com.threerings.servlet.util.Parameters Maven / Gradle / Ivy
//
// ooo-util - a place for OOO utilities
// Copyright (C) 2011 Three Rings Design, Inc., All Rights Reserved
// http://github.com/threerings/ooo-util/blob/master/LICENSE
package com.threerings.servlet.util;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import javax.servlet.ServletRequest;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.samskivert.util.Logger;
import com.samskivert.util.Tuple;
/**
* Provides convenient access to and conversion of the parameters of an HttpServletRequest.
*/
public class Parameters
{
public Parameters (ServletRequest req)
{
_req = req;
}
/**
* Returns an Iterable over all the parameter names for this request.
*/
public Set names ()
{
@SuppressWarnings("unchecked")
Set names = _req.getParameterMap().keySet();
return names;
}
/**
* Returns a Collection of all the parameter values for this request.
*/
public Collection values ()
{
@SuppressWarnings("unchecked")
Collection vals = _req.getParameterMap().values();
return vals;
}
/**
* Returns all the names and values in the parameters. The name is {@link Tuple#left} and the
* value is {@link Tuple#right}. If a name appears multiple times, it'll be in multiple
* tuples.
*/
public Collection> entries ()
{
Set names = names();
List> entries = Lists.newArrayListWithCapacity(names.size());
for (String name : names) {
for (String val : getAll(name)) {
entries.add(Tuple.newTuple(name, val));
}
}
return entries;
}
/**
* Returns true if the request contains the given parameter.
*/
public boolean has (String name)
{
return _req.getParameterValues(name) != null;
}
/**
* Returns the value for the parameter on this request or null if it has no such parameter.
* IllegalStateException is thrown if the request has multiple values for the parameter.
*/
public String get (String name)
{
return get(name, (String)null);
}
/**
* Returns the value for the parameter on this request or def if it has no such
* parameter. IllegalStateException is thrown if the request has multiple values for the
* parameter.
*/
public String get (String name, String def)
{
String[] vals = _req.getParameterValues(name);
if (vals != null) {
Preconditions.checkState(vals.length == 1,
Logger.format("Requested a single value parameter, but there were multiple values",
"name", name, "values", vals));
return vals[0];
}
return def;
}
/**
* Returns the value for the parameter on this request as converted by converter
* or defif it has no such parameter.
*
* If converter can't handle the value and throws
* ConversionFailedException, that will be propagated by this method with the
* parameter name and value filled in. Any other exceptions thrown by converter
* will be wrapped in ConversionFailedException and rethrown.
*
* IllegalStateException is thrown if the request has multiple values for the parameter.
*/
public T get (String name, Function converter, T def)
{
String val = get(name);
if (val != null) {
return convert(converter, name, val);
}
return def;
}
/**
* Returns the value for the parameter on this request or throws
* NullPointerException if it has no such parameter. IllegalStateException is
* thrown if the request has multiple values for the parameter.
*/
public String require (String name)
{
String val = get(name);
Preconditions.checkNotNull(val, "'" + name + "' was required but not present");
return val;
}
/**
* Returns the value for the parameter on this request as converted by converter
* or throws NullPointerException if it has no such parameter.
*
* If converter can't handle the value and throws
* ConversionFailedException, that will be propagated by this method with the
* parameter name and value filled in. Any other exceptions thrown by converter
* will be wrapped in ConversionFailedException and rethrown.
*
* IllegalStateException is thrown if the request has multiple values for the parameter.
*/
public T require (String name, Function converter)
{
return convert(converter, name, require(name));
}
/**
* Returns all the values for the given parameter on the request, or defaultValues
* if it has no such parameter.
*/
public String[] getAll (String name, String... defaultValues)
{
String[] vals = _req.getParameterValues(name);
if (vals == null) {
return defaultValues;
}
return vals;
}
/**
* Returns all the values for the given parameter on the request as converted by
* converter, or defaultValues if it has no such parameter.
*
* If converter can't handle the value and throws
* ConversionFailedException, that will be propagated by this method with the
* parameter name and value filled in. Any other exceptions thrown by converter
* will be wrapped in ConversionFailedException and rethrown.
*/
public Collection getAll (final String name, final Function converter,
T... defaultValues)
{
String[] vals = _req.getParameterValues(name);
if (vals == null) {
return Arrays.asList(defaultValues);
}
return Lists.transform(Arrays.asList(vals), new Function(){
public T apply (String from) {
return convert(converter, name, from);
}});
}
/**
* Returns the result of passing the given value into converter. If an exception is thrown by
* it, a ConversionFailedException is thrown with the name and value filled in as part of its
* message.
*/
protected static T convert (Function converter, String name, String val)
{
try {
return converter.apply(val);
} catch (RuntimeException re) {
ConversionFailedException fail;
if (re instanceof ConversionFailedException) {
fail = (ConversionFailedException)re;
} else {
fail = new ConversionFailedException(re, "Failed converting parameter");
}
fail.append("name", name, "value", val);
throw fail;
}
}
protected final ServletRequest _req;
}