使用common-dbutils进行dao操作

jar:

　　

先引出database工具类：

　

package cn.itcast.utils;

public class Stu {
    private int id;
    private String sname;
    private int age;
    private String gender;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Stu() {
        super();
    }
    public Stu(int id, String sname, int age, String gender) {
        super();
        this.id = id;
        this.sname = sname;
        this.age = age;
        this.gender = gender;
    }
    @Override
    public String toString() {
        return "Stu [id=" + id + ", sname=" + sname + ", age=" + age
                + ", gender=" + gender + "]";
    }
    
}
Stu
package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class JdbcUtils {
    /*
     * 配置文件的恶魔人配置！要求你必须给出c3p0-config。xnl!
     */
    private static ComboPooledDataSource dataSource=new ComboPooledDataSource();
    
    /**
     * 使用连接池返回一个连接对象
     * @return
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException{
        return dataSource.getConnection();
    }
    
    /**
     * 返回连接池对象
     * @return
     */
    public static DataSource getDataSource(){
        return dataSource;
    }
}
jdbcUtils

常规操作：　

package cn.itcast.utils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.junit.Test;

import cn.itcast.jdbc.JdbcUtils;

public class Demo1 {
    
    public int addStu(Stu stu){
        Connection con=null;
        PreparedStatement pstmt=null;
        try {
            con=JdbcUtils.getConnection();
            String sql="INSERT INTO t_stu VALUES (?,?,?,?)";
            pstmt=con.prepareStatement(sql);
            pstmt.setInt(1, stu.getId());
            pstmt.setString(2, stu.getSname());
            pstmt.setInt(3, stu.getAge());
            pstmt.setString(4, stu.getGender());
            
            return pstmt.executeUpdate(); 
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(con!=null) con.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        }
        
    }
    public int updateStu(Stu stu){
        Connection con=null;
        PreparedStatement pstmt=null;
        try {
            con=JdbcUtils.getConnection();
            String sql="UPDATE t_stu SET sname = ? , age = ? , gender = ? WHERE id=?";
            pstmt=con.prepareStatement(sql);
            pstmt.setInt(4, stu.getId());
            pstmt.setString(1, stu.getSname());
            pstmt.setInt(2, stu.getAge());
            pstmt.setString(3, stu.getGender());
            
            return pstmt.executeUpdate(); 
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(con!=null) con.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        }
    }
    public int deleteStu(int sid){
        Connection con=null;
        PreparedStatement pstmt=null;
        try {
            con=JdbcUtils.getConnection();
            String sql="DELETE FROM t_stu WHERE id=?";
            pstmt=con.prepareStatement(sql);
            pstmt.setInt(1, sid);
            return pstmt.executeUpdate(); 
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(con!=null) con.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        }
    }
    /**
     * 我们可以发现增删改具有共性，不同点：
     *     sql语句
     *     参数列表
     */
    
    public Stu load(int id){
        Connection con=null;
        PreparedStatement pstmt=null;
        ResultSet rs=null;
        try {
            con=JdbcUtils.getConnection();
            String sql="SELECT * FROM t_stu WHERE id=?";
            pstmt=con.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs=pstmt.executeQuery();
            Stu stu=new Stu();
            if(!rs.next()) return null;
            stu.setId(rs.getInt(1));
            stu.setSname(rs.getString(2));
            stu.setAge(rs.getInt(3));
            stu.setGender(rs.getString(4));
            return stu;
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(con!=null) con.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        }
    }
    /*
     * 查询的不同点：
     *    sql语句
     *    参数列表
     *    结果类型
     *    可以将查询多条数据和单条数据都当成集合处理
     */
    
    @Test
    public void fun1(){
//        Stu stu=new Stu(1001,"zs",21,"man");
//        addStu(stu);
//        Stu stu=new Stu(1001,"zs",22,"man");
//        updateStu(stu);
//        deleteStu(1001);
        System.out.println(load(1001));
    }
}
增删改查

自定义工具类：

package cn.itcast.utils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.sql.DataSource;

public class QR<T> {
    private DataSource dataSource;
    
    public QR(DataSource dataSource){
        this.dataSource=dataSource;
    }
    
    public QR(){
        super();
    }
    
    public int update(String sql,Object...params){
        Connection conn=null;
        PreparedStatement pstmt=null;
        try {
            
            conn=dataSource.getConnection();
            pstmt=conn.prepareStatement(sql);
            initParam(pstmt,params);
            
            return pstmt.executeUpdate();
            
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(conn!=null) conn.close();
            }catch(SQLException e1){
                throw new RuntimeException(e1);
            }
        }
    }
    
    public T query(String sql,RsHandler<T> rh,Object...params){
        Connection conn=null;
        PreparedStatement pstmt=null;
        ResultSet rs=null;
        try {
            
            conn=dataSource.getConnection();
            pstmt=conn.prepareStatement(sql);
            initParam(pstmt,params);
            
            rs= pstmt.executeQuery();
            return rh.handle(rs);
            
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally{
            try{
                if(pstmt!=null) pstmt.close();
                if(conn!=null) conn.close();
            }catch(SQLException e1){
                throw new RuntimeException(e1);
            }
        }
    }
    
    public void initParam(PreparedStatement pstmt,Object...params) throws SQLException{
        for(int i=0;i<params.length;i++){
            pstmt.setObject(i+1, params[i]);
        }
    }

}
interface RsHandler<T>{
    public T handle(ResultSet rs)throws SQLException;
}
模拟dbutils
package cn.itcast.utils;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.junit.Test;

import cn.itcast.jdbc.JdbcUtils;
@SuppressWarnings({"rawtypes","unchecked"})
public class Demo2 {
    
