blob: 8701d68af3d65adb9c8e36b0b27ff99eedaf9eb0 [file] [log] [blame]
package example.xml;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Binder;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import safesax.Element;
import safesax.ElementListener;
import safesax.Parsers;
import safesax.RootElement;
import safesax.StartElementListener;
public class XmlBeanModule implements Module {
final URL xmlUrl;
Locator locator;
Binder originalBinder;
BeanBuilder beanBuilder;
public XmlBeanModule(URL xmlUrl) {
this.xmlUrl = xmlUrl;
}
public void configure(Binder binder) {
this.originalBinder = binder;
try {
RootElement beans = new RootElement("beans");
locator = beans.getLocator();
Element bean = beans.getChild("bean");
bean.setElementListener(new BeanListener());
Element property = bean.getChild("property");
property.setStartElementListener(new PropertyListener());
Reader in = new InputStreamReader(xmlUrl.openStream());
Parsers.parse(in, beans.getContentHandler());
}
catch (Exception e) {
originalBinder.addError(e);
}
}
/** Handles "binding" elements. */
class BeanListener implements ElementListener {
public void start(final Attributes attributes) {
Binder sourced = originalBinder.withSource(xmlSource());
String typeString = attributes.getValue("type");
// Make sure 'type' is present.
if (typeString == null) {
sourced.addError("Missing 'type' attribute.");
return;
}
// Resolve 'type'.
Class<?> type;
try {
type = Class.forName(typeString);
}
catch (ClassNotFoundException e) {
sourced.addError(e);
return;
}
// Look for a no-arg constructor.
try {
type.getConstructor();
}
catch (NoSuchMethodException e) {
sourced.addError("%s doesn't have a no-arg constructor.");
return;
}
// Create a bean builder for the given type.
beanBuilder = new BeanBuilder(type);
}
public void end() {
if (beanBuilder != null) {
beanBuilder.build();
beanBuilder = null;
}
}
}
/** Handles "property" elements. */
class PropertyListener implements StartElementListener {
public void start(final Attributes attributes) {
Binder sourced = originalBinder.withSource(xmlSource());
if (beanBuilder == null) {
// We must have already run into an error.
return;
}
// Check for 'name'.
String name = attributes.getValue("name");
if (name == null) {
sourced.addError("Missing attribute name.");
return;
}
Class<?> type = beanBuilder.type;
// Find setter method for the given property name.
String setterName = "set" + capitalize(name);
Method setter = null;
for (Method method : type.getMethods()) {
if (method.getName().equals(setterName)) {
setter = method;
break;
}
}
if (setter == null) {
sourced.addError("%s.%s() not found.", type.getName(), setterName);
return;
}
// Validate number of parameters.
Type[] parameterTypes = setter.getGenericParameterTypes();
if (parameterTypes.length != 1) {
sourced.addError("%s.%s() must take one argument.",
setterName, type.getName());
return;
}
// Add property descriptor to builder.
Provider<?> provider = sourced.getProvider(Key.get(parameterTypes[0]));
beanBuilder.properties.add(
new Property(setter, provider));
}
}
static String capitalize(String s) {
return Character.toUpperCase(s.charAt(0)) +
s.substring(1);
}
static class Property {
final Method setter;
final Provider<?> provider;
Property(Method setter, Provider<?> provider) {
this.setter = setter;
this.provider = provider;
}
void setOn(Object o) {
try {
setter.invoke(o, provider.get());
}
catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
}
class BeanBuilder {
final List<Property> properties = new ArrayList<Property>();
final Class<?> type;
BeanBuilder(Class<?> type) {
this.type = type;
}
void build() {
addBinding(type);
}
<T> void addBinding(Class<T> type) {
originalBinder.withSource(xmlSource())
.bind(type).toProvider(new BeanProvider<T>(type, properties));
}
}
static class BeanProvider<T> implements Provider<T> {
final Class<T> type;
final List<Property> properties;
BeanProvider(Class<T> type, List<Property> properties) {
this.type = type;
this.properties = properties;
}
public T get() {
try {
T t = type.newInstance();
for (Property property : properties) {
property.setOn(t);
}
return t;
}
catch (InstantiationException e) {
throw new RuntimeException(e);
}
catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
}
Object xmlSource() {
return xmlUrl + ":" + locator.getLineNumber();
}
}