总结一下这几节Java课的...重点！！！

1.定义一个Person类，包含两个私有的属性（name、age）、一个含参的方法setValue(int age,String name)、一个不含参方法setValue()和一个普通方法tell()。

定义一个测试类Test，实例化一个Person类的对象，名为p；对两个属性赋值并输出结果。

class Person
{
    private int age;
    private String name;
    public void tell()
    {
        System.out.print("姓名："+name+"，年龄："+age);
    }
    public void setValue(int age,String name)
    {
        this.age=age;
        this.name=name;
    }
    public void setValue()
    {
        this.name="张三";
        this.age=21;
    }
}
public class Test
{

    public static void main(String[] args) 
    {
        Person p = new Person();
        p.setValue(21,"Mary");
        p.tell();
    }
}

2.定义一个Student类，继承自Person类，含有一个protected访问权限的字符型属性sex，定义Student类的构造方法，并覆写父类的tell()方法，实现对三个属性的赋值和输出。

class Person
{
    private int age;
    private String name;
    public void tell()
    {
        System.out.print("姓名："+name+"，年龄："+age);
    }
    public void setValue(int age,String name)
    {
        this.age=age;
        this.name=name;
    }
    public void setValue()
    {
        this.name="张三";
        this.age=21;
    }
}
class Student extends Person
{
    protected char sex;
    Student(int age,String name,char sex)
    {
        super.setValue(age,name);
        this.sex=sex;
    }
    public void tell()
    {
        super.tell();
        System.out.println("，性别："+sex);
    }
}
public class Test
{

    public static void main(String[] args) 
    {
        Student s = new Student(20,"Mary",'女');
        s.tell();
    }
}

3.数据库访问的实现

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

public class MySQL
{
    public static void main(String[] args){
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs =null;
        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/studentInfo","root","123456");
            stmt = conn.createStatement();
            rs = stmt.executeQuery("select * from student");
            while(rs.next())
            {
                String no = rs.getString(1);
                String name = rs.getString("sName");
                String sex = rs.getString(3);
                int age = rs.getInt(4);
                String dept = rs.getString("dept");
                System.out.println(no+"__"+name+"__"+sex+"  "+age+"  "+dept+"__");
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            try
            {
                if(rs !=null) rs.close();
                if(stmt!=null) stmt.close();
                if(conn !=null) conn.close();
             }
            catch(SQLException e)
            {
                e.printStackTrace();
            }
        }
    }
}

这是重点！这是重点！这是重点！重要的事情说三遍！！！