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Dbutils工具类的使用

程序员文章站 2022-11-08 20:46:52
一、什么是Dbutils？ Commons DbUtils是Apache组织提供的一个对JDBC进行简单封装的开源工具类库，使用它能够简化JDBC应用程序的开发，同时也不会影响程序的性能。来源百度百科 简而言之，Dbutils就是封装了jdbc的代码，简化了jdbc的dao层的操作。 二、Dbuti ......

一、什么是dbutils？

　　commons dbutils是apache组织提供的一个对jdbc进行简单封装的开源工具类库，使用它能够简化jdbc应用程序的开发，同时也不会影响程序的性能。来源百度百科

　　简而言之，dbutils就是封装了jdbc的代码，简化了jdbc的dao层的操作。

二、dbutils的使用

a：导入相关的依赖jar包

  • mysql-connector-java-5.1.7-bin.jar
  • commons-dbutils-1.7.jar

b：项目结构

Dbutils工具类的使用

  • studentdao接口：对student实体类对象操作的接口，使用接口利于维护
  • studentdaoimpl：studentdao接口的实现类，用于写具体的功能实现代码
  • student类：学生实体类对象，用于封装学生对象的相关属性信息
  • test类：功能测试类，用于测试功能实现的代码
  • jdbctools：对于jdbc的初步封装的工具类，用于获取数据库连接以及释放资源等操作
  • db-config.properties文件：用于存储数据库的连接的一些信息，防止硬编码格式，方便更改

　c：使用dbutils的具体步骤

　　a：创建queryrunner对象　

 

queryrunner queryrunner = new queryrunner();

 

　　b：调用queryrunner对象的方法执行相关操作，给queryrunner对象传递参数：connection，sql，具体的;，条件参数

 

public void insert(student student) {
        sql = "insert into student(name,clazz,grade) values(?,?,?)";
        try {
            //jdbctools.getconnection()：数据库连接
            //sql：数据库查询sql语句
            //student.getname():需要的参数，参数与sql中的参数的数量保持一致
            queryrunner.update(jdbctools.getconnection(),sql,student.getname(),student.getclazz(),student.getgrade());
        } catch (sqlexception e) {
            e.printstacktrace();
        }
    }
public student findbyid(int id) {
        sql = " select * from student where id = ?";
        student student = null;
        try {
            student = queryrunner.query(jdbctools.getconnection(),sql,new beanhandler<student>(student.class),id);
        } catch (sqlexception e) {
            e.printstacktrace();
        }
        return student;
    }

策略对象

  • beanhandler：把单行的结果集封装成javabean对象，返回值是resultsethandler，该方法用于将单行结果集封装成javabean对象，对象是通过反射完成创建的 
resultsethandler<javabean类型> rsh = new beanhandler<javabean类型>(javabean.class);
  • beanlisthandler：将多行结果集封装成对象，并将对象添加到list集合中
 list<javabean类型> list = <list<javabean类型>> new beanlisthandler<javabean类型>(javabean.class);
  • maphandler：将单行的结果集封装到一个map集合中，map集合中的建是表中的列名称，值对应表的列值。
map <string,object> map = new maphandler();
  • maplisthandler：用于多行结果集的处理，把每行的结果封装成一个map，最后把所有的map都放到一个集合中，返回的是一个list集合，list集合中存放的是map集合。
  list<map<string,object>> listmap = new maplisthandler();
  • columnhandler：本方法用于互殴去单列，单行或者多行的数据
list<object> namelist = new columnhandler();
  • scalarhandler：用户处理单行、单列的数据，多用于聚合函数的查询。注意：当聚合函数涉及到数字类型的时候，要注意返回值类型的转换，若使用integer或者long类型的时候，容易出现数据无法存储的时候，所以使用number（这个是所有数字数据类型的父类），对外提供了number.intvalue()和number.longvalue()等方法。

 

resultsethandler resultsethandler = new scalarhandler();

