java攻城狮之路--复习JDBC(利用BeanUtils、JDBC元数据编写通用的查询方法;元数据;Blob;事务;批量处理)

1、利用BeanUtils的前提得要加入以下两个jar包：

commons-beanutils-1.8.0.jar

commons-logging-1.1.1.jar

package com.shellway.jdbcDAO;

import java.util.List;
import org.junit.Test;

public class TestDAO {
    DAO dao = new DAO();

    @Test
    public void testUpdate() throws Exception {
        String sql = "update examstudent set grade=? where flow_id=12345";
        dao.update(sql, 88);
    }

    @Test
    public void test() throws Exception {

        String sql = "select flow_id flowID,type,id_card idCard, "
                + "exam_card examCard,student_name studentName,location,grade "
                + "from examstudent where flow_id = ? ";
        Student stu = dao.get(Student.class, sql, 12345);
        System.out.println(stu);
    }

    @Test
    public void testGetSome() throws Exception {
        String sql = "select flow_id flowID,type,id_card idCard, "
                + "exam_card examCard,student_name studentName,location,grade "
                + "from examstudent";
        List<Student> students = dao.getForList(Student.class, sql);
        System.out.println(students);
    }

    @Test
    public void testGetForValue() throws Exception {
        String sql = "select grade from examstudent where flow_id = ? ";
        Object obj = dao.getforvalue(sql, 123456);
        System.out.println(obj);
    }
}

package com.shellway.jdbcDAO;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;

public class DAO {

    public void update(String sql, Object... args) throws Exception {
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(null, ps, conn);
        }
    }

    // 获取一个对象通用的方法
    public <T> T get(Class<T> clazz, String sql, Object... args)
            throws Exception {
        T entity = null;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();
            ResultSetMetaData rsmd = rs.getMetaData();
            Map<String, Object> map = null;

            while (rs.next()) {
                map = new HashMap<String, Object>();
                for (int i = 0; i < rsmd.getColumnCount(); i++) {
                    String columnLabel = rsmd.getColumnLabel(i + 1);
                    Object columnValue = rs.getObject(i + 1);
                    map.put(columnLabel, columnValue);
                }
                if (map.size() > 0) {
                    entity = clazz.newInstance();
                    for (Map.Entry<String, Object> entry : map.entrySet()) {
                        String label = entry.getKey();
                        Object value = entry.getValue();
                        BeanUtils.setProperty(entity, label, value);
                    }
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(rs, ps, conn);
        }
        return entity;
    }

    // 获取一组对象通用的方法
    public <T> List<T> getForList(Class<T> clazz, String sql, Object... args)
            throws Exception {
        T entity = null;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        List<T> result = new ArrayList<T>();

        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();

            ResultSetMetaData rsmd = rs.getMetaData();
            List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
            Map<String, Object> map = new HashMap<String, Object>();

            while (rs.next()) {
                for (int i = 0; i < rsmd.getColumnCount(); i++) {
                    String columnLabel = rsmd.getColumnLabel(i + 1);
                    Object columnValue = rs.getObject(i + 1);
                    map.put(columnLabel, columnValue);
                }
                list.add(map);
                if (list.size() > 0) {
                    entity = clazz.newInstance();
                    for (Map<String, Object> ll : list) {
                        for (Map.Entry<String, Object> entry : ll.entrySet()) {
                            String label = entry.getKey();
                            Object value = entry.getValue();
                            BeanUtils.setProperty(entity, label, value);
                        }
                    }
                    result.add(entity);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(rs, ps, conn);
        }
        return result;
    }

    // 获取一个对象中一列的值通用的方法
    public <E> E getforvalue(String sql, Object... args) throws Exception {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();
            if (rs.next()) {
                return (E) rs.getObject(1);
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(rs, ps, conn);
        }
        return null;
    }
}

package com.shellway.jdbcDAO;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.sql.PreparedStatement;

public class JDBCTools {

    public static <T> T get(Class<T> clazz, String sql, Object... args)
            throws Exception {
        T entity = null;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();

            ResultSetMetaData rsmd = rs.getMetaData();
            Map<String, Object> map = new HashMap<String, Object>();
            while (rs.next()) {
                for (int i = 0; i < rsmd.getColumnCount(); i++) {
                    String columnLabel = rsmd.getColumnLabel(i + 1);
                    Object columnValue = rs.getObject(i + 1);
                    // Object columnValue = rs.getObject(columnLabel);
                    map.put(columnLabel, columnValue);
                }
            }
            if (map.size() > 0) {
                entity = clazz.newInstance();
                for (Map.Entry<String, Object> values : map.entrySet()) {
                    String key = values.getKey();
                    Object value = values.getValue();
                    ReflectionUtils.setFieldValue(entity, key, value);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(rs, ps, conn);
        }
        return entity;
    }

    public static void update(String sql, Object... args) throws Exception {
        Connection conn = null;
        PreparedStatement ps = null;

