附上之前的jdbcutil类：
package jdbc.mis.util;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class jdbcutil {
private static Properties p=new Properties();
static {
ClassLoader clo=Thread.currentThread().getContextClassLoader();
InputStream in=clo.getResourceAsStream("db.properties");
try {
p.load(in);
Class.forName(p.getProperty("conect"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static Connection getconn()
{
try {
return DriverManager.getConnection(p.getProperty("driver"), p.getProperty("username"), p.getProperty("password"));
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
throw new RuntimeException("数据库连接异常");
}
public static void close(Connection conn,Statement st,ResultSet re)
{
try {
if(re!=null)
re.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
finally {
try {
if(st!=null)
st.close();
} catch (Exception e3) {
// TODO: handle exception
e3.printStackTrace();
}finally {
try {
if(conn!=null)
conn.close();
} catch (Exception e4) {
// TODO: handle exception
e4.printStackTrace();
}
}
}
}
}
具体代码：
package jdbc.mis.yinghang;
import static org.junit.Assert.*;
import java.sql.Connection;
import org.junit.Test;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import jdbc.mis.util.jdbcutil;
public class anli {
@Test
public void test() throws Exception {
/*
* 1):检查张无忌的账户余额是否大于等于1000.
SELECT * FROM account WHERE name = '张无忌' AND balance >= 1000;
2):从张无忌的账户余额中减少1000.
UPDATE account SET balance = balance - 1000 WHERE name = '张无忌';
3):再在赵敏的账户余额中增加1000.
UPDATE account SET balance = balance + 1000 WHERE name = ' 赵敏';
* */
String sql="SELECT * FROM account WHERE name = ? AND money >= ?";
Connection conn=jdbcutil.getconn();
PreparedStatement ps=conn.prepareStatement(sql);
ps.setString(1,"张无忌");
ps.setInt(2, 15000);
ResultSet re=ps.executeQuery();
if(!re.next())
{
throw new RuntimeException("不存在");
}
sql="UPDATE account SET money = money - ? WHERE name = ?";
ps=conn.prepareStatement(sql);
ps.setString(2,"张无忌");
ps.setInt(1, 1000);
ps.executeUpdate();
sql="UPDATE account SET money = money + ? WHERE name = ?";
ps=conn.prepareStatement(sql);
ps.setString(2,"赵敏");
ps.setInt(1, 1000);
ps.executeUpdate();
jdbcutil.close(conn, ps, re);
}
@Test
public void test2() {
String sql=null;
Connection conn=null;
PreparedStatement ps=null;
try {
conn=jdbcutil.getconn();
conn.setAutoCommit(false);
sql="UPDATE account SET money = money - ? WHERE name = ?";
ps=conn.prepareStatement(sql);
ps.setString(2,"张无忌");
ps.setInt(1, 1000);
ps.executeUpdate();
//int a=1/0;
sql="UPDATE account SET money = money + ? WHERE name = ?";
ps=conn.prepareStatement(sql);
ps.setString(2,"赵敏");
ps.setInt(1, 1000);
ps.executeUpdate();
conn.commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
jdbcutil.close(conn, ps, null);
}
}
}