 

c：具体的实现代码

　　a：javabean对象

package com.dreambamboo.entity;

public class student {
    private int id;
    private string name;
    private string grade;
    private string clazz;

    public student(int id, string name, string grade, string clazz) {
        this.id = id;
        this.name = name;
        this.grade = grade;
        this.clazz = clazz;
    }

    public student() {
    }

    public int getid() {
        return id;
    }

    public void setid(int id) {
        this.id = id;
    }

    public string getname() {
        return name;
    }

    public void setname(string name) {
        this.name = name;
    }

    public string getgrade() {
        return grade;
    }

    public void setgrade(string grade) {
        this.grade = grade;
    }

    public string getclazz() {
        return clazz;
    }

    public void setclazz(string clazz) {
        this.clazz = clazz;
    }

    public student(string name, string grade, string clazz) {
        this.name = name;
        this.grade = grade;
        this.clazz = clazz;
    }

    @override
    public string tostring() {
        return "student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", grade='" + grade + '\'' +
                ", clazz='" + clazz + '\'' +
                '}';
    }
}

　　b：dao接口

package com.dreambamboo.dao;

import com.dreambamboo.entity.student;

import java.util.list;


public interface studentdao {
    /**
     * 添加学生信息
     * @param student
     */
    public void insert(student student);

    /**
     * 更新学生信息
     * @param student
     */
    public void update(student student);

    /**
     * 删除学生信息
     * @param id
     */
    public void delete(int id);

    /**
     * 根据学生编号查询学生信息
     * @param id
     * @return
     */
    public student findbyid(int id);

    /**
     * 查询所有学生信息
     * @return
     */
    public list<student> findall();

    /**
     * 查询学生总数
     * @return
     */
    public int studentcount();
}

　　c：dao接口实现类

package com.dreambamboo.dao.impl;

import com.dreambamboo.dao.studentdao;
import com.dreambamboo.entity.student;
import com.dreambamboo.util.jdbctools;
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.scalarhandler;

import java.sql.sqlexception;
import java.util.list;

public class studentdaoimpl implements studentdao {
    private queryrunner queryrunner = null;//查询运行器
    public studentdaoimpl(){
        queryrunner = new queryrunner();
    }
    string sql = null;
    @override
    public void insert(student student) {
        sql = "insert into student(name,clazz,grade) values(?,?,?)";
        try {
            //jdbctools.getconnection()：数据库连接
            //sql：数据库查询sql语句
            //student.getname():需要的参数，参数与sql中的参数的数量保持一致
            queryrunner.update(jdbctools.getconnection(),sql,student.getname(),student.getclazz(),student.getgrade());
        } catch (sqlexception e) {
            e.printstacktrace();
        }
    }

    @override
    public void update(student student) {
        sql = " update student set name = ? ,clazz = ?,grade = ? where id = ?";
        try {
            queryrunner.update(jdbctools.getconnection(),sql,student.getname(),student.getclazz(),student.getgrade(),student.getid());
        } catch (sqlexception e) {
            e.printstacktrace();
        }
    }

    @override
    public void delete(int id) {
        sql = "delete from student where id = ?";
        try {
            queryrunner.update(jdbctools.getconnection(),sql,id);
        } catch (sqlexception e) {
            e.printstacktrace();
        }
    }

    @override
    public student findbyid(int id) {
        sql = " select * from student where id = ?";
        student student = null;
        try {
            student = queryrunner.query(jdbctools.getconnection(),sql,new beanhandler<student>(student.class),id);
        } catch (sqlexception e) {
            e.printstacktrace();
        }
        return student;
    }

    @override
    public list<student> findall() {
        sql = "select * from student";
        list<student> list = null;
        try {
            list = queryrunner.query(jdbctools.getconnection(),sql,new beanlisthandler<>(student.class));
        } catch (sqlexception e) {
            e.printstacktrace();
        }
        return list;
    }
    @override
    public int studentcount() {
        sql = "select count(id) from student";
        int count = 0;
        try {
            count =  queryrunner.query(jdbctools.getconnection(),sql,new scalarhandler<integer>());

        } catch (sqlexception e) {
            e.printstacktrace();
        }
        return count;
    }
}

　　d：数据库接口连接工具类

package com.dreambamboo.util;



import java.sql.*;
import java.util.resourcebundle;

