I've made a ParamConverter which provides an Instant (Date) when given a string formatted as either Instant's native ISO-8601, or as an integer number of milliseconds since the epoch. This is working fine, but I also need to be able to support other date formats (the customers are fussy).
To avoid the classic dd/mm/yyyy vs mm/dd/yyyy ambiguity, I'd like to have the customer specify their preferred format as part of the request*. e.g:
GET http://api.example.com/filter?since=01/02/2000&dateformat=dd/mm/yyyy
passed to a method which looks like:
@GET
String getFilteredList( final @QueryParam( "since" ) Instant since ) {
...
}
(time & timezone parts omitted for clarity)
So I'd like my ParamConverter<Instant> to be able to read the dateformat parameter.
I've been able to use a combination of a filter which sets a ContainerRequestContext property and an AbstractValueFactoryProvider to do something similar, but that needs the parameter to have a custom annotation applied and doesn't let it work with QueryParam/FormParam/etc., making it far less useful.
Is there any way to get other parameters, or the request object itself, from inside a ParamConverter?
[*] In the real world this would be from a selection of pre-approved formats, but for now just assume they're providing the input to a DateTimeFormatter
For clarity, here's the code I have:
public class InstantParameterProvider implements ParamConverterProvider {
private static final ParamConverter<Instant> INSTANT_CONVERTER =
new ParamConverter<Instant>( ) {
@Override public final T fromString( final String value ) {
// This is where I would like to get the other parameter's value
// Is it possible?
}
@Override public final String toString( final T value ) {
return value.toString( );
}
};
@SuppressWarnings( "unchecked" )
@Override public <T> ParamConverter<T> getConverter(
final Class<T> rawType,
final Type genericType,
final Annotation[] annotations
) {
if( rawType == Instant.class ) {
return (ParamConverter<T>) INSTANT_CONVERTER;
}
return null;
}
}
As mentioned here, the key to this is injecting some context object with javax.inject.Provider, which allows us to retrieve the object lazily. Since the ParamConverterProvider is a component managed by Jersey, we should be able to inject other components.
The problem is that the component we need is going to be in a request scope. To get around that, we inject javax.inject.Provider<UriInfo> into the provider. When we actually call get() in the Provider to get the actual instance of UriInfo, it will be be in a request. The same goes for any other component that requires a request scope.
For example
public class InstantParamProvider implements ParamConverterProvider {
@Inject
private javax.inject.Provider<UriInfo> uriInfoProvider;
@Override
public <T> ParamConverter<T> getConverter(Class<T> rawType,
Type genericType,
Annotation[] annotations) {
if (rawType != Instant.class) return null;
return new ParamConverter<T>() {
@Override
public T fromString(String value) {
UriInfo uriInfo = uriInfoProvider.get();
String format = uriInfo.getQueryParameters().getFirst("date-format");
if (format == null) {
throw new WebApplicationException(Response.status(400)
.entity("data-format query parameter required").build());
} else {
try {
// parse and return here
} catch (Exception ex) {
throw new WebApplicationException(
Response.status(400).entity("Bad format " + format).build());
}
}
}
@Override
public String toString(T value) {
return value.toString();
}
};
}
}
UPDATE
Here is a complete example using Jersey Test Framework
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.logging.Logger;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.ParamConverter;
import javax.ws.rs.ext.ParamConverterProvider;
import org.glassfish.jersey.filter.LoggingFilter;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.test.JerseyTest;
import org.junit.Test;
import static org.junit.Assert.*;
import static org.junit.matchers.JUnitMatchers.*;
public class LocalDateTest extends JerseyTest {
public static class LocalDateParamProvider implements ParamConverterProvider {
@Inject
private javax.inject.Provider<UriInfo> uriInfoProvider;
@Override
public <T> ParamConverter<T> getConverter(Class<T> rawType,
Type genericType,
Annotation[] annotations) {
if (rawType != LocalDate.class) {
return null;
}
return new ParamConverter<T>() {
@Override
public T fromString(String value) {
UriInfo uriInfo = uriInfoProvider.get();
String format = uriInfo.getQueryParameters().getFirst("date-format");
if (format == null) {
throw new WebApplicationException(Response.status(400)
.entity("date-format query parameter required").build());
} else {
try {
return (T) LocalDate.parse(value, DateTimeFormatter.ofPattern(format));
// parse and return here
} catch (Exception ex) {
throw new WebApplicationException(
Response.status(400).entity("Bad format " + format).build());
}
}
}
@Override
public String toString(T value) {
return value.toString();
}
};
}
}
@Path("localdate")
public static class LocalDateResource {
@GET
public String get(@QueryParam("since") LocalDate since) {
return since.format(DateTimeFormatter.ofPattern("MM/dd/yyyy"));
}
}
@Override
public ResourceConfig configure() {
return new ResourceConfig(LocalDateResource.class)
.register(LocalDateParamProvider.class)
.register(new LoggingFilter(Logger.getAnonymousLogger(), true));
}
@Test
public void should_return_bad_request_with_bad_format() {
Response response = target("localdate")
.queryParam("since", "09/20/2015")
.queryParam("date-format", "yyyy/MM/dd")
.request().get();
assertEquals(400, response.getStatus());
assertThat(response.readEntity(String.class), containsString("format yyyy/MM/dd"));
response.close();
}
@Test
public void should_return_bad_request_with_no_date_format() {
Response response = target("localdate")
.queryParam("since", "09/20/2015")
.request().get();
assertEquals(400, response.getStatus());
assertThat(response.readEntity(String.class), containsString("query parameter required"));
response.close();
}
@Test
public void should_succeed_with_correct_format() {
Response response = target("localdate")
.queryParam("since", "09/20/2015")
.queryParam("date-format", "MM/dd/yyyy")
.request().get();
assertEquals(200, response.getStatus());
assertThat(response.readEntity(String.class), containsString("09/20/2015"));
response.close();
}
}
Here's the test dependency
<dependency>
<groupId>org.glassfish.jersey.test-framework.providers</groupId>
<artifactId>jersey-test-framework-provider-grizzly2</artifactId>
<version>${jersey2.version}</version>
<scope>test</scope>
</dependency>
来源：https://stackoverflow.com/questions/27584161/read-another-parameter-within-jerseys-paramconverter