如何在JDBC的可滚动结果集中移动光标？
在JDBC中，有两个可滚动的ResultSet，即，可滚动敏感的和不可滚动敏感的。
在TYPE_SCROLL_INSENSITIVE ResultSet中，光标向前或向后移动。这种类型的ResultSet对数据库中所做的更改不敏感，即，数据库中所做的修改不会反映在ResultSet中。
这意味着如果我们已使用JDBC程序与数据库建立了连接，并检索了一个保存有名为SampleTable的表中所有记录的ResultSet。同时，如果我们在表中添加了更多记录（检索到ResultSet之后），则这些最近的更改将不会反映在我们先前获得的ResultSet对象中。
在TYPE_SCROLL_INSENSITIVE ResultSet中，光标向前或向后移动。这种类型的ResultSet对数据库中所做的更改敏感，即，数据库中所做的修改将反映在ResultSet中。
这意味着如果我们已使用JDBC程序与数据库建立了连接，并检索了一个保存有名为SampleTable的表中所有记录的ResultSet。同时，如果我们在表中添加了更多记录（在检索ResultSet之后），这些最近的更改将反映在我们先前获得的ResultSet对象中。
滚动敏感的或滚动敏感的两个结果集都是双向的，即，您可以将它们向前和向后移动。
您可以使用createStatement()方法，将一个Statement对象创建为返回Scrollable结果集-
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE);
您可以使用next() 方法向前遍历ResultSet对象的内容，也可以使用forward()方法反向遍历ResultSet对象的内容。
让我们使用CREATE语句在MySQL数据库中创建一个名称为cricketers_data 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cricketers_data 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');我们已使用JDBC程序连接到数据库，并将上表的记录检索到ResultSet对象中，并使用next()和previous()方法以正向和反向遍历该表。
示例
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class ScrollableResultset {
public static void main(String args[])throws Exception {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/mydatabase";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//创建一个Statement对象
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE);
//查询以检索cricketers_data表的内容
String query = "select * from cricketers_Data";
//执行查询
ResultSet rs = stmt.executeQuery(query);
//ResultSet的内容正向
System.out.println("ResultSet的内容正向");
while (rs.next()) {
System.out.print("id: "+rs.getInt(1)+", ");
System.out.print("First name: "+rs.getString(2)+", ");
System.out.print("Last name: "+rs.getString(3)+", ");
System.out.print("Year of birth: "+rs.getDate(4)+", ");
System.out.print("Place of birth: "+rs.getString(5)+", ");
System.out.print("Country: "+rs.getString(6));
System.out.println(" ");
}
System.out.println(" ");
//反向的ResultSet的内容
System.out.println("反向的ResultSet的内容");
rs.afterLast();
while (rs.previous()) {
System.out.print("id: "+rs.getInt(1)+", ");
System.out.print("First name: "+rs.getString(2)+", ");
System.out.print("Last name: "+rs.getString(3)+", ");
System.out.print("Year of birth: "+rs.getDate(4)+", ");
System.out.print("Place of birth: "+rs.getString(5)+", ");
System.out.print("Country: "+rs.getString(6));
System.out.println(" ");
}
}
}输出结果
Connection established...... ResultSet的内容正向 id: 1, First name: Shikhar, Last name: Dhawan, Year of birth: 1981-12-05, Place of birth: Delhi, Country: India id: 2, First name: Jonathan, Last name: Trott, Year of birth: 1981-04-22, Place of birth: CapeTown, Country: SouthAfrica id: 3, First name: Kumara, Last name: Sangakkara, Year of birth: 1977-10-27, Place of birth: Matale, Country: Srilanka id: 4, First name: Virat, Last name: Kohli, Year of birth: 1988-11-05, Place of birth: Mumbai, Country: India id: 5, First name: Rohit, Last name: Sharma, Year of birth: 1987-04-30, Place of birth: Nagpur, Country: India id: 6, First name: Ravindra, Last name: Jadeja, Year of birth: 1988-12-06, Place of birth: Nagpur, Country: India id: 7, First name: James, Last name: Anderson, Year of birth: 1982-06-30, Place of birth: Burnley, Country: England 反向的ResultSet的内容 id: 7, First name: James, Last name: Anderson, Year of birth: 1982-06-30, Place of birth: Burnley, Country: England id: 6, First name: Ravindra, Last name: Jadeja, Year of birth: 1988-12-06, Place of birth: Nagpur, Country: India id: 5, First name: Rohit, Last name: Sharma, Year of birth: 1987-04-30, Place of birth: Nagpur, Country: India id: 4, First name: Virat, Last name: Kohli, Year of birth: 1988-11-05, Place of birth: Mumbai, Country: India id: 3, First name: Kumara, Last name: Sangakkara, Year of birth: 1977-10-27, Place of birth: Matale, Country: Srilanka id: 2, First name: Jonathan, Last name: Trott, Year of birth: 1981-04-22, Place of birth: CapeTown, Country: SouthAfrica id: 1, First name: Shikhar, Last name: Dhawan, Year of birth: 1981-12-05, Place of birth: Delhi, Country: India