databasemanager.java

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package ch07;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

//这个类继承自BaseDB类
public class DatabaseManager extends BaseDB {
    //数据库连接对象
    private Connection dbConn;

    private Statement stmt;

    private ResultSet rs;

    //描述 错误号 0=无错误，-1有错误
    private int errNum;

    //error 描述 错误信息
    private String errDesc;

    //初始化操作
    public DatabaseManager() {
        dbConn = super.getConn();
        stmt = null;
        rs = null;
        errNum = 0;
        errDesc = "";
    }

    //执行sql 执行语句，主要是执行插入和删除的SQL语句
    public boolean exeSql(String strSql) {
        try {
            stmt = dbConn.createStatement();
            stmt.executeUpdate(strSql);
            return true;
        } catch (Exception ex) {
            ex.printStackTrace();
            this.errNum = -1;
            this.errDesc = ex.toString();
            return false;
        }
    }

    //执行sql 查询语句
    public ResultSet exeSqlQuery(String strSql) {

        try {
            stmt = dbConn.createStatement();
            rs = stmt.executeQuery(strSql);
        } catch (Exception ex) {

            this.errNum = -1;
            this.errDesc = ex.toString();
            rs = null;
        }
        return rs;
    }

    //取得错误号码
    public int getErrNum() {
        return errNum;
    }

    //取得错误信息
    public String getErrDesc() {
        return errDesc;
    }
    
    //关闭数据库连接
    public void close(){
        try{
            if(dbConn != null)
                dbConn.close();
            if(stmt != null)
                stmt.close();
            if(rs != null)
                rs.close();
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}