/**
 * 数据库操作工具类
 */
public class jdbctools {
    private static string url;
    private static string username;
    private static string password;
    private static string driver;

    private static resourcebundle resourcebundle = resourcebundle.getbundle("com.dreambamboo.util.db-config");

    private jdbctools(){

    }

    /**
     * 使用静态代码块加载驱动程序
     *      防止重复代码，使用静态代码块在类加载的时候只会执行一次
     */
    static {
        url = resourcebundle.getstring("jdbc.url");
        username = resourcebundle.getstring("jdbc.username");
        password = resourcebundle.getstring("jdbc.password");
        driver = resourcebundle.getstring("jdbc.driver");
    }

    /**
     * 获取数据库连接
     * @return
     */
    public static connection getconnection(){
        connection connection = null;
        try {
            connection = drivermanager.getconnection(url,username,password);
        } catch (sqlexception e) {
            e.printstacktrace();
            system.out.println("获取连接失败");
        }
        return connection;
    }

    /**
     * 关闭数据库连接资源
     * @param connection    数据库连接
     * @param statement     数据库会话语句
     * @param resultset     数据库查询结果集
     */
    public static void release(connection connection, statement statement, resultset resultset){
        try {
            if (connection != null) {
                connection.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (resultset != null) {
                resultset.close();
            }
        } catch (sqlexception e) {
            e.printstacktrace();
        }
    }

}

　　e：数据库配置文件

jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=mysql
jdbc.driver=com.mysql.jdbc.driver

　　f：测试代码

package com.dreambamboo.test;

import com.dreambamboo.dao.studentdao;
import com.dreambamboo.dao.impl.studentdaoimpl;
import com.dreambamboo.entity.student;

import java.util.list;

public class test {
    public static void main(string[] args) {
        studentdao studentdao = new studentdaoimpl();
        //studentdao.insert(new student("孙悟空","高三年级","五班"));
        //studentdao.update(new student(14,"孙悟空111","高三年级","十一班"));
        //studentdao.delete(14);
        list<student> list = studentdao.findall();
        for (student st : list) {
            system.out.println(st.getid() + "===>>>" + st.getname() + "===>>>>" + st.getclazz() + "===>>> "+ st.getgrade());
        }
    }
}

 三、自定义的dbutils工具类

a：接口结构图分析

Dbutils工具类的使用

 

Dbutils工具类的使用

b：自定义的策略对象

  • queryruuner的封装
package com.dreambamboo.utils;
import java.sql.*;

/**
 * @classname：queryutils
 * @description：自定义queryrunner中的（crud）增、删、改、查的方法
 */
public class queryutils {
    /**
     * @method：update
     * @description：所有实体的cud操作（create、update、delete）
     *      由于所有实体的cud操作代码基本相同，仅仅是操作执行的sql语句不同
     *      因此将实体的cud方法统一抽取成update方法
     * @param connection        数据库连接对象
     * @param sql               执行操作的sql语句
     * @param params            执行sql语句时的参数列表
     */
    public static void update(connection connection,string sql,object params[]){
        preparedstatement preparedstatement = null;
        resultset resultset = null;
        try {
            preparedstatement = connection.preparestatement(sql);
            for (int i = 0; i < params.length; i++) {
                preparedstatement.setobject(i+1,params[i]);
            }
            preparedstatement.executeupdate();
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,preparedstatement,resultset);
        }
    }

    /**
     * @method：query
     * @description：所有实体的r（retrieve）读取查询操作
     *          实体的r操作，除了执行的sql语句不同，根据实体对象的不同，处理结果集的resultset的映射对象也不同
     *          因此在定义query方法时，可以将resultset的映射策略对象交由调用者提供，根据调用者提供的策略对象进行
     *          相对应的映射
     * @param connection        数据库连接对象
     * @param sql               执行的sql语句
     * @param params            执行sql语句时所需的参数列表
     * @param resultsethandler  调用者提供的策略对象
     * @return                  与调用者提供的策略对象相对应的映射对象
     */
    public static object query(connection connection,string sql, object params[], myresultsethandler resultsethandler){
        preparedstatement preparedstatement = null;
        resultset resultset = null;
        object object = null;
        try {
            preparedstatement = connection.preparestatement(sql);
            for (int i = 0; i < params.length; i++) {
                preparedstatement.setobject(i+1,params[i]);
            }
            resultset = preparedstatement.executequery();
            object = resultsethandler.handle(resultset);
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection, preparedstatement,resultset);
        }
        return object;
    }
}
  •  resultsethandler的封装
package com.dreambamboo.utils;

import java.sql.resultset;

