SQLite的使用

DBHelper继承了SQLiteOpenHelper，作为维护和管理数据库的基类

/**
 * 创建数据库
 * @author daihuie
  */
public class DBHelper extends SQLiteOpenHelper {
	private static final String DATABASE_NAME = "honglin.db";
	private static final int DATABASE_VERSION = 1;
	public DBHelper(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
	}
	

	@Override
	public void onCreate(SQLiteDatabase db) {//<span style="font-family: Consolas, 'Courier New', Courier, mono, serif; line-height: 18px;"> </span><span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(0, 130, 0); font-family: Consolas, 'Courier New', Courier, mono, serif; line-height: 18px;">//数据库第一次被创建时onCreate会被调用</span><span style="margin: 0px; padding: 0px; border: none; font-family: Consolas, 'Courier New', Courier, mono, serif; line-height: 18px;">  </span>
		String sql1 = "CREATE TABLE IF NOT EXISTS t_latelymessage"
				+ "(_id INTEGER PRIMARY KEY AUTOINCREMENT,"
				+ "friendName TEXT,"
				+ "myName TEXT,"
				+ "content TEXT,"
				+ "time TEXT,"
				+ "number INTEGER)";
		db.execSQL(sql1);
		String sql2 = "CREATE TABLE IF NOT EXISTS t_chatrecord"
				+ "(_id INTEGER PRIMARY KEY AUTOINCREMENT,"
				+ "friendName TEXT,"
				+ "myName TEXT,"
				+ "time TEXT,"
				+ "content TEXT,"
				+ "url TEXT,"
				+ "type INTEGER,"
				+ "state INTEGER)";
		db.execSQL(sql2);
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		 db.execSQL("DROP TABLE IF EXISTS t_latelymessage");//把原先的删除掉
		 db.execSQL("DROP TABLE IF EXISTS t_chatrecord");
	     onCreate(db);
	}

}

DBManager是建立在DBHelper之上，封装了常用的业务方法：增删改查

package hl.view.mydb;

i

/**
 * 数据库操作
 * @author daihuie
 *
 */

public class DBManager {
	private DBHelper mDbHelper;
	private SQLiteDatabase db;
	private String TABLE_NAME_1 = "t_latelymessage";
	private String TABLE_NAME_2 = "t_chatrecord";
	public DBManager(Context context) {
		this.mDbHelper = new DBHelper(context);
		this.db = this.mDbHelper.getWritableDatabase();
	}
	/**
	 * 添加最新消息
	 * @param mLatelyMessage
	 */
	public void addLatelyMessage(LatelyMessage mLatelyMessage){
		db.beginTransaction();
		ContentValues values = new ContentValues();
		values.put("friendName", mLatelyMessage.getFriendName());
		values.put("myName", mLatelyMessage.getMyName());
		values.put("content", mLatelyMessage.getContent());
		values.put("time", mLatelyMessage.getTime());
		values.put("number", mLatelyMessage.getNumber());
		db.insert(TABLE_NAME_1, null, values);
		db.setTransactionSuccessful();
		db.endTransaction();
	}
	/**
	 * 根据时间删除最新消息 
	 * @param mLatelyMessage
	 */
	public void deleteLatelyMessage(LatelyMessage mLatelyMessage){
		String[] time = {mLatelyMessage.getTime()};
		db.delete(TABLE_NAME_1, "time=?",time);
	}
	/**
	 * 根据id修改最新消息 
	 * @param mLatelyMessage
	 */
	public void updateLatelyMessageById(LatelyMessage mLatelyMessage){
		ContentValues values = new ContentValues();
		values.put("_id", mLatelyMessage.getMessageId());
		values.put("friendName", mLatelyMessage.getFriendName());
		values.put("myName", mLatelyMessage.getMyName());
		values.put("content", mLatelyMessage.getContent());
		values.put("time", mLatelyMessage.getTime());
		values.put("number", mLatelyMessage.getNumber());
		String[] whereArgs = {mLatelyMessage.getMessageId()+""};
		db.update(TABLE_NAME_1, values, "_id=?", whereArgs);
	}
	
