day24 JDBC批处理(通用泛型查询方法 & 下划线转驼峰命名法)

批处理

public static Integer addBatch(String[] sqls){
 		
	init();
	try {
		//设置关闭自动提交
		conn.setAutoCommit(false);
		Statement stmt = conn.createStatement();
		for (int i = 0; i < sqls.length; i++) {
			stmt.addBatch(sqls[i]);
		}
		//批量执行
		stmt.executeBatch();
		//提交事务
		conn.commit();
		return 1;
	} catch (SQLException e) {
		e.printStackTrace();
		return 0;
	}finally {
		close();
	}
}

批处理在main方法中调用

   String[] sql3 = new String[3];
   sql3[0] = "insert into student(s_name, s_age)values('zs',11);";
   sql3[1] = "insert into student(s_name, s_age)values('lis',22);";
   sql3[2] = "insert into student(s_name, s_age)values('ww',33);";
   int res = addBatch(sql3);
   System.out.println(res);

通用泛型查询方法

 	public static <T> List<T> query1(String sql, Class<T> cls, Object...params){
 		init();
 		try {
 			//编译sql语句，返回PrepareStatement对象
			ps = conn.prepareStatement(sql);
			//参数替换sql中的占位符
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					ps.setObject(i+1,params[i]);
				}
			}
			//执行sql语句，结果集封装给ResultSet
			rs = ps.executeQuery();
			
			List<T> list = new ArrayList<T>();
			//检索resultSet对象中的列数，类型和字段(结果集元数据)
			ResultSetMetaData resultSetMetaData = rs.getMetaData();
			
			while(rs.next()){
				T t = cls.newInstance();//泛型实例化
				
				//获取结果集的列数
				int count = resultSetMetaData.getColumnCount();	
				for (int i = 0; i < count; i++) {
					//获取每一列的别名，如果没有别名就返回resultSetMetaData.getColumnName();
					String cName = resultSetMetaData.getColumnLabel(i + 1);
					Object cValue = rs.getObject(cName);//通过获取的别名或者列名获取列的值
					
					try {
						Field field = cls.getDeclaredField(cName);//通过获取的别名或者列名获取类的属性
						field.setAccessible(true);//开启私有访问权限
						field.set(t, cValue);//变量赋值
					} catch (NoSuchFieldException e) {
					}
					
				}
				list.add(t);
				
			}
			return list;
			
			
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}finally{
			close();
		}
 	}

下划线转驼峰命名法

 	//下划线转驼峰命名
public static void conversion(String column){
	// 		String[] conName = name.split("");
	// 		String string = "";
	// 		for (int i = 0; i < conName.length; i++) {
	//			if(conName[i].equals("_")){
	//				string = string + conName[i+1].toUpperCase();
	//				i++;
	//			}else {
	//				string = string +conName[i];
	//			}
	//		}
	// 		System.out.println(string);

	String[] arr = column.split("_");
	StringBuffer sf = new StringBuffer(arr[0]);
	for (int i = 1; i < arr.length; i++) {
		String string = arr[i];
		String firstStr = string.substring(0, 1).toUpperCase();
	}
}