    @Test
    public void fun1(){
//        Stu s=new Stu(1002,"lisi",23,"woman");
//        addStu(s);
        Stu s=load(1002);
        System.out.println(s);
        
    }
    
    public void addStu(Stu stu){
        QR qr=new QR(JdbcUtils.getDataSource());
        String sql="INSERT INTO t_stu VALUES(?,?,?,?)";
        Object[] params={stu.getId(),stu.getSname(),stu.getAge(),stu.getGender()};
        qr.update(sql, params);
    }
    
    
    public Stu load(int sid){
        QR qr=new QR(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu WHERE id=?";
        Object[] params={sid};
        
        RsHandler<Stu> rh=new RsHandler<Stu>(){

            @Override
            public Stu handle(ResultSet rs) throws SQLException {
                if(!rs.next()) return null;
                Stu stu=new Stu();
                stu.setId(rs.getInt(1));
                stu.setSname(rs.getString(1));
                stu.setAge(rs.getInt(3));
                stu.setGender(rs.getString(4));
                return stu;
            }
            
        };
        return (Stu) qr.query(sql, rh, params);
    }
}
使用自定义的工具类

dbUtils：

common-dbutils.jar

QueryRunner

update方法：
*int update(String sql,Object...params)-->可执行增、删、改语句
*int update(Connection con,String sql,Object...params)，调用者提供Connection，便于事务

query方法
*T query(String sql,ResultSetHandler rsh,Object...params)-->可执行查询
>它会先得到ResultSet，然后调用rsh的handle()把rs转换成需要的；类型
*T query(Connection con,String sql,ResultSetHandler rsh,Object...params)

ResultSetHandler接口：
*BeanHandler(单行)-->构造器需要一个Class类型的参数，用来将一行结果转换成指定类型的javaBean对象
*BeanListHandler(多行)-->构造器也是需要一个Class类型的参数，用来将一行结果转换成一个javaBean，多行就是转换成list对象，一堆javaBean
*MapHandler(单行)-->将一行结果转换为Map对象
>一行记录：
sid sname age gender
1001 zs 99 male
>一个Map：
{sid:1001,sname:zs,age:99,gender:male}
*MapListHandler(多行)-->把一列记录转换成一个Map，多列记录转换成一个Map为子元素的List集合
*ScalarHandler(单列多行)-->通常用于select count(*) from t_stu语句，结果集是单行单列的，它的类型是Object

例子：

package cn.itcast.utils;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.junit.Test;

import cn.itcast.jdbc.JdbcUtils;

public class Demo3 {
    @Test
    public void fun1() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="INSERT INTO t_stu VALUES (?,?,?,?)";
        Object[] params={1003,"wangwu",23,"woman"};
        
        qr.update(sql,params);
    }
    
    @Test
    public void fun2() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu WHERE id=?";
        Object[] params={1003};
        
        ResultSetHandler<Stu> rsh=new ResultSetHandler<Stu>(){

            @Override
            public Stu handle(ResultSet rs) throws SQLException {
                if(!rs.next()) return null;
                Stu stu=new Stu();
                stu.setId(rs.getInt(1));
                stu.setSname(rs.getString(2));
                stu.setAge(rs.getInt(3));
                stu.setGender(rs.getString(4));
                return stu;
            }
            
        };
        /*
         *执行query()方法，需要给出结果集处理器，即ResultSetHandler的实现类 对象，完成ResultSet到指定类型的转换
         */
        Stu stu=qr.query(sql, rsh,params);
        System.out.println(stu);
    }
    
    /**
     * BeanHandler 单行
     * Bean有关的需要注意内部可能是使用BeanUtils或者内省实现，需要每一个成员字段都有对应的属性
     * @throws SQLException
     */
    @Test
    public void fun3() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu WHERE id=?";
        Object[] params={1003};
        ResultSetHandler<Stu> rsh=new BeanHandler<Stu>(Stu.class); 
        Stu stu=qr.query(sql,rsh ,params);
        System.out.println(stu);
    }
    /**
     * BeanListHandler 多行
     * @throws SQLException
     */
    @Test
    public void fun4() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu";
        ResultSetHandler<List<Stu>> rsh=new BeanListHandler<Stu>(Stu.class); 
        List<Stu> stus=qr.query(sql,rsh);
        System.out.println(stus);
    }
    /**
     * MapHandler 单行
     * @throws SQLException
     */
    @Test
    public void fun5() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu WHERE id=?";
        Object[] params={1003};
        ResultSetHandler<Map<String, Object>> rsh=new MapHandler(); 
        Map<String, Object> stu=qr.query(sql,rsh ,params);
        System.out.println(stu);
    }
    
    /**
     * MapListHandler 多行
     * @throws SQLException
     */
    @Test
    public void fun6() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT * FROM t_stu";
        ResultSetHandler<List<Map<String, Object>>> rsh=new MapListHandler(); 
        List<Map<String, Object>> stus=qr.query(sql,rsh);
        System.out.println(stus);
    }
    /**
     * ScalarHandler 单行单列
     * @throws SQLException
     */
    @Test
    public void fun7() throws SQLException{
        QueryRunner qr=new QueryRunner(JdbcUtils.getDataSource());
        String sql="SELECT COUNT(*) FROM t_stu";
        ResultSetHandler<Object> rsh=new ScalarHandler(); 
        long count=(Long) qr.query(sql,rsh );
        System.out.println(count);
    }
}
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原文地址：https://www.cnblogs.com/aigeileshei/p/5716131.html