Question

如何从文件中将一堆记录插入MySQL 我正在为一个带有java和JDBC的库编写这个应用程序我到目前为止已经有了这个。

该程序能够导出包含大量书籍的文件，我想加载该文件的内容，但在插入数据之前，我必须验证每条记录并显示插入的记录数量。当我跑步说 连接太多 我该怎么办？

public class BookDAO extends BaseDAO {

   private static final String SELECT_SAME = "SELECT COUNT(*) AS counter 
        FROM Book WHERE "name=? AND ISBN=?";
   ...

    public void create(Book book) throws SQLException {
        PreparedStatement ps = null;
    try {            
        ps = conn.prepareStatement(SQL_INSERT);
        ps.setLong(1, com.getISBN());
        ps.setString(2, com.getName());
        ps.executeUpdate();
    } finally {
        close(ps);
        close(conn);
    }
}
...

public boolean isRegistered(Book book) throws SQLException {
    PreparedStatement ps = null;
    ResultSet rs = null;
    int counter = 0;        
    try {
        ps = conn.prepareStatement(SELECT_SAME);
        ps.setLong(1, book.getISBN());
        ps.setString(2, book.getName());
        rs = ps.executeQuery();
        if (rs.next()) {
            counter = rs.getInt("counter");
        }
    } catch (SQLException e) {
        LOGGER.warn("BookDAO fail to check if is registered :" + e);
    } finally {
        close(rs);
        close(ps);
        close(conn);
    }
    return counter < 1;
}

public List<Number> loadFromFile(List<Book> book) throws SQLException {
    PreparedStatement ps = null;
    int added = 0;
    int notAdded = 0;
    List<Number> values = new ArrayList<>();
    try {
        this.conn.setAutoCommit(false);
        ps = conn.prepareStatement(INSERT);
        for (Book book : books) {
            ps.setISBN(1, book.getISBN());
            ps.setString(2, book.getName());
            ps.addBatch();
            ps.clearParameters();
            added++;                
        }
        ps.executeBatch();
        this.conn.commit();
        values.add(added);
        values.add(notAdded);
    } catch (SQLException e) {
        LOGGER.warn("BookDAO fail getting the books from file :" + e);
    } finally {
        close(ps);
        this.conn.setAutoCommit(true);
        close(conn);
    }
    return values;
}

... more methods

BaseDAO类包含。

  public class BaseDAO {   
     protected Connection conn;

     public Base2DAO() {
        try {
          Class.forName("com.mysql.jdbc.Driver");
           conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/database", "user", "");
        LOGGER.info("Connected to database");
    } catch (ClassNotFoundException | SQLException e) {
        LOGGER.fatal("Database not found!" + e);
    }
}

    protected void close(Connection cnn) throws SQLException {
     ...
    }

    protected void close(PreparedStatement ps) throws SQLException {
     ...
    }

    protected void close(ResultSet rs) {
    ...
    }

    public Connection getConnection() {
       return conn;
    }

    public void close() throws SQLException {
      conn.close();
    }
 }

所以在主应用程序中我有这个

public static void main(){
  ...
      ArrayList<Book> bookList = (ArrayList<Book>) xstream.fromXML(xml);
        List<Book> checkedBooks = new ArrayList<>();
        //the problem begins here
        for (Book book : bookList) {
            if (new BookDAO().isRegistered(book)) {
                checkedBooks.add(book);
            }
        }
        List<Number> result = new BookDAO().loadBooksFromFile(checkedBooks);
        results += ("\nNew records:");
        results += (String.valueOf(result.get(0)));
        results += ("\nRegistered previously:");
        results += (String.valueOf(bookList.size() - checkedBooks.size()));

   }

感谢。

如何从文件中将一堆记录插入MySQL

0 个答案: