項目配置
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'生成代碼
項目示例2
我們需要在包根目錄新建一個Java文件，做初始化工作。
如圖所示，包的根目錄是'com.usst.chensl.greendaodemo'，創建一個名為'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) {
//指定實體類
Entity entity = schema.addEntity("User");
//添加id屬性
entity.addIdProperty();
//添加列userId,指定非空，默認可為空
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 {
//生成數據庫文件的目標包名//target package for dao files
//第一個參數是數據庫版本號，第二個參數是包的根目錄的包
Schema schema = new Schema(1, "db");
addDetail(schema);
try {
//第二個參數是src-gen文件夾相對路徑
//'..'代表工程前一個目錄,接著是工程名/app(AndroidStudio生成)/
new DaoGenerator().generateAll(schema, "../GreenDaoDemo/app/src/main/java/com/usst/chensl/greendaodemo/");
} catch (Exception e) {
e.printStackTrace();
}
}
}
Entity可以看作是一張表,它使用構造器模式來設計，可以指定某一列的各種數據庫屬性，例如非空，自增，升降序，主鍵等。
同時，在工程目錄下新建src-gen文件夾，放置代碼生成的數據庫文件。
項目文件結構目錄
對著ExampleDaoGenerator右鍵，選擇run ... main()，會在src-gen文件夾中生成四個文件。
注意：必須要使用run main()這種方法，在AndroidStudio下直接對該文件右鍵即可選擇run main(),之前LZ試過在onCreate()里跑結果報錯
下面來看看初始化出來的東西：
項目實例3
將db包拖動到包的根目錄下，然后可以將src-gen文件夾下的東西全部刪掉了。
初始化完成
初始化完成后，'ExampleDaoGenerator'就沒用了，留著修改后可以創建另一個表，不需要可以刪除。
-
user實體類，注釋已經說明是GreenDao自動生成的。其實就跟自己建實體類一樣，不過現在是代碼自動生成
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，如果自己實現過簡單的ORM框架的話，很容易就看出這個是對sql語句的包裝，有
createTable（），dropTable,readEntity,updateKeyAfterInsert,這些望文生義的方法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 { //參數分別是(列數，類型，Java實體類的變量名，是否主鍵，數據庫列名) //因為上面有entity.addIdProperty()，所以自動生成了主鍵'_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,數據庫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,對
SQLiteDatabase的封裝,包含了UserDaopackage 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); } //抽象類 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); } } //真正實現類 /** 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的最終目的是獲取DbSession,通過DbSession對數據庫進行操作。
下一篇說GreenDao具體使用，敬請期待~
