APPLICATION_GRAPHQL.equals(request.getContentType())) {
String query = CharStreams.toString(request.getReader());
query(queryInvoker, graphQLObjectMapper, invocationInputFactory.create(new GraphQLRequest(query, null, null)), response);
} else if (request.getContentType() != null && request.getContentType().startsWith("multipart/form-data") && !request.getParts().isEmpty()) {
final Map> fileItems = request.getParts().stream()
.collect(Collectors.toMap(
Part::getName,
Collections::singletonList,
(l1, l2) -> Stream.concat(l1.stream(), l2.stream()).collect(Collectors.toList())));
if (fileItems.containsKey("graphql")) {
final Optional graphqlItem = getFileItem(fileItems, "graphql");
if (graphqlItem.isPresent()) {
InputStream inputStream = graphqlItem.get().getInputStream();
if (!inputStream.markSupported()) {
inputStream = new BufferedInputStream(inputStream);
}
if (isBatchedQuery(inputStream)) {
GraphQLBatchedInvocationInput invocationInput = invocationInputFactory.create(graphQLObjectMapper.readBatchedGraphQLRequest(inputStream), request);
invocationInput.getContext().setFiles(fileItems);
queryBatched(queryInvoker, graphQLObjectMapper, invocationInput, response);
return;
} else {
GraphQLSingleInvocationInput invocationInput = invocationInputFactory.create(graphQLObjectMapper.readGraphQLRequest(inputStream), request);
invocationInput.getContext().setFiles(fileItems);
query(queryInvoker, graphQLObjectMapper, invocationInput, response);
return;
}
}
} else if (fileItems.containsKey("query")) {
final Optional queryItem = getFileItem(fileItems, "query");
if (queryItem.isPresent()) {
InputStream inputStream = queryItem.get().getInputStream();
if (!inputStream.markSupported()) {
inputStream = new BufferedInputStream(inputStream);
}
if (isBatchedQuery(inputStream)) {
GraphQLBatchedInvocationInput invocationInput = invocationInputFactory.create(graphQLObjectMapper.readBatchedGraphQLRequest(inputStream), request);
invocationInput.getContext().setFiles(fileItems);
queryBatched(queryInvoker, graphQLObjectMapper, invocationInput, response);
return;
} else {
String query = new String(ByteStreams.toByteArray(inputStream));
Map variables = null;
final Optional variablesItem = getFileItem(fileItems, "variables");
if (variablesItem.isPresent()) {
variables = graphQLObjectMapper.deserializeVariables(new String(ByteStreams.toByteArray(variablesItem.get().getInputStream())));
}
String operationName = null;
final Optional operationNameItem = getFileItem(fileItems, "operationName");
if (operationNameItem.isPresent()) {
operationName = new String(ByteStreams.toByteArray(operationNameItem.get().getInputStream())).trim();
}
GraphQLSingleInvocationInput invocationInput = invocationInputFactory.create(new GraphQLRequest(query, variables, operationName), request);
invocationInput.getContext().setFiles(fileItems);
query(queryInvoker, graphQLObjectMapper, invocationInput, response);
return;
}
}
}
response.setStatus(STATUS_BAD_REQUEST);
log.info("Bad POST multipart request: no part named \"graphql\" or \"query\"");
} else {
// this is not a multipart request
InputStream inputStream = request.getInputStream();
if (!inputStream.markSupported()) {
inputStream = new BufferedInputStream(inputStream);
}
if (isBatchedQuery(inputStream)) {
queryBatched(queryInvoker, graphQLObjectMapper, invocationInputFactory.create(graphQLObjectMapper.readBatchedGraphQLRequest(inputStream), request), response);
} else {
query(queryInvoker, graphQLObjectMapper, invocationInputFactory.create(graphQLObjectMapper.readGraphQLRequest(inputStream), request), response);
}
}
} catch (Exception e) {
log.info("Bad POST request: parsing failed", e);
response.setStatus(STATUS_BAD_REQUEST);
}
};
}
public void addListener(GraphQLServletListener servletListener) {
listeners.add(servletListener);
}
public void removeListener(GraphQLServletListener servletListener) {
listeners.remove(servletListener);
}
@Override
public String[] getQueries() {
return getInvocationInputFactory().getSchemaProvider().getSchema().getQueryType().getFieldDefinitions().stream().map(GraphQLFieldDefinition::getName).toArray(String[]::new);
}
@Override
public String[] getMutations() {
return getInvocationInputFactory().getSchemaProvider().getSchema().getMutationType().getFieldDefinitions().stream().map(GraphQLFieldDefinition::getName).toArray(String[]::new);
}
@Override
public String executeQuery(String query) {
try {
