/**
 * 什么时候用PreparedStatement替代Statement
 * 反复执行一条结构相似的语句
 * 可以用占位符实现(?)
 *
 */
package ConnectMySql;
import  java.sql.*;
public class ConnMySQL03PrepareStatement {
    private  String diver;
    private  String url;
    private  String username;
    private  String password;
    Connection connection;
    Statement statement;
    PreparedStatement preparedStatement;
    public  ConnMySQL03PrepareStatement(){
        this.diver="com.mysql.cj.jdbc.Driver";
        this.url="jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=GMT";
        this.username = "root";
        this.password="123456";
    }
    public ConnMySQL03PrepareStatement(String diver, String url, String username, String password) {
        this.diver = diver;
        this.url = url;
        this.username = username;
        this.password = password;
    }
    public void insertByStatement( )throws Exception {
        try {
            long start =System.currentTimeMillis();
            statement =connection.createStatement();/*创建一个基本对象*/
            for (int i = 0; i < 100; i++) {
                statement.executeUpdate("insert into for_compare_jdbc values (null ,'姓名"+i+"',1)");
            }
            System.out.println("使用Statement费时:"+(System.currentTimeMillis()-start));
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            if (statement != null) {
                statement.close();
            }
        }
    }
    public void insertUsePrepareStatement()throws Exception{
        try {
            long start=System.currentTimeMillis();
            preparedStatement =connection.prepareStatement("insert  into for_compare_jdbc values (null ,?,1 )");
            for (int i = 0; i < 100; i++) {
                preparedStatement.setString(1,"姓名"+i);
                preparedStatement.executeUpdate();
            }
            System.out.println("使用PreparedStatement 费时:"+(System.currentTimeMillis()-start));
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            if (preparedStatement != null) {
                preparedStatement.close();
            }
        }
    }
    public void getConnect()throws Exception{
        if(connection==null) {
            Class.forName(diver);
            connection=DriverManager.getConnection(url,username,password);
         }
     }
     public void closeClean()throws  Exception{
         if (connection != null) {
             connection.close();
         }
     }
}

运行时间
使用PreparedStatement 费时:7496
使用Statement费时:39688
如果换了顺序
使用Statement费时:7657
使用PreparedStatement 费时:9925

这是为什么呢,诡异呀