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
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();
}
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();
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
2.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();
}
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();
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();
}
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);
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);
}
}
}
