MySQL第五天

Posted 2021-02-15 y-mmeng

　　C3P0连接池配置文件

public static void main(String[] args) throws Exception {
    //从控制台输入用户名和密码
    Scanner sc = new Scanner(System.in);
    System.out.println("请输入用户名");
    String name = sc.nextLine();
    System.out.println("请输入密码");
    String password = sc.nextLine();
    login(name,password);
}
public static void login(String name,String password) throws Exception{
    Connection con = JDBCUtils.getConnection();
    //1.编写sql 未知内容使用？占位符
    String sql = "select*from yang where ename=? and mgr=?";
    //2.获得PreparedStatemnet对象
    PreparedStatement ps = con.prepareStatement(sql);
    //3.获得实际的参数
    ps.setString(1,name);
    ps.setString(2,password);
    //4.执行sql语句
    ResultSet rs = ps.executeQuery();
    if (rs.next()){
        System.out.println("登陆成功");
    }else {
        System.out.println("登陆失败");
    }
    //5.关闭资源
    JDBCUtils.close(con,ps, rs);
}
Druid连接池配置文件

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///girl
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000
工具类

public class JDBCUtils {
    //1.定义成员变量
    private static DataSource ds;
    static {
        //2.加载配置文件 获得连接池
        try {
            Properties pro = new Properties();
            pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
            ds= DruidDataSourceFactory.createDataSource(pro);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    //3.获得链接
    public static Connection getConnection() throws Exception{
        return ds.getConnection();
    }
    //4.释放资源
    public static void close(Connection con, Statement stat){
        if (stat!=null){
            try {
                stat.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        if (con!=null){
            try {
                con.close();
            }
            catch (Exception e){
                e.printStackTrace();
            }
        }
    }
    public static void close(Connection con, Statement stat, ResultSet rs){
        if (rs!=null){
            try {
                rs.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        if (stat!=null){
            try {
                stat.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        if (con!=null){
            try {
                con.close();
            }
            catch (Exception e){
                e.printStackTrace();
            }
        }
    }
    //4.获得链接池
    public static DataSource getDataSource(){
        return  ds;
    }
}
Spring连接池

public static void main(String[] args) {
    //1 导包
    //2 创建JDBCTemplate 对象  依赖于DataSource
    JdbcTemplate jt = new JdbcTemplate(JDBCUtils.getDataSource());
    String sql = "update yang set salary=2019 where id=?";
    int i = jt.update(sql,1001);
    System.out.println(i);
    }
封装一个类，类名与已存的某个表名一致，对表的内容进行操作

public class TempleteDemo3 {
    JdbcTemplate jt =new JdbcTemplate(JDBCUtils.getDataSource());
    //1,修改
    @Test
    public void test1(){
        String sql ="update yang set salary = 1999 where id=?";
        int i = jt.update(sql,1001);
        System.out.println(i);
    }
    //2添加一条记录
    @Test
    public void test2(){
        String sql = "insert into yang (id,ename,salary) values(?,?,?)";
        int i = jt.update(sql,1015,"杨蒙蒙","12001");
        System.out.println(i);
    }
    //3删除一条记录
    @Test
    public void test3(){
        String sql = "delete from yang where id=?";
        int i = jt.update(sql,1015);
        System.out.println(i);
    }
    //4.查询id为1001的记录，将其封装为map集合
    @Test
   public void test4(){
       String sql  ="select *from yang where id=?";
       Map<String,Object> map = jt.queryForMap(sql,1001);
        System.out.println(map);
    }
    //5.查询所有记录，将其封装为List集合
    @Test

    public void test5(){
        String sql = "select*from yang";
        List<Map<String,Object>> list = jt.queryForList(sql);
        for (Map<String,Object> map :list){
            System.out.println(map);
        }
    }
    //6.查询所有记录，将其封装为yang对象的List集合
    @Test
   public void test6(){
       String sql = "select*from yang";
       List<yang> list = jt.query(sql,new BeanPropertyRowMapper<yang>(yang.class));
       for (yang y:list){
           System.out.println(y);
       }
    }
    //7.查询总记录数
    @Test
    public void test7(){
        String sql = "select count(id) from yang";
        Long l = jt.queryForObject(sql,Long.class);
        System.out.println(l);
    }