以下是示例，該示例使用setSavepoint和rollback在事務(wù)教程中進(jìn)行了描述。
該示例代碼是根據(jù)前幾章中的環(huán)境和數(shù)據(jù)庫(kù)設(shè)置編寫(xiě)的。
復(fù)制并粘貼以下示例到JDBCExample.java中，如下編譯并運(yùn)行：
//步驟1.導(dǎo)入所需的軟件包
import java.sql.*;
public class JDBCExample {
// JDBC驅(qū)動(dòng)程序名稱(chēng)和數(shù)據(jù)庫(kù)URL
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/EMP";
// 數(shù)據(jù)庫(kù)憑證
static final String USER = "username";
static final String PASS = "password";
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try{
//步驟2：注冊(cè)JDBC驅(qū)動(dòng)程序
Class.forName("com.mysql.jdbc.Driver");
//步驟3：建立連接
System.out.println("Connecting to database...");
conn = DriverManager.getConnection(DB_URL,USER,PASS);
//步驟4：將自動(dòng)提交設(shè)置為false。
conn.setAutoCommit(false);
//步驟5：執(zhí)行查詢(xún)以刪除陳述
// RS示例的必需參數(shù)。
System.out.println("Creating statement...");
stmt = conn.createStatement();
//步驟6：現(xiàn)在列出所有可用的記錄。
String sql = "SELECT id, first, last, age FROM Employees";
ResultSet rs = stmt.executeQuery(sql);
System.out.println("List result set for reference....");
printRs(rs);
// 步驟7：刪除ID大于104的行
// 但是在這樣做之前要先保存點(diǎn)。
Savepoint savepoint1 = conn.setSavepoint("ROWS_DELETED_1");
System.out.println("Deleting row....");
String SQL = "DELETE FROM Employees " +
"WHERE ID = 110";
stmt.executeUpdate(SQL);
// 糟糕...我們刪除了太錯(cuò)誤的員工！
//步驟8：在保存點(diǎn)2之后回滾更改。
conn.rollback(savepoint1);
// 步驟9：刪除ID大于104的行
// 但是在這樣做之前要先保存點(diǎn)。
Savepoint savepoint2 = conn.setSavepoint("ROWS_DELETED_2");
System.out.println("Deleting row....");
SQL = "DELETE FROM Employees " +
"WHERE ID = 95";
stmt.executeUpdate(SQL);
//步驟10：現(xiàn)在列出所有可用的記錄。
sql = "SELECT id, first, last, age FROM Employees";
rs = stmt.executeQuery(sql);
System.out.println("List result set for reference....");
printRs(rs);
//步驟10：清理環(huán)境
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
//處理JDBC錯(cuò)誤
se.printStackTrace();
// 如果有錯(cuò)誤，則回滾更改。
System.out.println("Rolling back data here....");
try{
if(conn!=null)
conn.rollback();
}catch(SQLException se2){
se2.printStackTrace();
}//結(jié)束try
}catch(Exception e){
//處理Class.forName的錯(cuò)誤
e.printStackTrace();
}finally{
//用于關(guān)閉資源
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
}
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}//結(jié)束try
System.out.println("Goodbye!");
}//結(jié)束main
public static void printRs(ResultSet rs) throws SQLException{
//確保我們從第一行開(kāi)始
rs.beforeFirst();
while(rs.next()){
//按列名檢索
int id = rs.getInt("id");
int age = rs.getInt("age");
String first = rs.getString("first");
String last = rs.getString("last");
//顯示值
System.out.print("ID: " + id);
System.out.print(", Age: " + age);
System.out.print(", First: " + first);
System.out.println(", Last: " + last);
}
System.out.println();
}//結(jié)束printRs()
}//結(jié)束JDBCExample現(xiàn)在，讓我們編譯上面的示例，如下所示：
C:\>javac JDBCExample.java C:\>
運(yùn)行時(shí)JDBCExample，它將產(chǎn)生以下結(jié)果-
C:\>java JDBCExample Connecting to database... Creating statement... List result set for reference.... ID: 95, Age: 20, First: Sima, Last: Chug ID: 100, Age: 18, First: Zara, Last: Ali ID: 101, Age: 25, First: Mahnaz, Last: Fatma ID: 102, Age: 30, First: Zaid, Last: Khan ID: 103, Age: 30, First: Sumit, Last: Mittal ID: 110, Age: 20, First: Sima, Last: Chug Deleting row.... Deleting row.... List result set for reference.... ID: 100, Age: 18, First: Zara, Last: Ali ID: 101, Age: 25, First: Mahnaz, Last: Fatma ID: 102, Age: 30, First: Zaid, Last: Khan ID: 103, Age: 30, First: Sumit, Last: Mittal ID: 110, Age: 20, First: Sima, Last: Chug Goodbye! C:\>