/** 文件名称：JDBCTestCase.java* 版权：Copyright 2006-2011 Huawei Tech. Co. Ltd. All Rights Reserved. * 描写叙述： JDBCTestCase.java* 改动人：z00106659* 改动时间：2011-12-2* 改动内容：新增*/
​
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Properties;
/*** 这个是一个简单演示JDBC操作的实例。相应胶片解说的七个操作步骤, 使用JDK 自带的Derby数据库;* * Derby 是由IBM捐献给Apache的DB项目的一个纯Java数据库，两种使用模式。 一种是作为嵌入式数据库,还有一种是作为网络数据库* * 此用例參考的Derby自带的Demo 在嵌入式 场景的使用有非常具体的凝视，在使用时降低安装数据库的麻烦。* * * @author z00106659* @version ONIP BME V300R001 2011-12-2* @since ONIP BME V300R001C00*/
public class JDBCTestCase {/*** 驱动类名称*/private String driver = "org.apache.derby.jdbc.EmbeddedDriver";/*** derby驱动协议头*/private String protocol = "jdbc:derby:";public static void main(String[] args) {new JDBCTestCase().go();System.out.println("SimpleApp finished");}@SuppressWarnings("unchecked")void go() {/* load the desired JDBC driver */loadDriver();/** We will be using Statement and PreparedStatement objects for* executing SQL. These objects, as well as Connections and ResultSets,* are resources that should be released explicitly after use, hence the* try-catch-finally pattern used below. We are storing the Statement* and Prepared statement object references in an array list for* convenience.*/Connection conn = null;/** This ArrayList usage may cause a warning when compiling this class* with a compiler for J2SE 5.0 or newer. We are not using generics* because we want the source to support J2SE 1.4.2 environments.*/ArrayList statements = new ArrayList(); // list of Statements,// PreparedStatementsPreparedStatement psInsert = null;PreparedStatement psUpdate = null;PreparedStatement psDelete = null;Statement s = null;ResultSet rs = null;try {Properties props = new Properties(); // connection properties// providing a user name and password is optional in the embedded// and derbyclient frameworksprops.put("user", "user1");props.put("password", "user1");String dbName = "derbyDB"; // the name of the databaseconn = DriverManager.getConnection(protocol + dbName+ ";create=true", props);System.out.println("Connected to and created database " + dbName);// We want to control transactions manually. Autocommit is on by// default in JDBC./*** 支持事物*/conn.setAutoCommit(false);/** Creating a statement object that we can use for running various* SQL statements commands against the database.*/s = conn.createStatement();statements.add(s);// We create a table...s.execute("create table location(num int, addr varchar(40))");System.out.println("Created table location");// and add a few rows...psInsert = conn.prepareStatement("insert into location values (?, ?

)"); statements.add(psInsert); psInsert.setInt(1, 2014); psInsert.setString(2, "zhangyaun"); psInsert.executeUpdate(); psInsert.setInt(1, 1956); psInsert.setString(2, "Webster St."); psInsert.executeUpdate(); System.out.println("Inserted 1956 Webster"); psInsert.setInt(1, 180); psInsert.setString(2, "Union St."); psInsert.executeUpdate(); System.out.println("Inserted 1910 Union"); conn.commit();//这里将操作提交 // Let's update some rows as well... // parameter 1 and 3 are num (int), parameter 2 is addr (varchar) try { psDelete = conn .prepareStatement("delete from location where num=?"); statements.add(psDelete); psDelete.setInt(1, 2014); psDelete.executeUpdate(); conn.rollback();//这里回滚。能够将删除的2014 回滚回来 } catch (RuntimeException e1) { e1.printStackTrace(); } psUpdate = conn .prepareStatement("update location set num=?, addr=?

where num=?