	/**
	 * 根据买家名字查找出所有的最新消息
	 * @param name
	 * @return
	 */
	public List<LatelyMessage> queryLatelyByMyName(String name){
		String[] selectArgs = {name};
		List<LatelyMessage> list = new ArrayList<LatelyMessage>();
		Cursor c = db.query(TABLE_NAME_1, null, "myName=?", selectArgs, null, null, null);
		while(c.moveToNext()){
			int messageId = c.getInt(c.getColumnIndex("_id"));
			String friendName = c.getString(c.getColumnIndex("friendName"));
			String myName = c.getString(c.getColumnIndex("myName"));
			String content = c.getString(c.getColumnIndex("content"));
			String time = c.getString(c.getColumnIndex("time"));
			int number = c.getInt(c.getColumnIndex("number"));
			LatelyMessage mLatelyMessage = new LatelyMessage(messageId, friendName, myName, content, time, number);
			list.add(mLatelyMessage);
		}
		return list;
	}
	/**
	 * 根据买、卖家的名字查找出所有的最新消息
	 * @param name1：买家名字
	 * @param name2：卖家名字
	 * @return
	 */
	public List<LatelyMessage> queryLatelyByMyNameAndFriendName(String name1,String name2){
		String[] selectArgs = {name1,name2};
		List<LatelyMessage> list = new ArrayList<LatelyMessage>();
		Cursor c = db.query(TABLE_NAME_1, null, "myName=? and friendName=?", selectArgs, null, null, null);
		while(c.moveToNext()){
			int messageId = c.getInt(c.getColumnIndex("_id"));
			String friendName = c.getString(c.getColumnIndex("friendName"));
			String myName = c.getString(c.getColumnIndex("myName"));
			String content = c.getString(c.getColumnIndex("content"));
			String time = c.getString(c.getColumnIndex("time"));
			int number = c.getInt(c.getColumnIndex("number"));
			LatelyMessage mLatelyMessage = new LatelyMessage(messageId, friendName, myName, content, time, number);
			list.add(mLatelyMessage);
		}
		return list;
	}
	/**
	 * 查找出所有的最新消息
	 * @return
	 */
	public List<LatelyMessage> queryAllLatelyMessage(){
		List<LatelyMessage> list = new ArrayList<LatelyMessage>();
		Cursor c = db.query(TABLE_NAME_1, null, null, null, null, null, null);
		while(c.moveToNext()){
			int messageId = c.getInt(c.getColumnIndex("_id"));
			String friendName = c.getString(c.getColumnIndex("friendName"));
			String myName = c.getString(c.getColumnIndex("myName"));
			String content = c.getString(c.getColumnIndex("content"));
			String time = c.getString(c.getColumnIndex("time"));
			int number = c.getInt(c.getColumnIndex("number"));
			LatelyMessage mLatelyMessage = new LatelyMessage(messageId, friendName, myName, content, time, number);
			list.add(mLatelyMessage);
		}
		return list;
	}
	
	/**
	 * 添加消息记录
	 * @param mChatRecord
	 */
	public void addChatRecord(ChatRecord mChatRecord){
		ContentValues values = new ContentValues();
		values.put("state", mChatRecord.getState());
		values.put("friendName", mChatRecord.getFriendName());
		values.put("content", mChatRecord.getContent());
		values.put("time", mChatRecord.getTime());
		values.put("type", mChatRecord.getType());
		values.put("myName", mChatRecord.getMyName());
		values.put("url", mChatRecord.getUrl());
		db.insert(TABLE_NAME_2,null,values);
	}
	
	/**
	 * 根据时间删除消息记录
	 * @param mChatRecord
	 */
	public void deleteChatRecord(ChatRecord mChatRecord){
		String[] time = {mChatRecord.getTime()};
		db.delete(TABLE_NAME_2, "time=?",time);
	}
	
	/**
	 * 根据买、卖家名字查出消息记录
	 * @param name1：卖家名字
	 * @param name2：买家名字
	 * @param page:当前页数
	 * @return
	 */
	public List<ChatRecord> queryChatRecord(String name1,String name2,int page){
		String[] selectArgs = {name1,name2};
		List<ChatRecord> list = new ArrayList<ChatRecord>();
		List<ChatRecord> list2 = new ArrayList<ChatRecord>();
		Cursor c = db.query(TABLE_NAME_2, null, "friendName=? and myName=?", selectArgs, null, null, "time DESC limit "+page*5);
		while(c.moveToNext()){
			int recordId = c.getInt(c.getColumnIndex("_id"));
			String friendName = c.getString(c.getColumnIndex("friendName"));
			String myName = c.getString(c.getColumnIndex("myName"));
			String time = c.getString(c.getColumnIndex("time"));
			String content = c.getString(c.getColumnIndex("content"));
			String url = c.getString(c.getColumnIndex("url"));
			int type = c.getInt(c.getColumnIndex("type"));
			int state = c.getInt(c.getColumnIndex("state"));
			ChatRecord mChatRecord = new ChatRecord(recordId, friendName, myName, time, content, url, type, state);
			list.add(mChatRecord);
		}
		
		for (int i = list.size()-1; i>=0; i--) {
			list2.add(list.get(i));
		}
		return list2;
	}
	/**
	 * 根据买、卖家名字查询消息总条数
	 * @param name1
	 * @param name2
	 * @param page
	 * @return 总条数
	 */
	public int getChatRecord_Count(String name1,String name2){
		String[] selectArgs = {name1,name2};
		List<ChatRecord> list = new ArrayList<ChatRecord>();
		Cursor c = db.query(TABLE_NAME_2, null, "friendName=? and myName=?", selectArgs, null, null, null);
		return c.getCount();
	}
	
	
	/**
	 * 关闭数据库
	 */
	public void closeDataBase(){
		db.close();
	}
}

开始调用：

<pre name="code" class="html" style="font-family: 'microsoft yahei';">private DBManager mDbManager;
mDbManager  = new DBManager(this);

chatRecordList = mDbManager.queryChatRecord(sendName,MainActivity.username,page);//查询

其他增删改同样调用<span style="font-family: 'microsoft yahei';">DBManager 里的相应方法即可。</span>

<span style="font-family:microsoft yahei;">注：最后一定要调用</span><span style="font-family: 'microsoft yahei';">closeDataBase方法 关闭数据库，一般在Activity的onDestory（）里调用。</span><span style="font-family:microsoft yahei;">

</span><span style="font-family:microsoft yahei;">
</span>