一、數據庫操作

package com.ping.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

/**
?* @describe <數據庫操作>
?*/
public class SQLiteTool extends SQLiteOpenHelper {
?private static final String DB_NAME = "medicalscience.db"; // 數據庫文件名
?private static final int VERSION = 1;// 數據庫版本
?
?
?public static SQLiteTool newInstance(Context context) {
??return new SQLiteTool(context, DB_NAME, null, VERSION);
?}

?private SQLiteTool(Context context, String name, CursorFactory factory, int version) {
??super(context, name, factory, version);
?}

?@Override
?public void onCreate(SQLiteDatabase db) {
??db.execSQL(DBTCollect.createTableSQL());//有需要創建表時，可以在這添加
?}

?@Override
?public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//當數據庫版本變大時調用
??onCreate(db);
?}
}

?

二、數據庫管理類

package com.ping.db;

import java.util.concurrent.atomic.AtomicInteger;

import android.annotation.SuppressLint;
import android.database.sqlite.SQLiteDatabase;
import android.os.Build;

import com.ping.MyApplication;

/**
?* @describe <數據庫管理類>
?*/
public class DBManager {
?private AtomicInteger dbOpenCount = new AtomicInteger();//計數器
?private static DBManager instance;
?private static SQLiteTool sqlLiteTool;
?private SQLiteDatabase database;

?public static synchronized DBManager getInstance() {
??if (instance == null) {
???synchronized (DBManager.class) {
????if (instance == null) {
?????instance = new DBManager();
????}
???}
??}
??return instance;
?}

?private DBManager() {
??sqlLiteTool = SQLiteTool.newInstance(MyApplication.getInstance().getApplicationContext());
?}

?@SuppressLint("NewApi")
?public synchronized SQLiteDatabase openDatabase() {
??if (dbOpenCount.incrementAndGet() == 1) {
???database = sqlLiteTool.getWritableDatabase();
???if (Build.VERSION.SDK_INT >= 11) {
????database.enableWriteAheadLogging();// 允許讀寫同時進行
???}
??}
??return database;
?}

?public synchronized void closeDatabase() {
??if (dbOpenCount.decrementAndGet() == 0) {
???database.close();
???database = null;
??}
?}
}

?

三、數據增刪改查

package com.ping.db;

import java.util.ArrayList;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

/**
?* @describe <數據庫操作--收藏表的操作 >
?*/
public class DBTCollect {
?public static final String TNAME = "Tcollect";

?// 創建表的語句
?public static String createTableSQL() {
??return "CREATE TABLE IF NOT EXISTS " + TNAME + " (kid INTEGER PRIMARY KEY AUTOINCREMENT, id TEXT, title TEXT)";
?}

?// 刪除表的語句
?public static String deleteTabelSQL() {
??return "DROP TABLE IF EXISTS " + TNAME;
?}

?//查詢數據是否存在
?public static boolean isCollected(String id) {
??boolean isCollected = false;
??SQLiteDatabase db = DBManager.getInstance().openDatabase();//獲得SQLiteDatabase對象
??String sql = "select * from " + TNAME + " where id = '" + id + "'";
??Cursor cursor = db.rawQuery(sql, null);
??if (cursor.getCount() > 0) {
???isCollected = true;
??}
??cursor.close();
??DBManager.getInstance().closeDatabase();//關閉
??return isCollected;
?}
?
??? // 刪除數據
?public static void deleteCollect(String mid) {
??SQLiteDatabase db = DBManager.getInstance().openDatabase();
??db.delete(TNAME, "id = ?", new String[] { id });
??DBManager.getInstance().closeDatabase();
?}
???
?//增加數據
?public static void addCollect(Object obj) {
??SQLiteDatabase db = DBManager.getInstance().openDatabase();
??ContentValues cv = new ContentValues();
??cv.put("id", obj.id);
??cv.put("title", obj.title);
??db.insert(TNAME, null, cv);
??DBManager.getInstance().closeDatabase();
?}

?//查詢數據
?public static ArrayList<Object> getAllCollect() {
??SQLiteDatabase db = DBManager.getInstance().openDatabase();
??Cursor cursor = db.query(TNAME, null, null, null, null, null, null);
??ArrayList<Object> objs = new ArrayList<Object>();
??while (cursor.moveToNext()) {
???Object obj = new Object();
???obj.id = cursor.getString(cursor.getColumnIndex("id"));
???obj.title = cursor.getString(cursor.getColumnIndex("title"));
???objs.add(obj);
??}
??cursor.close();
??DBManager.getInstance().closeDatabase();
??return objs;
?}
}

轉載于:https://blog.51cto.com/9437752/1579041

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