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);
        }
    }
}