Java项目：学生管理系统（JDBC）

项目要求

能够实现以下四种需求：
1、添加学生信息
2、删除学生信息
3、修改学生信息
4、查询学生信息
代码展示：
main包中的Main类代码：

package com.zzu.main;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;

import javax.swing.tree.RowMapper;

import com.zzu.tool.db.DBLink;
import com.zzu.tool.db.IRowMapper;

public class Main {

	private static DBLink db = new DBLink();
	
	public static void main(String[] args) {
		System.out.println("*********************************");
		System.out.println("*\t\t\t\t*");
		System.out.println("*\t欢迎使用学生信息管理系统\t*");
		System.out.println("*\t\t\t\t*");
		System.out.println("*********************************");
		while (true) {
			menu();
		}
	}

	static void menu() {
		System.out.println("1、添加学生信息");
		System.out.println("2、删除学生信息");
		System.out.println("3、修改学生信息");//地址传递
		System.out.println("4、查询学生信息");//name
		System.out.println("请输入操作，以Enter键结束:");
		Scanner scanner = new Scanner(System.in);
		int option  = scanner.nextInt();
		switch (option) {
			case 1:{
				System.out.println("请输入学生学号");
				String id = scanner.next();
				String sql = "select name from student where id = '"+id+"'";
				if(db.exist(sql)) {
					System.out.println("学号不允许重复，请重新输入");
					return;
				}
				System.out.println("请输入学生姓名");
				String name = scanner.next();
				System.out.println("请输入学生电话");
				String mobile = scanner.next();
				System.out.println("请输入学生住址");
				String address = scanner.next();
				sql = "insert into student(id,name,mobile,address) values ('"+id+"','"+name+"','"+mobile+"','"+address+"')";
				if(db.update(sql)) {
					System.out.println("添加成功");
					return;
				}
				System.out.println("添加失败");
				break;
			}

			case 2:{
				System.out.println("请输入学生学号");
				String id = scanner.next();
				String sql = "select name from student where id = '"+id+"'";
				if(!db.exist(sql)) {
					System.out.println("学号不存在，删除失败");
					return;
				}
				sql = "delete from student where id = '"+id+"'";
				db.update(sql);
				System.out.println("删除成功");
				break;
			}

			case 3:{
				System.out.println("请输入学生学号");
				String id = scanner.next();
				String sql = "select name from student where id = '"+id+"'";
				if(!db.exist(sql)) {
					System.out.println("学号不存在，修改失败");
					return;
				}
				System.out.println("请输入学生新姓名");
				String name = scanner.next();
				System.out.println("请输入学生新电话");
				String mobile = scanner.next();
				System.out.println("请输入学生新住址");
				String address = scanner.next();
				sql = "update student set name = '"+name+"',mobile = '"+mobile+"',address = '"+address+"' where id = '"+id+"'";
				if(db.update(sql)){
					System.out.println("修改成功");
					return ;
				}
				System.out.println("修改失败");
				break;
			}

			case 4:{
				System.out.println("请输入学生学号");
				String id = scanner.next();
				String sql = "select name from student where id = '"+id+"'";
				if(!db.exist(sql)) {
					System.out.println("学号不存在，删除失败");
					return;
				}
				sql="select id,name,mobile,address from student where id = '"+id+"'";
//有名内部类				
//				class RowMapper implements IRowMapper {
//					@Override
//					public void rowMapper(ResultSet rs) {
//						try {
//							while(rs.next()) {
//								String name = rs.getString("name");
//								String mobile = rs.getString("mobile");
//								String address = rs.getString("address");
//								System.out.println(id+","+name+","+mobile+","+address);
//							}
//						} catch (SQLException e) {
//							e.printStackTrace();
//						}
//					}
//				}
//				db.select(sql, new IRowMapper());
//匿名内部类				
//				db.select(sql, new IRowMapper(){
//					public void rowMapper(ResultSet rs) {
//						try {
//							while(rs.next()) {
//								String name = rs.getString("name");
//								String mobile = rs.getString("mobile");
//								String address = rs.getString("address");
//								System.out.println(id+","+name+","+mobile+","+address);
//							}
//						} catch (SQLException e) {
//							e.printStackTrace();
//						}
//					}
//				});
//拉姆达表达式				
				db.select(sql, (/*ResultSet*/ rs)-> {
						try {
							while(rs.next()) {
								String name = rs.getString("name");
								String mobile = rs.getString("mobile");
								String address = rs.getString("address");
								System.out.println(id+","+name+","+mobile+","+address);
							}
						} catch (SQLException e) {
							e.printStackTrace();
						}
					});
				break;
			}
			default:
				System.out.println("I'm Sorry,there is not the "+option+" option,please try again.");
		}
	}
}

tool包中db包中的DBLink类代码：

package com.zzu.tool.db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBLink {
	
	private Connection getConnection() {
		try {
			Class.forName("com.mysql.jdbc.Driver");//加载驱动
			String url = "jdbc:mysql://127.0.0.1:3306/test";
			return DriverManager.getConnection(url, "root", "root");//获取连接
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	public void select(String sql,IRowMapper rowMapper) {//接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象
	    Connection connection = null;					//此处的rowMapper就是一个形参，到时候接口实现类里的实参再传给它
	    Statement statement =null;
	    ResultSet resultSet=null;
	    try {
	    	connection = getConnection();
	    	statement = connection.createStatement();
	        resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中
	      rowMapper.rowMapper(resultSet);//因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法  多态
	    } catch (Exception e) {
	      e.printStackTrace();
	    }finally {
	    	close(resultSet,statement,connection);
	    }
	  }
	
	public boolean exist(String sql) {
	    Connection connection = null;
	    Statement statement =null;
	    ResultSet resultSet=null;
	    try {
	      connection = getConnection();
	      statement = connection.createStatement();
	      resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中
	      return resultSet.next();
	    } catch (Exception e) {
	      e.printStackTrace();
	    }finally {
	    	close(resultSet,statement,connection);
	     }
	    return false;
	  }
	
	public boolean update(String sql) {
		Connection connection =null;
		Statement statement = null;
		try {
			connection = getConnection();
			statement = connection.createStatement();
			int result = statement.executeUpdate(sql);
			/*
			  statement.close();//如果上面代码出现异常，则该行代码及其下面代码无法执行，所以资源无法释放；比如sql语句语法错误，则statement和connection无法释放
		      connection.close();
		    */
			return result>0 ;
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			close(statement,connection);
		}
		return false;
	}
	
	private void close(Statement statement,Connection connection) {
		try {
			if(statement!=null) {//由于异常statement没有赋值，statement异常，Eg：URL出错
				statement.close();	
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		try {
			if(connection!=null) {
				connection.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}


	private void close(ResultSet resultSet,Statement statement,Connection connection) {
		try {
	        if(resultSet!=null) {
	          resultSet.close();
	        }
	      } catch (SQLException e) {
	        e.printStackTrace();
	      }
	      close(statement,connection);
	}
}

tool包中db包中的IRowMapper代码：

package com.zzu.tool.db;

import java.sql.ResultSet;
@FunctionalInterface
public interface IRowMapper {

	void rowMapper(ResultSet rs);
}

在使用DBLink类中方法时，需要添加第三方jar包，创建路径，才能完成链接数据库等步骤。