Android基础学习之SQLite数据库

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item android:id="@+id/add" android:title="@string/add"></item>
<item android:id="@+id/remove" android:title="@string/remove"></item>
<item android:id="@+id/update" android:title="@string/update"></item>
<item android:id="@+id/query" android:title="@string/query"></item>
</menu>

public class MainActivity extends Activity {
private static final String DBNAME = "myDB.db";//数据库名
private static final String TABLENAME = "student";//表名
private static final String NAME_COL = "name";//表字段1
private static final String AGE_COL = "age";//表字段2
private ListView db_list;
private SQLiteDatabase database;//数据库

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

db_list = (ListView) findViewById(R.id.db_list);

createMyDB();//封装创建或打开数据库方法
createMyTable();//封装创建表方法

registerForContextMenu(db_list);//设置列表项弹出上下文菜单
}

private void createMyTable() {
String sql = "create table student(id integer primary key autoincrement,name varchar(20),age integer)";
try {
database.execSQL(sql);
} catch (Exception e) {
e.printStackTrace();
}
}

private void createMyDB() {
// 打开或创建数据库
// 1.在私有目录下创建
// database = this.openOrCreateDatabase(DBNAME, MODE_PRIVATE, null);

// 2.在sd卡下创建
// String sdFile = Environment.getExternalStorageDirectory() +
// "/"+DBNAME;
// database = SQLiteDatabase.openOrCreateDatabase(sdFile, null);

// 3.从apk中创建数据库（用到提前放入工程的数据库文件）
String sdFile = Environment.getExternalStorageDirectory() + "/"
+ DBNAME;
InputStream is = getResources().openRawResource(R.raw.mydb);
FileOutputStream fos = null;
try {
fos = new FileOutputStream(sdFile);
byte[] buff = new byte[1024];
int num = -1;
while ((num = is.read(buff)) != -1) {
fos.write(buff, 0, num);
}
fos.flush();

} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
fos.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
database = SQLiteDatabase.openOrCreateDatabase(sdFile, null);
}

@Override
protected void onDestroy() {
super.onDestroy();
database.close();
}

@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
getMenuInflater().inflate(R.menu.context_menu, menu);//上下文菜单绑定视图
}

@Override
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.c_update:

break;
case R.id.c_remove:

break;
default:
break;
}
return super.onContextItemSelected(item);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.add:
doAdd();
break;
case R.id.remove:
doRemove();
break;
case R.id.update:
doUpdate();
break;
case R.id.query:
doQuery();
break;

default:
break;
}
return super.onOptionsItemSelected(item);
}

private void doAdd() {
// 1.方法1
String sql = "insert into student(name,age) values('rose',23)";
database.execSQL(sql);

// 2.方法2
// ContentValues cv=new ContentValues();
// cv.put(NAME_COL, "jack");
// cv.put(AGE_COL, 24);
// database.insert(TABLENAME, null, cv);

// 3.方法3
// String sql="insert into student(name,age) values(?,?)";
// database.execSQL(sql, new Object[]{"karl",32});

// 4.预编译
// String sql="insert into student(name,age) values(?,?)";
// SQLiteStatement stmt=database.compileStatement(sql);
// stmt.bindString(1, "alice");
// stmt.bindLong(2, 30);
// stmt.executeInsert();
// setTitle("add over.");
}

private void doRemove() {
//方法1
//      String sql = "delete from student where id=?";
//      database.execSQL(sql, new Object[]{"1"});
//方法2
database.delete(TABLENAME, "id=? or name=?", new String[]{"1","karl"});
}

private void doUpdate() {
ContentValues values=new ContentValues();
values.put(NAME_COL, "sdsfd");
values.put(AGE_COL, 11);
database.update(TABLENAME, values, "id=1", null);
ContentValues values2=new ContentValues();
values.put(NAME_COL, "aaaaaa");
values.put(AGE_COL, 38);
database.update(TABLENAME, values, "id=2", null);
}

private void doQuery() {
// 1.方法1
String sql = "select id as _id , name, age from " + TABLENAME;
Cursor cursor = database.rawQuery(sql, null);

// 2.方法2
// Cursor cursor=database.query(TABLENAME, null, null, null, null,null,
// "age desc");
// StringBuilder builder=new StringBuilder();

// 3.方法3
// SQLiteQueryBuilder sbuilder=new SQLiteQueryBuilder();
// sbuilder.setTables(TABLENAME);
// sbuilder.appendWhere("name like '%e%'");
// Cursor cursor=sbuilder.query(database, null, null, null, null, null,
// null);

@SuppressWarnings("deprecation")
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_2, cursor,
new String[] {NAME_COL, AGE_COL },
new int[] { android.R.id.text1,
android.R.id.text2 });

db_list.setAdapter(adapter);
}
}