java学习笔记之DBUtils工具包详解

QueryRunner qr =new QueryRunner();

QueryRunner qr= new QueryRunner(DataSource dataSource);

public class Demo {
 public static void main(String[] args) throws Exception {
  /*
   * 演示有参构造的update()方法
   * 
   * 首先得导入jar包
   * 配置好C3P0的配置文件与准备好C3P0工具类
   * 然后创建QueryRunner对象
   * 调用update方法
   * 最后处理结果
   */
  QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
  int re = qr.update("update user set name=? where uid=?","张三",2);
  if(re>0){
   System.out.println("修改成功");
  }else {
   System.out.println("修改失败");
  }
 }
}

public class C3P0Utils {
 private static DataSource dataSource=new ComboPooledDataSource();
 /**
  * 获得DataSource实现类对象
  * @return
  */
 public static DataSource getDataSource(){
  return dataSource;
 }
 /**
  * 获得连接
  * @return
  * @throws Exception
  */
 public static Connection getConnection()throws Exception{
  return dataSource.getConnection();
 }
}

public void demo1() throws Exception{
  QueryRunner qr = new QueryRunner(MyC3P0Utils.getDataSource()); 
  List<Car> list = qr.query("select * from car where price<20 order by price desc", new BeanListHandler<>(Car.class));
  for (Car car : list) {
   System.out.println(car);
  }
 
 }

public class Car {
 private int cid;
 private String cname;
 private String company;
 private String grade;
 private double price;
 @Override
 public String toString() {
  return "Car [cid=" + cid + ", cname=" + cname + ", company=" + company + ", grade=" + grade + ", price=" + price
    + "]";
 }
 public int getCid() {
  return cid;
 }
 public void setCid(int cid) {
  this.cid = cid;
 }
 public String getCname() {
  return cname;
 }
 public void setCname(String cname) {
  this.cname = cname;
 }
 public String getCompany() {
  return company;
 }
 public void setCompany(String company) {
  this.company = company;
 }
 public String getGrade() {
  return grade;
 }
 public void setGrade(String grade) {
  this.grade = grade;
 }
 public double getPrice() {
  return price;
 }
 public void setPrice(double price) {
  this.price = price;
 }
 public Car(int cid, String cname, String company, String grade, double price) {
  super();
  this.cid = cid;
  this.cname = cname;
  this.company = company;
  this.grade = grade;
  this.price = price;
 }
 public Car() {
  super();
  // TODO Auto-generated constructor stub
 }
}