今日总结

package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import org.junit.jupiter.api.Test;

import bean.Bean;
import dbutil.DBUtil;

public class Dao {//dao层
        private DBUtil dbutil=new DBUtil();


    public Dao() {
        // TODO Auto-generated constructor stub
    }
    @Test
    public boolean insert(Bean bean) {//插入数据的方法
        boolean f=false;
        String sql="insert into info(id,name,password,sex) values('"+bean.getId()+"','"+bean.getName()+"','"+bean.getPassword()+"','"+bean.getSex()+"')";
        Connection conn=DBUtil.getConnection();//数据库连接，加载驱动
        Statement state=null;
        try
        {
            state=conn.createStatement();//实例化Statement对象,方便对sql语句进行操作
            System.out.println(conn);
            state.executeUpdate(sql);
            f=true;
            //执行数据库更新操作用于执行INSERT、UPDATE或DELETE语句以及SQLDDL（数据定义语言）语句，
            //例如CREATETABLE和DROPTABLE,（创建表和删除表）
        }catch(Exception e)//当try语句中s出现异常时，会执行catch中的语句
          {
            e.printStackTrace();//捕获异常的语句
          }
         finally //finally作为异常处理的一部分，它只能用在try/catch语句中，并且附带一个语句块，表示这段语句最终一定会被执行（不管有没有抛出异常），经常被用在需要释放资源的情况下。
         {
             DBUtil.close(conn);
         }
        return f;
    }

    public boolean delete(int id ) {//删除方法
        String sql="delete from info where id='"+id+"'";
        boolean f=false;
        Connection conn =DBUtil.getConnection();
        Statement st=null;
        try {
            st=conn.createStatement();
            st.executeUpdate(sql);
            f=true;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally{
            DBUtil.close(st, conn);
        }
        return f;
    }
    public boolean update(Bean bean) {//更新方法
        String sql="update info set name='"+bean.getName()+"',password='"+bean.getPassword()+"',sex='"+bean.getSex()+"'where id='"+bean.getId()+"'";
        Connection conn=DBUtil.getConnection();
        boolean f=false;
        Statement st=null;
        try {
            st=conn.createStatement();
            st.executeUpdate(sql);
            f=true;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return f;
    }

    public List<Bean> list(){//查询所有方法
        String sql="select * from info order by id ASC";
        Connection conn=DBUtil.getConnection();
        Statement st=null;
        List<Bean> list=new ArrayList<>();
        ResultSet rs=null;
        Bean bean=null;
        try {
            st=conn.createStatement();
            st.executeQuery(sql);
            rs=st.executeQuery(sql);
            while(rs.next()) {

                int id=rs.getInt("id");
                String name = rs.getString("name");
                String password = rs.getString("password");
                String sex = rs.getString("sex");
                bean=new Bean(id,name,password,sex);
                list.add(bean);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally {
            DBUtil.close(rs, st, conn);
        }
        return list;
    }





    }

package dbutil;

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


public class DBUtil {
    private static String url = "jdbc:mysql://localhost:3306/nanfeng?useUnicode=true&characterEncoding=utf8";
    private static String user = "root";
    private static String password = "301101zw.";
    private static String jdbcName="com.mysql.jdbc.Driver";
    private Connection con=null;
    public static  Connection getConnection() {
        Connection con=null;
        try {
            Class.forName(jdbcName);
            con=DriverManager.getConnection(url, user, password);
            //System.out.println("数据库连接成功");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            //System.out.println("数据库连接失败");
            e.printStackTrace();
        }
        return con;
        
    }
    public static void close(Connection con) {
        if(con!=null)
            try {
                con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        
    }
    public static void close(Statement state, Connection conn) {
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    public static void close(ResultSet rs, Statement state, Connection conn) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}

 

 

package bean;

public class Bean {
    private int id;
    private String name;
    private String password;
    private String sex;
    
    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 getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Bean [id=" + id + ", name=" + name + ", password=" + password + ", sex=" + sex + "]";
    }

    public Bean(int id, String name, String password, String sex) {
        super();
        this.id = id;
        this.name = name;
        this.password = password;
        this.sex = sex;
    }

    public Bean() {
        // TODO Auto-generated constructor stub
    }

}