Java 将数据库记录存储到列表中

如何将数据库记录放入ArrayList？我想在jsp文件中查看它。但是，ArrayList中所有对象的值与我选择的数据库中的最后一条记录相同

我的项目中有以下代码：

IPBean.java

public class IPBean {
    private String ip;
    private String userName;
    private String password;
    private int maxRetry;    

    public String getIp() {
        return ip;
    }    
    protected void setIp(String ip) {
        this.ip = ip;
    }    
    public String getUserName() {
        return userName;
    }    
    protected void setUserName(String userName) {
        this.userName = userName;
    }    
    public String getPassword() {
        return password;
    }    
    protected void setPassword(String password) {
        this.password = password;
    }    
    public int getMaxRetry() {
        return maxRetry;
    }    
    protected void setMaxRetry(int maxRetry) {
        this.maxRetry = maxRetry;
    }    
}

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

public class IPBeanMapper {
    public ArrayList<IPBean> getIPList() throws SQLException, ClassNotFoundException {
        ArrayList<IPBean> ipList = new ArrayList<IPBean>();
        Connection conn = null;
        conn = ConnectionTools.getConnection();
        String SQL = "SELECT * FROM LIST_IPM";
        Statement statement = conn.createStatement();
        ResultSet rs = statement.executeQuery(SQL);
        IPBean ipBean = new IPBean();

        while (rs.next()){

            ipBean.setIp(rs.getString("IP"));
            ipBean.setMaxRetry(rs.getInt("NUM_OF_RETRY"));
            ipBean.setPassword(rs.getString("PASSWORD"));
            ipBean.setUserName(rs.getString("USERNAME"));

            ipList.add(ipBean);

        }
        ConnectionTools.attemptClose(rs);
        ConnectionTools.attemptClose(statement);
        ConnectionTools.attemptClose(conn);
        System.out.print(ipList.size());
        return ipList;
    }
}

while (rs.next()){ 
IPBean ipBean = new IPBean();   
.
.

IPBeanMapper.java

public class IPBean {
    private String ip;
    private String userName;
    private String password;
    private int maxRetry;    

    public String getIp() {
        return ip;
    }    
    protected void setIp(String ip) {
        this.ip = ip;
    }    
    public String getUserName() {
        return userName;
    }    
    protected void setUserName(String userName) {
        this.userName = userName;
    }    
    public String getPassword() {
        return password;
    }    
    protected void setPassword(String password) {
        this.password = password;
    }    
    public int getMaxRetry() {
        return maxRetry;
    }    
    protected void setMaxRetry(int maxRetry) {
        this.maxRetry = maxRetry;
    }    
}

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

public class IPBeanMapper {
    public ArrayList<IPBean> getIPList() throws SQLException, ClassNotFoundException {
        ArrayList<IPBean> ipList = new ArrayList<IPBean>();
        Connection conn = null;
        conn = ConnectionTools.getConnection();
        String SQL = "SELECT * FROM LIST_IPM";
        Statement statement = conn.createStatement();
        ResultSet rs = statement.executeQuery(SQL);
        IPBean ipBean = new IPBean();

        while (rs.next()){

            ipBean.setIp(rs.getString("IP"));
            ipBean.setMaxRetry(rs.getInt("NUM_OF_RETRY"));
            ipBean.setPassword(rs.getString("PASSWORD"));
            ipBean.setUserName(rs.getString("USERNAME"));

            ipList.add(ipBean);

        }
        ConnectionTools.attemptClose(rs);
        ConnectionTools.attemptClose(statement);
        ConnectionTools.attemptClose(conn);
        System.out.print(ipList.size());
        return ipList;
    }
}

while (rs.next()){ 
IPBean ipBean = new IPBean();   
.
.

import java.sql.*；
导入java.util.ArrayList；
公共类IPBeanMapper{
public ArrayList getIPList（）抛出SQLException、ClassNotFoundException{
ArrayList ipList=新的ArrayList（）；
连接conn=null；
conn=ConnectionTools.getConnection（）；
String SQL=“从列表中选择*_IPM”；
语句Statement=conn.createStatement（）；
ResultSet rs=语句.executeQuery（SQL）；
IPBean=newIPBean（）；
while（rs.next（））{
setIp（rs.getString（“IP”）；
setMaxRetry（rs.getInt（“NUM_OF_RETRY”）；
setPassword（rs.getString（“PASSWORD”）；
setUserName（rs.getString（“用户名”）；
添加（ipBean）；
}
连接工具。尝试关闭（rs）；
ConnectionTools.attemptClose（语句）；
连接工具。尝试关闭（康涅狄格州）；
System.out.print（ipList.size（））；
返回ipList；
}
}

