SQLite簡介

SQLite是一個實現了自給自足的、無伺服器的、零配置的、事務性的SQL資料庫引擎，並且是一個開源專案。

Android上自帶SQLite，因此是Android專案上常用的資料庫。

 一個簡單的demo通過SQLiteOpenHelper類實現了SQLite的增刪改查操作

Person.java

public class Person implements Serializable {

    //序列化的版本號
    private static final long serialVersionUID = 1L;

    private int id;

    private String name;

    private int age;

    private String sex;

    public Person() {
    }

    public Person(String name, int age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    public Person(int id, String name, int age, String sex) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
    }



    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
}
 

 SQLiteHelper.java

public class SQLiteHelper extends SQLiteOpenHelper {

    private static final String TAG = "SQLiteHelper";
	//資料庫名
    private static final String DATABASE_NAME = "mydb.db";
	//資料庫 表名
    public static final String PERSON_TABLE_NAME = "person";
    public static final String USER_TABLE_NAME = "user";

    public SQLiteHelper(Context context, int version) {
        super(context, DATABASE_NAME, null, version);
    }

    //建立資料庫
    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.e(TAG, "資料庫建立");
        String sql1 = "create table if not exists " + PERSON_TABLE_NAME +
                "(id integer Primary Key autoincrement," +
                "name varchar(20)," +
                "age integer," +
                "sex varchar(20))";
        String sql2 = "create table if not exists " + USER_TABLE_NAME +
                "(id integer Primary Key autoincrement," +
                "name varchar(20)," +
                "age integer," +
                "sex varchar(20))";
		//執行sql語句
        db.execSQL(sql1);
        db.execSQL(sql2);
    }

    //更新資料庫
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.e(TAG, "資料庫更新");
    }

    //以下 增刪改查函式可以放到Activity中
    //插入
    public void insertPerson(Person person) {
        Log.e(TAG, "插入");

        SQLiteDatabase db = getWritableDatabase();
        String sql = "insert into " + PERSON_TABLE_NAME + "(name,age,sex) values("
                + String.format("'%s'", person.getName()) + ","
                + person.getAge() + ","
                + String.format("'%s'", person.getSex()) +
                ");";
        //插入資料庫
        db.execSQL(sql);

        db.close();
    }

    //更新
    public void updatePerson(Person person) {
        Log.e(TAG, "更新");
        SQLiteDatabase db = getWritableDatabase();
        String sql = "update " + PERSON_TABLE_NAME + " set name = "
                + String.format("'%s'", person.getName())
                + ",age = " + person.getAge()
                + ",sex = " + String.format("'%s'", person.getSex())
                + "where id = " + person.getId();
        db.execSQL(sql);
        db.close();
    }

    //刪除
    public void deletePersonById(int id) {
        Log.e(TAG, "刪除");
        SQLiteDatabase db = getWritableDatabase();
        String sql = "id = ?";
        String wheres[] = {String.valueOf(id)};
        db.delete(PERSON_TABLE_NAME, sql, wheres);
        db.close();
    }

    //查詢所有
    public List<Person> queryAllPerson() {
        List<Person> list = new ArrayList<>();
        SQLiteDatabase db = getReadableDatabase();
        String sql = "select * from " + PERSON_TABLE_NAME;
        Cursor cursor = db.rawQuery(sql, null);
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            int age = cursor.getInt(cursor.getColumnIndex("age"));
            String sex = cursor.getString(cursor.getColumnIndex("sex"));

            Person person = new Person();
            person.setId(id);
            person.setName(name);
            person.setAge(age);
            person.setSex(sex);
            list.add(person);
        }
        cursor.close();
        db.close();
        return list;
    }

    //根據id查詢
    public Person queryPersonById(int id) {
        Person person = null;
        SQLiteDatabase db = getReadableDatabase();
        String[] columns = {"id", "name", "age", "sex"};
        String selection = "id = ?";
        String[] selectionArgs = {String.valueOf(id)};
        Cursor cursor = db.query(PERSON_TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        if (cursor.moveToNext()) {
            person = new Person();
            person.setId(cursor.getInt(cursor.getColumnIndex("id")));
            person.setAge(cursor.getInt(cursor.getColumnIndex("age")));
            person.setName(cursor.getString(cursor.getColumnIndex("name")));
            person.setSex(cursor.getString(cursor.getColumnIndex("sex")));
        }
        cursor.close();
        db.close();
        return person;
    }
}
 

