Google App Engine for Java で CRUD

次はGAE/Jを使ったAndroidアプリを作りたいので、GAE/Jの勉強中。
とりあえず簡単なCRUD作ってみました。

ソース

PMF.java

PersistenceManagerFactoryを保持するユーティリティクラス

import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;

public class PMF {
  private static final PersistenceManagerFactory INSTANCE = JDOHelper.getPersistenceManagerFactory("transactions-optional");

  public static final PersistenceManagerFactory get() {
    return INSTANCE;
  }

  public static final PersistenceManager createManager() {
    return get().getPersistenceManager();
  }

  private PMF() {
  }
}

Content.java

コメントを保持するエンティティクラス

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.IdentityType;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

import com.google.appengine.api.datastore.Key;

@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true")
public class Content {
  @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
  @PrimaryKey
  private Key key;
  @Persistent
  private String title;
  @Persistent
  private String comment;

  public Content() {

  }

  public Content(Key key, String title, String comment) {
    this.key = key;
    this.title = title;
    this.comment = comment;
  }

  public Key getKey() {
    return key;
  }

  public void setKey(Key key) {
    this.key = key;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }

  public String getComment() {
    return comment;
  }

  public void setComment(String comment) {
    this.comment = comment;
  }
}

CommentDAO.java

CRUDするクラス

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import javax.jdo.PersistenceManager;
import javax.jdo.annotations.Transactional;

public class CommentDAO{

  @Transactional
  public boolean addContent(Content content) {
    PersistenceManager pm = PMF.createManager();
    try {
      pm.makePersistent(content);
      return true;
    } catch (Exception e) {
      return false;
    } finally {
      pm.close();
    }
  }

  @Transactional
  public boolean updateContent(Content content) {
    PersistenceManager pm = PMF.createManager();
    try {
      Content persistenctContent = pm.getObjectById(Content.class, content.getKey());
      persistenctContent.setTitle(content.getTitle());
      persistenctContent.setComment(content.getComment());
      return true;
    } catch (Exception e) {
      return false;
    } finally {
      pm.close();
    }
  }

  @Transactional
  public boolean deleteContent(Integer id) {
    PersistenceManager pm = PMF.createManager();
    try {
      Content persistenctContent = pm.getObjectById(Content.class, id);
      pm.deletePersistent(persistenctContent);
      return true;
    } catch (Exception e) {
      return false;
    } finally {
      pm.close();
    }
  }

  @Transactional
  @SuppressWarnings("unchecked")
  public List<Content> getContentList() {
    PersistenceManager pm = PMF.createManager();
    try {
      String query = "select from " + Content.class.getName();
      Collection<Content> result = (Collection<Content>) pm.newQuery(query).execute();
      return new ArrayList(pm.detachCopyAll(result));
    } finally {
      pm.close();
    }
  }
}

とりあえず

動きます。
おかしい所があったら教えてください。

参考

Google App Engine for Java [実践]クラウドシステム構築

まだデータストアの最初くらいしか読んでないですが、とても参考になります。

Google App Engine for Java (GAE/J) で Bigtable CRUDを行う Flex アプリ作成法 - hamadakoichi blog

http://d.hatena.ne.jp/hamadakoichi/20090611/1244673675