开发: C++知识库 Java知识库 JavaScript Python PHP知识库人工智能区块链大数据移动开发嵌入式开发工具数据结构与算法开发测试游戏开发网络协议系统运维
教程: HTML教程 CSS教程 JavaScript教程 Go语言教程 JQuery教程 VUE教程 VUE3教程 Bootstrap教程 SQL数据库教程 C语言教程 C++教程 Java教程 Python教程 Python3教程 C#教程
数码: 电脑笔记本显卡显示器固态硬盘硬盘耳机手机 iphone vivo oppo 小米华为单反装机图拉丁

-> 大数据 -> 17.9处理大数据对象(血干JAVA系类) -> 正文阅读

[大数据]17.9处理大数据对象(血干JAVA系类)

总结：

处理CLOB数据(文本)
【例17.16】写入大文本数据（pstmt写入）
【例17.17】读取大文本字段（直接ResultSet）
【例17.18】使用Clob读取内容（使用Clob）
2.17.9.2 处理BLOB数据（视频，图片）
【例17.19］将图片写入到数据表中（pstmt存入）
【例17.20】读取内容，并将图片信息保存（直接ResultSet）
【例17.21】使用Blob读取内容（使用Blob）

在这里插入图片描述

17.9.1 处理CLOB数据

在这里插入图片描述

【例17.16】写入大文本数据（pstmt写入）

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;

public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		Class.forName(DBDRIVER);//加载驱动
		String sql = "insert into userclob(name,note) values(?,?)";
		File f = new File("d:"+File.separator+"mldn.txt");
		InputStream input = new FileInputStream(f);
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		
		pstmt.setString(1, "文本");
		pstmt.setAsciiStream(2,input,(int)f.length());
		pstmt.executeUpdate();
		
		pstmt.close();
		conn.close();
	}
}

因为现在的内容是保存在文件中，所以使用FilelnputStream类将文本文件读取进来，然后直接通过PreparedStatement对象将其写入到对应的大文本字段中。

写入完成后，下面直接使用ResultSet将其读取进来，因为写入的时候是按照输入流的方式写入的，所以此时也需要按照输入流的方式读取进来.

【例17.17】（直接ResultSet）读取大文本字段

InputStream input = rs.getAsciiStream(2);
Scanner scan = new Scanner(input);
scan.useDelimiter("\r\n");//换行
while(scan.hasNext())
{
	XXXX；
}

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		int id = 1;
		Class.forName(DBDRIVER);//驱动
		String sql = "select name,note from userclob where id=?";
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		pstmt.setInt(1, id);
		ResultSet rs =pstmt.executeQuery();
		
		while(rs.next())
		{
			String name = rs.getString(1);
			StringBuffer buf = new StringBuffer();
			System.out.println("name:"+name);
			InputStream input = rs.getAsciiStream(2);
			Scanner scan = new Scanner(input);
			scan.useDelimiter("\r\n");//换行
			while(scan.hasNext())
			{
				buf.append(scan.next()).append("\n");
			}
			System.out.println("内容"+buf);
			input.close();
		}
		
		rs.close();
		pstmt.close();
		conn.close();
	}
}

在这里插入图片描述

【例17.18】使用Clob读取内容

Clob c =rs.getClob(2);
String str = c.getSubString(1,(int)c.length());

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;


public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		int id = 1;
		Class.forName(DBDRIVER);//驱动
		String sql = "select name,note from userclob where id=?";
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		pstmt.setInt(1, id);
		ResultSet rs =pstmt.executeQuery();
		
		while(rs.next())
		{
			String name = rs.getString(1);
			Clob c =rs.getClob(2);
			String str = c.getSubString(1,(int)c.length());
			System.out.println("全部："+str);
			System.out.println("---------------------------------------------");
			c.truncate(100);//读取100字符
			System.out.println("部分："+c.getSubString(1,(int)c.length()));
		}
		
		rs.close();
		pstmt.close();
		conn.close();
	}
}

在这里插入图片描述

17.9.2 处理BLOB数据

【例17.19］将图片写入到数据表中（pstmt存入）

		File f = new File("d:"+File.separator+"mldn.gif");
		InputStream input = new FileInputStream(f); 
		pstmt.setString(1, name);
		pstmt.setBinaryStream(2, input,(int)f.length());

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;


public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		String name ="gif图";
		Class.forName(DBDRIVER);//驱动
		String sql = "insert into userblob(name,photo) values(?,?)";
		
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		
		File f = new File("d:"+File.separator+"mldn.gif");
		InputStream input = new FileInputStream(f); 
		pstmt.setString(1, name);
		pstmt.setBinaryStream(2, input,(int)f.length());
		
		pstmt.executeUpdate();
		
		pstmt.close();
		conn.close();
		
	}
}

在这里插入图片描述

【例17.20】读取内容，并将图片信息保存

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;


public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		int id = 1;
		Class.forName(DBDRIVER);//驱动
		String sql = "select name,photo from userblob where id=?";
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		 
		pstmt.setInt(1, id);
		ResultSet rs = pstmt.executeQuery();//结果集
		
		//读取
		while(rs.next())
		{
			String name = rs.getString(1);
			System.out.println("name:"+name);
			InputStream input = rs.getBinaryStream(2);//输入流
			File f = new File("d:"+File.separator+"loadmldn.gif");
			OutputStream output = new FileOutputStream(f);	//输出流
			int temp = 0;
			while((temp=input.read())!=-1)
			{
				output.write(temp);
			}
			input.close();
			output.close();
		}
		rs.close();
		pstmt.close();
		conn.close();
	}
}

在这里插入图片描述

【例17.21】使用Blob读取内容

package file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;


public class demo 
{
	public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/java_mysql";
	public static final String DBUSER = "root";
	public static final String DBPASS = "dyh20011022";
	
	public static void main(String[] args) throws Exception
	{		
		int id = 1;
		Class.forName(DBDRIVER);//驱动
		String sql = "select name,photo from userblob where id=?";
		
		Connection conn =DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		PreparedStatement pstmt = conn.prepareStatement(sql);
		 
		pstmt.setInt(1, id);
		ResultSet rs = pstmt.executeQuery();//结果集
		
		//读取
		while(rs.next())
		{
			String name = rs.getString(1);
			System.out.println("name:"+name);
			Blob b = rs.getBlob(2);
			File f = new File("d:"+File.separator+"loadmldn.gif");
			OutputStream output = new FileOutputStream(f);	//输出流
			output.write(b.getBytes(1, (int)f.length()));
			output.close();
		}
		rs.close();
		pstmt.close();
		conn.close();
	}
}