Java游戏服务器数据库存取封装：Table与Record自动映射实现

<Table name="user" primaryKey="user_id" primaryField="userId">
  <Column name="username" field="username" type="2" />
  <Column name="password" field="password" type="2" />
  <Column name="salt" field="salt" type="1" />
  <Column name="reg_time" field="registerTime" type="3" />
</Table>

public class Table<T> {
  public static final int TYPE_INTEGER = 1;
  public static final int TYPE_STRING = 2;
  public static final int TYPE_TIMESTAMP = 3;
  
  public class TableField {
    public String columnName = "";
    public String fieldName = "";
    public int type = 0;
  }
  // ...省略Getter/Setter...
}

private String generateUpdateSql() {
    StringBuilder sql = new StringBuilder("UPDATE ").append(tableName).append(" SET ");
    int size = tableFields.size();
    for (int index = 0; index < size; ++index) {
      TableField field = tableFields.get(index);
      if (index != 0) sql.append(",");
      sql.append(field.columnName).append(" = ?");
    }
    sql.append(" WHERE ").append(primaryField.columnName).append(" = ?");
    return sql.toString();
}

// 假设 UserData 是与 user.xml 对应的业务实体
public class UserData implements Serializable {
  public int userId = 0;
  public String username = "";
  public String password = "";
  public long regTime = 0L;
  // ... getters/setters ...
}

public class Record<T> {
  private Table<T> table;
  private T object;

  public int setNormalParams(int start, PreparedStatement pst) throws Exception {
    ArrayList<TableField> fields = table.getNoramlFields(); // 排除主键的非主键字段
    for (TableField field : fields) {
      Object value = getFieldValue(field);     // 反射取值
      value = toDBValue(field, value);          // 类型转换
      pst.setObject(start++, value);            // 设置参数
    }
    return start;
  }
  
  public int setPrimaryParams(int start, PreparedStatement pst) throws Exception {
    TableField pf = table.getPrimaryField();
    Object value = getFieldValue(pf);
    value = toDBValue(pf, value);
    pst.setObject(start, value);
    return start + 1;
  }
  
  private Object getFieldValue(TableField field) throws Exception {
    java.lang.reflect.Field f = object.getClass().getDeclaredField(field.fieldName);
    f.setAccessible(true);
    return f.get(object);
  }
  
  private Object toDBValue(TableField field, Object value) {
    // 简单的类型适配，例如 TimeStamp
    if (field.type == Table.TYPE_TIMESTAMP && value instanceof Long) {
       return new java.sql.Timestamp((Long) value);
    }
    return value;
  }
}

public class UserService {
  private static final Table<UserData> udTable = new Table<>();

  @PostConstruct
  public void init() {// 或其他启动逻辑
    udTable.load("user.xml"); // 从配置文件加载结构
  }

  public boolean updateUserData(UserData userData) {
    Record<UserData> record = udTable.createRecord();
    record.setObject(userData); // 绑定当前业务对象
    
    Connection conn = null;
    PreparedStatement pst = null;
    try {
      conn = DbUtil.openConnection(); // 获取连接
      String sql = udTable.getUpdateSql(); // 获取生成的SQL
      pst = conn.prepareStatement(sql);
      
      // 自动绑定参数：先普通字段，再主键
      record.setUpdateParams(pst); // 该方法内部调用 setNormalParams & setPrimaryParams
      
      return pst.executeUpdate() > 0;
    } catch (Exception e) {
      e.printStackTrace();
      return false;
    } finally {
      DbUtil.closeConnection(conn, pst); // 资源释放
    }
  }
}