開發中在不用資料庫的情況下操作資料庫，比如說對資料庫的增刪改查，每次都重新擼一遍重複的程式碼，那樣就會很麻煩，這裡就給安利一個很簡單的工具類來對資料庫進行讀寫操作，當然並不能涵蓋所有的功能，說了，只是很簡單的操作資料庫，當然你可以直接使用框架來操作，那樣更好。。。

話不多說，直接上程式碼。。。

public class DBOperate<T> {

    private static Connection connection = null;
    private static PreparedStatement statement = null;
    private
 
 static ResultSet query = null;
    private static ResultSetMetaData metaData = null;


    /**
     * 增刪改 操作
     * @param sql
     * @param params
     * @return
     */
    public static int operateDB(String sql,Object...params){
        int value = -1;
        try {
            connection = DBManager.getConnection();
            connection.setAutoCommit(false
 
);
            statement = connection.prepareStatement(sql);

            for(int i = 0;i<params.length;i++){
                statement.setObject(i+1, params[i]);
            }
            System.out.println(sql);
            value = statement.executeUpdate();
            connection.commit();
        } catch
 
 (SQLException e) {
            e.printStackTrace();
            if(connection!=null){
                try {
                    connection.rollback();
                    connection.setAutoCommit(true);
                } catch (SQLException e1) {
                    e1.printStackTrace();
                }
            }
        } finally {
            DBManager.closeAll(statement,connection);
        }
        return value;
    }

    /**
     * 獲取集合
     * @param sql
     * @param clazz
     * @param params
     * @return
     */
    public List<T> getList(String sql,Class<T> clazz,Object...params){
        List<T> list = new ArrayList<>();
        try {
            connection = DBManager.getConnection();
            statement = connection.prepareStatement(sql);
            for(int i = 0;i<params.length;i++){
                statement.setObject(i+1, params[i]);
            }
            query = statement.executeQuery();
            metaData = query.getMetaData();
            int column = metaData.getColumnCount();
            while(query.next()){
                T t = clazz.newInstance();
                for(int i = 1;i<=column;i++){
                    String name = metaData.getColumnName(i);
                    Object value = query.getObject(i);
                    Field field = clazz.getDeclaredField(name);
                    field.setAccessible(true);
                    field.set(t, value);
                }
                list.add(t);
            }
        } catch (SQLException | InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } finally {
            DBManager.closeAll(query,statement,connection);
        }
        return list;
    }


    /**
     * 獲取物件
     * @param sql
     * @param clazz
     * @param params
     * @return
     */
    public T getInstance(String sql,Class<T> clazz,Object...params){

        try {
            connection = DBManager.getConnection();
            statement = connection.prepareStatement(sql);
            for(int i = 0;i<params.length;i++){
                statement.setObject(i+1,params[i]);
            }
            query = statement.executeQuery();
            metaData = query.getMetaData();
            int column = metaData.getColumnCount();

            if(query.next()){
                T t = clazz.newInstance();
                for(int i = 1;i<=column;i++){
                    String name = metaData.getColumnName(i);
                    Object value = query.getObject(i);
                    Field field = clazz.getDeclaredField(name);
                    field.setAccessible(true);
                    field.set(t, value);
                }
                return t;
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        }finally {
            DBManager.closeAll(statement,connection);
        }
        return null;
    }

}

這裡面會有DBManager類，主要就是連線資料庫和關閉的，可以自行補全。

很簡單，簡單使用反射的方法來給每一個屬性賦值，然後返回就行。。。

當我們要使用的時候就可以這樣：

public class StudentDaoImpl extends DBOperator<Student> {


    public List<Student> getList() {
        String sql = "select * from student";
        return super.getList(sql, Student.class);
    }

    public Student getStudentById(int id) {
        String sql = "select * from student where id=?";
        return super.getInstance(sql, GoodsInfo.class, id);
    }

}

Over。

寫的不好，歡迎指正，不喜勿噴！！！