项目配置

• grdle配置
  在Android Studio的build.gradle配上
  compile 'de.greenrobot:greendao:1.3.7'
  compile 'de.greenrobot:greendao-generator:1.3.1'

• 生成代码

项目示例2

我们需要在包根目录新建一个Java文件，做初始化工作。
如图所示，包的根目录是'com.usst.chensl.greendaodemo'，创建一个名为'ExampleDaoGenerator'的Java文件。

ExampleDaoGenerator文件如下

package com.usst.chensl.introducdemo.db;    
import de.greenrobot.daogenerator.DaoGenerator;
import de.greenrobot.daogenerator.Entity;
import de.greenrobot.daogenerator.Schema;

/**
 * 初始化工作

 * Created by ChenSL on 2015/8/14.
 */
public class ExampleDaoGenerator {

    private static void addTaskDetail(Schema schema) {
        //指定实体类
        Entity entity = schema.addEntity("User");
        //添加id属性
        entity.addIdProperty();
        //添加列userId,指定非空，默认可为空
        entity.addStringProperty("userId").notNull();
        //添加列username  
        entity.addStringProperty("username");
        //添加列age
        entity.addIntProperty("age");
        //添加列phone
        entity.addStringProperty("phone");
    }

    public static void main(String[] args) throws Exception {
        //生成数据库文件的目标包名//target package for dao files
        //第一个参数是数据库版本号，第二个参数是包的根目录的包
        Schema schema = new Schema(1, "db");
        addDetail(schema);
        try {
            //第二个参数是src-gen文件夹相对路径
            //'..'代表工程前一个目录,接着是工程名/app(AndroidStudio生成)/
            new DaoGenerator().generateAll(schema, "../GreenDaoDemo/app/src/main/java/com/usst/chensl/greendaodemo/");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Entity可以看作是一张表,它使用构造器模式来设计，可以指定某一列的各种数据库属性，例如非空，自增，升降序，主键等。

同时，在工程目录下新建src-gen文件夹，放置代码生成的数据库文件。

项目文件结构目录

对着ExampleDaoGenerator右键，选择run ... main()，会在src-gen文件夹中生成四个文件。

注意：必须要使用run main()这种方法，在AndroidStudio下直接对该文件右键即可选择run main(),之前LZ试过在onCreate()里跑结果报错

下面来看看初始化出来的东西：

项目实例3

将db包拖动到包的根目录下，然后可以将src-gen文件夹下的东西全部删掉了。

初始化完成

初始化完成后，'ExampleDaoGenerator'就没用了，留着修改后可以创建另一个表，不需要可以删除。

• user实体类，注释已经说明是GreenDao自动生成的。其实就跟自己建实体类一样，不过现在是代码自动生成

   package com.usst.chensl.introductdemo.db;
  
   // THIS CODE IS GENERATED BY greenDAO, DO NOT EDIT. Enable "keep" sections if you want to edit. 
   /**
    * Entity mapped to table USER.
    */
   public class User {
   
       private Long id;
       private String userId;
       private String username;
       private String age;
       private String phone;
   
       public User() {
       }
   
       public User(Long id) {
           this.id = id;
       }
   
       public User(Long id, String userId, String username, String age, String phone) {
           this.id = id;
           this.userId = userId;
           this.username = username;
           this.age = age;
           this.phone = phone;
       }
   
       public Long getId() {
           return id;
       }
   
       public void setId(Long id) {
           this.id = id;
       }
   
       public String getUserId() {
           return userId;
       }
   
       public void setUserId(String userId) {
           this.userId = userId;
       }
   
       public String getUsername() {
           return username;
       }
   
       public void setUsername(String username) {
           this.username = username;
       }
   
       public String getAge() {
           return age;
       }
   
       public void setAge(String age) {
           this.age = age;
       }
   
       public String getPhone() {
           return phone;
       }
   
       public void setPhone(String phone) {
           this.phone = phone;
       }
   
   }
  

• userDao，如果自己实现过简单的ORM框架的话，很容易就看出这个是对sql语句的包装，有createTable（），dropTable,readEntity,updateKeyAfterInsert,这些望文生义的方法

   package com.usst.chensl.introductdemo.db;
   
   import android.database.Cursor;
   import android.database.sqlite.SQLiteDatabase;
   import android.database.sqlite.SQLiteStatement;
   
   import de.greenrobot.dao.AbstractDao;
   import de.greenrobot.dao.Property;
   import de.greenrobot.dao.internal.DaoConfig;
   
   import com.usst.chensl.introductdemo.db.User;
   
   // THIS CODE IS GENERATED BY greenDAO, DO NOT EDIT.
   /** 
    * DAO for table USER.
   */
   public class UserDao extends AbstractDao<User, Long> {
   
       public static final String TABLENAME = "USER";
   
       /**
        * Properties of entity User.<br/>
        * Can be used for QueryBuilder and for referencing column names.
       */
       public static class Properties {
           //参数分别是(列数，类型，Java实体类的变量名，是否主键，数据库列名)
           //因为上面有entity.addIdProperty()，所以自动生成了主键'_id'
           public final static Property Id = new Property(0, Long.class, "id", true, "_id");
           public final static Property UserId = new Property(1, String.class, "userId", false, "USER_ID");
           public final static Property Username = new Property(2, String.class, "username", false, "USERNAME");
           public final static Property Age = new Property(3, String.class, "age", false, "AGE");
           public final static Property Phone = new Property(4, String.class, "phone", false, "PHONE");
       };
   
       public UserDao(DaoConfig config) {
           super(config);
       }
       
       public UserDao(DaoConfig config, DaoSession daoSession) {
           super(config, daoSession);
       }
   
       /** Creates the underlying database table. */
       public static void createTable(SQLiteDatabase db, boolean ifNotExists) {
           String constraint = ifNotExists? "IF NOT EXISTS ": "";
           db.execSQL("CREATE TABLE " + constraint + "'USER' (" + //
                   "'_id' INTEGER PRIMARY KEY ," + // 0: id
                   "'USER_ID' TEXT," + // 1: userId
                   "'USERNAME' TEXT," + // 2: username
                   "'AGE' TEXT," + // 3: age
                   "'PHONE' TEXT);"); // 4: phone
       }
   
       /** Drops the underlying database table. */
       public static void dropTable(SQLiteDatabase db, boolean ifExists) {
           String sql = "DROP TABLE " + (ifExists ? "IF EXISTS " : "") + "'USER'";
           db.execSQL(sql);
       }
   
       /** @inheritdoc */
       @Override
       protected void bindValues(SQLiteStatement stmt, User entity) {
           stmt.clearBindings();
    
           Long id = entity.getId();
           if (id != null) {
               stmt.bindLong(1, id);
           }
    
           String userId = entity.getUserId();
           if (userId != null) {
               stmt.bindString(2, userId);
           }
    
           String username = entity.getUsername();
           if (username != null) {
               stmt.bindString(3, username);
           }
    
           String age = entity.getAge();
           if (age != null) {
               stmt.bindString(4, age);
           }
    
           String phone = entity.getPhone();
           if (phone != null) {
               stmt.bindString(5, phone);
           }
       }
   
       /** @inheritdoc */
       @Override
       public Long readKey(Cursor cursor, int offset) {
           return cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0);
       }    
   
       /** @inheritdoc */
       @Override
       public User readEntity(Cursor cursor, int offset) {
           User entity = new User( //
               cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0), // id
               cursor.isNull(offset + 1) ? null : cursor.getString(offset + 1), // userId
               cursor.isNull(offset + 2) ? null : cursor.getString(offset + 2), // username
               cursor.isNull(offset + 3) ? null : cursor.getString(offset + 3), // age
               cursor.isNull(offset + 4) ? null : cursor.getString(offset + 4) // phone
           );
           return entity;
       }
        
       /** @inheritdoc */
       @Override
       public void readEntity(Cursor cursor, User entity, int offset) {
           entity.setId(cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0));
           entity.setUserId(cursor.isNull(offset + 1) ? null : cursor.getString(offset + 1));
           entity.setUsername(cursor.isNull(offset + 2) ? null : cursor.getString(offset + 2));
           entity.setAge(cursor.isNull(offset + 3) ? null : cursor.getString(offset + 3));
           entity.setPhone(cursor.isNull(offset + 4) ? null : cursor.getString(offset + 4));
        }
       
       /** @inheritdoc */
       @Override
       protected Long updateKeyAfterInsert(User entity, long rowId) {
           entity.setId(rowId);
           return rowId;
       }
       
       /** @inheritdoc */
       @Override
       public Long getKey(User entity) {
           if(entity != null) {
               return entity.getId();
           } else {
               return null;
           }
       }
   
