我们能在 JDBC 中返回结果集吗?


是的,就像 Java 中的任何其他对象一样,我们可以将 ResultSet 对象作为参数传递给方法并从方法中返回它。

让我们使用 CREATE 语句在 MySQL 数据库中使用名称为MyPlayers 的表,如下所示 -

CREATE TABLE MyPlayers(
   ID INT,
   First_Name VARCHAR(255),
   Last_Name VARCHAR(255),
   Date_Of_Birth date,
   Place_Of_Birth VARCHAR(255),
   Country VARCHAR(255),
   PRIMARY KEY (ID)
);

现在,我们将使用 INSERT 语句在MyPlayers表中插入 7 条记录 -

insert into MyPlayers values(1, 'Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India');
insert into MyPlayers values(2, 'Jonathan', 'Trott', DATE('1981-04-22'), 'CapeTown', 'SouthAfrica');
insert into MyPlayers values(3, 'Kumara', 'Sangakkara', DATE('1977-10-27'), 'Matale', 'Srilanka');
insert into MyPlayers values(4, 'Virat', 'Kohli', DATE('1988-11-05'), 'Delhi', 'India');
insert into MyPlayers values(5, 'Rohit', 'Sharma', DATE('1987-04-30'), 'Nagpur', 'India');
insert into MyPlayers values(6, 'Ravindra', 'Jadeja', DATE('1988-12-06'), 'Nagpur', 'India');
insert into MyPlayers values(7, 'James', 'Anderson', DATE('1982-06-30'), 'Burnley', 'England');

在下面的 JDBC 示例中,retrieveData() 方法建立与数据库的连接并将 MyPlayers 表中的内容检索到 ResultSet 对象中并返回它。

main 方法调用 retrieveData() 方法并打印获得的 ResultSet 的内容。

范例

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ReturningResultSet {
   public static ResultSet retrieveData() throws SQLException{
      //Registering the Driver
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());
      //Getting the connection
      String mysqlUrl = "jdbc:mysql://127.0.0.1/mydatabase";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating a Statement object
      Statement stmt = con.createStatement();
      //Retrieving the data
      ResultSet rs = stmt.executeQuery("select * from MyPlayers");
      return rs;
   }
   public static void main(String args[]) throws Exception {
      //Getting the ResultSet object from the retrieveData() method
      ResultSet rs = retrieveData();
      System.out.println("Contents of the Table MyPlayers: ");
      while(rs.next()) {
         System.out.print(rs.getInt("ID")+", ");
         System.out.print(rs.getString("First_Name")+", ");
         System.out.print(rs.getString("Last_Name")+", ");
         System.out.print(rs.getDate("Date_Of_Birth")+", ");
         System.out.print(rs.getString("Place_Of_Birth")+", ");
         System.out.print(rs.getString("Country"));
         System.out.println();
      }
   }
}

输出

Connection established......
Contents of the Table MyPlayers:
1, Shikhar, Dhawan, 1981-12-05, Delhi, India
2, Jonathan, Trott, 1981-04-22, CapeTown, SouthAfrica
3, Kumara, Sangakkara, 1977-10-27, Matale, Srilanka
4, Virat, Kohli, 1988-11-05, Mumbai, India
5, Rohit, Sharma, 1987-04-30, Nagpur, India
6, Ravindra, Jadeja, 1988-12-06, Nagpur, India
7, James, Anderson, 1982-06-30, Burnely, England
8, Ryan, McLaren, 1983-02-09, Kumberly, null

更新于: 2019 年 7 月 30 日

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