 InsertDialog.java

public class InsertDialog extends Activity implements View.OnClickListener {

    //插入請求程式碼 大於0
    private static final int INSERT_RESULTCODE = 11;
    //姓名控制元件
    private EditText nameView;
    //年齡控制元件
    private EditText ageView;
    //性別控制元件
    private EditText sexView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //去掉標題欄
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_insert_dialog);

        nameView = (EditText) findViewById(R.id.insert_edit_name);
        ageView = (EditText) findViewById(R.id.insert_edit_age);
        sexView = (EditText) findViewById(R.id.insert_edit_sex);

        Button confirmBtn = (Button) findViewById(R.id.insert_confirm);
        Button cancelBtn = (Button) findViewById(R.id.insert_cancel);
        confirmBtn.setOnClickListener(this);
        cancelBtn.setOnClickListener(this);

    }

    private void confirm() {
        String name = String.valueOf(nameView.getText());
        int age = Integer.valueOf(String.valueOf(ageView.getText()));
        String sex = String.valueOf(sexView.getText());
        Person person = new Person(name, age, sex);
        Intent intent = new Intent();
        intent.putExtra("person", person);
        setResult(INSERT_RESULTCODE, intent);
        finish();
    }

    private void cancel() {
        setResult(INSERT_RESULTCODE);
        finish();
    }

    @Override
    public void onClick(View v) {

        switch (v.getId()) {
            case R.id.insert_confirm:
                confirm();
                break;
            case R.id.insert_cancel:
                cancel();
                break;
            default:
                break;
        }

    }
}
 

 DeleteDialog.java

public class DeleteDialog extends Activity implements View.OnClickListener {

    //插入請求程式碼
    private static final int DELETE_RESULTCODE = 22;
    //id控制元件
    private EditText idView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_delete_dialog);

        idView = (EditText) findViewById(R.id.delete_edit_id);
        Button confirmBtn = (Button) findViewById(R.id.delete_confirm);
        Button cancelBtn = (Button) findViewById(R.id.delete_cancel);
        confirmBtn.setOnClickListener(this);
        cancelBtn.setOnClickListener(this);
    }

    private void confirm() {
        int id = Integer.valueOf(String.valueOf(idView.getText()));
        Intent intent = new Intent();
        intent.putExtra("id", id);
        setResult(DELETE_RESULTCODE, intent);
        finish();
    }

    private void cancel() {
        setResult(DELETE_RESULTCODE);
        finish();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.delete_confirm:
                confirm();
                break;
            case R.id.delete_cancel:
                cancel();
                break;
            default:
                break;

        }
    }
}

 UpdateDialog.java

public class UpdateDialog extends Activity implements View.OnClickListener {
    //修改請求程式碼
    private static final int UPDATE_RESULTCODE = 33;
    //id控制元件
    private EditText idView;
    //姓名控制元件
    private EditText nameView;
    //年齡控制元件
    private EditText ageView;
    //性別控制元件
    private EditText sexView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_update_dialog);

        idView = (EditText) findViewById(R.id.update_edit_id);
        nameView = (EditText) findViewById(R.id.update_edit_name);
        ageView = (EditText) findViewById(R.id.update_edit_age);
        sexView = (EditText) findViewById(R.id.update_edit_sex);

        Button confirmBtn = (Button) findViewById(R.id.update_confirm);
        Button cancelBtn = (Button) findViewById(R.id.update_cancel);
        confirmBtn.setOnClickListener(this);
        cancelBtn.setOnClickListener(this);
    }

    private void confirm() {
        int id = Integer.valueOf(String.valueOf(idView.getText()));
        String name = String.valueOf(nameView.getText());
        int age = Integer.valueOf(String.valueOf(ageView.getText()));
        String sex = String.valueOf(sexView.getText());
        Person person = new Person(id, name, age, sex);

        Intent intent = new Intent();
        intent.putExtra("person", person);
        setResult(UPDATE_RESULTCODE, intent);
        finish();
    }

    private void cancel() {
        setResult(UPDATE_RESULTCODE);
        finish();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.update_confirm:
                confirm();
                break;
            case R.id.update_cancel:
                cancel();
                break;
            default:
                break;
        }
    }
}

 ListAdapter.java

public class ListAdapter extends BaseAdapter {

    private List<Person> list;
    private LayoutInflater inflater;

    public ListAdapter(List<Person> list, Context context) {
        this.list = list;
        this.inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }


    public void setList(List<Person> list) {
        this.list = list;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Person 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 = inflater.inflate(R.layout.activity_main_list1, null);
        TextView idView = (TextView) convertView.findViewById(R.id.text_id);
        TextView nameView = (TextView) convertView.findViewById(R.id.text_name);
        TextView ageView = (TextView) convertView.findViewById(R.id.text_age);
        TextView sexView = (TextView) convertView.findViewById(R.id.text_sex);
        Person person = list.get(position);
        idView.setText(String.valueOf(person.getId()));
        nameView.setText(person.getName());
        ageView.setText(String.valueOf(person.getAge()));
        sexView.setText(String.valueOf(person.getSex()));
        return convertView;
    }
}

