android之SQLOpenHelper(开源)

public class SQLiteHelperActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView et_name;
    private EditText et_age;
    private EditText et_height;
    private EditText et_weight;
    private CheckBox ck_married;
    private UserDBHelper mHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sqlite_helper);
        et_name = findViewById(R.id.et_name);
        et_age = findViewById(R.id.et_age);
        et_height = findViewById(R.id.et_height);
        et_weight = findViewById(R.id.et_weight);
        ck_married = findViewById(R.id.ck_married);


        findViewById(R.id.bth_save).setOnClickListener(this);
        findViewById(R.id.bth_delete).setOnClickListener(this);
        findViewById(R.id.bth_updata).setOnClickListener(this);
        findViewById(R.id.bth_query).setOnClickListener(this);
    }

    @Override
    protected void onStart() {
        super.onStart();
        //获得数据库帮助器的实例
        mHelper = UserDBHelper.getInstance(this);
        //打开数据库帮助器的写连接
        mHelper.openWriteLink();
        //打开数据库的读连接
        mHelper.openReadLink();
    }

    @Override
    protected void onStop() {
        super.onStop();
        //关闭数据库连接
       mHelper.closeLink();
    }

    @Override
    public void onClick(View v) {
        String name=et_name.getText().toString();
        String age=et_age.getText().toString();
        String height=et_height.getText().toString();
        String weight=et_weight.getText().toString();
        User user=null;

        switch (v.getId()){
            case R.id.bth_save:
                //以下声明一个用户信息对象,并填写它的各字段值
                user=new User(name,
                        Integer.parseInt(age),
                        Long.parseLong(height),
                        Long.parseLong(weight),
                        ck_married.isChecked());
              mHelper.insert(user);
              if(mHelper.insert(user)>0){
                  ToastUtil.show(this,"添加成功");
              }
                break;

        }
    }
}

public class UserDBHelper extends SQLiteOpenHelper {

    private  static  final  String DB_NAME="user.db";
    private  static  final  String TABLE_NAME="user_info";
    private  static  final  int DB_VERISON=1;

    private SQLiteDatabase mRDB=null;
    private SQLiteDatabase mWDB=null;

    private  static  UserDBHelper mHelper=null;


    private  UserDBHelper(Context context){
        super(context,DB_NAME,null,DB_VERISON);
    }

    //利用单例模式获取数据库帮助器的唯一实例
    public static UserDBHelper getInstance(Context context){
   if(mHelper==null){
       mHelper=new UserDBHelper(context);
   }
    return mHelper;
   }
   //打开数据库的读连接
    public  SQLiteDatabase openReadLink(){
        if(mRDB==null || !mRDB.isOpen()){
            mRDB=mHelper.getReadableDatabase();
        }
        return mRDB;
    }

    //打开数据库的写连接
    public  SQLiteDatabase openWriteLink(){
        if(mWDB==null || !mWDB.isOpen()){
            mWDB=mHelper.getWritableDatabase();
        }
        return mWDB;
    }


    //关闭数据的连接
    public void closeLink(){
    if(mRDB !=null && mRDB.isOpen()){
        mRDB.close();
        mRDB=null;
    }else if(mWDB !=null && mWDB.isOpen()){
        mWDB.close();
    }
    }

    //创建数据库,执行建表语句
    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql="CREATE TABLE IF NOT EXISTS "+TABLE_NAME+"("+
                "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,"+
                "name VARCHAR NOT NULL, "+
                "age  INTEGER NOT NULL, "+
                "height LONG NOT NULL, "+
                "weight Float NOT NULL, "+
                "married  INTEGER NOT NULL);";
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    public long insert(User user){
        ContentValues values=new ContentValues();
        values.put("name",user.name);
        values.put("age",user.age);
        values.put("height",user.height);
        values.put("weight",user.weight);
        values.put("married",user.married);
        return mWDB.insert(TABLE_NAME,null,values);

    }
}