ANDROID DB帮助类

import java.lang.reflect.Field; 
import java.lang.reflect.Method; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
   
import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteStatement; 
import android.util.Log; 
/**
 * 数据库管理类，具备增删改查操作。
 *      增删改 --> 操作一个sql语句，并且有返回值。
 *      查询    --> 1. 返回一个游标类型
 *                2. 返回一个List<Object>
 *                3. 返回一个List<Map<String, Object>>
 * @author zxy
 * 时间： 2012-09-28
 */ 
public class DataBaseManager { 
   
    private DBHelper dbHelper; 
    public static DataBaseManager instance = null; 
    private SQLiteDatabase sqliteDatabase; 
   
    /**
     * 构造函数
     * @param context   上下文对象
     */ 
    private DataBaseManager(Context context) { 
        dbHelper = new DBHelper(context); 
        sqliteDatabase = dbHelper.getReadableDatabase();                                                         
    } 
       
    /***
     * 获取本类对象实例
     * @param context   上下文对象
     * @return
     */ 
    public static final DataBaseManager getInstance(Context context) { 
        if (instance == null)  
            instance = new DataBaseManager(context); 
        return instance; 
    } 
       
    /**
     * 关闭数据库
     */ 
    public void close() { 
        if(sqliteDatabase.isOpen()) sqliteDatabase.close(); 
        if(dbHelper != null) dbHelper.close(); 
        if(instance != null) instance = null; 
    } 
   
    /**
     * 插入数据
     * @param sql       执行更新操作的sql语句
     * @param bindArgs      sql语句中的参数,参数的顺序对应占位符顺序
     * @return  result      返回新添记录的行号，与主键id无关 
     */ 
    public Long insertDataBySql(String sql, String[] bindArgs) throws Exception{ 
        long result = 0; 
        if(sqliteDatabase.isOpen()){ 
            SQLiteStatement statement = sqliteDatabase.compileStatement(sql); 
            if(bindArgs != null){ 
                int size = bindArgs.length; 
                for(int i = 0; i < size; i++){ 
                    //将参数和占位符绑定，对应 
                    statement.bindString(i+1, bindArgs[i]); 
                } 
                result = statement.executeInsert(); 
                statement.close(); 
            } 
        }else{ 
            Log.i("info", "数据库已关闭"); 
        } 
        return result; 
    } 
       
    /**
     * 插入数据
     * @param table         表名
     * @param values        要插入的数据
     * @return  result      返回新添记录的行号，与主键id无关 
     */ 
    public Long insertData(String table, ContentValues values){ 
        long result = 0; 
        if(sqliteDatabase.isOpen()){ 
            result = sqliteDatabase.insert(table, null, values); 
        } 
        return result; 
    } 
       
    /**
     * 更新数据
     * @param sql       执行更新操作的sql语句
     * @param bindArgs  sql语句中的参数,参数的顺序对应占位符顺序
     */ 
    public void updateDataBySql(String sql, String[] bindArgs) throws Exception{ 
        if(sqliteDatabase.isOpen()){ 
            SQLiteStatement statement = sqliteDatabase.compileStatement(sql); 
            if(bindArgs != null){ 
                int size = bindArgs.length; 
                for(int i = 0; i < size; i++){ 
                    statement.bindString(i+1, bindArgs[i]); 
                } 
                statement.execute(); 
                statement.close(); 
            } 
        }else{ 
            Log.i("info", "数据库已关闭"); 
        } 
    } 
       
    /**
     * 更新数据
     * @param table         表名
     * @param values        表示更新的数据
     * @param whereClause   表示SQL语句中条件部分的语句
     * @param whereArgs     表示占位符的值
     * @return
     */ 
    public int updataData(String table, ContentValues values, String whereClause, String[] whereArgs){ 
        int result = 0; 
        if(sqliteDatabase.isOpen()){ 
            result = sqliteDatabase.update(table, values, whereClause, whereArgs); 
        } 
        return result; 
    } 
   
    /**
     * 删除数据
     * @param sql       执行更新操作的sql语句
     * @param bindArgs  sql语句中的参数,参数的顺序对应占位符顺序
     */ 
    public void deleteDataBySql(String sql, String[] bindArgs) throws Exception{ 
        if(sqliteDatabase.isOpen()){ 
            SQLiteStatement statement = sqliteDatabase.compileStatement(sql); 
            if(bindArgs != null){ 
                int size = bindArgs.length; 
                for(int i = 0; i < size; i++){ 
                    statement.bindString(i+1, bindArgs[i]); 
                } 
                Method[] mm = statement.getClass().getDeclaredMethods(); 
                for (Method method : mm) { 
                    Log.i("info", method.getName());         
                    /**
                     *  反射查看是否能获取executeUpdateDelete方法
                     *  查看源码可知 executeUpdateDelete是public的方法，但是好像被隐藏了所以不能被调用，
                     *      利用反射貌似只能在root以后的机器上才能调用，小米是可以，其他机器却不行，所以还是不能用。
                     */ 
                } 
                statement.execute();     
                statement.close(); 
            } 
        }else{ 
            Log.i("info", "数据库已关闭"); 
        } 
    } 
   
