GreenDao数据库

ORM框架

首先，来认识ORM是什么

ORM是一种对象关系映射，它的实现思想就是把数据库的表数据映射成对象，以便我们对这些对象的操作，我们把对数据库的操作简化成对对象的操作，提高开发效率。

GreenDao

这里参考了老罗视频第三季的视频，总结一下，做了个小实例

关于GreenDao的配置

1. 建包

新建一个与java同级别的包以及一个Module（daogenerator），选择的是javaLibrary

2、 在module包中写一个类
在module里面也要导第三方包

public class DaoMaker {    public static void main(String[] args){        //生成数据库的实体类XXentity 对应的是数据库的表，参数1是版本号        Schema schema = new Schema(1,"com.student.entity");        //添加一张表        addStudent(schema);        schema.setDefaultJavaPackageDao("com.student.dao");        try {            //生成到java-gen，传入javagen的地址            new DaoGenerator().generateAll(schema,"E:\\Frame\\app\\src\\main\\java-gen");        } catch (Exception e) {            e.printStackTrace();        }    }    private static void addStudent(Schema schema){        //创建数据库的表        Entity entity = schema.addEntity("Student");        //主键是int类型        entity.addIdProperty();        entity.addStringProperty("name");        entity.addStringProperty("address");        entity.addIntProperty("age");    }}

在原来的项目中的build.gradle中添加依赖

//greendao依赖    compile 'de.greenrobot:greendao:2.1.0'    compile 'de.greenrobot:greendao-generator:2.1.0'

android {    sourceSets{        main{            java.srcDirs=['src/main/java','src/main/java-gen']        }     }   }

运行之后javagen就有类了

GreenDao的核心类

• greendao-generator.jar产生的是DAO的接口(即我们建立的Mdoule包产生的接口)

• 核心的greendao.jar产生的类

  

XXEntity：对应的是数据库的表。

DaoMester: 就是用来建表和删除表，并且提供了内部帮助类OpenHelper,DevOpenHelper

DaoSession: 对应的会话层，具体操作数据库表对应的对象，并且提供了对应的增删改查的操作

XXDao: 通常对应具体的java类，为每一个数据库表对象创建一个DAO,它有批量或者具体操作数据的方法，比DaoSession更牛逼

Schema : 生产实体对象的类

3、操作数据库

• 建立一个管理数据库的类，对数据库对象进行获取，创建，删除，提供操作的接口

public class DBManager {    public static final String TAG = DBManager.class.getSimpleName();    public static final String DB_NAME = "mydb.sqlite";    //多线程访问    public volatile static DBManager dbManager;    public static DaoMaster.DevOpenHelper devOpenHelper;    public static DaoSession daoSession;    public static DaoMaster daoMaster;    public Context context;    /**     * 单例模式获取操作数据库对象     * @return     */    public static DBManager getInstance(){        DBManager instance = null;        if(dbManager == null){            synchronized (DBManager.class){                if(instance == null){                    dbManager = new DBManager();                    instance = dbManager;                }            }        }        return instance;    }    public void init(Context context){        this.context = context;    }    /**     * 判断是否创建数据库，没有就创建     * @return     */    public DaoMaster getDaoMaster(){        if(daoMaster == null){            DaoMaster.DevOpenHelper devOpenHelper = new DaoMaster.DevOpenHelper(context,DB_NAME,null);            daoMaster = new DaoMaster(devOpenHelper.getWritableDatabase());        }        return daoMaster;    }    /**     * 完成对数据库的操作 ，仅仅是个接口     * @return     */    public DaoSession getDaoSession(){        if(daoSession == null){            if(daoMaster == null){                daoMaster = getDaoMaster();            }            daoSession = daoMaster.newSession();        }        return daoSession;    }    /**     * 打开输出日志的方法     */    public void setDug(){        QueryBuilder.LOG_SQL = true;        QueryBuilder.LOG_VALUES = true;    }    /**     * 关闭所有操作     */    public void closeConnection(){        closeHelper();        closeSession();    }    public void closeSession(){        if(daoSession != null){            daoSession.clear();            daoSession = null;        }    }    public void closeHelper(){        if(devOpenHelper != null){            devOpenHelper.close();            devOpenHelper = null;        }    }}

