java String类型转换为Blob类型怎么转

0沫随缘0 2023-03-17 08:24

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  0陈浩南

  2023-03-17 09:00

  这个是mysql下存取blob字段的一个很简单的类，跟据自己的需要改改就行了/*** Title: BlobPros.java* Project: test* Description: 把图片存入mysql中的blob字段，并取出* Call Mole: mtools数据库中的tmp表 * File: C:\downloads\luozsh.jpg* Copyright: Copyright (c) 2003-2003* Company: uniware* Create Date: 2002.12.5* @Author: FeiFan* @version 1.0 版本* * * Revision history* Name Date Description* ---- ---- -----------* Chenqh 2003.12.5 对图片进行存取** note: 要把数据库中的Blob字段设为longblob **///package com.uniware;import java.io.*;import java.util.*;import java.sql.*;public class BlobPros{ private static final String URL = "jdbc:mysql://10.144.123.63:3306/mtools?user=wind&password=123&useUnicode=true"; private Connection conn = null; private PreparedStatement pstmt = null; private ResultSet rs = null; private File file = null; public BlobPros() { } /** * 向数据库中插入一个新的BLOB对象(图片) * * @param infile - 要输入的数据文件 * @throws java.lang.Exception * */ public void blobInsert(String infile) throws Exception { FileInputStream fis = null; try { Class.forName("org.gjt.mm.mysql.Driver").newInstance(); conn = DriverManager.getConnection(URL); file = new File(infile); fis = new FileInputStream(file); //InputStream fis = new FileInputStream(infile); pstmt = conn.prepareStatement("insert into tmp(descs,pic) values(?,?)"); pstmt.setString(1,file.getName()); //把传过来的第一个参数设为文件名 //pstmt.setBinaryStream(2,fis,(int)file.length()); //这种方法原理上会丢数据，因为file.length()返回的是long型 pstmt.setBinaryStream(2,fis,fis.available()); //第二个参数为文件的内容 pstmt.executeUpdate(); } catch(Exception ex) { System.out.println("[blobInsert error : ]" + ex.toString()); } finally { //关闭所打开的对像// pstmt.close(); fis.close(); conn.close(); } }/** * 从数据库中读出BLOB对象 * * @param outfile - 输出的数据文件 * @param picID - 要取的图片在数据库中的ID * @throws java.lang.Exception * */ public void blobRead(String outfile,int picID) throws Exception { FileOutputStream fos = null; InputStream is = null; byte[] Buffer = new byte[4096]; try { Class.forName("org.gjt.mm.mysql.Driver").newInstance(); conn = DriverManager.getConnection(URL); pstmt = conn.prepareStatement("select pic from tmp where id=?"); pstmt.setInt(1,picID); //传入要取的图片的ID rs = pstmt.executeQuery(); rs.next(); file = new File(outfile); if(!file.exists()) { file.createNewFile(); //如果文件不存在，则创建 } fos = new FileOutputStream(file); is = rs.getBinaryStream("pic"); int size = 0; /* while(size != -1) { size = is.read(Buffer); //从数据库中一段一段的读出数据 //System.out.println(size); if(size != -1) //-1表示读到了文件末 fos.write(Buffer,0,size); } */ while((size = is.read(Buffer)) != -1) { //System.out.println(size); fos.write(Buffer,0,size); } } catch(Exception e) { System.out.println("[OutPutFile error : ]" + e.getMessage()); } finally { //关闭用到的资源 fos.close(); rs.close(); pstmt.close(); conn.close(); } } public static void main(String[] args) { try { BlobPros blob = new BlobPros(); //blob.blobInsert("C:\\Downloads\\luozsh1.jpg"); blob.blobRead("c:/downloads/luozishang.jpg",47); } catch(Exception e) { System.out.println("[Main func error: ]" + e.getMessage()); } }}

  那你可以用异常处理啊try{} catch()
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