JAVA 数据库操作工具类----sqllite

package com.asc.db;

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

/**
 * 数据库公共类，提供基本数据库操作*/
public class DBManager {
    // 默认数据库
    private static final String DB_NAME = "asc.db";

    // 数据库版本
    private static final int DB_VERSION = 1;

    // 执行open()打开数据库时，保存返回的数据库对象
    private SQLiteDatabase mSQLiteDatabase = null;

    // 由SQLiteOpenHelper继承过来
    private DatabaseHelper mDatabaseHelper = null;

    // 本地Context对象
    private Context mContext = null;
    
    private static DBManager dbConn= null;
    
    // 查询游标对象
    private Cursor cursor;

    /**
     * SQLiteOpenHelper内部类
     */
    private static class DatabaseHelper extends SQLiteOpenHelper {

        DatabaseHelper(Context context) {
            // 当调用getWritableDatabase()或 getReadableDatabase()方法时,创建一个数据库
            super(context, DB_NAME, null, DB_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE ad_record(id PRIMARY KEY NOT NULL, adUrl TEXT, apMac TEXT, createDate DATETIME);");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS ad_record");
            onCreate(db);
        }
    }

    /**
     * 构造函数
     * 
     * @param mContext
     */
    private DBManager(Context mContext) {
        super();
        this.mContext = mContext;
    }
    
    public static DBManager getInstance(Context mContext){
        if (null == dbConn) {
            dbConn = new DBManager(mContext);
        }
        return dbConn;
    }

    /**
     * 打开数据库
     */
    public void open() {
        mDatabaseHelper = new DatabaseHelper(mContext);
        mSQLiteDatabase = mDatabaseHelper.getWritableDatabase();
    }

    /**
     * 关闭数据库
     */
    public void close() {
        if (null != mDatabaseHelper) {
            mDatabaseHelper.close();
        }
        if (null != cursor) {
            cursor.close();
        }
    }

    /**
     * 插入数据
     * @param tableName 表名
     * @param nullColumn null
     * @param contentValues 名值对
     * @return 新插入数据的ID，错误返回-1
     * @throws Exception
     */
    public long insert(String tableName, String nullColumn,
            ContentValues contentValues) throws Exception {
        try {
            return mSQLiteDatabase.insert(tableName, nullColumn, contentValues);
        } catch (Exception e) {
            throw e;
        }
    }

    /**
     * 通过主键ID删除数据
     * @param tableName 表名
     * @param key 主键名
     * @param id 主键值
     * @return 受影响的记录数
     * @throws Exception
     */
    public long delete(String tableName, String key, int id) throws Exception {
        try {
            return mSQLiteDatabase.delete(tableName, key + " = " + id, null);
        } catch (Exception e) {
            throw e;
        }
    }
    
    /**
     * 查找表的所有数据
     * @param tableName 表名
     * @param columns 如果返回所有列，则填null
     * @return
     * @throws Exception
     */
    public Cursor findAll(String tableName, String [] columns) throws Exception{
        try {
            cursor = mSQLiteDatabase.query(tableName, columns, null, null, null, null, null);
            cursor.moveToFirst();
            return cursor;
        } catch (Exception e) {
            throw e;
        }
    }
    
    /**
     * 根据主键查找数据
     * @param tableName 表名
     * @param key 主键名
     * @param id  主键值
     * @param columns 如果返回所有列，则填null
     * @return Cursor游标
     * @throws Exception 
     */
    public Cursor findById(String tableName, String key, int id, String [] columns) throws Exception {
        try {
            return mSQLiteDatabase.query(tableName, columns, key + " = " + id, null, null, null, null);
        } catch (Exception e) {
            throw e;
        }
    }
    
    /**
     * 根据条件查询数据
     * @param tableName 表名
     * @param names 查询条件
     * @param values 查询条件值
     * @param columns 如果返回所有列，则填null
     * @param orderColumn 排序的列
     * @param limit 限制返回数
     * @return Cursor游标
     * @throws Exception
     */
    public Cursor find(String tableName, String [] names, String [] values, String [] columns, String orderColumn, String limit) throws Exception{
        try {
            StringBuffer selection = new StringBuffer();
            for (int i = 0; i < names.length; i++) {
                selection.append(names[i]);
                selection.append(" = ?");
                if (i != names.length - 1) {
                    selection.append(",");
                }
            }
            cursor = mSQLiteDatabase.query(true, tableName, columns, selection.toString(), values, null, null, orderColumn, limit);
            cursor.moveToFirst();
            return cursor;
        } catch (Exception e) {
            throw e;
        }
    }
    
    /**
     * 
     * @param tableName 表名
     * @param names 查询条件
     * @param values 查询条件值
     * @param args 更新列-值对
     * @return true或false
     * @throws Exception
     */
    public boolean udpate(String tableName, String [] names, String [] values, ContentValues args) throws Exception{
        try {
            StringBuffer selection = new StringBuffer();
            for (int i = 0; i < names.length; i++) {
                selection.append(names[i]);
                selection.append(" = ?");
                if (i != names.length - 1) {
                    selection.append(",");
                }
            }
            return mSQLiteDatabase.update(tableName, args, selection.toString(), values) > 0;
        } catch (Exception e) {
            throw e;
        }
    }
    
    /**
     * 执行sql语句，包括创建表、删除、插入
     * 
     * @param sql
     */
    public void executeSql(String sql) {
        mSQLiteDatabase.execSQL(sql);
    }

}