ResultSet
ResultSet是我们使用jdbc连接时，查询的一个返回结果集,ResultSet resultSet = stmt.executeQuery(sql),下面就使用例子介绍ResultSet的使用
例子是通过jdbc连接查account表中的数据，然后用实体类Account封装起来，返回这个类的集合。
jdbc工具类代码
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package com.lingaolu.Utils; import java.io.FileReader;import java.io.IOException;import java.net.URL;import java.sql.*;import java.util.Properties; /** * @author 林高禄 * @create 2020-06-23-11:12 */public class JdbcUtils { private static String driver; private static String url; private static String userName; private static String pw; static{ try { Properties p = new Properties(); ClassLoader classLoader = JdbcUtils.class.getClassLoader(); // 这个路径相对于src的路径来说 URL resource = classLoader.getResource("com/lingaolu/file/jdbc.properties"); String path = resource.getPath(); p.load(new FileReader(path)); driver = p.getProperty("driver"); url = p.getProperty("url"); userName = p.getProperty("user"); pw = p.getProperty("password"); Class.forName(driver); } catch (IOException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public static Connection createConnection() throws SQLException { return DriverManager.getConnection(url, userName, pw); } public static void close(Statement stmt,Connection con){ if(null != stmt){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(null != con){ try { con.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void close(ResultSet set,Statement s,Connection con){ if(null != set){ try { set.close(); } catch (SQLException e) { e.printStackTrace(); } } close(s,con); }} |
Account实体类代码
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package com.lingaolu.jdbcConnector; /** * @author 林高禄 * @create 2020-06-24-8:28 */public class Account { private int id; private String name; private double balance; private int myAge; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getBalance() { return balance; } public void setBalance(double balance) { this.balance = balance; } public int getMyAge() { return myAge; } public void setMyAge(int myAge) { this.myAge = myAge; } @Override public String toString() { return "Account{" + "id=" + id + ", name='" + name + '\'' + ", balance=" + balance + ", myAge=" + myAge + '}'; }} |
测试Demo3的代码
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package com.lingaolu.jdbcConnector; import com.lingaolu.Utils.JdbcUtils; import java.sql.*;import java.util.ArrayList;import java.util.List; /** * @author 林高禄 * @create 2020-06-23-17:27 */public class Demo3 { public static void main(String[] args) { String sql = "select * from account"; List<Account> accounts = fineAccount(sql); accounts.forEach(System.out::println); System.out.println("----------------------------------"); sql = "select * from account where name='张三'"; accounts = fineAccount(sql); accounts.forEach(System.out::println); } public static List<Account> fineAccount(String sql){ Connection con = null; Statement stmt = null; ResultSet resultSet = null; List<Account> rerurnList = new ArrayList<>(); try { con = JdbcUtils.createConnection(); stmt = con.createStatement(); resultSet = stmt.executeQuery(sql); Account acc = null; while(resultSet.next()){ // 引号里的字段要与表里的一样 int id = resultSet.getInt("id"); String name = resultSet.getString("name"); double balance = resultSet.getDouble("balance"); int age = resultSet.getInt("age"); acc = new Account(); acc.setId(id); acc.setName(name); acc.setBalance(balance); acc.setMyAge(age); rerurnList.add(acc); } } catch (SQLException e) { e.printStackTrace(); }finally { JdbcUtils.close(resultSet,stmt,con); } return rerurnList; }} |
表中的数据
运行输出：
Account{id=1, name='张三', balance=500.0, myAge=17}
Account{id=2, name='李四', balance=1000.0, myAge=16}
Account{id=7, name='张三', balance=600.0, myAge=19}
Account{id=11, name='林帅', balance=20000.0, myAge=18}
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Account{id=1, name='张三', balance=500.0, myAge=17}
Account{id=7, name='张三', balance=600.0, myAge=19}
结果与预期的一致
到此这篇关于Java ResultSet案例讲解的文章就介绍到这了,更多相关Java ResultSet讲解内容请搜索服务器之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持服务器之家！
原文链接：https://blog.csdn.net/lgl782519197/article/details/106936495