        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            System.out.println(sql);
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(null, ps, conn);
        }
    }

    public static Connection getConnection() throws Exception {

        Properties proper = new Properties();
        InputStream in = JDBCTools.class.getClassLoader().getResourceAsStream(
                "jdbc.properties");
        proper.load(in);
        String driverClass = proper.getProperty("driver");
        String jdbcUrl = proper.getProperty("jdbcUrl");
        String user = proper.getProperty("user");
        String password = proper.getProperty("password");

        Class.forName(driverClass);
        Connection connection = DriverManager.getConnection(jdbcUrl, user,
                password);
        return connection;
    }

    public static void release(ResultSet rs, Statement state, Connection conn)
            throws Exception {
        if (rs != null) {
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if (state != null) {
            try {
                state.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}

driver=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql://localhost:3306/test
user=root
password=123

package com.shellway.jdbc;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

/**
 * 反射的 Utils 函数集合 提供访问私有变量, 获取泛型类型 Class, 提取集合中元素属性等 Utils 函数
 * 
 * @author Administrator
 * 
 */
public class ReflectionUtils {

    /**
     * 通过反射, 获得定义 Class 时声明的父类的泛型参数的类型 如: public EmployeeDao extends
     * BaseDao<Employee, String>
     * 
     * @param clazz
     * @param index
     * @return
     */
    @SuppressWarnings("unchecked")
    public static Class getSuperClassGenricType(Class clazz, int index) {
        Type genType = clazz.getGenericSuperclass();

        if (!(genType instanceof ParameterizedType)) {
            return Object.class;
        }

        Type[] params = ((ParameterizedType) genType).getActualTypeArguments();

        if (index >= params.length || index < 0) {
            return Object.class;
        }

        if (!(params[index] instanceof Class)) {
            return Object.class;
        }

        return (Class) params[index];
    }

    /**
     * 通过反射, 获得 Class 定义中声明的父类的泛型参数类型 如: public EmployeeDao extends
     * BaseDao<Employee, String>
     * 
     * @param <T>
     * @param clazz
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <T> Class<T> getSuperGenericType(Class clazz) {
        return getSuperClassGenricType(clazz, 0);
    }

    /**
     * 循环向上转型, 获取对象的 DeclaredMethod
     * 
     * @param object
     * @param methodName
     * @param parameterTypes
     * @return
     */
    public static Method getDeclaredMethod(Object object, String methodName,
            Class<?>[] parameterTypes) {

        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass
                .getSuperclass()) {
            try {
                // superClass.getMethod(methodName, parameterTypes);
                return superClass.getDeclaredMethod(methodName, parameterTypes);
            } catch (NoSuchMethodException e) {
                // Method 不在当前类定义, 继续向上转型
            }
            // ..
        }

        return null;
    }

    /**
     * 使 filed 变为可访问
     * 
     * @param field
     */
    public static void makeAccessible(Field field) {
        if (!Modifier.isPublic(field.getModifiers())) {
            field.setAccessible(true);
        }
    }

    /**
     * 循环向上转型, 获取对象的 DeclaredField
     * 
     * @param object
     * @param filedName
     * @return
     */
    public static Field getDeclaredField(Object object, String filedName) {

        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass
                .getSuperclass()) {
            try {
                return superClass.getDeclaredField(filedName);
            } catch (NoSuchFieldException e) {
                // Field 不在当前类定义, 继续向上转型
            }
        }
        return null;
    }

    /**
     * 直接调用对象方法, 而忽略修饰符(private, protected)
     * 
     * @param object
     * @param methodName
     * @param parameterTypes
     * @param parameters
     * @return
     * @throws InvocationTargetException
     * @throws IllegalArgumentException
     */
    public static Object invokeMethod(Object object, String methodName,
            Class<?>[] parameterTypes, Object[] parameters)
            throws InvocationTargetException {

