GreenDao3基本配置和简单使用

作者: l1zheng | 来源:发表于2017-03-27 18:28 被阅读70次

简介

greenDao是一个将对象映射到SQLite数据库中的轻量且快速的ORM解决方案。

参考

官网 http://greenrobot.org/greendao/
Github https://github.com/greenrobot/greenDAO

配置greenDao

//根目录下的build.gradle下配置
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.0'
        classpath 'org.greenrobot:greendao-gradle-plugin:3.2.1' //<-- add greenDao plugin
    }
}
//app目录下的build.gradle配置
apply plugin: 'com.neenbedankt.android-apt'

greendao {
    schemaVersion 1 //指定版本号,数据库升级的时候用
    //可选属性
    //daoPackage 'xxxx' 生成的DAOs，daomaster，和daosession包名。 默认为源实体的包名
    //targetGenDir 'xxxx' 生成源应保存在该位置。 默认为构建目录里面生成的源文件夹（ build/generated/source/greendao ）。
    //generatetests true  设置为true 自动生成单元测试。
    //targetGenDirTests 'xxxx' 指定单元测试存储目录。默认为 src/androidTest/java。
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'org.greenrobot:greendao:3.2.0' //<-- greenDao
}

实体和注解

@Entity
public class Student {
    @Id
    private long stuId;
    @Property(nameInDb = "NAME")
    private String stuName;
    @NotNull
    private int age;
    @Transient
    private String desc;
}

Build - > Make Project 后会自动生成get/set方法并在build/generated/source/greendao/项目entity包名目录下生成相关Dao类

实体注解

schema：告知GreenDao当前实体属于哪个schema
active：标记一个实体处于活动状态，活动实体有更新、删除和刷新方法
nameInDb：在数据中使用的别名，默认使用的是实体的类名
indexes：定义索引，可以跨越多个列
createInDb：标记创建数据库表

基础属性注解

@Id :主键 Long型，可以通过@Id(autoincrement = true)设置自增长
@Property：设置保存到数据库中的列名，默认是的使用字段名 
@NotNul：设置数据库表当前列非空
@Transient ：添加次标记该属性不会插入到数据库

索引注解

@Index：使用@Index作为一个属性来创建一个索引，通过name设置索引别名，也可以通过unique给索引添加约束
@Unique：向数据库列添加了一个唯一的约束

关系注解

@ToOne：定义与另一个实体（一个实体对象）的关系
@ToMany：定义与多个实体对象的关系

@generated 由greendao产生的构造函数或方法(官方不建议修改此处的代码)

使用

在程序Application中配置

public class App extends Application {

    private static DaoSession daoSession;

    @Override
    public void onCreate() {
        super.onCreate();
        //配置数据库
        setupDatabase();
        //配置可加密的数据库
        //setupPwdDatabase();
    }

    /**
     * 配置数据库
     */
    private void setupDatabase() {
        //创建数据库study.db"
        DaoMaster.DevOpenHelper helper = new DaoMaster.DevOpenHelper(this, "study.db", null);
        //获取可写数据库
        SQLiteDatabase db = helper.getWritableDatabase();
        //获取数据库对象
        DaoMaster daoMaster = new DaoMaster(db);
        //获取Dao对象管理者
        daoSession = daoMaster.newSession();
    }

    /**
     * 配置可加密的数据库(pwd为字符串密码)
     */
    private void setupPwdDatabase(){
        //创建数据库study.db"
        DaoMaster.DevOpenHelper helper = new DaoMaster.DevOpenHelper(this, "study.db", null);
        //获取数据库对象
        DaoMaster daoMaster = new DaoMaster(helper.getEncryptedWritableDb("pwd"));
        //获取Dao对象管理者
        daoSession = daoMaster.newSession();
    }

    public static DaoSession getDaoInstant() {
        return daoSession;
    }
}

获取StudentDao对象

StudentDao studentDao=App.getDaoInstant().getStudentDao();

简单的增删改查实现

增

Student stu = new Student(1, "小明", 10);
studentDao.insert(stu);
studentDao.insertOrReplace(stu); //替换插入,当id相同情况下replace否则为insert

删

studentDao.deleteByKey(key);
studentDao.deleteAll();//批量删除

改

Student stu = new Student(1, "小明", 11);
studentDao.update(stu);

查

List<Student> stuList = studentDao.loadAll(); //批量查询
Student stu = studentDao.load(key);  //根据id查询
//条件查询(id>1并且stuName like "小",根据age降序)
List<Student> stuList = studentDao.queryBuilder().where(StudentDao.Properties.StuId.gt(1), StudentDao.Properties.StuName.like("小"))
                .orderDesc(StudentDao.Properties.Age).list();

数据库升级

首先在module的gradle文件中修改版本号

greendao {
    schemaVersion 2  //之前是1
//    daoPackage 'greendao'
//    targetGenDir 'src/main/java'
}

如果只做了上边的操作,默认的会清除数据库的所有表,然后再重建数据库,查看DaoMaster.DevOpenHelper源码如下

/** WARNING: Drops all table on Upgrade! Use only during development. */
    public static class DevOpenHelper extends OpenHelper {
        public DevOpenHelper(Context context, String name) {
            super(context, name);
        }

        public DevOpenHelper(Context context, String name, CursorFactory factory) {
            super(context, name, factory);
        }

