数据未保存在ArrayList中

Question

我有两个类 - 一个类作为"电影"的bean,一个类用于处理数据库.

我遇到的问题是尝试从数据库接收数据.正如您在我的代码中看到的,我将结果集添加到链表中,这是参数"Movies",因此我可以轻松获取我想要的特定对象.

我遇到的问题是,当我尝试从链表中打印特定对象时,它始终是数据库的最后一个值,并且它不会打印出所有"movienames".似乎while循环中的set方法被覆盖,直到最后一个值,这就是正在保存的内容.这很奇怪,因为在while循环中的setValue之后,我立即将它保存在数据库中.

为什么它没有给我数据库中的所有值,我该如何解决这个问题呢？谢谢!

我的豆子:

import java.io.Serializable;
import javax.persistence.*;

/**
 * Entity implementation class for Entity: Movies
 *
 */
@Entity
public class Movies implements Serializable {


    private static final long serialVersionUID = 1L;

    public Movies() {
        super();
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;


    public String getImagepath() {
        return imagepath;
    }

    public void setImagepath(String imagepath) {
        this.imagepath = imagepath;
    }

    private String moviename, movieinfo, mediapath, imagepath;

    public String getMediapath() {
        return mediapath;
    }

    public void setMediapath(String mediapath) {
        this.mediapath = mediapath;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getMoviename() {
        return moviename;
    }

    public void setMoviename(String moviename) {
        this.moviename = moviename;
    }

    public String getMovieinfo() {
        return movieinfo;
    }

    public void setMovieinfo(String movieinfo) {
        this.movieinfo = movieinfo;
    }
}

我的数据库类:

package JDBC;
import java.sql.*;
import java.util.ArrayList;

import com.commerce.models.Movies;

public class MovieService2 {

    //

       static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  


       static Connection conn = null;
       static Statement stmt = null;    

    public void insertData (String imagepath,String mediapath, String moviename) throws Exception{
          conn = DriverManager.getConnection("jdbc:mysql://192.168.51.123:3306/movies","app","app");

          stmt = conn.createStatement();
          String sql;
          sql = "INSERT INTO movies (id, imagepath, mediapath, moviename) VALUES (null, '"+imagepath+"', '"+mediapath+"','"+moviename+"')";
          stmt.executeUpdate(sql);

    }
    public static ArrayList<Movies> getData () throws Exception{
          System.out.println("Connecting to database...");

          Movies m = new Movies ();
          ArrayList <Movies> data = new ArrayList <Movies> ();
          conn = DriverManager.getConnection("jdbc:mysql://192.168.51.123:3306/movies","app","app");

          System.out.println("Creating statement...");
          stmt = conn.createStatement();
          String sql;
          sql = "SELECT * from movies";
          ResultSet rs = stmt.executeQuery(sql);

          while (rs.next()){
            m.setImagepath(rs.getString("imagepath"));
            m.setMoviename(rs.getString("moviename"));
            m.setMediapath(rs.getString("mediapath"));
            data.add(m);

          }

          System.out.println (data.get(0).getMoviename());

          return data;

    }

    public static void main (String [] args) throws Exception{
        ArrayList <Movies> data = getData ();
        for (int i = 0; i < data.size(); i++){
            //System.out.println("hej: " + getData().get(0).getMoviename());


        }
    }

}

Answer 1

Movies在while循环内创建对象:

  while (rs.next()){
        Movies m = new Movies ();
        m.setImagepath(rs.getString("imagepath"));
        m.setMoviename(rs.getString("moviename"));
        m.setMediapath(rs.getString("mediapath"));
        data.add(m);

      }

作为一个侧节点:Movie更好的命名不是Movies.

此外,使用PreparedStatment:sql = "INSERT INTO movies (id, imagepath, mediapath, moviename) VALUES (null, ?, ?,?)"; 以防止SQL Injection Attacks.

最后但并非最不重要的:"app"是一个真正的弱密码:-)