转自：http://blog.csdn.net/krislight/article/details/9391455
greenDaoMaster的学习研究 分类： 心得笔记 2013-07-20 16:59 603人阅读 评论(11) 收藏 举报 greenDao 最近一直在研究一个第三方的开源框架，greenDaoMaster是一个移动开发的ORM框架，由于网上一直查不到使用资料，所以自己摸索总结下用法。 首先需要新建一个JAVA项目用来自动生成文件。需要导入greendao-generator-1.3.0.jar和freemarker.jar到项目中 示例代码如下： [java] view plaincopy /* * Copyright (C) 2011 Markus Junginger, greenrobot (http://greenrobot.de) * * 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 de.greenrobot.daogenerator.gentest; import de.greenrobot.daogenerator.DaoGenerator; import de.greenrobot.daogenerator.Entity; import de.greenrobot.daogenerator.Property; import de.greenrobot.daogenerator.Schema; import de.greenrobot.daogenerator.ToMany; /** * Generates entities and DAOs for the example project DaoExample. * * Run it as a Java application (not Android). * * @author Markus */ public class ExampleDaoGenerator { public static void main(String[] args) throws Exception { Schema schema = new Schema(3, "de.greenrobot.daoexample"); addNote(schema); addCustomerOrder(schema); new DaoGenerator().generateAll(schema, "../DaoExample/src-gen"); } private static void addNote(Schema schema) { Entity note = schema.addEntity("Note"); note.addIdProperty(); note.addStringProperty("text").notNull(); note.addStringProperty("comment"); note.addDateProperty("date"); } private static void addCustomerOrder(Schema schema) { Entity customer = schema.addEntity("Customer"); customer.addIdProperty(); customer.addStringProperty("name").notNull(); Entity order = schema.addEntity("Order"); order.setTableName("ORDERS"); // "ORDER" is a reserved keyword order.addIdProperty(); Property orderDate = order.addDateProperty("date").getProperty(); Property customerId = order.addLongProperty("customerId").notNull().getProperty(); order.addToOne(customer, customerId); ToMany customerToOrders = customer.addToMany(order, customerId); customerToOrders.setName("orders"); customerToOrders.orderAsc(orderDate); } } 来分析这段代码： [java] view plaincopy Schema schema = new Schema(3, "de.greenrobot.daoexample"); Schema对象接受2个参数，第一个参数是DB的版本号，通过更新版本号来更新数据库。第二个参数是自动生成代码的包路径。包路径系统自动生成 在来看这段代码 [java] view plaincopy Entity note = schema.addEntity("Note"); note.addIdProperty(); note.addStringProperty("text").notNull(); note.addStringProperty("comment"); note.addDateProperty("date"); Entity表示一个实体可以对应成数据库中的表 系统自动会以传入的参数作为表的名字，这里表名就是NOTE 当然也可以自己设置表的名字，像这样： [java] view plaincopy order.setTableName("ORDERS"); 接下来是一些字段参数设置。 如果想ID自动增长可以像这样： [java] view plaincopy order.addIdProperty().autoincrement(); 再来看这一段： [java] view plaincopy new DaoGenerator().generateAll(schema, "../DaoExample/src-gen"); 第一个参数是Schema对象，第二个参数是希望自动生成的代码对应的项目路径。 试了下src-gen这个文件夹必须手动创建,这里路径如果错了会抛出异常。 好了先别慌运行这段程序。新建一个Android项目名字是DaoExample，和刚才的JAVA项目保持在同一个文件夹下。 接着就可以运行刚才的JAVA程序，会看到src-gen下面自动生成了8个文件，3个实体对象，3个dao，1个DaoMaster, 1个DaoSession [java] view plaincopy greenDAO Generator Copyright 2011-2013 Markus Junginger, greenrobot.de. Licensed under GPL V3. This program comes with ABSOLUTELY NO WARRANTY Processing schema version 3... Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleNoteDao.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleNote.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleCustomerDao.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleCustomer.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleOrderDao.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleOrder.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleDaoMaster.java Written D:android workspaceOpen SourcegreenDAO-masterDaoExamplesrc-gendegreenrobotdaoexampleDaoSession.java Processed 3 entities in 7743ms 可以看到DaoMaster中封装了SQLiteDatabase和SQLiteOpenHelper 来看看如何使用GreenDao实现CRUD 如下代码实现插入一个Note对象： [java] view plaincopy DevOpenHelper helper = new DaoMaster.DevOpenHelper(this, "notes-db", null); db = helper.getWritableDatabase(); daoMaster = new DaoMaster(db); daoSession = daoMaster.newSession(); noteDao = daoSession.getNoteDao(); Note note = new Note(null, noteText, comment, new Date()); noteDao.insert(note); 代码变得如此简单。 