JDBC基础一

JDBC:java database connectivity SUN公司提供的一套操作数据库的标准规范。

JDBC与数据库驱动的关系：接口与实现的关系。

JDBC规范（掌握四个核心对象）：

DriverManager:用于注册驱动

Connection: 表示与数据库创建的连接

Statement: 操作数据库sql语句的对象

ResultSet: 结果集或一张虚拟表

实体类

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

package com.mf.domain; import java.util.Date;   public class User { private int id; private String name; private int age; private Date createtime; 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 getAge() {     return age; } public void setAge(int age) {     this.age = age; } public Date getCreatetime() {     return createtime; } public void setCreatetime(Date createtime) {     this.createtime = createtime; }       }

CRUD

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106

package com.mf.jdbc; import java.sql.DriverManager; import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import java.util.List; import com.mf.domain.User; public class CRUD {     public static void  main(String[] args) throws Exception  {         //3种连接方式         Connection conn=null;         //得到执行sequel语句的对象Statement         Statement stmt=null;         //查 执行sql语句，并返回结果         ResultSet rs=null;         try {             //注册驱动             //DriverManager.registerDriver(new com.mysql.jdbc.Driver());//不建议使用原因有2个：> 导致驱动被注册2次。> 强烈依赖数据库的驱动jar             Class.forName("com.mysql.jdbc.Driver");//此处采用反射机制加载             //获取连接Connection //Connection 接口   多态   父类的壳子接收子类的实现，有利于后期代码的扩展                           conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");                           /*Properties  info=new Properties();             info.setProperty("user", "root");             info.setProperty("password", "root");             Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", info);*/                           //Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&password=root");                           stmt = conn.createStatement();                           //增             /*stmt = conn.prepareStatement("INSERT INTO users VALUES(?,?)");             ((PreparedStatement) stmt).setString(1, "tom");             ((PreparedStatement) stmt).setInt(2, 5);*/                           /*int i = stmt.executeUpdate("INSERT INTO USER (`Name`, `Age`) VALUES('mf',20)");             if(i>0){                 System.out.println("success");             }             //删             int j = stmt.executeUpdate("UPDATE USER SET Age=25 WHERE ID=1");             if(j>0){                 System.out.println("success");             }             //改             int k = stmt.executeUpdate("DELETE  FROM  USER   WHERE ID = 1 ");             if(k>0){                 System.out.println("success");             }*/                           rs = stmt.executeQuery("select * from user");             //处理结果             List<User> list=new ArrayList<User>();             while(rs.next()){                 User user=new User();                 user.setName(rs.getString("Name"));                 user.setAge(rs.getInt("Age"));                 user.setCreatetime(rs.getDate("CreatTime"));                 list.add(user);                 System.out.println(list.size());                 System.out.println("---------------------------------------------------");                 System.out.println(rs.getObject("Name")+":"+rs.getObject("Age")+":"+rs.getObject("CreatTime"));                               }         } catch (ClassNotFoundException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }         finally{             //关闭资源             if(rs!=null)             {              try {                 rs.close();             } catch (Exception e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }              rs=null;             }             if(stmt!=null)             {                 try {                     stmt.close();                 } catch (Exception e) {                     // TODO Auto-generated catch block                     e.printStackTrace();                 }                 stmt=null;             }             if(conn!=null)             {                 try {                     conn.close();                 } catch (Exception e) {                     // TODO Auto-generated catch block                     e.printStackTrace();                 }                 conn=null;             }           }     }   }