[转]SQLite的工具类 ---
在写DAO层时，觉得从Cursor里一个一个的取出字段值再装到VO(值对象)里太麻烦了，就写了一个工具类，用到了反射，可以把查询记录的值装到对应的VO里，也可以生成该VO的List。使用时需要注意：
考虑到Android的性能问题，VO没有使用Setter和Getter，而是直接用public的属性。
表中的字段名需要和VO的属性名一样，要是不一样就得在查询的SQL中使用字段别名让字段别名和VO属性名一样。
下面是实现代码：
import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.util.HashMap;import java.util.LinkedList;import java.util.List;import java.util.Map;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;/** * 通过SQL语句查询出结果并封闭到VO里 ***/public class HappySQL {/** * 通过SQL语句获得对应的VO。注意：Cursor的字段名或者别名一定要和VO的成员名一样 ** @param db * @param sql * @param clazz * @return */@SuppressWarnings("rawtypes")public static Object sql2VO(SQLiteDatabase db, String sql, Class clazz) {Cursor c = db.rawQuery(sql, null);return cursor2VO(c, clazz);}/** * 通过SQL语句获得对应的VO。注意：Cursor的字段名或者别名一定要和VO的成员名一样 ** @param db * @param sql * @param selectionArgs * @param clazz * @return */@SuppressWarnings("rawtypes")public static Object sql2VO(SQLiteDatabase db, String sql,String[] selectionArgs, Class clazz) {Cursor c = db.rawQuery(sql, selectionArgs);return cursor2VO(c, clazz);}/** * 通过SQL语句获得对应的VO的List。注意：Cursor的字段名或者别名一定要和VO的成员名一样 ** @param db * @param sql * @param clazz * @return */@SuppressWarnings("rawtypes")public static List sql2VOList(SQLiteDatabase db, String sql, Class clazz) {Cursor c = db.rawQuery(sql, null);return cursor2VOList(c, clazz);}/** * 通过SQL语句获得对应的VO的List。注意：Cursor的字段名或者别名一定要和VO的成员名一样 ** @param db * @param sql * @param selectionArgs * @param clazz * @return */@SuppressWarnings("rawtypes")public static List sql2VOList(SQLiteDatabase db, String sql,String[] selectionArgs, Class clazz) {Cursor c = db.rawQuery(sql, selectionArgs);return cursor2VOList(c, clazz);}/** * 通过Cursor转换成对应的VO。注意：Cursor里的字段名（可用别名）必须要和VO的属性名一致 ** @param c * @param clazz * @return */@SuppressWarnings({ "rawtypes", "unused" })private static Object cursor2VO(Cursor c, Class clazz) {if (c == null) {return null;}Object obj;int i = 1;try {c.moveToNext();obj = setValues2Fields(c, clazz);return obj;} catch (Exception e) {System.out.println(e);System.out.println("ERROR @：cursor2VO");return null;} finally {c.close();}}/** * 通过Cursor转换成对应的VO集合。注意：Cursor里的字段名（可用别名）必须要和VO的属性名一致 ** @param c * @param clazz * @return */@SuppressWarnings({ "rawtypes", "unchecked" })private static List cursor2VOList(Cursor c, Class clazz) {if (c == null) {return null;}List list = new LinkedList();Object obj;try {while (c.moveToNext()) {obj = setValues2Fields(c, clazz);list.add(obj);}return list;} catch (Exception e) {e.printStackTrace();System.out.println("ERROR @：cursor2VOList");return null;} finally {c.close();}}/** * 把值设置进类属性里 ** @param columnNames * @param fields * @param c * @param obj * @throws Exception */@SuppressWarnings("rawtypes")private static Object setValues2Fields(Cursor c, Class clazz)throws Exception {String[] columnNames = c.getColumnNames();// 字段数组Object obj = clazz.newInstance();Field[] fields = clazz.getFields();for (Field _field : fields) {Class<? extends Object> typeClass = _field.getType();// 属性类型for (int j = 0; j < columnNames.length; j++) {String columnName = columnNames;typeClass = getBasicClass(typeClass);boolean isBasicType = isBasicType(typeClass);if (isBasicType) {if (columnName.equalsIgnoreCase(_field.getName())) {// 是基本类型String _str = c.getString(c.getColumnIndex(columnName));if (_str == null) {break;}_str = _str == null ? "" : _str;Constructor<? extends Object> cons = typeClass.getConstructor(String.class);Object attribute = cons.newInstance(_str);_field.setAccessible(true);_field.set(obj, attribute);break;}} else {Object obj2 = setValues2Fields(c, typeClass);// 递归_field.set(obj, obj2);break;}}}return obj;}/** * 判断是不是基本类型 ** @param typeClass * @return */@SuppressWarnings("rawtypes")private static boolean isBasicType(Class typeClass) {if (typeClass.equals(Integer.class) || typeClass.equals(Long.class)|| typeClass.equals(Float.class)|| typeClass.equals(Double.class)|| typeClass.equals(Boolean.class)|| typeClass.equals(Byte.class)|| typeClass.equals(Short.class)|| typeClass.equals(String.class)) {return true;} else {return false;}}/** * 获得包装类 ** @param typeClass * @return */@SuppressWarnings("all")public static Class<? extends Object> getBasicClass(Class typeClass) {Class _class = basicMap.get(typeClass);if (_class == null)_class = typeClass;return _class;}@SuppressWarnings("rawtypes")private static Map<Class, Class> basicMap = new HashMap<Class, Class>();static {basicMap.put(int.class, Integer.class);basicMap.put(long.class, Long.class);basicMap.put(float.class, Float.class);basicMap.put(double.class, Double.class);basicMap.put(boolean.class, Boolean.class);basicMap.put(byte.class, Byte.class);basicMap.put(short.class, Short.class);}}
调用例子：
获得单个VO：
String sql = "select * from tb_info_review where info_id = "+ info_id;return (Info_re) HappySQL.sql2VO(db, sql,Info_re.class);
获得List：
String sql = "select * from tb_info m, tb_sub2 f where m.send_state = 1 and review_state = 0 and m.info_id = f.info_id";List<Info> infos = HappySQL.sql2VOList(db, sql, Info.class);
带变参获得List：
String sql = "select * from tb_info m,tb_ttf f where m.info_id = ? and m.info_id = f.info_id";return (SbMan) HappySQL.sql2VO(db, sql, new String[] { info_id + "" }, SbMan.class);
转自：http://blog.csdn.net/oo8_8oo/article/details/7003162
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