JDBC完成CRUD

package zjtool;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.Properties;import com.mysql.jdbc.Connection;import com.mysql.jdbc.Statement;/* * JDBC工具类的封装 */public class jdbctool {private static String driverClass;private static String url;private static String username;private static String password;static{InputStream in = null;try {in = new FileInputStream("src/jdbc.properties");//读取jdbc.properties文件} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}Properties pro=new Properties();try {pro.load(in);//通过Properties来加载jdbc.properties文件} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} driverClass = pro.getProperty("driverClass");//获得jdbc.properties文件中的值 url = pro.getProperty("url"); username = pro.getProperty("username");password = pro.getProperty("password");}public static void loadDriver(){try {Class.forName(driverClass);//注册驱动} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public static Connection getConnectiom () {Connection con = null;loadDriver();try { con=(Connection) DriverManager.getConnection(url,username,password);//获得连接} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return con;}public static void release(ResultSet rs,PreparedStatement pstmt,java.sql.Connection con){if(rs!=null){  try{rs.close();}catch(SQLException e){e.printStackTrace();}rs=null;}if(pstmt!=null){  try{pstmt.close();}catch(SQLException e){e.printStackTrace();}pstmt=null;}if(con!=null){  try{con.close();}catch(SQLException e){e.printStackTrace();}con=null;}}public static void release(PreparedStatement sta,Connection con){if(sta!=null){  try{sta.close();}catch(SQLException e){e.printStackTrace();}sta=null;}if(con!=null){  try{con.close();}catch(SQLException e){e.printStackTrace();}con=null;}}}

import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.Properties;import org.junit.Test;import com.mysql.jdbc.Statement;import zjtool.jdbctool;/* * 使用JDBC进行增删改查操作 */public class test {private com.mysql.jdbc.Connection con;private PreparedStatement pst;private int rs;@Testpublic void demo1(){Connection conn=null;PreparedStatement pstmt=null;ResultSet rs=null;try{Class.forName("com.mysql.jdbc.Driver");//注册驱动conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/zdb","root","942686");//建立连接String sql="select * from category";pstmt=conn.prepareStatement(sql);//获得操作数据库的对象rs= pstmt.executeQuery();//向数据库发送执行操作while (rs.next()) {System.out.println(rs.getInt("cid")+"  "+rs.getString("cname"));}}catch(Exception e){e.printStackTrace(); }finally{//释放资源if(rs!=null){  try{rs.close();}catch(SQLException e){e.printStackTrace();}rs=null;}if(pstmt!=null){  try{pstmt.close();}catch(SQLException e){e.printStackTrace();}pstmt=null;}if(conn!=null){  try{conn.close();}catch(SQLException e){e.printStackTrace();}conn=null;}}}@Testpublic void demo2(){//将jdbc封装Connection con=null;PreparedStatement pstmt=null;ResultSet rs=null;try{con=jdbctool.getConnectiom();String sql="select * from category";pstmt=con.prepareStatement(sql);rs= pstmt.executeQuery();while (rs.next()) {System.out.println(rs.getInt("cid")+"  "+rs.getString("cname"));}}catch(Exception e){e.printStackTrace();}finally{jdbctool.release(rs, pstmt, con);}}@Test//向表格插入值public void demo3(){con=jdbctool.getConnectiom();String sql="insert into category values (null,?)";try {pst=con.prepareStatement(sql);pst.setString(1, "鞋靴箱包");rs=pst.executeUpdate();if (rs>0) {System.out.println("执行成功");}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{jdbctool.release(pst, con);}}@Test//更新表格的值public void demo4(){con=jdbctool.getConnectiom();String sql="update category set cname=? where cid=?";try {pst=con.prepareStatement(sql);pst.setString(1, "烟酒糖茶");pst.setInt(2, 5);rs=pst.executeUpdate();if (rs>0) {System.out.println("执行成功");}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{jdbctool.release(pst, con);}}@Test//删除表格的值public void demo5(){con=jdbctool.getConnectiom();String sql="delete from category where cid=?";try {pst=con.prepareStatement(sql);pst.setInt(1, 7);rs=pst.executeUpdate();if (rs>0) {System.out.println("执行成功");}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{jdbctool.release(pst, con);}}}