/**
 * @classname：myresultsethandler
 * @description：结果集处理器接口
 */
public interface myresultsethandler {
    /**
     * @method：handler
     * @description：结果集处理方法
     * @param resultset 查询结果集
     * @return
     */
    public object handle(resultset resultset);
}
  • beanhandler的封装
    • 方式一
package com.dreambamboo.utils;

import org.apache.commons.dbutils.resultsethandler;

import java.lang.reflect.invocationtargetexception;
import java.lang.reflect.method;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;

public class mybeanhandler implements resultsethandler {

    private class aclass;
    public mybeanhandler(class aclass) {
        this.aclass = aclass;
    }


    @override
    public object handle(resultset resultset) throws sqlexception {
        //结果集的结构
        resultsetmetadata resultsetmetadata = resultset.getmetadata();
        int size = resultsetmetadata.getcolumncount();
        object object = null;
        try {
            object = aclass.getconstructor().newinstance();
            if (resultset.next()){
                //根据结果集获取的操作
                //resultsetmetadata下标从1开始
                for (int i = 1; i <= size; i++) {
                    //mysql中的数据类型对应的javabean中的数据类型
                    string classname = resultsetmetadata.getcolumnclassname(i);
                    string columnname = resultsetmetadata.getcolumnname(i);
                    string methodname = "set" + columnname.substring(0,1).touppercase() + columnname.substring(1);
                    method method = null;
                    switch (classname){
                        case "java.lang.string":
                            string valuestr = resultset.getstring(columnname);
                            method = aclass.getmethod(methodname,string.class);
                            method.invoke(object,valuestr);
                            break;
                        case "java.lang.integer":
                            int valueint = resultset.getint(columnname);
                            method = aclass.getmethod(methodname,int.class);
                            method.invoke(object,valueint);
                            break;
                    }
                }
            }
        } catch (instantiationexception e) {
            e.printstacktrace();
        } catch (illegalaccessexception e) {
            e.printstacktrace();
        } catch (invocationtargetexception e) {
            e.printstacktrace();
        } catch (nosuchmethodexception e) {
            e.printstacktrace();
        }
        return object;
    }
}
    • 方式二
package com.dreambamboo.utils;


import java.lang.reflect.field;
import java.sql.connection;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;

/**
 * @classname：
 * @description：将结果集封装成javabean对象
 * @author：dreambamboo
 */
public class javabeanhandler implements myresultsethandler {
    private class  clazz;
    public javabeanhandler(class clazz){
        this.clazz = clazz;
    }
    @override
    public object handle(resultset resultset) {
        object bean = null;
        object value = null;
        try {
            if (!resultset.next()) {
                return null;
            }
            bean = clazz.newinstance();
            //获取结果集的元数据
            resultsetmetadata resultsetmetadata = resultset.getmetadata();
            //获取结果集的总数
            int size = resultsetmetadata.getcolumncount();
            for (int i = 0; i < size; i++) {
                //获取元数据的列名称
                string columnname = resultsetmetadata.getcolumnname(i+1);
                value = resultset.getobject(i+1);
                //反射出类上列名对应的属性
                field field = clazz.getdeclaredfield(columnname);
                field.setaccessible(true);
                field.set(bean,value);
            }
        } catch (sqlexception e) {
            e.printstacktrace();
        } catch (illegalaccessexception e) {
            e.printstacktrace();
        } catch (instantiationexception e) {
            e.printstacktrace();
        } catch (nosuchfieldexception e) {
            e.printstacktrace();
        }
        return bean;
    }
}
  • beanlisthandler的封装
    • 方式一
package com.dreambamboo.utils;

import org.apache.commons.dbutils.resultsethandler;

import java.lang.reflect.invocationtargetexception;
import java.lang.reflect.method;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.arraylist;
import java.util.list;

