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A framework for building RESTful web APIs.
/*
* Copyright 2016 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.api.server.spi;
import com.google.auto.value.AutoValue;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
/**
* Initialization parameters supported by the {@link EndpointsServlet}.
*/
@AutoValue
public abstract class ServletInitializationParameters {
// Initialization parameter names used to extract values from a ServletConfig.
private static final String SERVICES = "services";
private static final String RESTRICTED = "restricted";
private static final String CLIENT_ID_WHITELIST_ENABLED = "clientIdWhitelistEnabled";
private static final String ILLEGAL_ARGUMENT_BACKEND_ERROR = "illegalArgumentIsBackendError";
private static final String EXCEPTION_COMPATIBILITY = "enableExceptionCompatibility";
private static final String PRETTY_PRINT = "prettyPrint";
private static final Splitter CSV_SPLITTER = Splitter.on(',').omitEmptyStrings().trimResults();
private static final Joiner CSV_JOINER = Joiner.on(',').skipNulls();
private static final Function, String> CLASS_TO_NAME = new Function, String>() {
@Override
public String apply(Class clazz) {
return clazz.getName();
}
};
/**
* Returns the endpoint service classes to serve.
*/
public abstract ImmutableSet> getServiceClasses();
/**
* Returns if the SPI servlet is restricted.
*
* @deprecated No longer serves any purpose and will be removed in a future release
*/
@Deprecated
public abstract boolean isServletRestricted();
/**
* Returns if client ID whitelisting is enabled.
*/
public abstract boolean isClientIdWhitelistEnabled();
/**
* Returns if an {@link IllegalArgumentException} should be returned as a backend error (500
* level) instead of a user error (400 level).
*/
public abstract boolean isIllegalArgumentBackendError();
/**
* Returns if v1.0 style exceptions should be returned to users. In v1.0, certain codes are not
* permissible, and other codes are translated to other status codes.
*/
public abstract boolean isExceptionCompatibilityEnabled();
/**
* Returns if pretty printing should be enabled for responses by default. Defaults to true.
*/
public abstract boolean isPrettyPrintEnabled();
public static Builder builder() {
return new AutoValue_ServletInitializationParameters.Builder()
.setServletRestricted(true)
.setClientIdWhitelistEnabled(true)
.setIllegalArgumentBackendError(false)
.setExceptionCompatibilityEnabled(true)
.setPrettyPrintEnabled(true);
}
/**
* A builder for {@link ServletInitializationParameters}.
*/
@AutoValue.Builder
public abstract static class Builder {
private final ImmutableSet.Builder> serviceClasses = ImmutableSet.builder();
/**
* Adds an endpoint service class to serve.
*/
public Builder addServiceClass(Class serviceClass) {
this.serviceClasses.add(serviceClass);
return this;
}
/**
* Adds some endpoint service classes to serve.
*/
public Builder addServiceClasses(Iterable> serviceClasses) {
this.serviceClasses.addAll(serviceClasses);
return this;
}
/**
* Sets the complete list of endpoint service classes to serve.
*/
public abstract Builder setServiceClasses(ImmutableSet> clazzes);
/**
* Sets if the servlet is restricted. Defaults to {@code true}.
*
* @deprecated No longer serves any purpose and will be removed in a future release
*/
@Deprecated
public abstract Builder setServletRestricted(boolean servletRestricted);
/**
* Sets if the servlet is restricted. Retained for API compatibility.
*
* @deprecated Retained for API compatibility
*/
@Deprecated
public Builder setRestricted(boolean servletRestricted) {
return setServletRestricted(servletRestricted);
}
/**
* Sets if the client ID whitelist is enabled, defaulting to {@code true}.
*/
public abstract Builder setClientIdWhitelistEnabled(boolean clientIdWhitelist);
/**
* Sets if an {@link IllegalArgumentException} should be treated as a backend error (500)
* instead of a user error (400). Defaults to {@code false}.
