public class DBManager {
private DBHelper dbHelper;
private SQLiteDatabase database;
public DBManager(Context context) {
dbHelper = new DBHelper(context);
}
/*
* 用于更新数据的包括插入、删除、修改
*/
public boolean updateBySQL(String sql, Object[] bindArgs) {
boolean flag = false;
try {
database.execSQL(sql, bindArgs);
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} /*
* finally { if (database != null) { database.close(); } }
*/
return flag;
}
/*
* 单独一个方法，获得数据库的链接
*/
public void getDataBaseConn() {
database = dbHelper.getWritableDatabase();
}
/*
* 释放数据库链接
*/
public void releaseConn() {
if (database != null) {
database.close();
}
}
/*
* 查找数据的测试程序
*/
public void queryBySQL(String sql, String[] selectionArgs) {
Cursor cursor = database.rawQuery(sql, selectionArgs);
while (cursor.moveToNext()) {
System.out.println("-->>"
+ cursor.getString(cursor.getColumnIndex("name")));
System.out.println("-->>"
+ cursor.getString(cursor.getColumnIndex("address")));
System.out.println("-->>"
+ cursor.getInt(cursor.getColumnIndex("age")));
}
}
/*
* 查找单条数据的查询方法
*/
public Map<string, string=""> querySingleResultBySQL(String sql,
String[] selectionArgs) {
Map<string, string=""> map = new HashMap<string, string="">();
Cursor cursor = database.rawQuery(sql, selectionArgs);
int cols_len = cursor.getColumnCount();
while (cursor.moveToNext()) {
for (int i = 0; i < cols_len; i++) {
String cols_name = cursor.getColumnName(i);
String cols_value = cursor.getString(cursor
.getColumnIndex(cols_name));
if (cols_value == null) {
cols_value = "";
}
map.put(cols_name, cols_value);
}
}
return map;
}
/**
* 同构反射获得数据库的记录; 声明Class的属性必须都是String类型
*
* @param sql
* @param selectionArgs
* @param cls
* @return
*/
public <t> T querySingleCursor(String sql, String[] selectionArgs,
Class<t> cls) {
T t = null;
Cursor cursor = database.rawQuery(sql, selectionArgs);
int cols_len = cursor.getColumnCount();
while (cursor.moveToNext()) {
try {
t = cls.newInstance();
for (int i = 0; i < cols_len; i++) {
String cols_name = cursor.getColumnName(i);
String cols_value = cursor.getString(cursor
.getColumnIndex(cols_name));
if (cols_value == null) {
cols_value = "";
}
Field field = null;
try {
field = cls.getDeclaredField(cols_name);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
field.setAccessible(true);
field.set(t, cols_value);
}
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
return t;
}
/**
* 同构反射获得多条数据库的记录; 声明Class的属性必须都是String类型
*
* @param sql
* @param selectionArgs
* @param cls
* @return
*/
public <t> List<t> queryMutilCursor(String sql, String[] selectionArgs,
Class<t> cls) {
List<t> list = new ArrayList<t>();
Cursor cursor = database.rawQuery(sql, selectionArgs);
int cols_len = cursor.getColumnCount();
while (cursor.moveToNext()) {
try {
T t = cls.newInstance();
for (int i = 0; i < cols_len; i++) {
String cols_name = cursor.getColumnName(i);
String cols_value = cursor.getString(cursor
.getColumnIndex(cols_name));
if (cols_value == null) {
cols_value = "";
}
Field field = null;
try {
field = cls.getDeclaredField(cols_name);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
field.setAccessible(true);
field.set(t, cols_value);
list.add(t);
}
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
return list;
}
/*
* 查找多条数据的查询方法
*/
public List<map<string, string="">> queryMutiResultBySQL(String sql,
String[] selectionArgs) {
List<map<string, string="">> list = new ArrayList<map<string, string="">>();
Cursor cursor = database.rawQuery(sql, selectionArgs);
int cols_len = cursor.getColumnCount();
while (cursor.moveToNext()) {
Map<string, string=""> map = new HashMap<string, string="">();
for (int i = 0; i < cols_len; i++) {
String cols_name = cursor.getColumnName(i);
String cols_value = cursor.getString(cursor
.getColumnIndex(cols_name));
if (cols_value == null) {
cols_value = "";
}
map.put(cols_name, cols_value);
}
list.add(map);
}
return list;
}
public Cursor queryMutiCursor(String sql, String[] selectionArgs) {
Cursor cursor = database.rawQuery(sql, selectionArgs);
return cursor;
}
/**************************** 以下是不需要sql语句的查询方法 **********************************/
/**
*
* @param tabeName
* @param nullColumnHack
* @param values
* @return
*/
public boolean insertByNotSQL(String tabeName, String nullColumnHack,
ContentValues values) {
boolean flag = false;
// insert into tableName(a,,b,c) values(?,?,?)
long id = database.insert(tabeName, nullColumnHack, values);
flag = (id > 0 ? true : false);
return flag;
}
/**
* 无sql语句的更新操作
*
* @param tabeName
* @param values
* @param whereClause
* @param whereArgs
* @return
*/
public boolean updateByNotSQL(String tabeName, ContentValues values,
String whereClause, String[] whereArgs) {
boolean flag = false;
// update tableName set name =?,address=?,age=? where pid=?
int count = database.update(tabeName, values, whereClause, whereArgs); // 影响数据的行数
flag = (count > 0 ? true : false);
return flag;
}
/**
* 无sql语句的删除操作
*
* @param table
* @param whereClause
* @param whereArgs
* @return
*/
public boolean deleteNotSQL(String table, String whereClause,
String[] whereArgs) {
boolean flag = false;
// delete from tableName where pid=?
int count = database.delete(table, whereClause, whereArgs);
flag = (count > 0 ? true : false);
return flag;
}
/**
* sql标准写法：select [distinct][columnName] ... from tableName
* [where][selection][selectionArgs][groupBy][having][order by][limit]
*
* @param distinct
* @param table
* @param columns
* @param selection
* @param selectionArgs
* @param groupBy
* @param having
* @param orderBy
* @param limit
* @return
*/
public Cursor queryByNotSQL(boolean distinct, String table,
String[] columns, String selection, String[] selectionArgs,
String groupBy, String having, String orderBy, String limit) {
Cursor cursor = null;
/*
* 这是一条折中 的查询方法，其他的方法就是一系列的构造函数
*/
cursor = database.query(distinct, table, columns, selection,
selectionArgs, groupBy, having, orderBy, limit);
return cursor;
}
}
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