        Method method = getDeclaredMethod(object, methodName, parameterTypes);

        if (method == null) {
            throw new IllegalArgumentException("Could not find method ["
                    + methodName + "] on target [" + object + "]");
        }

        method.setAccessible(true);

        try {
            return method.invoke(object, parameters);
        } catch (IllegalAccessException e) {
            System.out.println("不可能抛出的异常");
        }

        return null;
    }

    /**
     * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter
     * 
     * @param object
     * @param fieldName
     * @param value
     */
    public static void setFieldValue(Object object, String fieldName,
            Object value) {
        Field field = getDeclaredField(object, fieldName);

        if (field == null)
            throw new IllegalArgumentException("Could not find field ["
                    + fieldName + "] on target [" + object + "]");

        makeAccessible(field);

        try {
            field.set(object, value);
        } catch (IllegalAccessException e) {
            System.out.println("不可能抛出的异常");
        }
    }

    /**
     * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter
     * 
     * @param object
     * @param fieldName
     * @return
     */
    public static Object getFieldValue(Object object, String fieldName) {
        Field field = getDeclaredField(object, fieldName);

        if (field == null)
            throw new IllegalArgumentException("Could not find field ["
                    + fieldName + "] on target [" + object + "]");

        makeAccessible(field);

        Object result = null;

        try {
            result = field.get(object);
        } catch (IllegalAccessException e) {
            System.out.println("不可能抛出的异常");
        }

        return result;
    }
}

2、获取数据库中的一些元数据：

    @Test
    public void testDatebaseMetaData() throws Exception {
        Connection conn = null;
        ResultSet rs = null;
        try {
            conn = JDBCTools.getConnection();
            DatabaseMetaData dbmd = conn.getMetaData();
            // 得到数据库的一些基本信息
            int version = dbmd.getDatabaseMajorVersion();
            System.out.println(version);
            String user = dbmd.getUserName();
            System.out.println(user);
            rs = dbmd.getCatalogs();
            while (rs.next()) {
                String str = rs.getString(1);
                System.out.println(str);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(rs, null, conn);
        }
    }

3、获取插入记录的主键值，在加入购物车时用到:

    @Test
    public void testPrimeryKey() throws Exception {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        String sql = "insert into customer(name,email,birth) values(?,?,?)  ";

        try {
            conn = JDBCTools.getConnection();
            ps = conn.prepareStatement(sql, ps.RETURN_GENERATED_KEYS);
            ps.setString(1, "BBBB");
            ps.setString(2, "BBBB@163.COM");
            ps.setDate(3, new Date(new java.util.Date().getTime()));
            ps.executeUpdate();
            rs = ps.getGeneratedKeys();
            if (rs.next()) {
                Object obj = rs.getObject(1);
                System.out.println(obj);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCTools.release(null, ps, conn);
        }
    }

4、读取 blob 数据:
 1. 使用 getBlob 方法读取到 Blob 对象
 2. 调用 Blob 的 getBinaryStream() 方法得到输入流。再使用 IO 操作即可.

@Test
    public void readBlob(){
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        
        try {
            connection = JDBCTools.getConnection();
            String sql = "SELECT id, name customerName, email, birth, picture " 
                    + "FROM customers WHERE id = 13";
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            
            if(resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString(2);
                String email = resultSet.getString(3);
                
                System.out.println(id + ", " + name  + ", " + email);
                Blob picture = resultSet.getBlob(5);
                
                InputStream in = picture.getBinaryStream();
                System.out.println(in.available()); 
                
                OutputStream out = new FileOutputStream("flower.jpg");
                
                byte [] buffer = new byte[1024];
                int len = 0;
                while((len = in.read(buffer)) != -1){
                    out.write(buffer, 0, len);
                }
                
                in.close();
                out.close();
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            JDBCTools.releaseDB(resultSet, preparedStatement, connection);
        }
    }

5、事务：

•  事务：指构成单个逻辑工作单元的操作集合

•  事务处理：保证所有事务都作为一个工作单元来执行，即使出现了故障，都不能改变这种执行方式。当在一个事务中执行多个操作时，要么所有的事务都被提交(commit)，要么整个事务回滚(rollback)到最初状态

•  当一个连接对象被创建时，默认情况下是自动提交事务：每次执行一个 SQL 语句时，如果执行成功，就会向数据库自动提交，而不能回滚

•  为了让多个 SQL 语句作为一个事务执行：

––调用 Connection 对象的 setAutoCommit(false); 以取消自动提交事务

––在所有的 SQL 语句都成功执行后，调用 commit(); 方法提交事务

––在出现异常时，调用 rollback(); 方法回滚事务

––若此时 Connection 没有被关闭, 则需要恢复其自动提交状态。

数据库的隔离级别：

•  对于同时运行的多个事务, 当这些事务访问数据库中相同的数据时, 如果没有采取必要的隔离机制,

   就会导致各种并发问题:

–––脏读: 对于两个事物 T1, T2, T1 读取了已经被 T2 更新但还没有被提交的字段. 之后, 若 T2 回滚,

             T1读取的内容就是临时且无效的.