    /**
     * 删除数据
     * @param table         表名
     * @param whereClause   表示SQL语句中条件部分的语句
     * @param whereArgs     表示占位符的值
     * @return              
     */ 
    public int deleteData(String table, String whereClause, String[] whereArgs){ 
        int result = 0; 
        if(sqliteDatabase.isOpen()){ 
            result = sqliteDatabase.delete(table, whereClause, whereArgs); 
        } 
        return result; 
    } 
       
    /**
     * 查询数据
     * @param searchSQL         执行查询操作的sql语句
     * @param selectionArgs     查询条件
     * @return                  返回查询的游标，可对数据自行操作，需要自己关闭游标
     */ 
    public Cursor queryData2Cursor(String sql, String[] selectionArgs) throws Exception{ 
        if(sqliteDatabase.isOpen()){ 
            Cursor cursor = sqliteDatabase.rawQuery(sql, selectionArgs); 
            if (cursor != null) { 
                cursor.moveToFirst(); 
            } 
            return cursor; 
        } 
        return null; 
    } 
       
    /**
     * 查询数据
     * @param sql               执行查询操作的sql语句    
     * @param selectionArgs     查询条件
     * @param object                Object的对象
     * @return List<Object>       返回查询结果  
     */ 
    public List<Object> queryData2Object(String sql, String[] selectionArgs, Object object) throws Exception{ 
        List<Object> mList = new ArrayList<Object>(); 
        if(sqliteDatabase.isOpen()){ 
            Cursor cursor = sqliteDatabase.rawQuery(sql, selectionArgs); 
            Field[] f; 
            if(cursor != null && cursor.getCount() > 0) { 
                while(cursor.moveToNext()){ 
                    f = object.getClass().getDeclaredFields(); 
                    for(int i = 0; i < f.length; i++) { 
                        //为JavaBean 设值 
                        invokeSet(object, f[i].getName(), cursor.getString(cursor.getColumnIndex(f[i].getName()))); 
                    } 
                    mList.add(object); 
                } 
            } 
            cursor.close(); 
        }else{ 
            Log.i("info", "数据库已关闭"); 
        } 
        return mList; 
    } 
       
    /**
     * 查询数据
     * @param sql                           执行查询操作的sql语句    
     * @param selectionArgs                 查询条件
     * @param object                            Object的对象
     * @return  List<Map<String, Object>>   返回查询结果  
     * @throws Exception
     */ 
    public List<Map<String, Object>> queryData2Map(String sql, String[] selectionArgs, Object object)throws Exception{ 
        List<Map<String, Object>> mList = new ArrayList<Map<String,Object>>(); 
        if(sqliteDatabase.isOpen()){ 
            Cursor cursor = sqliteDatabase.rawQuery(sql, selectionArgs); 
            Field[] f; 
            Map<String, Object> map; 
            if(cursor != null && cursor.getCount() > 0) { 
                while(cursor.moveToNext()){ 
                    map = new HashMap<String, Object>(); 
                    f = object.getClass().getDeclaredFields(); 
                    for(int i = 0; i < f.length; i++) { 
                        map.put(f[i].getName(), cursor.getString(cursor.getColumnIndex(f[i].getName()))); 
                    } 
                    mList.add(map); 
                } 
            } 
            cursor.close(); 
        }else{ 
            Log.i("info", "数据库已关闭"); 
        } 
        return mList; 
    }  
       
    /**    
     * java反射bean的set方法    
     * @param objectClass    
     * @param fieldName    
     * @return    
     */        
    @SuppressWarnings("unchecked")        
    public static Method getSetMethod(Class objectClass, String fieldName) {        
        try {        
            Class[] parameterTypes = new Class[1];        
            Field field = objectClass.getDeclaredField(fieldName);        
            parameterTypes[0] = field.getType();        
            StringBuffer sb = new StringBuffer();        
            sb.append("set");        
            sb.append(fieldName.substring(0, 1).toUpperCase());        
            sb.append(fieldName.substring(1));        
            Method method = objectClass.getMethod(sb.toString(), parameterTypes);        
            return method;        
        } catch (Exception e) {        
            e.printStackTrace();        
        }        
        return null;        
    }        
         
    /**    
     * 执行set方法    
     * @param object    执行对象    
     * @param fieldName 属性    
     * @param value     值    
     */        
    public static void invokeSet(Object object, String fieldName, Object value) {        
        Method method = getSetMethod(object.getClass(), fieldName);        
        try {        
            method.invoke(object, new Object[] { value });        
        } catch (Exception e) {        
            e.printStackTrace();        
        }        
    }        
}