public class mybeanlisthandler implements resultsethandler {
    private class aclass;
    public mybeanlisthandler(class aclass){
        this.aclass = aclass;
    }
    @override
    public object handle(resultset resultset) throws sqlexception {
        resultsetmetadata resultsetmetadata = resultset.getmetadata();
        list list = new arraylist();
        int size = resultsetmetadata.getcolumncount();
        object object = null;
        while (resultset.next()){
            try {
                object = aclass.getconstructor().newinstance();
                for (int i = 1; i <= size; i++) {
                    string classname = resultsetmetadata.getcolumnclassname(i);
                    string columnname = resultsetmetadata.getcolumnname(i);
                    string methodname = "set" + columnname.substring(0,1).touppercase() + columnname.substring(1);
                    method method = null;
                    object value = null;
                    switch (classname){
                        case "java.lang.string":
                            value = resultset.getstring(i);
                            method = aclass.getmethod(methodname,string.class);
                            break;
                        case "java.lang.integer":
                            value = resultset.getint(i);
                            method = aclass.getmethod(methodname,int.class);
                            break;
                    }
                    method.invoke(object,value);
                }
                list.add(object);
            } catch (instantiationexception e) {
                e.printstacktrace();
            } catch (illegalaccessexception e) {
                e.printstacktrace();
            } catch (invocationtargetexception e) {
                e.printstacktrace();
            } catch (nosuchmethodexception e) {
                e.printstacktrace();
            }

        }
        return list;
    }
}
    • 方式二
package com.dreambamboo.utils;

import java.lang.reflect.field;
import java.sql.connection;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.arraylist;
import java.util.list;

/**
 * @classname：listhandler
 * @description：将结果集封装成list对象
 */
public class listhandler implements myresultsethandler {
    private class<?> clazz;
    public listhandler(class clazz){
        this.clazz = clazz;
    }
    @override
    public object handle(resultset resultset) {
        list<object> list = new arraylist<>();
        object bean = null;
        field field = null;
        try {
            while (resultset.next()){
                bean = clazz.newinstance();
                resultsetmetadata resultsetmetadata = resultset.getmetadata();
                int size = resultsetmetadata.getcolumncount();
                for (int i = 0; i < size; i++) {
                    string columnname = resultsetmetadata.getcolumnname(i+1);
                    object value = resultset.getobject(i+1);
                    field = bean.getclass().getdeclaredfield(columnname);
                    field.setaccessible(true);
                    field.set(bean,value);
                }
                list.add(bean);
            }
        } catch (sqlexception e) {
            e.printstacktrace();
        } catch (illegalaccessexception e) {
            e.printstacktrace();
        } catch (instantiationexception e) {
            e.printstacktrace();
        } catch (nosuchfieldexception e) {
            e.printstacktrace();
        } finally {
        }
        return  list;
    }
}
  • beanmaphandler的封装
    • 方式一
package com.dreambamboo.utils;

import com.sun.org.apache.bcel.internal.generic.ret;
import org.apache.commons.dbutils.resultsethandler;

import java.lang.reflect.invocationtargetexception;
import java.lang.reflect.method;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.hashmap;
import java.util.map;

public class mymaphandler implements resultsethandler {
    private class aclass;
    public mymaphandler(class aclass){
        this.aclass =aclass;
    }
    @override
    public map<integer, object> handle(resultset resultset) throws sqlexception {
        resultsetmetadata resultsetmetadata = resultset.getmetadata();
        int size = resultsetmetadata.getcolumncount();
        map<integer,object> map = new hashmap<>();
        object value = null;
        object object = null;
        string columnname = null;
        method method  = null;
        string methodname = null;
        string classname = null;
        int id = 0;
        try {
            if (resultset.next()){
                object = aclass.getconstructor().newinstance();
                for (int i = 1; i <= size; i++) {
                    classname = resultsetmetadata.getcolumnclassname(i);
                    columnname = resultsetmetadata.getcolumnname(i);
                    methodname = "set" + columnname.substring(0,1).touppercase() + columnname.substring(1);
                    if (columnname.equals("id")){
                        id = resultset.getint("id");
                    }
                    switch (classname){
                        case "java.lang.string":
                            value = resultset.getstring(i);
                            method =aclass.getmethod(methodname,string.class);
                            break;
                        case "java.lang.integer":
                            value = resultset.getint(i);
                            method = aclass.getmethod(methodname,int.class);
                            break;
                    }
                    method.invoke(object,value);
                }
            }
        } catch (illegalaccessexception e) {
            e.printstacktrace();
        } catch (invocationtargetexception e) {
            e.printstacktrace();
        } catch (nosuchmethodexception e) {
            e.printstacktrace();
        } catch (instantiationexception e) {
            e.printstacktrace();
        }
        map.put(id,object);
        return map;
    }