View.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" import="DSIP.*" import="java.util.ArrayList" %>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
    <title>DSIP.Insert</title>
</head>

<body>
<jsp:useBean id="ipList" scope="application" class="IPBeanMapper"/>
<jsp:useBean id="bean" scope="application" class="IPBean"/>
<form name="form1" method="post" action="viewServlet">
    <table width="" border="">
        <tr bgcolor="#0099FF">
            <td width="90"><div align="center">ip</div></td>
            <td width="90"><div align="center">username</div></td>
            <td width="90"><div align="center">password</div></td>
            <td width="90"><div align="center">maxRetry</div></td>
        </tr>
        <%
            ArrayList<IPBean> list;
            list = ipList.getIPList();
            for (int i = 0; i < list.size(); i++){
                bean = list.get(i);
        %>
        <tr>
            <td><input name="ip"        type="text" size="15" value="<%=list.getIp()%>"></td>
            <td><input name="userName"  type="text" size="15" value="<%=bean.getUserName()%>"></td>
            <td><input name="password"  type="text" size="15" value="<%=bean.getPassword()%>"></td>
            <td><input name="maxRetry"  type="text" size="15" value="<%=bean.getMaxRetry()%>"></td>
        </tr>
        <%
            }
        %>
    </table>
</form>
</body>
</html>

插入
知识产权
用户名
密码
最大重试

我的浏览器中的结果显示，第一条记录和第二条记录是相同的，但实际上并不相同。所以，请有人帮我显示数据库中的真实记录

要查看我的结果：

非常感谢你帮助我

致以最良好的祝愿

---

Faizal Rizky

您需要将这个

IPBean-IPBean=new-IPBean（）内部while循环

因此，您的代码将成为-

IPBeanMapper.java

public class IPBean {
    private String ip;
    private String userName;
    private String password;
    private int maxRetry;    

    public String getIp() {
        return ip;
    }    
    protected void setIp(String ip) {
        this.ip = ip;
    }    
    public String getUserName() {
        return userName;
    }    
    protected void setUserName(String userName) {
        this.userName = userName;
    }    
    public String getPassword() {
        return password;
    }    
    protected void setPassword(String password) {
        this.password = password;
    }    
    public int getMaxRetry() {
        return maxRetry;
    }    
    protected void setMaxRetry(int maxRetry) {
        this.maxRetry = maxRetry;
    }    
}

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

public class IPBeanMapper {
    public ArrayList<IPBean> getIPList() throws SQLException, ClassNotFoundException {
        ArrayList<IPBean> ipList = new ArrayList<IPBean>();
        Connection conn = null;
        conn = ConnectionTools.getConnection();
        String SQL = "SELECT * FROM LIST_IPM";
        Statement statement = conn.createStatement();
        ResultSet rs = statement.executeQuery(SQL);
        IPBean ipBean = new IPBean();

        while (rs.next()){

            ipBean.setIp(rs.getString("IP"));
            ipBean.setMaxRetry(rs.getInt("NUM_OF_RETRY"));
            ipBean.setPassword(rs.getString("PASSWORD"));
            ipBean.setUserName(rs.getString("USERNAME"));

            ipList.add(ipBean);

        }
        ConnectionTools.attemptClose(rs);
        ConnectionTools.attemptClose(statement);
        ConnectionTools.attemptClose(conn);
        System.out.print(ipList.size());
        return ipList;
    }
}

while (rs.next()){ 
IPBean ipBean = new IPBean();   
.
.

问题是同一对象引用正在添加到列表中。因此，所有初始条目都与您的上一条记录相同。
更改

   IPBean ipBean = new IPBean(); 

    while (rs.next()){

到

这将为每行创建新实例，这是必需的，否则它将在单个实例中保持覆盖数据

    IPBean ipBean = new IPBean();

    while (rs.next()){

        ipBean.setIp(rs.getString("IP"));

您需要为每一行创建一个新实例。将
新IPBean
移动到循环内部。否则，您将在列表中多次使用同一实例，并使用上一次迭代中设置的值。
我认为您不必将整个

ipBean bean = new IPBean();

进入循环。那将是一种糟糕的做法。申报

ipBean-ipBean

while(rs.next()){
      bean = new ipBean();
} 

嗯，非常感谢@Thilo我现在明白了：）