JDBC处理大数据

JDBC处理大数据

一.JDBC处理大数据概述

1.大数据分类

大数据(Large Objects)	存储类型
CLOB(Character Large Object)	存储大文本（文章，段落，文本等）
BLOB(binary large object)	存储二进制数据（图像，声音，视频等）

2.关键技术

• 在JDBC开发中操作LOB必须使用PreparedStatement并结合IO流对其进行存储。

二.JDBC处理CLOB

1.CLOB在数据库中数据类型

• 在MySQL中可用 text 类型存放CLOB数据

2.创建表

-- 创建表
DROP TABLE IF EXISTS clob01;
CREATE TABLE clob01(
   id INT PRIMARY KEY auto_increment,
   words text
);

3.JDBCUtils工具类

package cn.com.demo;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCUtils {
	// 加载驱动并建立数据库连接
	public static Connection getConnection() throws SQLException, ClassNotFoundException {
		Class.forName("com.mysql.jdbc.Driver");
		String databaseUrl = "jdbc:mysql://localhost:3306/mydb";
		String username = "root";
		String password = "test";
		Connection connection = DriverManager.getConnection(databaseUrl, username, password);
		return connection;
	}

	// 关闭数据库连接释放资源
	public static void release(Statement statement) {
		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			statement = null;
		}
	}
	
	// 关闭数据库连接释放资源
	public static void release(Connection connection) {
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			connection = null;
		}
	}

	// 关闭数据库连接释放资源
	public static void release(Statement statement, Connection connection) {
		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			statement = null;
		}
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			connection = null;
		}
	}

	// 关闭数据库连接释放资源
	public static void release(ResultSet resultSet, Statement statement, Connection connection) {
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			resultSet = null;
		}
		release(statement, connection);
	}
}

4.将CLOB数据存入数据库

package cn.com.demo;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Writer;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class TestCLOB {
	public static void main(String[] args) {
		TestCLOB test=new TestCLOB();
		test.saveCLOBToDatabase();
	}
	
	/**
	 * 从本地文件E:\\test.txt中读取CLOB数据并存至数据库
	 */
	public void saveCLOBToDatabase() {
		Connection connection = null;
		PreparedStatement  preparedStatement = null;
		try {
			connection = JDBCUtils.getConnection();
			String sql = "INSERT INTO clob01 values(?,?)";
			preparedStatement = connection.prepareStatement(sql);
			File file = new File("E:\\test.txt");
			FileInputStream fileInputStream=new FileInputStream(file);
			Reader reader = new InputStreamReader(fileInputStream,"utf-8");
			preparedStatement.setInt(1,1);
			int length= (int) file.length();
            // 关键操作
			preparedStatement.setCharacterStream(2,reader,length);
			preparedStatement.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.release(null, preparedStatement, connection);
		}
	}
	
}

5.从数据库读取CLOB数据

package cn.com.demo;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Writer;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class TestCLOB {
	public static void main(String[] args) {
		TestCLOB test=new TestCLOB();
		test.getCLOBFromDatabase();
	}
	/**
	 * 从数据库读取CLOB数据并将其保存至本地test02.txt文件中
	 */
	public void getCLOBFromDatabase() {
		Connection connection = null;
		PreparedStatement preparedStatement  = null;
		ResultSet resultSet = null;
		try {
			connection = JDBCUtils.getConnection();
			String sql = "SELECT * FROM clob01";
			preparedStatement  = connection.prepareStatement(sql);
			resultSet = preparedStatement.executeQuery();
			if (resultSet.next()) {
				// 关键操作
				Reader reader = resultSet.getCharacterStream("words");
				Writer writer = new FileWriter("test02.txt");
				int ch;
				while ((ch = reader.read()) != -1) {
					writer.write(ch);
				}
				writer.close();
				reader.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.release(resultSet, preparedStatement , connection);
		}
	}
}

三.JDBC处理BLOB

1.BLOB在数据库中数据类型

• 在MySQL中可用 BLOB类型存放BLOB数据

2.创建表

-- 创建表
DROP TABLE IF EXISTS blob01;
CREATE TABLE blob01(
   id INT PRIMARY KEY auto_increment,
   image BLOB
);

3.JDBCUtils工具类

package cn.com.demo;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCUtils {
	// 加载驱动并建立数据库连接
	public static Connection getConnection() throws SQLException, ClassNotFoundException {
		Class.forName("com.mysql.jdbc.Driver");
		String databaseUrl = "jdbc:mysql://localhost:3306/mydb";
		String username = "root";
		String password = "test";
		Connection connection = DriverManager.getConnection(databaseUrl, username, password);
		return connection;
	}

	// 关闭数据库连接释放资源
	public static void release(Statement statement) {
		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			statement = null;
		}
	}
	
	// 关闭数据库连接释放资源
	public static void release(Connection connection) {
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			connection = null;
		}
	}

	// 关闭数据库连接释放资源
	public static void release(Statement statement, Connection connection) {
		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			statement = null;
		}
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			connection = null;
		}
	}

	// 关闭数据库连接释放资源
	public static void release(ResultSet resultSet, Statement statement, Connection connection) {
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			resultSet = null;
		}
		release(statement, connection);
	}
}

4.将BLOB数据存入数据库

package cn.com.demo;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class TestBLOB {
	public static void main(String[] args) {
		TestBLOB test=new TestBLOB();
		test.saveBLOBToDatabase();
	}
	
	/**
	 * 将本地文件E:\\test.jpg读取BLOB数据并存至数据库
	 */
	public void saveBLOBToDatabase() {
		Connection connection = null;
		PreparedStatement  preparedStatement = null;
		try {
			connection = JDBCUtils.getConnection();
			String sql = "INSERT INTO blob01 values(?,?)";
			preparedStatement = connection.prepareStatement(sql);
			preparedStatement.setInt(1, 1);
			File file = new File("E:\\test.jpg");
			InputStream inputStream = new FileInputStream(file);
			int length= (int) file.length();
            // 关键操作
			preparedStatement.setBinaryStream(2,inputStream,length);		
			preparedStatement.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.release(null, preparedStatement, connection);
		}
	}
}

5.从数据库读取BLOB数据

package cn.com.demo;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class TestBLOB {
	public static void main(String[] args) {
		TestBLOB test=new TestBLOB();
		test.getBLOBFromDatabase();
	}
	/**
	 * 从数据库读取BLOB数据并保存至本地mytest.jpg
	 */
	public void getBLOBFromDatabase() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		ResultSet resultSet = null;
		try {
			connection = JDBCUtils.getConnection();
			String sql = "SELECT * FROM tblob01 where id = ?";
			preparedStatement = connection.prepareStatement(sql);
			preparedStatement.setInt(1, 1);
                // 关键操作
			resultSet = preparedStatement.executeQuery();
			if (resultSet.next()) {
				InputStream inputStream = resultSet.getBinaryStream("image");
				BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
				OutputStream outputStream = new FileOutputStream("mytest.jpg");
				OutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);
				int b;
				while ((b = bufferedInputStream.read()) != -1) {
					bufferedOutputStream.write(b);
				}
				bufferedOutputStream.close();
				bufferedInputStream.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.release(resultSet, preparedStatement, connection);
		}
	}
}