}
    • 方式二
package com.dreambamboo.utils;

import java.lang.reflect.field;
import java.security.privatekey;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.hashmap;
import java.util.map;

public class maphandler implements myresultsethandler {
    private class<?> clazz;
    public maphandler(class clazz){
        this.clazz = clazz;
    }
    @override
    public object handle(resultset resultset) {
        map<string,object> map = new hashmap<>();
        object bean = null;
        field field = null;
        string idstr = null;
        try {
            while (resultset.next()){
                bean = clazz.newinstance();
                resultsetmetadata resultsetmetadata = resultset.getmetadata();
                int size = resultsetmetadata.getcolumncount();
                for (int i = 0; i < size; i++) {
                    string columnname = resultsetmetadata.getcolumnname(i+1);
                    if ("id".equals(columnname)){
                        idstr = string.valueof(resultset.getobject(columnname));
                    }
                    object value = resultset.getobject(i+1);
                    field = bean.getclass().getdeclaredfield(columnname);
                    field.setaccessible(true);
                    field.set(bean,value);
                }
                map.put(idstr,bean);
            }
        } catch (sqlexception e) {
            e.printstacktrace();
        } catch (illegalaccessexception e) {
            e.printstacktrace();
        } catch (instantiationexception e) {
            e.printstacktrace();
        } catch (nosuchfieldexception e) {
            e.printstacktrace();
        }
        return map;
    }
}
  • maplisthandler的封装
    • 方式一
package com.dreambamboo.utils;

import org.apache.commons.dbutils.resultsethandler;

import javax.jws.oneway;
import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.arraylist;
import java.util.hashmap;
import java.util.list;
import java.util.map;

public class mymaplisthandler implements resultsethandler {

    @override
    public object handle(resultset resultset) throws sqlexception {
        resultsetmetadata resultsetmetadata = resultset.getmetadata();
        int size = resultsetmetadata.getcolumncount();
        list<map<string,object>> list = new arraylist<>();
        object object = null;
        map<string,object> map = null;
        while (resultset.next()){
            map = new hashmap<>();
            for (int i = 1; i <= size; i++) {
                string columnclass = resultsetmetadata.getcolumnclassname(i);
                string columnname = resultsetmetadata.getcolumnname(i);
                switch (columnclass){
                    case "java.lang.string":
                        object = resultset.getstring(i);
                        break;
                    case "java.lang.integer":
                        object = resultset.getint(i);
                        break;
                }
                map.put(columnname, object);
                list.add(map);
            }
         }
        return list;
    }
}
  • 方式二
package com.dreambamboo.utils;

import java.sql.resultset;
import java.sql.resultsetmetadata;
import java.sql.sqlexception;
import java.util.arraylist;
import java.util.hashmap;
import java.util.list;
import java.util.map;

public class maplisthandler implements myresultsethandler {
    @override
    public object handle(resultset resultset) {
        string columnname = null;
        object value = null;
        list<map<string,object>> list = new arraylist<>();
        try {
            while (resultset.next()){
                resultsetmetadata resultsetmetadata = resultset.getmetadata();
                int size = resultsetmetadata.getcolumncount();
                map<string,object> map = new hashmap<>();
                for (int i = 0; i < size; i++) {
                    columnname = resultsetmetadata.getcolumnname(i+1);
                    value = resultset.getobject(columnname);
                    map.put(columnname,value);
                }
                list.add(map);
            }
        } catch (sqlexception e) {
            e.printstacktrace();
        }

        return list;
    }
}

c：测试代码

a：basedao

package com.dreambamboo.dao;

import com.dreambamboo.entity.student;

import java.util.list;

public interface basedao {
    public void save(student student);
    public void delete(int id);
    public void update(student student);
    public student getbyid(int id);
    public list<student> getall();
}