• 封装一个工具类，实现操作接口，对数据进行操作

package com.gzucm.frame.GreenDao.dbManager;import android.content.Context;import com.student.dao.StudentDao;import com.student.entity.Student;import java.util.List;import de.greenrobot.dao.query.QueryBuilder;public class CommonUtils {    private DBManager dbManager;    public CommonUtils(Context context){        dbManager = DBManager.getInstance();        dbManager.init(context);    }    public boolean insertStudent(Student student){        boolean flag = false;        flag = dbManager.getDaoSession().insert(student) != -1? true:false;        return flag;    }    public boolean insertMultStudent(final List<Student> students){        boolean flag = false;        try{            dbManager.getDaoSession().runInTx(new Runnable() {                @Override                public void run() {                    for(Student student:students){                        dbManager.getDaoSession().insertOrReplace(student);                    }                }            });            flag = true;        }catch(Exception e){            e.printStackTrace();        }        return flag;    }    /**     * 完成对student的某一条记录的修改     * @param student     * @return     */    public boolean updateStudent(Student student){        boolean flag = false;        try{            dbManager.getDaoSession().update(student);            flag = true;        }catch(Exception e){            e.printStackTrace();        }        return  flag;    }    /**     * 删除一条记录     * @param student     * @return     */    public boolean deleteStudent(Student student){        boolean flag = false;        try{            dbManager.getDaoSession().delete(student);            flag = true;        }catch(Exception e){            e.printStackTrace();        }        return  flag;    }    /**     * 删除所有记录     * @param cls     * @return     */    public boolean deleteAllStudent(Class cls){        boolean flag = false;        try{            //删除Student所有对象            dbManager.getDaoSession().deleteAll(Student.class);            flag = true;        }catch(Exception e){            e.printStackTrace();        }        return  flag;    }    /**     * 返回多条记录     * @return     */    public List<Student> listAll(){        return dbManager.getDaoSession().loadAll(Student.class);    }    /**     * 按照主键返回单行记录     * @param key     * @return     */    public Student listOneStudent(long key){        return dbManager.getDaoSession().load(Student.class,key);    }    public void query1(){        //使用native sql进行查询操作        List<Student> list = dbManager.getDaoSession().queryRaw(Student.class,                " where name like ? and _id > ? ",new String[]{"%李%","1001"});    }    public void query2(){        QueryBuilder<Student> builder = dbManager.getDaoSession().queryBuilder(Student.class);        List<Student> list = builder.where(StudentDao.Properties.Age.ge(23))                .where(StudentDao.Properties.Address.like("江西")).list();    }    public void query3(){        QueryBuilder<Student> builder = dbManager.getDaoSession().queryBuilder(Student.class);        builder.whereOr(StudentDao.Properties.Age.ge(50),StudentDao.Properties.Address.eq("北京"));        //取前三条数据        builder.whereOr(StudentDao.Properties.Id.ge(2),StudentDao.Properties.Age.ge(10)).limit(3);        List<Student> list = builder.list();    }}

• 对应的activity,通过UI进行操作数据

package com.gzucm.frame.GreenDao;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ListView;import com.gzucm.frame.GreenDao.dbManager.CommonUtils;import com.gzucm.frame.R;import com.student.entity.Student;import java.util.ArrayList;import java.util.List;public class GreenActivity extends AppCompatActivity{    private ListView lv_content;    private StudentListAdapter adapter;    private List<Student> students;    CommonUtils commonUtils;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activitygreendao);        lv_content = (ListView) findViewById(R.id.lv_content);        commonUtils = new CommonUtils(this);        insertMultData();    }    public void add(View view){        addStudent();    }    public void delete(View view){        commonUtils.deleteAllStudent(Student.class);//        insertMultData();    }    public void update(View view){        updateStudent();    }    public void query(View view){        queryStudent();    }    public void insert(View view){        insertMultData();    }    private void queryStudent() {//        students = new ArrayList<>();        students = commonUtils.listAll();        adapter = new StudentListAdapter(this, students);        lv_content.setAdapter(adapter);    }    private void addStudent() {        Student student = new Student();        student.setAddress("广州三元里");        student.setName("XXX");        student.setAge(22);        student.setId(5201314l);        commonUtils.insertStudent(student);        queryStudent();    }    private void updateStudent() {        Student student = new Student();        student.setId(1l);        student.setAge(100);        student.setName("jack");        student.setAddress("北京育知同创科技有限公司");        commonUtils.updateStudent(student);        queryStudent();    }    public void insertMultData(){        List<Student> students = new ArrayList<>();        for(int i=0;i<10;i++){            Student student = new Student();            student.setAddress("江西");            student.setName("李四" +i);            student.setAge(24+i);            students.add(student);        }        commonUtils.insertMultStudent(students);        queryStudent();    }}

package com.gzucm.frame.GreenDao;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;import com.gzucm.frame.R;import com.student.entity.Student;import java.util.List;public class StudentListAdapter extends BaseAdapter {    private List<Student> list;    private LayoutInflater mInflater;    public StudentListAdapter(Context context, List<Student> list) {        this.list = list;        mInflater = LayoutInflater.from(context);    }    @Override    public int getCount() {        return list.size();    }    @Override    public Object getItem(int position) {        return list.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        if (convertView == null) {            convertView = mInflater.inflate(R.layout.activity_greendao_item, null);        }        ViewHolder holder = getViewHolder(convertView);        Student student = list.get(position);        holder.tv_name.setText(student.getName());        holder.tv_address.setText(student.getAddress());        holder.tv_age.setText(student.getAge() + "");        holder.tv_id.setText(student.getId() + "");        return convertView;    }    /**     * 获得控件管理对象     *     * @param view     * @return     */    private ViewHolder getViewHolder(View view) {        ViewHolder holder = (ViewHolder) view.getTag();        if (holder == null) {            holder = new ViewHolder(view);            view.setTag(holder);        }        return holder;    }    /**     * 控件管理类     */    private class ViewHolder {        private TextView tv_name, tv_address, tv_age, tv_id;        ViewHolder(View view) {            tv_name = (TextView) view.findViewById(R.id.textView);            tv_address = (TextView) view.findViewById(R.id.textView2);            tv_age = (TextView) view.findViewById(R.id.textView3);            tv_id = (TextView) view.findViewById(R.id.textView4);        }    }}