jdbc增删查改
前言：
Java数据库连贯（Java Database Connectivity,J 简称JDBC）,简略来说就是 应用Java执行sql语句的，面向关系型数据库的java_API
- 创立 Directory包 > 取名为 lib
- 后导入 MySQL-connector-java-5.1.37 文件
创立数据库（不然连贯什么）
// 根据实体类创立数据库字段和类型
- 创立实体类(BankModel.java)
package com.kjzz;public class Teacher{ // 成员变量 private int SID; // id private String SName; // name private String birthday; // birthday 生日 // 无参结构 / 有参结构 public Teacher(){ } public Teacher(int SID, String SName,String birthday) { this.SID = SID; this.SName = SName; this.birthday = birthday; } // get / set 办法 public int getSID() { return SID; } public void setSID(int SID) { this.SID = SID; } public String getSName() { return SName; } public void setSName(String SName) { this.SName = SName; } public String getBirthday(){ return birthday; } public void setBirthday(String birthday){ this.birthday = birthday; }}5.创立数据库驱动类（DBUtill.java）
public class DBConn{ // 驱动 , 门路 , 用户名 明码 // DRIVER--URL---USER-PWD public static String DRIVER = "com.mysql.jdbc.Driver"; // jdbc:数据库名:// localhost:端口号/连贯的数据库 public static String URL = "jdbc:mysql://localhost:3306/test"; public static String USER = "root"; public static String PWD = "root"; // 获取链接,为了解决找不到这个类，所以要异样解决 static{ try{ Class.forName(DRIVER); // 通过这个驱动名去找这个类 } catch(ClassNotFoundException e){ e.printStackTrace(); } } // 连贯 public static Connection getConnection(){ // 要导入sql的包 不要带jdbc的 Connection conn = null; try{ // 获取链接用的 conn = DriverManager.getConnection(URL,USER,PWD) // 路劲 用户名 明码 } catch(SQLException e){ e.printStackTrace(); } } /** 敞开连贯 当数据库应用后必须敞开,如果没有敞开数据库, 数据库接口无限，下次不能连贯 */ public static void CloseConn(Conncetion conn,PerpredStatement prep,ResultSet rs){ try{ if(rs != null){ // 不等于空 阐明在应用 rs.close(); } if(perp != null){ prep.close(); } if(coon != null){ coon.close(); } }catch(Exception e){ e.printStackTrace(); } } // 测试 public static void main(String[] args) { Connection conn = getConnectionV(); System.out.println("ConnDB测试" + conn); } // 输入后果 ConnDB测试 com.mysql.jdbc.JDBC4Connection@289d1c02 }6.创立数据库操作类
public class ZSGC { public static Connection conn = null; // 连贯对象 public static PreparedStatement prep = null; // 解决语句 public static ResultSet rs = null; // 查问后返回的后果集 /* 查询方法 实现思路 1. 加载数据库驱动(曾经写好了 连贯) 2. 获取数据库连贯 3. 通过Conncetion 实列获取 Statement 对象 4. 通过 Statement 实列执行 SQL 语句 5. 解决 ResultSet 后果集 6. 回收数据库资源 */ public List<Teacher> ChaXun(){ List<Teacher> list = new ArrayList<>(); String SelectSql = "select * from teacher"; // 表 try { conn = Conn.getConnection(); // 1. 连贯 prep = conn.prepareStatement(SelectSql); // 2. 解决sql rs = prep.executeQuery(); // 3. 查问返回的后果集 while(rs.next()){ //rs 有内容,不为空 Teacher t = new Teacher(); int ID = rs.getInt("sid"); String NAME = rs.getString("sname"); String BIRTHDAY = rs.getString("birthday"); t = new Teacher(ID,NAME,BIRTHDAY); list.add(t); list.add(stu); // 都要加进list汇合 } } catch (SQLException e) { e.printStackTrace(); } finally{ Conn.CloseConn(conn,prep,rs); } return list; } // 增加 public static boolean Insert(Teacher teacher){ int num = 0; String InsertSql = "INSERT INTO teacher values(?,?,?)"; try { conn = Conn.getConnection(); prep = conn.prepareStatement(InsertSql); prep.setInt(1,teacher.getSID()); prep.setString(2,teacher.getSName()); prep.setString(3,teacher.getBirthday()); num = prep.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } finally { Conn.CloseConn(conn,prep,rs); } return num > 0; } // 删除 public static boolean Delete(int key){ int num = 0; String DeleteSql = "Delete from teacher where id = ?"; try { conn = Conn.getConnection(); // 执行sql语句 prep = conn.prepareStatement(DeleteSql); prep.setInt(1,key); num = prep.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); }finally{ Conn.CloseConn(conn,prep,rs); } return num > 0; } // 批改 public static boolean Update(Teacher teacher){ int num = 0; // 定义影响的行数 String UpdateSql = "update teacher set sid = ?,sname = ? where sid = ? "; try { conn = Conn.getConnection(); prep = conn.prepareStatement(UpdateSql); prep.setInt(1,teacher.getSID()); prep.setString(2,teacher.getSName()); prep.setInt(3,teacher.getSID()); num = prep.executeUpdate(); // 增删改都是这个,然会INT类型 } catch (SQLException e) { e.printStackTrace(); }finally { Conn.CloseConn(conn, prep, rs); } return num > 0; }}- 测试
public class Text1 { public static void main(String[] args) { Conn conn = new Conn(); System.out.println("conn = " + conn); CRUD crud = new CRUD(); List<Teacher> list = crud.ChaXun(); for (Teacher t : list) { System.out.println(t.getSID()); System.out.println(t.getSName()); System.out.println(t.getBirthday()); } // 增加 Teacher t1 = new Teacher(3,"白居易","1001-11-11"); boolean insert = CRUD.Insert(t1); if (insert == true){ System.out.println("增加胜利"); } else{ System.out.println("增加失败"); } // 批改 boolean delete = CRUD.Delete(2); if (delete == true){ System.out.println("删除胜利"); } else { System.out.println("报错咯"); } // 批改 Teacher t2 = new Teacher(); t2.setSID(1); t2.setSName("张三"); t2.setSID(1); boolean update = CRUD.Update(t2); if (update == true){ System.out.println("1号名字已被批改为张三"); } else { System.out.println("失败"); } }}