       /** @inheritdoc */
       @Override    
       protected boolean isEntityUpdateable() {
           return true;
       }
       
   }
  

• DaoSession,数据库Session

   package com.usst.chensl.introductdemo.db;
   
   import android.database.sqlite.SQLiteDatabase;
   
   import java.util.Map;
   
   import de.greenrobot.dao.AbstractDao;
   import de.greenrobot.dao.AbstractDaoSession;
   import de.greenrobot.dao.identityscope.IdentityScopeType;
   import de.greenrobot.dao.internal.DaoConfig;
   
   import com.usst.chensl.introductdemo.db.User;
   
   import com.usst.chensl.introductdemo.db.UserDao;
   
   // THIS CODE IS GENERATED BY greenDAO, DO NOT EDIT.
   
   /**
    * {@inheritDoc}
    * 
    * @see de.greenrobot.dao.AbstractDaoSession
    */
   public class DaoSession extends AbstractDaoSession {
   
       private final DaoConfig userDaoConfig;
   
       private final UserDao userDao;
   
       public DaoSession(SQLiteDatabase db, IdentityScopeType type, Map<Class<? extends AbstractDao<?, ?>>, DaoConfig>
               daoConfigMap) {
           super(db);
   
           userDaoConfig = daoConfigMap.get(UserDao.class).clone();
           userDaoConfig.initIdentityScope(type);
   
           userDao = new UserDao(userDaoConfig, this);
   
           registerDao(User.class, userDao);
       }
       
       public void clear() {
           userDaoConfig.getIdentityScope().clear();
       }
   
       public UserDao getUserDao() {
           return userDao;
       }
   
   }
  

• DaoMaster,对SQLiteDatabase的封装,包含了UserDao

   package com.usst.chensl.introductdemo.db;
   
   import android.content.Context;
   import android.database.sqlite.SQLiteDatabase;
   import android.database.sqlite.SQLiteDatabase.CursorFactory;
   import android.database.sqlite.SQLiteOpenHelper;
   import android.util.Log;
   import de.greenrobot.dao.AbstractDaoMaster;
   import de.greenrobot.dao.identityscope.IdentityScopeType;
   
   import com.usst.chensl.introductdemo.db.UserDao;
   
   // THIS CODE IS GENERATED BY greenDAO, DO NOT EDIT.
   /** 
    * Master of DAO (schema version 1): knows all DAOs.
   */
   public class DaoMaster extends AbstractDaoMaster {
       public static final int SCHEMA_VERSION = 1;
   
       /** Creates underlying database table using DAOs. */
       public static void createAllTables(SQLiteDatabase db, boolean ifNotExists) {
           UserDao.createTable(db, ifNotExists);
       }
       
       /** Drops underlying database table using DAOs. */
       public static void dropAllTables(SQLiteDatabase db, boolean ifExists) {
           UserDao.dropTable(db, ifExists);
       }
       
       //抽象类
       public static abstract class OpenHelper extends SQLiteOpenHelper {
           
           public OpenHelper(Context context, String name, CursorFactory factory) {
               super(context, name, factory, SCHEMA_VERSION);
           }
   
           @Override
           public void onCreate(SQLiteDatabase db) {
               Log.i("greenDAO", "Creating tables for schema version " + SCHEMA_VERSION);
               createAllTables(db, false);
           }
       }
       
       //真正实现类
       /** WARNING: Drops all table on Upgrade! Use only during development. */
       public static class DevOpenHelper extends OpenHelper {
       
           public DevOpenHelper(Context context, String name, CursorFactory factory) {
               super(context, name, factory);
           }
   
           @Override
           public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
               Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by dropping all tables");
               dropAllTables(db, true);
               onCreate(db);
           }
       }
   
       public DaoMaster(SQLiteDatabase db) {
           super(db, SCHEMA_VERSION);
           registerDaoClass(UserDao.class);
       }
       
       public DaoSession newSession() {
           return new DaoSession(db, IdentityScopeType.Session, daoConfigMap);
       }
       
       public DaoSession newSession(IdentityScopeType type) {
           return new DaoSession(db, type, daoConfigMap);
       }
       
   }
  

DbMaster的最终目的是获取DbSession,通过DbSession对数据库进行操作。

下一篇说GreenDao具体使用，敬请期待~