dbutil操作數據庫工具類

步驟

導入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目錄下(src下一級目錄，否則出錯)，

c3p0-config.xml? (連接數據庫的驅動，url,名字，密碼，，，，等)

創建連接池

ComboPooledDataSource ?ds = new ComboPooledDataSource();

拿到執行sql的關鍵對象QueryRunner

QueryRunner ?qr = new QueryRunner(ds);

寫sql語句

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

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

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

查：

查一個：String ?sql="select * from user where id=?";

查一批：String sql="select * from user";

將sql語句放入Query對象，調用相應方法增刪改查

不要疑惑，增加、修改、刪除都可以調用update方法，內部會通過判斷有無id而具體實行增加還是修改，只有sql時刪除。

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

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

刪：int ?num=qr.update(sql);

查：

查一個

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

查一批

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

注：增刪改都可用Query對象的update方法，查詢的同時將查到的數據封裝成對應的對象或者集合。

示例代碼：

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 {

//構造數據源

private static ComboPooledDataSource ds=new ComboPooledDataSource();

public static QueryRunner getRuertyRunner(){

//拿到操作數據庫的關鍵對象QueryRunner,把數據源放進去

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;

}

}

總結

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