项目介绍：Java基础+mysql的一个简单练习
一.数据库
二.项目结构
lib下的jar包下载地址：Maven Repository: mysql » mysql-connector-java (mvnrepository.com)
1.db.properties
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/student?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
user=root
password=1234562.Student类
package pojo;
public class Student {
private int id;
private String name;
private int score;
public Student(int id, String name, int score) {
this.id = id;
this.name = name;
this.score = score;
}
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 int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", score=" + score +
'}';
}
}
3.JDBCUtil工具类
package util;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
import pojo.Student;
import java.io.IOException;
import java.io.InputStream;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Properties;
public class JDBCUtil {
private static String driver;
private static String url;
private static String user;
private static String password;
private static Connection connection = null;
static {
Properties properties = new Properties();
InputStream inputStream = JDBCUtil.class.getClassLoader().getResourceAsStream("resources/db.properties");
try {
properties.load(inputStream);
} catch (IOException e) {
throw new RuntimeException(e);
}
driver = properties.getProperty("driver");
url = properties.getProperty("url");
user = properties.getProperty("user");
password = properties.getProperty("password");
try {
Class.forName(driver);
connection = (Connection) DriverManager.getConnection(url,user,password);
} catch (Exception e) {
e.printStackTrace();
}
}
// 编写公共查询类
public static ArrayList<Student> executeQuery(String sql) {
ResultSet resultSet = null;
Statement statement = null;
ArrayList<Student> arrayList = null;
try {
statement = (Statement) connection.createStatement();
resultSet = statement.executeQuery(sql);
arrayList = new ArrayList<>();
while (resultSet.next()) {
arrayList.add(new Student(resultSet.getInt(1),
resultSet.getString(2),resultSet.getInt(3)));
}
return arrayList;
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
}
// 编写公共删除，增加，更改类
public static int executeUpdate(String sql) {
Statement statement = null;
try {
statement = (Statement) connection.createStatement();
int update = statement.executeUpdate(sql);
return update;
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
}
}
4.Dao层
StudentDao
package dao;
public interface StudentDao {
// 查询全部
public void searchAll();
// 名字查找
public void searchByName(String name);
// 学号查找
public void searchById(int id);
// 根据学号删除
public void deleteById(int Id);
// 根据学号更新名字
public void updateByName(int id,String name);
// 根据学号更新成绩
public void updateByScore(int id,int score);
// 新增用户
public void add(String name,int score);
}
StudentDaoImpl
package dao;
import pojo.Student;
import util.JDBCUtil;
import java.util.ArrayList;
public class StudentDaoImpl implements StudentDao{
@Override
public void searchAll() {
String sql = "select * from student;";
ArrayList<Student> arrayList = JDBCUtil.executeQuery(sql);
for(Student student: arrayList) {
System.out.println(student.toString());
}
}
@Override
public void searchByName(String name) {
try {
StringBuilder sql = new StringBuilder();
sql.append("select * from student where name = ");
sql.append("'");
sql.append(name);
sql.append("';");
System.out.println(JDBCUtil.executeQuery(sql.toString()).toString());
} catch (NullPointerException e) {
System.out.println("用户不存在");
}
}
@Override
public void searchById(int id) {
try {
StringBuilder sql = new StringBuilder();
sql.append("select * from student where id = ");
sql.append(id);
System.out.println(JDBCUtil.executeQuery(sql.toString()).toString());
} catch (NullPointerException e) {
System.out.println("用户不存在");
}
}
@Override
public void deleteById(int id) {
StringBuilder sql = new StringBuilder();
sql.append("delete from student where id=");
sql.append(id);
if (JDBCUtil.executeUpdate(sql.toString()) > 0) {
System.out.println("删除成功");
}
}
@Override
public void updateByName(int id, String name) {
StringBuilder sql = new StringBuilder();
sql.append("update student set name=");
sql.append("'");
sql.append(name);
sql.append("'");
sql.append(" where id = ");
sql.append(id);
sql.append(";");
if (JDBCUtil.executeUpdate(sql.toString()) > 0) {
System.out.println("name修改成功");
}
}
@Override
public void updateByScore(int id, int score) {
StringBuilder sql = new StringBuilder();
sql.append("update student set score=");
sql.append(score);
sql.append(" where id = ");
sql.append(id);
sql.append(";");
if (JDBCUtil.executeUpdate(sql.toString()) > 0) {
System.out.println("score修改成功");
}
}
@Override
public void add(String name, int score) {
StringBuilder sql = new StringBuilder();
sql.append("insert student(name,score) values('");
sql.append(name);
sql.append("',");
sql.append(score);
sql.append(");");
if (JDBCUtil.executeUpdate(sql.toString()) > 0) {
System.out.println("添加成功,新用户如下");
String sql2 = "select * from student order by id desc limit 0,1;";
System.out.println(JDBCUtil.executeQuery(sql2).toString());
}
}
}