官方推荐将取得DaoMaster对象的方法放到Application层这样避免多次创建生成Session对象。 感觉这个框架和Web的Hibernate有异曲同工之妙。 这里列出自己实际开发中的代码方便记忆： 首先是在Application层实现得到DaoMaster和DaoSession的方法： [java] view plaincopy public class BaseApplication extends Application { private static BaseApplication mInstance; private static DaoMaster daoMaster; private static DaoSession daoSession; @Override public void onCreate() { super.onCreate(); if(mInstance == null) mInstance = this; } /** * 取得DaoMaster * * @param context * @return */ public static DaoMaster getDaoMaster(Context context) { if (daoMaster == null) { OpenHelper helper = new DaoMaster.DevOpenHelper(context,Constants.DB_NAME, null); daoMaster = new DaoMaster(helper.getWritableDatabase()); } return daoMaster; } /** * 取得DaoSession * * @param context * @return */ public static DaoSession getDaoSession(Context context) { if (daoSession == null) { if (daoMaster == null) { daoMaster = getDaoMaster(context); } daoSession = daoMaster.newSession(); } return daoSession; } } 然后写一个Db工具类： [java] view plaincopy public class DbService { private static final String TAG = DbService.class.getSimpleName(); private static DbService instance; private static Context appContext; private DaoSession mDaoSession; private NoteDao noteDao; private DbService() { } public static DbService getInstance(Context context) { if (instance == null) { instance = new DbService(); if (appContext == null){ appContext = context.getApplicationContext(); } instance.mDaoSession = BaseApplication.getDaoSession(context); instance.noteDao = instance.mDaoSession.getNoteDao(); } return instance; } public Note loadNote(long id) { return noteDao.load(id); } public List<Note> loadAllNote(){ return noteDao.loadAll(); } /** * query list with where clause * ex: begin_date_time >= ? AND end_date_time <= ? * @param where where clause, include 'where' word * @param params query parameters * @return */ public List<Note> queryNote(String where, String... params){ return noteDao.queryRaw(where, params); } /** * insert or update note * @param note * @return insert or update note id */ public long saveNote(Note note){ return noteDao.insertOrReplace(note); } /** * insert or update noteList use transaction * @param list */ public void saveNoteLists(final List<Note> list){ if(list == null || list.isEmpty()){ return; } noteDao.getSession().runInTx(new Runnable() { @Override public void run() { for(int i=0; i<list.size(); i++){ Note note = list.get(i); noteDao.insertOrReplace(note); } } }); } /** * delete all note */ public void deleteAllNote(){ noteDao.deleteAll(); } /** * delete note by id * @param id */ public void deleteNote(long id){ noteDao.deleteByKey(id); Log.i(TAG, "delete"); } public void deleteNote(Note note){ noteDao.delete(note); } } DB常量： [java] view plaincopy public class Constants { public static final String DB_NAME = "note_db"; } Note实体类： [java] view plaincopy // THIS CODE IS GENERATED BY greenDAO, DO NOT EDIT. Enable "keep" sections if you want to edit. /** * Entity mapped to table note. */ public class Note { private Long id; /** Not-null value. */ private String title; /** Not-null value. */ private String content; private java.util.Date createDate; public Note() { } public Note(Long id) { this.id = id; } public Note(Long id, String title, String content, java.util.Date createDate) { this.id = id; this.title = title; this.content = content; this.createDate = createDate; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } /** Not-null value. */ public String getTitle() { return title; } /** Not-null value; ensure this value is available before it is saved to the database. */ public void setTitle(String title) { this.title = title; } /** Not-null value. */ public String getContent() { return content; } /** Not-null value; ensure this value is available before it is saved to the database. */ public void setContent(String content) { this.content = content; } public java.util.Date getCreateDate() { return createDate; } public void setCreateDate(java.util.Date createDate) { this.createDate = createDate; } }