–––不可重复读: 对于两个事物 T1, T2, T1 读取了一个字段, 然后 T2 更新了该字段. 

                     之后,T1再次读取同一个字段, 值就不同了.

–––幻读: 对于两个事物 T1, T2, T1 从一个表中读取了一个字段, 然后 T2 在该表中插入了一些新的行.  

             之后, 如果 T1 再次读取同一个表, 就会多出几行.

•  数据库事务的隔离性: 数据库系统必须具有隔离并发运行各个事务的能力, 使它们不会相互影响,

    避免各种并发问题.

•  一个事务与其他事务隔离的程度称为隔离级别. 数据库规定了多种事务隔离级别, 不同隔离级别对应不同的

   干扰程度,隔离级别越高, 数据一致性就越好, 但并发性越弱.

•  Oracle 支持的 2 种事务隔离级别：READ COMMITED, SERIALIZABLE,Oracle 默认的事务隔离级别为:

    READ COMMITED。

•  Mysql 支持 4 中事务隔离级别. Mysql 默认的事务隔离级别为: REPEATABLE READ。

在 MySql 中设置隔离级别:

•  每启动一个 mysql 程序, 就会获得一个单独的数据库连接. 每个数据库连接都有一个全局变量

   @@tx_isolation, 表示当前的事务隔离级别. MySQL 默认的隔离级别为 Repeatable Read

•  查看当前的隔离级别: SELECT @@tx_isolation;

•  设置当前 mySQL 连接的隔离级别: 

    –set  transaction isolation level read committed;

•  设置数据库系统的全局的隔离级别:

    –set global transaction isolation level read committed;

关于事务:
1. 如果多个操作, 每个操作使用的是自己的单独的连接, 则无法保证事务.
2. 具体步骤: 1). 事务操作开始前, 开始事务:取消Connection 的默认提交行为. connection.setAutoCommit(false).
2). 如果事务的操作都成功,则提交事务: connection.commit();
3). 回滚事务: 若出现异常, 则在 catch 块中回滚事务:connection.rollback();

    @Test
    public void testTransaction() {

        Connection connection = null;

        try {

            connection = JDBCTools.getConnection();
            System.out.println(connection.getAutoCommit());

            // 开始事务: 取消默认提交.
            connection.setAutoCommit(false);

            String sql = "UPDATE users SET balance = "
                    + "balance - 500 WHERE id = 1";
            update(connection, sql);

            int i = 10 / 0;
            System.out.println(i);

            sql = "UPDATE users SET balance = " + "balance + 500 WHERE id = 2";
            update(connection, sql);

            // 提交事务
            connection.commit();
        } catch (Exception e) {
            e.printStackTrace();

            // 回滚事务
            try {
                connection.rollback();
            } catch (SQLException e1) {
                e1.printStackTrace();
            }
        } finally {
            JDBCTools.releaseDB(null, null, connection);
        }

        /*
         * try {
         * 
         * //开始事务: 取消默认提交. connection.setAutoCommit(false);
         * 
         * //...
         * 
         * //提交事务 connection.commit(); } catch (Exception e) { //...
         * 
         * //回滚事务 try { connection.rollback(); } catch (SQLException e1) {
         * e1.printStackTrace(); } } finally{ JDBCTools.releaseDB(null, null,
         * connection); }
         */

        // DAO dao = new DAO();
        //
        // String sql = "UPDATE users SET balance = " +
        // "balance - 500 WHERE id = 1";
        // dao.update(sql);
        //
        // int i = 10 / 0;
        // System.out.println(i);
        //
        // sql = "UPDATE users SET balance = " +
        // "balance + 500 WHERE id = 2";
        // dao.update(sql);

    }

    @Test
    public void testTransactionIsolationRead() {
        String sql = "SELECT balance FROM users WHERE id = 1";
        Integer balance = getForValue(sql);
        System.out.println(balance); 
    }

    // 返回某条记录的某一个字段的值 或 一个统计的值(一共有多少条记录等.)
    public <E> E getForValue(String sql, Object... args) {

        // 1. 得到结果集: 该结果集应该只有一行, 且只有一列
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        try {
            // 1. 得到结果集
            connection = JDBCTools.getConnection();
            System.out.println(connection.getTransactionIsolation()); 
            
