[JavaWeb]DBUtils中的QueryRunner

QueryRunner类

QueryRunner中提供对sql语句操作的API
它主要有三个方法

　　query() 用于执行select
　　update() 用于执行insert/update/delete
　　batch() 批处理
public class JdbcUtil {
/**
* 去src目录下加载c3p0-config.xml配置文件
*/
private static ComboPooledDataSource dataSource = new ComboPooledDataSource();
/**
* 获取数据源
*/
public static ComboPooledDataSource getDataSource() {
return dataSource;
}
}

操作数据
int topicNum=0;
QueryRunner runner= new QueryRunner(JdbcUtil.getDataSource());
String sql ="select count(*) from topic where type_id= ? order by time desc";
Object[] params={typeId};
topicNum=(int)(long) runner.query(sql,new ScalarHandler(),params);
return topicNum;

Topic newlyTopic=null;
QueryRunner runner= new QueryRunner(JdbcUtil.getDataSource());
String sql ="select * from topic where type_id= ? order by time desc";
Object[] params={typeId};
newlyTopic= runner.query(sql,new BeanHandler<Topic>(Topic.class),params);
return newlyTopic;

List<Topic> topicList=new ArrayList<Topic>();
QueryRunner runner= new QueryRunner(JdbcUtil.getDataSource());
String sql ="select * from topic where type_id= ? order by time desc";
Object[] params={typeId};
topicList=runner.query(sql, new BeanListHandler<Topic>(Topic.class),params);
return topicList;

public void add(Emp emp) throws Exception{
QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());
String sql = "insert into emps(id,username,salary,hiredate) values(?,?,?,?)";
Object[] params = {emp.getId(),emp.getUsername(),emp.getSalary(),emp.getHiredate()};
runner.update(sql,params);
}