b：basedaoimpl实现类

package com.dreambamboo.dao.impl;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.entity.student;
import com.dreambamboo.utils.javabeanhandler;
import com.dreambamboo.utils.listhandler;
import com.dreambamboo.utils.queryutils;
import com.dreambamboo.utils.releaseutils;

import java.sql.connection;
import java.sql.sqlexception;
import java.util.arraylist;
import java.util.list;

public class basedaoimpl implements basedao {
    private connection connection = null;
    private string sql = null;
    private object[] params = null;
    @override
    public void save(student student) {
        try {
            connection = releaseutils.getconnection();
            sql = "insert into student(name,clazz,grade) values(?,?,?)";
            params = new object[]{student.getname(),student.getclazz(),student.getgrade()};
            queryutils.update(connection,sql,params);
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,null,null);
        }
    }

    @override
    public void delete(int id) {
        try {
            connection = releaseutils.getconnection();
            sql = "delete from student where id = ?";
            params = new object[]{id};
            queryutils.update(connection,sql,params);
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,null,null);
        }
    }

    @override
    public void update(student student) {
        try {
            connection = releaseutils.getconnection();
            sql = "update student set name = ?,clazz = ?, grade = ? where id = ?";
            params = new object[]{student.getname(),student.getclazz(),student.getgrade(),student.getid()};
            queryutils.update(connection,sql,params);
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,null,null);
        }
    }

    @override
    public student getbyid(int id) {
        student student = null;
        try {
            connection = releaseutils.getconnection();
            sql = "select * from student where id = ?";
            params = new object[]{id};
            student = (student) queryutils.query(connection,sql,params,new javabeanhandler(student.class));

        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,null,null);
        }
        return student;
    }

    @override
    public list<student> getall() {
        list<student> list = null;
        try {
            connection = releaseutils.getconnection();
            list = new arraylist<>();
            sql = "select * from student";
            params = new object[]{};
            list = (list<student>) queryutils.query(connection,sql,params,new listhandler(student.class));
        } catch (sqlexception e) {
            e.printstacktrace();
        } finally {
            releaseutils.release(connection,null,null);
        }
        return list;
    }
}

c：测试类test

  • 测试添加代码
package com.dreambamboo.test;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.dao.impl.basedaoimpl;
import com.dreambamboo.entity.student;

public class test03 {
    public static void main(string[] args) {
        basedao basedao = new basedaoimpl();
        basedao.save(new student("张三","六班","高三"));
    }
}
    • 运行效果

Dbutils工具类的使用

Dbutils工具类的使用

  • 测试更新代码
package com.dreambamboo.test;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.dao.impl.basedaoimpl;
import com.dreambamboo.entity.student;

public class test03 {
    public static void main(string[] args) {
        basedao basedao = new basedaoimpl();
        student student = new student(13,"李四","gaosan","wuban");
        basedao.update(student);
    }
}
    • 运行结果

Dbutils工具类的使用

  • 测试删除代码
package com.dreambamboo.test;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.dao.impl.basedaoimpl;

public class test03 {
    public static void main(string[] args) {
        basedao basedao = new basedaoimpl();
       basedao.delete(13);
    }
}
    • 运行结果

Dbutils工具类的使用

Dbutils工具类的使用

  • 测试查询代码
    • 查询单条记录
package com.dreambamboo.test;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.dao.impl.basedaoimpl;
import com.dreambamboo.entity.student;


public class test03 {
    public static void main(string[] args) {
        basedao basedao = new basedaoimpl();
        student student = basedao.getbyid(14);
        system.out.println(student);
    }
}
      • 运行结果

Dbutils工具类的使用

    • 查询所有
package com.dreambamboo.test;

import com.dreambamboo.dao.basedao;
import com.dreambamboo.dao.impl.basedaoimpl;
import com.dreambamboo.entity.student;

import java.util.list;


public class test03 {
    public static void main(string[] args) {
        basedao basedao = new basedaoimpl();
        list<student> list = basedao.getall();
        for (student stu:list
             ) {
            system.out.println(stu);
        }
    }
}
      • 运行结果

Dbutils工具类的使用

 

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