//            connection.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
            connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
            
            preparedStatement = connection.prepareStatement(sql);

            for (int i = 0; i < args.length; i++) {
                preparedStatement.setObject(i + 1, args[i]);
            }

            resultSet = preparedStatement.executeQuery();

            if (resultSet.next()) {
                return (E) resultSet.getObject(1);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            JDBCTools.releaseDB(resultSet, preparedStatement, connection);
        }
        // 2. 取得结果

        return null;
    }

6、批量处理JDBC语句提高处理速度:

•  当需要成批插入或者更新记录时。可以采用Java的批量更新机制，

   这一机制允许多条语句一次性提交给数据库批量处理。通常情况下比单独提交处理更有效率

•  JDBC的批量处理语句包括下面两个方法：

   –addBatch(String)：添加需要批量处理的SQL语句或是参数；

   –executeBatch(): 执行批量处理语句；

•  通常我们会遇到两种批量执行SQL语句的情况：

   – 多条SQL语句的批量处理；

   – 一个SQL语句的批量传参；

    @Test
    public void testBatch(){
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        String sql = null;
        
        try {
            connection = JDBCTools.getConnection();
            JDBCTools.beginTx(connection);
            sql = "INSERT INTO customers VALUES(?,?,?)";
            preparedStatement = connection.prepareStatement(sql);
            Date date = new Date(new java.util.Date().getTime());
            
            long begin = System.currentTimeMillis();
            for(int i = 0; i < 100000; i++){
                preparedStatement.setInt(1, i + 1);
                preparedStatement.setString(2, "name_" + i);
                preparedStatement.setDate(3, date);
                
                //"积攒" SQL 
                preparedStatement.addBatch();
                
                //当 "积攒" 到一定程度, 就统一的执行一次. 并且清空先前 "积攒" 的 SQL
                if((i + 1) % 300 == 0){
                    preparedStatement.executeBatch();
                    preparedStatement.clearBatch();
                }
            }
            
            //若总条数不是批量数值的整数倍, 则还需要再额外的执行一次. 
            if(100000 % 300 != 0){
                preparedStatement.executeBatch();
                preparedStatement.clearBatch();
            }
            
            long end = System.currentTimeMillis();
            
            System.out.println("Time: " + (end - begin)); //569
            
            JDBCTools.commit(connection);
        } catch (Exception e) {
            e.printStackTrace();
            JDBCTools.rollback(connection);
        } finally{
            JDBCTools.releaseDB(null, preparedStatement, connection);
        }
    }
    

    @Test
    public void testBatchWithPreparedStatement(){
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        String sql = null;
        
        try {
            connection = JDBCTools.getConnection();
            JDBCTools.beginTx(connection);
            sql = "INSERT INTO customers VALUES(?,?,?)";
            preparedStatement = connection.prepareStatement(sql);
            Date date = new Date(new java.util.Date().getTime());
            
            long begin = System.currentTimeMillis();
            for(int i = 0; i < 100000; i++){
                preparedStatement.setInt(1, i + 1);
                preparedStatement.setString(2, "name_" + i);
                preparedStatement.setDate(3, date);
                
                preparedStatement.executeUpdate();
            }
            long end = System.currentTimeMillis();
            
            System.out.println("Time: " + (end - begin)); //9819
            
            JDBCTools.commit(connection);
        } catch (Exception e) {
            e.printStackTrace();
            JDBCTools.rollback(connection);
        } finally{
            JDBCTools.releaseDB(null, preparedStatement, connection);
        }
    }
    
    /**
     * 向  Oracle 的 customers 数据表中插入 10 万条记录
     * 测试如何插入, 用时最短. 
     * 1. 使用 Statement.
     */
    @Test
    public void testBatchWithStatement(){
        Connection connection = null;
        Statement statement = null;
        String sql = null;
        
        try {
            connection = JDBCTools.getConnection();
            JDBCTools.beginTx(connection);
            
            statement = connection.createStatement();
            
            long begin = System.currentTimeMillis();
            for(int i = 0; i < 100000; i++){
                sql = "INSERT INTO customers VALUES(" + (i + 1) 
                        + ", 'name_" + i + "', '29-6月 -13')";
                statement.addBatch(sql);
            }
            long end = System.currentTimeMillis();
            
            System.out.println("Time: " + (end - begin)); //39567
            
            JDBCTools.commit(connection);
        } catch (Exception e) {
            e.printStackTrace();
            JDBCTools.rollback(connection);
        } finally{
            JDBCTools.releaseDB(null, statement, connection);
        }
    }