android orm映射框架 ormlite (类似于hibernate) 很强大
程序员文章站
2022-07-15 12:45:39
...
初学android不久,由于我是以前学过j2ee,什么ssh曾经用过,java的数据库持久化框架hibernate给程序操作数据库提供了方便,学习android的时候,想看看是否有个操作数据库的框架,谷歌了下,发现android的数据库框架很多什么,但都缺乏中文文档(本人还没过六级。。英语很差),几乎找不到例子,最后找到了ormlite,一个android orm映射框架,可像hibernate一样操作数据库。 以下代码是我从网上摘录下来的,仅供参考.
package com.cng.utils; import java.sql.SQLException; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.util.Log; import com.cng.modal.Hello; import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper; import com.j256.ormlite.dao.Dao; import com.j256.ormlite.support.ConnectionSource; import com.j256.ormlite.table.TableUtils; public class DataHelper extends OrmLiteSqliteOpenHelper { private static final String DATABASE_NAME = "HelloOrmlite.db"; private static final int DATABASE_VERSION = 1; private Dao<Hello, Integer> helloDao = null; public DataHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) { try { TableUtils.createTable(connectionSource, Hello.class); } catch (SQLException e) { Log.e(DataHelper.class.getName(), "创建数据库失败", e); e.printStackTrace(); } } @Override public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int arg2, int arg3) { try { TableUtils.dropTable(connectionSource, Hello.class, true); onCreate(db, connectionSource); } catch (SQLException e) { Log.e(DataHelper.class.getName(), "更新数据库失败", e); e.printStackTrace(); } } @Override public void close() { super.close(); helloDao = null; } public Dao<Hello, Integer> getHelloDataDao() throws SQLException { if (helloDao == null) { helloDao = getDao(Hello.class); } return helloDao; } }
package com.cng; import java.sql.SQLException; import java.util.List; import com.cng.modal.Hello; import com.cng.utils.DataHelper; import com.j256.ormlite.android.apptools.OrmLiteBaseActivity; import com.j256.ormlite.dao.Dao; import android.os.Bundle; import android.widget.TextView; public class OrmliteLoginActivity extends OrmLiteBaseActivity<DataHelper> { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) this.findViewById(R.id.output); try { Dao<Hello, Integer> helloDao = getHelper().getHelloDataDao(); // 添加数据 for (int i = 0; i < 2; i++) { Hello hello = new Hello("Hello" + i); helloDao.create(hello); } tv.setText(tv.getText() + "\n" + "添加数据完成"); // 查询添加的数据 List<Hello> hellos = helloDao.queryForAll(); for (Hello h : hellos) { tv.setText(tv.getText() + "\n" + h.toString()); } // 删除数据第一条数据 helloDao.delete(hellos.get(0)); tv.setText(tv.getText() + "\n" + "删除数据完成"); // 重新查询数据 hellos = helloDao.queryForAll(); for (Hello h : hellos) { tv.setText(tv.getText() + "\n" + h.toString()); } // 修改数据 Hello h1 = hellos.get(0); h1.setWord("这是修改过的数据"); tv.setText(tv.getText() + "\n" + "修改数据完成"); helloDao.update(h1); // 重新查询数据 hellos = helloDao.queryForAll(); for (Hello h : hellos) { tv.setText(tv.getText() + "\n" + h.toString()); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
package com.cng.modal; import android.R.integer; import com.j256.ormlite.field.DatabaseField; public class Hello { @DatabaseField(generatedId = true,unique=true) int id; @DatabaseField String word; //这是必须加的,否则会出错 public Hello(){} public int getId() { return id; } public Hello(String word) { super(); this.word = word; } public void setId(int id) { this.id = id; } public String getWord() { return word; } public void setWord(String word) { this.word = word; } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("id=").append(id); sb.append(" ,word=").append(word); return sb.toString(); } }
就这三个类,datahelper是操作数据库的类,可新建,更新表,Hello是一个映射到数据库表的类,具体的看api 文档的下载地址是http://ormlite.com/releases/(其中的jar包也在这里下载) OrmliteLoginActivity就是activity类,它没继承activity,而是继承了OrmLiteBaseActivity类。
ormlite还在学习中,表示这个android框架很强大>_<。