return getGraphQLObjectMapper().serializeResultAsJson(getQueryInvoker().query(getInvocationInputFactory().create(new GraphQLRequest(query, new HashMap<>(), null))));
} catch (Exception e) {
return e.getMessage();
}
}
private void doRequestAsync(HttpServletRequest request, HttpServletResponse response, HttpRequestHandler handler) {
if (asyncServletMode) {
AsyncContext asyncContext = request.startAsync();
HttpServletRequest asyncRequest = (HttpServletRequest) asyncContext.getRequest();
HttpServletResponse asyncResponse = (HttpServletResponse) asyncContext.getResponse();
new Thread(() -> doRequest(asyncRequest, asyncResponse, handler, asyncContext)).start();
} else {
doRequest(request, response, handler, null);
}
}
private void doRequest(HttpServletRequest request, HttpServletResponse response, HttpRequestHandler handler, AsyncContext asyncContext) {
List requestCallbacks = runListeners(l -> l.onRequest(request, response));
try {
handler.handle(request, response);
runCallbacks(requestCallbacks, c -> c.onSuccess(request, response));
} catch (Throwable t) {
response.setStatus(500);
log.error("Error executing GraphQL request!", t);
runCallbacks(requestCallbacks, c -> c.onError(request, response, t));
} finally {
runCallbacks(requestCallbacks, c -> c.onFinally(request, response));
if (asyncContext != null) {
asyncContext.complete();
}
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doRequestAsync(req, resp, getHandler);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doRequestAsync(req, resp, postHandler);
}
private Optional getFileItem(Map> fileItems, String name) {
return Optional.ofNullable(fileItems.get(name)).filter(list -> !list.isEmpty()).map(list -> list.get(0));
}
private void query(GraphQLQueryInvoker queryInvoker, GraphQLObjectMapper graphQLObjectMapper, GraphQLSingleInvocationInput invocationInput, HttpServletResponse resp) throws IOException {
ExecutionResult result = queryInvoker.query(invocationInput);
resp.setContentType(APPLICATION_JSON_UTF8);
resp.setStatus(STATUS_OK);
resp.getWriter().write(graphQLObjectMapper.serializeResultAsJson(result));
}
private void queryBatched(GraphQLQueryInvoker queryInvoker, GraphQLObjectMapper graphQLObjectMapper, GraphQLBatchedInvocationInput invocationInput, HttpServletResponse resp) throws Exception {
resp.setContentType(APPLICATION_JSON_UTF8);
resp.setStatus(STATUS_OK);
Writer respWriter = resp.getWriter();
respWriter.write('[');
queryInvoker.query(invocationInput, (result, hasNext) -> {
respWriter.write(graphQLObjectMapper.serializeResultAsJson(result));
if (hasNext) {
respWriter.write(',');
}
});
respWriter.write(']');
}
private List runListeners(Function action) {
if (listeners == null) {
return Collections.emptyList();
}
return listeners.stream()
.map(listener -> {
try {
return action.apply(listener);
} catch (Throwable t) {
log.error("Error running listener: {}", listener, t);
return null;
}
})
.filter(Objects::nonNull)
.collect(Collectors.toList());
}
private void runCallbacks(List callbacks, Consumer action) {
callbacks.forEach(callback -> {
try {
action.accept(callback);
} catch (Throwable t) {
log.error("Error running callback: {}", callback, t);
}
});
}
private boolean isBatchedQuery(InputStream inputStream) throws IOException {
if (inputStream == null) {
return false;
}
ByteArrayOutputStream result = new ByteArrayOutputStream();
byte[] buffer = new byte[128];
int length;
inputStream.mark(0);
while ((length = inputStream.read(buffer)) != -1) {
result.write(buffer, 0, length);
String chunk = result.toString();
Boolean isArrayStart = isArrayStart(chunk);
if (isArrayStart != null) {
inputStream.reset();
return isArrayStart;
}
}
inputStream.reset();
return false;
}
private boolean isBatchedQuery(String query) {
if (query == null) {
return false;
}
Boolean isArrayStart = isArrayStart(query);
return isArrayStart != null && isArrayStart;
}
// return true if the first non whitespace character is the beginning of an array
private Boolean isArrayStart(String s) {
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
if (!Character.isWhitespace(ch)) {
return ch == '[';
}
}
return null;
}
protected interface HttpRequestHandler extends BiConsumer {
@Override
default void accept(HttpServletRequest request, HttpServletResponse response) {
try {
handle(request, response);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
void handle(HttpServletRequest request, HttpServletResponse response) throws Exception;
}
}