dbutil操作数据库工具类

步骤

导入jar包

c3p0-0.9.1.2.jar         commons-dbutils-1.6.jar         mysql-connector-java-5.1.12-bin.jar

把c3p0配置文件放到src目录下(src下一级目录，否则出错)，

c3p0-config.xml  (连接数据库的驱动，url,名字，密码，，，，等)

创建连接池

ComboPooledDataSource  ds = new ComboPooledDataSource();

拿到执行sql的关键对象QueryRunner

QueryRunner  qr = new QueryRunner(ds);

写sql语句

增：String  sql=” insert into user(name,age) values(?,?)”;

删：String  sql="delete from user where id="+u.getId();

改：String  sql="update user set name=?,age=? where id=?";

查：

查一个：String  sql="select * from user where id=?";

查一批：String sql="select * from user";

将sql语句放入Query对象，调用相应方法增删改查

不要疑惑，增加、修改、删除都可以调用update方法，内部会通过判断有无id而具体实行增加还是修改，只有sql时删除。

增：int  num = qr.update(sql, u.getName(),u.getAge());

改：int  num = qr.update(sql, u.getName(),u.getAge()，u.getId());

删：int  num=qr.update(sql);

查：

查一个

User  user = qr.query(sql, new BeanHandler(User.class), id);

查一批

List  users = qr.query(sql, new BeanListHandler(User.class));

注：增删改都可用Query对象的update方法，查询的同时将查到的数据封装成对应的对象或者集合。

示例代码：

c3p0-config.xml

com.mysql.jdbc.Driver

jdbc:mysql://localhost/test

root

5

10

DbUtil.java

package util;

import org.apache.commons.dbutils.QueryRunner;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DbUtil {

//构造数据源

private static ComboPooledDataSource ds=new ComboPooledDataSource();

public static QueryRunner getRuertyRunner(){

//拿到操作数据库的关键对象QueryRunner,把数据源放进去

QueryRunner qr = new QueryRunner(ds);

return qr;

}

}

User.java

package entity;

public class User {

private int id;

private int age;

private String name;

public User() {

super();

}

public User(int id, int age, String name) {

super();

this.id = id;

this.age = age;

this.name = name;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

}

UserDao.java

package dao;

import java.sql.SQLException;

import java.util.List;

import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.handlers.BeanHandler;

import org.apache.commons.dbutils.handlers.BeanListHandler;

import util.DbUtil;

import entity.User;

public class UserDao {

/*public int add(User u){

Connection conn = JdbcUtil.getConnection();

String sql="insert into user(name,age) values(?,?)";

PreparedStatement ps=null;

int num=0;

try {

ps = conn.prepareStatement(sql);

ps.setObject(1, u.getName());

ps.setObject(2, u.getAge());

num=ps.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();

}finally{

try {

ps.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

return num;

}*/

//dbutil

QueryRunner qr = DbUtil.getRuertyRunner();

public int add(User u){

String sql="insert into user(name,age) values(?,?)";

int num=0;

try {

num = qr.update(sql, u.getName(),u.getAge());

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return num;

}

public int delete(User u){

String sql="delete from user where id="+u.getId();

int num=0;

try {

num = qr.update(sql);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return num;

}

public int update(User u){

String sql="update user set name=?,age=? where id=?";

int num =0;

try {

num= qr.update(sql, u.getName(),u.getAge(),u.getId());

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return num;

}

public User selectOne(int id){

String sql="select * from user where id=?";

User user=null;

try {

user = qr.query(sql, new BeanHandler(User.class), id);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return user;

}

public List selectAll(){

String sql="select * from user";

List users=null;

try {

users = qr.query(sql, new BeanListHandler(User.class));

} catch (SQLException e) {

e.printStackTrace();

}

return users;

}

}