 MainActivity.java

/**
 * SQLite 資料庫操作 增刪改查
 */
public class DBMainActivity extends AppCompatActivity implements View.OnClickListener {

    private SQLiteHelper db;
    private ListAdapter listAdapter;

    private static final int INSERT_REQUESTCODE = 1;
    private static final int INSERT_RESULTCODE = 11;
    private static final int DELETE_REQUESTCODE = 2;
    private static final int DELETE_RESULTCODE = 22;
    private static final int UPDATE_REQUESTCODE = 3;
    private static final int UPDATE_RESULTCODE = 33;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dbmain);

        db = new SQLiteHelper(this, 1);

        Button insertBtn = (Button) findViewById(R.id.btn_insert);
        Button deleteBtn = (Button) findViewById(R.id.btn_delete);
        Button updateBtn = (Button) findViewById(R.id.btn_update);
        Button queryBtn = (Button) findViewById(R.id.btn_query);
        insertBtn.setOnClickListener(this);
        deleteBtn.setOnClickListener(this);
        updateBtn.setOnClickListener(this);
        queryBtn.setOnClickListener(this);

        listAdapter = new ListAdapter(new ArrayList<Person>(), this);
        ListView listView = (ListView) findViewById(R.id.list_data);
        listView.setAdapter(listAdapter);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_insert:
                insert();
                break;
            case R.id.btn_delete:
                delete();
                break;
            case R.id.btn_update:
                update();
                break;
            case R.id.btn_query:
                query();
                break;
            default:
                break;
        }
    }

    private void insert() {
        Intent intent = new Intent(this, InsertDialog.class);
        startActivityForResult(intent, INSERT_REQUESTCODE);
    }

    private void delete() {
        Intent intent = new Intent(this, DeleteDialog.class);
        startActivityForResult(intent, DELETE_REQUESTCODE);
    }

    private void update() {
        Intent intent = new Intent(this, UpdateDialog.class);
        startActivityForResult(intent, UPDATE_REQUESTCODE);
    }

    private void query() {
        List<Person> list = db.queryAllPerson();
        loadData(list);
    }

    private void loadData(List<Person> list) {
        listAdapter.setList(list);
        listAdapter.notifyDataSetChanged();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case INSERT_REQUESTCODE:
                if (resultCode == INSERT_RESULTCODE) {
                    if (data != null) {
                        db.insertPerson((Person) data.getSerializableExtra("person"));
                        Toast.makeText(this, "Insert Success!", Toast.LENGTH_SHORT).show();
                        query();
                    } else {
                        Toast.makeText(this, "Insert Cancel!", Toast.LENGTH_SHORT).show();
                    }
                }
                break;
            case DELETE_REQUESTCODE:
                if (resultCode == DELETE_RESULTCODE) {
                    if (data != null) {
                        int id = data.getIntExtra("id", -1);
                        if (id != -1) {
                            if (db.queryPersonById(id) != null) {
                                db.deletePersonById(id);
                                Toast.makeText(this, "Delete Success!", Toast.LENGTH_SHORT).show();
                                query();
                            } else {
                                Toast.makeText(this, "Delete Fail! id" + id + "not exist", Toast.LENGTH_SHORT).show();
                            }
                        } else {
                            Toast.makeText(this, "Delete Fail!", Toast.LENGTH_SHORT).show();

                        }
                    } else {
                        Toast.makeText(this, "Delete Cancel!", Toast.LENGTH_SHORT).show();
                    }
                }
                break;
            case UPDATE_REQUESTCODE:
                if (resultCode == UPDATE_RESULTCODE) {
                    if (data != null) {
                        Person person = (Person) data.getSerializableExtra("person");
                        int id = person.getId();
                        if (db.queryPersonById(person.getId()) != null) {
                            db.updatePerson(person);
                            Toast.makeText(this, "Update Success!", Toast.LENGTH_SHORT).show();
                            query();
                        } else {
                            Toast.makeText(this, "Update Fail! id" + id + "not exist", Toast.LENGTH_SHORT).show();
                        }
                    } else {
                        Toast.makeText(this, "Update Cancel!", Toast.LENGTH_SHORT).show();
                    }
                }
                break;
            default:
                break;
        }

    }
}