一、数据库操作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 <数据库操作> */public class SQLiteTool extends SQLiteOpenHelper { private static final String DB_NAME = "medicalscience.db"; // 数据库文件名 private static final int VERSION = 1;// 数据库版本   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());//有需要创建表时，可以在这添加 } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//当数据库版本变大时调用  onCreate(db); }} 二、数据库管理类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 <数据库管理类> */public class DBManager { private AtomicInteger dbOpenCount = new AtomicInteger();//计数器 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();// 允许读写同时进行   }  }  return database; } public synchronized void closeDatabase() {  if (dbOpenCount.decrementAndGet() == 0) {   database.close();   database = null;  } }} 三、数据增删改查package com.ping.db;import java.util.ArrayList;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;/** * @describe <数据库操作--收藏表的操作 > */public class DBTCollect { public static final String TNAME = "Tcollect"; // 创建表的语句 public static String createTableSQL() {  return "CREATE TABLE IF NOT EXISTS " + TNAME + " (kid INTEGER PRIMARY KEY AUTOINCREMENT, id TEXT, title TEXT)"; } // 删除表的语句 public static String deleteTabelSQL() {  return "DROP TABLE IF EXISTS " + TNAME; } //查询数据是否存在 public static boolean isCollected(String id) {  boolean isCollected = false;  SQLiteDatabase db = DBManager.getInstance().openDatabase();//获得SQLiteDatabase对象  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();//关闭  return isCollected; }     // 删除数据 public static void deleteCollect(String mid) {  SQLiteDatabase db = DBManager.getInstance().openDatabase();  db.delete(TNAME, "id = ?", new String[] { id });  DBManager.getInstance().closeDatabase(); }     //增加数据 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(); } //查询数据 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; }}