"); statements.add(psUpdate); psUpdate.setInt(1, 180); psUpdate.setString(2, "Grand Ave."); psUpdate.setInt(3, 1956); psUpdate.executeUpdate(); System.out.println("Updated 1956 Webster to 180 Grand"); conn.commit(); try { psUpdate.setInt(1, 300); psUpdate.setString(2, "Lakeshore Ave."); psUpdate.setInt(3, 180); psUpdate.executeUpdate(); System.out.println("Updated 180 Grand to 300 Lakeshore"); conn.commit(); } catch (RuntimeException e) { // TODO Auto-generated catch block e.printStackTrace(); } /* * We select the rows and verify the results. */ rs = s.executeQuery("SELECT num, addr FROM location ORDER BY num"); while (rs.next()) { System.out.println(rs.getInt(1)); } int number; // street number retrieved from the database boolean failure = false; if (!failure) { System.out.println("Verified the rows"); } // delete the table s.execute("drop table location"); System.out.println("Dropped table location"); /* * We commit the transaction. Any changes will be persisted to the * database now. */ conn.commit(); System.out.println("Committed the transaction"); try { // the shutdown=true attribute shuts down Derby DriverManager.getConnection("jdbc:derby:;shutdown=true"); // To shut down a specific database only, but keep the // engine running (for example for connecting to other // databases), specify a database in the connection URL: // DriverManager.getConnection("jdbc:derby:" + dbName + // ";shutdown=true"); } catch (SQLException se) { if (((se.getErrorCode() == 50000) && ("XJ015".equals(se .getSQLState())))) { // we got the expected exception System.out.println("Derby shut down normally"); // Note that for single database shutdown, the expected // SQL state is "08006", and the error code is 45000. } else { // if the error code or SQLState is different, we have // an unexpected exception (shutdown failed) System.err.println("Derby did not shut down normally"); printSQLException(se); } } } catch (SQLException sqle) { printSQLException(sqle); } finally { // release all open resources to avoid unnecessary memory usage // ResultSet try { if (rs != null) { rs.close(); rs = null; } } catch (SQLException sqle) { printSQLException(sqle); } // Statements and PreparedStatements int i = 0; while (!statements.isEmpty()) { // PreparedStatement extend Statement Statement st = (Statement) statements.remove(i); try { if (st != null) { st.close(); st = null; } } catch (SQLException sqle) { printSQLException(sqle); } } // Connection try { if (conn != null) { conn.close(); conn = null; } } catch (SQLException sqle) { printSQLException(sqle); } } } /** * Reports a data verification failure to System.err with the given message. * * @param message * A message describing what failed. */ private void reportFailure(String message) { System.err.println("\nData verification failed:"); System.err.println('\t' + message); } /** * Prints details of an SQLException chain to <code>System.err</code>. * Details included are SQL State, Error code, Exception message. * * @param e * the SQLException from which to print details. */ public static void printSQLException(SQLException e) { // Unwraps the entire exception chain to unveil the real cause of the // Exception. while (e != null) { System.err.println("\n----- SQLException -----"); System.err.println(" SQL State: " + e.getSQLState()); System.err.println(" Error Code: " + e.getErrorCode()); System.err.println(" Message: " + e.getMessage()); // for stack traces, refer to derby.log or uncomment this: // e.printStackTrace(System.err); e = e.getNextException(); } } /** * Loads the appropriate JDBC driver for this environment/framework. For * example, if we are in an embedded environment, we load Derby's embedded * Driver, <code>org.apache.derby.jdbc.EmbeddedDriver</code>. */ private void loadDriver() { try { Class.forName(driver).newInstance(); System.out.println("Loaded the appropriate driver"); } catch (ClassNotFoundException cnfe) { System.err.println("\nUnable to load the JDBC driver " + driver); System.err.println("Please check your CLASSPATH."); cnfe.printStackTrace(System.err); } catch (InstantiationException ie) { System.err.println("\nUnable to instantiate the JDBC driver " + driver); ie.printStackTrace(System.err); } catch (IllegalAccessException iae) { System.err.println("\nNot allowed to access the JDBC driver " + driver); iae.printStackTrace(System.err); } } }

实现数据库事务

首先设置：

conn.setAutoCommit(false);

在commit()方法和rollback方法之间的操作会被回滚。我们做实验：

conn.commit();//这里将操作提交// Let's update some rows as well...// parameter 1 and 3 are num (int), parameter 2 is addr (varchar)try {psDelete = conn.prepareStatement("delete from location where num=?");statements.add(psDelete);psDelete.setInt(1, 2014);psDelete.executeUpdate();conn.rollback();//这里回滚，能够将删除的2014 回滚回来

这时删除的2014将回滚回来。回滚一般用于发生异常时，因此一般能够写在catch中，当删除不存在的编号时。回滚就起作用了。