        @Override
        public void onUpgrade(Database db, int oldVersion, int newVersion) {
            Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by dropping all tables");
            dropAllTables(db, true); // 这里会删除所有表
            onCreate(db);  //重建数据库
        }
    }

对于上线的项目,必须要做数据迁移,借用stackoverflow里大神的工具类:

public class MigrationHelper{

    private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION = "MIGRATION HELPER - CLASS DOESN'T MATCH WITH THE CURRENT PARAMETERS";
    private static MigrationHelper instance;

    public static MigrationHelper getInstance() {
        if(instance == null) {
            instance = new MigrationHelper();
        }
        return instance;
    }

    public void migrate(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        generateTempTables(db, daoClasses);
        DaoMaster.dropAllTables(db, true);
        DaoMaster.createAllTables(db, false);
        restoreData(db, daoClasses);
    }

    private void generateTempTables(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for(int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);

            String divider = "";
            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            ArrayList<String> properties = new ArrayList<>();

            StringBuilder createTableStringBuilder = new StringBuilder();

            createTableStringBuilder.append("CREATE TABLE ").append(tempTableName).append(" (");

            for(int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if(getColumns(db, tableName).contains(columnName)) {
                    properties.add(columnName);

                    String type = null;

                    try {
                        type = getTypeByClass(daoConfig.properties[j].type);
                    } catch (Exception exception) {
                        exception.printStackTrace();
                        //Crashlytics.logException(exception);
                    }

                    createTableStringBuilder.append(divider).append(columnName).append(" ").append(type);

                    if(daoConfig.properties[j].primaryKey) {
                        createTableStringBuilder.append(" PRIMARY KEY");
                    }

                    divider = ",";
                }
            }
            createTableStringBuilder.append(");");

            db.execSQL(createTableStringBuilder.toString());

            StringBuilder insertTableStringBuilder = new StringBuilder();

            insertTableStringBuilder.append("INSERT INTO ").append(tempTableName).append(" (");
            insertTableStringBuilder.append(TextUtils.join(",",properties));
            insertTableStringBuilder.append(") SELECT ");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(" FROM ").append(tableName).append(";");

            db.execSQL(insertTableStringBuilder.toString());
        }
    }

    private void restoreData(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for(int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);

            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            ArrayList<String> properties = new ArrayList<>();

            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if(getColumns(db, tempTableName).contains(columnName)) {
                    properties.add(columnName);
                }
            }

            StringBuilder insertTableStringBuilder = new StringBuilder();

            insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(") SELECT ");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");

            StringBuilder dropTableStringBuilder = new StringBuilder();

            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);

            db.execSQL(insertTableStringBuilder.toString());
            db.execSQL(dropTableStringBuilder.toString());
        }
    }

    private String getTypeByClass(Class<?> type) throws Exception{
        if(type.equals(String.class)) {
            return "TEXT";
        }
        if(type.equals(Long.class) || type.equals(Integer.class) || type.equals(long.class)) {
            return "INTEGER";
        }
        if(type.equals(Boolean.class)) {
            return "BOOLEAN";
        }

        Exception exception = new Exception(CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat(" - Class: ").concat(type.toString()));
        //Crashlytics.logException(exception);
        throw exception;
    }

    private static List<String> getColumns(Database db,String tableName) {
        List<String> columns = new ArrayList<>();
        Cursor cursor = null;
        try {
            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 1", null);
            if (cursor != null) {
                columns = new ArrayList<>(Arrays.asList(cursor.getColumnNames()));
            }
        } catch (Exception e) {
            Log.v(tableName,e.getMessage(),e);
            e.printStackTrace();
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return columns;
    }
}

用法

新建类继承DaoMaster.DevOpenHelper,重写onUpgrade方法判断版本变化

public class MyOpenHelper extends DaoMaster.DevOpenHelper {

    public MyOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
        super(context, name, factory);
    }

    @Override
    public void onUpgrade(Database db, int oldVersion, int newVersion) {
        switch (newVersion){
            case 1:break;
            case 2:
                //新版本,执行数据迁移
                MigrationHelper.getInstance().migrate(db, StudentDao.class, TeacherDao.class);
                break;
        }
    }
}

然后替换Application中初始化的DaoMaster.DevOpenHelper为MyOpenHelper

    /**
     * 配置数据库
     */
    private void setupDatabase() {
        //创建数据库study.db"
        MyOpenHelper helper = new MyOpenHelper(this, "study.db", null);
        //获取可写数据库
        SQLiteDatabase db = helper.getWritableDatabase();
        //获取数据库对象
        DaoMaster daoMaster = new DaoMaster(db);
        //获取Dao对象管理者
        daoSession = daoMaster.newSession();
    }

over~
此文只是简单的greenDao的配置和使用,详细使用及文档,请移步官网

GreenDao3基本配置和简单使用

简介

参考

配置greenDao

实体和注解

使用

简单的增删改查实现

增

删

改

查

数据库升级

用法

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