ClassInfo.java :  » Google-tech » siena » siena » Java Open Source

/*
 * Copyright 2009 Alberto Gimeno <gimenete at gmail.com>
 *
 *   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 siena;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ClassInfo {
  
  private static Map<Class<?>, ClassInfo> infoClasses = new HashMap<Class<?>, ClassInfo>();
  
  public String tableName;

  public List<Field> keys = new ArrayList<Field>();
  public List<Field> insertFields = new ArrayList<Field>();
  public List<Field> updateFields = new ArrayList<Field>();
  public List<Field> generatedKeys = new ArrayList<Field>();
  public List<Field> allFields = new ArrayList<Field>();

  private ClassInfo(Class<?> clazz) {
    tableName = getTableName(clazz);

    Field[] fields = clazz.getDeclaredFields();
    for (Field field : fields) {
      
      Class<?> type = field.getType();
      if(type == Class.class || type == Query.class ||
          (field.getModifiers() & Modifier.TRANSIENT) == Modifier.TRANSIENT ||
          (field.getModifiers() & Modifier.STATIC) == Modifier.STATIC)
        continue;
      
      Id id = field.getAnnotation(Id.class);
      if(id != null) {
        if(id.value() == Generator.AUTO_INCREMENT) {
          generatedKeys.add(field);
        } else {
          insertFields.add(field);
        }
        keys.add(field);
      } else {
        updateFields.add(field);
        insertFields.add(field);
      }
      allFields.add(field);
    }
  }

  private String getTableName(Class<?> clazz) {
    Table t = clazz.getAnnotation(Table.class);
    if(t == null) return clazz.getSimpleName();
    return t.value();
  }

  public static String[] getColumnNames(Field field) {
    Column c = field.getAnnotation(Column.class);
    if(c != null && c.value().length > 0) return c.value();
    
    // default mapping: field names
    if(isModel(field.getType())) {
      ClassInfo ci = getClassInfo(field.getType());
      List<String> keys = new ArrayList<String>();
      for (Field key : ci.keys) {
        keys.addAll(Arrays.asList(getColumnNames(key)));
      }
      return keys.toArray(new String[keys.size()]);
    }
    return new String[]{ field.getName() };
  }

  public static boolean isModel(Class<?> type) {
    if(type.getSuperclass() == Model.class)
      return true;
    // TODO: this needs to be tested
    if(type.getName().startsWith("java.")) return false;
    if(type == Json.class) return false;
    return !ClassInfo.getClassInfo(type).keys.isEmpty();
  }

  public static boolean isId(Field field) {
    return field.getAnnotation(Id.class) != null;
  }
  
  /**
   * Useful for those PersistenceManagers that only support one @Id
   * @param clazz
   * @return
   */
  public static Field getIdField(Class<?> clazz) {
    List<Field> keys = ClassInfo.getClassInfo(clazz).keys;
    if(keys.isEmpty())
      throw new SienaException("No valid @Id defined in class "+clazz.getName());
    if(keys.size() > 1)
      throw new SienaException("Multiple @Id defined in class "+clazz.getName());
    return keys.get(0);
  }

  public static ClassInfo getClassInfo(Class<?> clazz) {
    ClassInfo ci = infoClasses.get(clazz);
    if(ci == null) {
      ci = new ClassInfo(clazz);
      infoClasses.put(clazz, ci);
    }
    return ci;
  }

}