一个简单的数据查询到前端展示总结

前言

做了一个后台查询前端展示的小项目，背景是在前端才刚开始学的时候，以当时能力肯定还差点意思（hh，出自宋老师），当然结果就是面向百度编程啦。项目做完了，从开发到部署一个人搞定历时5天。也算是本人第一个小项目啦，下面当然是要总结了
首先如果我写的有幸被网友大佬们看到，任何细节问题都欢迎指正。（俺才刚开始，是个粗人）
用到的知识

结构（就很简单）

获取数据库连接和操作（druid dbutil)

bean包这里犯过两个错
1.bean包要写空参构造器，dbutil获取查询结构要调用的
2.成员变量名字不要有特殊字符比如class
3.查询结果对的但是不全，变量名字要和数据库字段一致

/**
 * @autor kevin
 * @detatil
 * @create 2021-04-19-18:16
 */
public class bookfare {
    private String Year;
    private int Term;
    private int Grade;
    private String CLASS;
    private Long Number;
    private String Name;
    private String ClassCode;
    private String ClassName;
    private double BookDiscount;

    public bookfare() {
    }

    public bookfare(String year, int term, int grade, String CLASS, Long number, String name, String classCode, String className, double bookDiscount) {
        Year = year;
        Term = term;
        Grade = grade;
        this.CLASS = CLASS;
        Number = number;
        Name = name;
        ClassCode = classCode;
        ClassName = className;
        BookDiscount = bookDiscount;
    }

    @Override
    public String toString() {
        return "bookfare{" +
                "Year='" + Year + '\'' +
                ", Term=" + Term +
                ", Grade=" + Grade +
                ", CLASS='" + CLASS + '\'' +
                ", Number=" + Number +
                ", Name='" + Name + '\'' +
                ", ClassCode='" + ClassCode + '\'' +
                ", ClassName='" + ClassName + '\'' +
                ", BookDiscount=" + BookDiscount +
                '}';
    }

    public String getYear() {
        return Year;
    }

    public void setYear(String year) {
        Year = year;
    }

    public int getTerm() {
        return Term;
    }

    public void setTerm(int term) {
        Term = term;
    }

    public int getGrade() {
        return Grade;
    }

    public void setGrade(int grade) {
        Grade = grade;
    }

    public String getCLASS() {
        return CLASS;
    }

    public void setCLASS(String CLASS) {
        this.CLASS = CLASS;
    }

    public Long getNumber() {
        return Number;
    }

    public void setNumber(Long number) {
        Number = number;
    }

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }

    public String getClassCode() {
        return ClassCode;
    }

    public void setClassCode(String classCode) {
        ClassCode = classCode;
    }

    public String getClassName() {
        return ClassName;
    }

    public void setClassName(String className) {
        ClassName = className;
    }

    public double getBookDiscount() {
        return BookDiscount;
    }

    public void setBookDiscount(double bookDiscount) {
        BookDiscount = bookDiscount;
    }
}

功能包只需要查询

要注意的是Javautil.class.getClassLoader().getResourceAsStream(“JDBC.property”)获取连接文件，要这么些，原来教的貌似后端test可以但是到前端会报错
这里按照康师傅教的写，获取连接要写静态代码块上，不然每调用一次方法就得创建一个连接池
还有为保证数据库事务安全运行（这里没有）连接要调用者关闭

import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.junit.Test;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

/**
 * @autor kevin
 * @detatil
 * @create 2021-04-19-18:26
 */
public class Javautil {
    static DataSource dataSource =null;
    static {
        try {
            Properties properties =new Properties();
            properties.load(Javautil.class.getClassLoader().getResourceAsStream("JDBC.property"));
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static Connection getconnect(){
        Connection connection = null;
        try {