*/
public abstract Builder setIllegalArgumentBackendError(boolean illegalArgumentBackendError);
/**
* Sets if v1.0 style exceptions should be returned to users. In v1.0, certain codes are not
* permissible, and other codes are translated to other status codes. Defaults to {@code true}.
*/
public abstract Builder setExceptionCompatibilityEnabled(boolean exceptionCompatibility);
/**
* Sets if pretty printing should be enabled for responses by default. Defaults to {@code true}.
*/
public abstract Builder setPrettyPrintEnabled(boolean prettyPrint);
abstract ServletInitializationParameters autoBuild();
public ServletInitializationParameters build() {
return setServiceClasses(serviceClasses.build()).autoBuild();
}
}
/**
* Constructs a new instance from the provided {@link ServletConfig} and {@link ClassLoader}.
*/
public static ServletInitializationParameters fromServletConfig(
ServletConfig config, ClassLoader classLoader) throws ServletException {
Builder builder = builder();
if (config != null) {
String serviceClassNames = config.getInitParameter(SERVICES);
if (serviceClassNames != null) {
for (String serviceClassName : CSV_SPLITTER.split(serviceClassNames)) {
builder.addServiceClass(getClassForName(serviceClassName, classLoader));
}
}
String servletRestricted = config.getInitParameter(RESTRICTED);
if (servletRestricted != null) {
builder.setServletRestricted(parseBoolean(servletRestricted, RESTRICTED));
}
String clientIdWhitelist = config.getInitParameter(CLIENT_ID_WHITELIST_ENABLED);
if (clientIdWhitelist != null) {
builder.setClientIdWhitelistEnabled(
parseBoolean(clientIdWhitelist, CLIENT_ID_WHITELIST_ENABLED));
}
String illegalArgumentBackendError = config.getInitParameter(ILLEGAL_ARGUMENT_BACKEND_ERROR);
if (illegalArgumentBackendError != null) {
builder.setIllegalArgumentBackendError(
parseBoolean(illegalArgumentBackendError, ILLEGAL_ARGUMENT_BACKEND_ERROR));
}
String exceptionCompatibility = config.getInitParameter(EXCEPTION_COMPATIBILITY);
if (exceptionCompatibility != null) {
builder.setExceptionCompatibilityEnabled(
parseBoolean(exceptionCompatibility, EXCEPTION_COMPATIBILITY));
}
String prettyPrint = config.getInitParameter(PRETTY_PRINT);
if (prettyPrint != null) {
builder.setPrettyPrintEnabled(parseBoolean(prettyPrint, PRETTY_PRINT));
}
}
return builder.build();
}
private static boolean parseBoolean(String booleanString, String descriptionForErrors) {
if ("true".equalsIgnoreCase(booleanString)) {
return true;
} else if ("false".equalsIgnoreCase(booleanString)) {
return false;
}
throw new IllegalArgumentException(String.format(
"Expected 'true' or 'false' for '%s' servlet initialization parameter but got '%s'",
descriptionForErrors, booleanString));
}
private static Class getClassForName(String className, ClassLoader classLoader)
throws ServletException {
try {
return Class.forName(className, true, classLoader);
} catch (ClassNotFoundException e) {
throw new ServletException(String.format("Cannot find service class: %s", className), e);
}
}
/**
* Returns the parameters as a {@link java.util.Map} of parameter name to {@link String} value.
*/
public ImmutableMap asMap() {
return ImmutableMap.builder()
.put(SERVICES, CSV_JOINER.join(Iterables.transform(getServiceClasses(), CLASS_TO_NAME)))
.put(RESTRICTED, Boolean.toString(isServletRestricted()))
.put(CLIENT_ID_WHITELIST_ENABLED, Boolean.toString(isClientIdWhitelistEnabled()))
.put(ILLEGAL_ARGUMENT_BACKEND_ERROR, Boolean.toString(isIllegalArgumentBackendError()))
.put(EXCEPTION_COMPATIBILITY, Boolean.toString(isExceptionCompatibilityEnabled()))
.put(PRETTY_PRINT, Boolean.toString(isPrettyPrintEnabled()))
.build();
}
}