Android：数据存储之SQLite

Android在运行时集成了SQLite ，所以每个Android应用程序都可以使用SQLite数据库。

我们通过SQLiteDatabase这个类的对象操作SQLite数据库，而且不需要身份验证。

数据库存放的位置：data/data/<项目文件夹>/databases/，查看数据库>>

实例：

public class MainActivity extends Activity {    private Button createDatabase, createTable, selectData, insertData,            updateData, deleteDaata;    private MySQLiteOpenHelper helper;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.demo);        // 初始化按钮        createDatabase = (Button) findViewById(R.id.createDatabase);        createTable = (Button) findViewById(R.id.createTable);        selectData = (Button) findViewById(R.id.selectData);        insertData = (Button) findViewById(R.id.insertData);        updateData = (Button) findViewById(R.id.updateData);        deleteDaata = (Button) findViewById(R.id.deleteDaata);                        helper = new MySQLiteOpenHelper(MainActivity.this, "mydb.db",                null, 1);                /*         * 创建数据库         */        createDatabase.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase = helper.getWritableDatabase();                Toast.makeText(MainActivity.this, "数据库创建成功", 1000).show();            }        });        /*         * 创建表         */        createTable.setOnClickListener(new OnClickListener() {            public void onClick(View arg0) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase = helper.getWritableDatabase();                // 创建表                sqlitedatabase                        .execSQL("create table student(id INTEGER PRIMARY KEY autoincrement,name text)");                Toast.makeText(MainActivity.this, "表创建成功", 1000).show();            }        });        /*         * 插入数据         */        insertData.setOnClickListener(new OnClickListener() {            public void onClick(View v) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase = helper.getWritableDatabase();                sqlitedatabase                        .execSQL("insert into student(name) values ('tinyphp')");                Toast.makeText(MainActivity.this, "插入数据成功", 1000).show();            }        });        /*         * 更新数据         */        updateData.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase = helper.getWritableDatabase();                sqlitedatabase                        .execSQL("update student set name='monkey' where id='1'");                Toast.makeText(MainActivity.this, "数据更新成功", 1000).show();            }        });        /*         * 查询数据         */        selectData.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase = helper.getReadableDatabase();                                //参数：表名、查询的列、查询条件、查询参数、查询结果分组、分组结果限制、排序                Cursor cursor = sqlitedatabase.query("student", new String[] {                        "id", "name" }, "id=?", new String[] { "1" }, null,                        null, null);                String name=null;                while(cursor.moveToNext()){                    name =cursor.getString(cursor.getColumnIndex("name"));                                    }                Toast.makeText(MainActivity.this, "查询结果name为："+name, 1000).show();            }        });                /*         * 删除数据         * */                        deleteDaata.setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View v) {                // TODO Auto-generated method stub                SQLiteDatabase sqlitedatabase =helper.getWritableDatabase();                sqlitedatabase.delete("student", "id=?", new String[]{"1"});                Toast.makeText(MainActivity.this, "数据删除成功", 1000).show();            }        });            }}

使用getWritableDatabase或getReadableDatabase的时候，数据库才会链接，通过execSQL执行SQL语句。

实例下载>>>>>>>>

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