数据库读取、保存图片

java 向数据库中保存图片
  

Part1 : 保存图片到数据库中

import java.io.*;
import java.sql.*;

public class PutImg {

    public void putimg(String filename) {
        try {
           Class.forName("com.mysql.jdbc.Driver").newInstance();
           Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mydefault","root","skychen");
           PreparedStatement pstmt = null;
           String sql = "";
           File file = new File(filename);

           InputStream photoStream = new FileInputStream(file);
           //sql = "   UPDATE   imgt   SET   img   =   ?   ";
           
           sql = "INSERT INTO imgtable (id,img) VALUES (1,?)";
           //insert into images(PicNum,Content,Image) values(1,?,?)
          
           pstmt = con.prepareStatement(sql);
           pstmt.setBinaryStream(1,photoStream,(int)file.length());
           //需获取文件输出流及其大小
           pstmt.execute();
           pstmt.close();
           con.close();
        } catch (Exception e) {
                System.err.println("Error");
                e.printStackTrace();
        }
    }
    public static void main(String[] args){
            if (!args[0].equals(null))
            {
                PutImg pi=new PutImg();
                pi.putimg(args[0]);   
                System.out.println("Upload file success");
            }
            else{
                System.out.println(args[0]);
                System.out.println("Warnning: Please type your wanted filename!");
            }           
    }
}

Part2 : 保存图片到文件

import java.io.*;
import java.sql.*;


class GetImg {

    private String URL = "jdbc:mysql://localhost:3306/mydefault?user=root&password=skychen";
    private Connection conn = null;
    private PreparedStatement pstmt = null;
    private ResultSet rs = null;
    private File file = null;

    public void blobRead(String outfilename, int picID) throws Exception {
    FileOutputStream fos = null;
    InputStream is = null;
    byte[] Buffer = new byte[4096];
    try {
       Class.forName("com.mysql.jdbc.Driver").newInstance();
       conn = DriverManager.getConnection(URL);
       pstmt = conn.prepareStatement("select img from imgtable where id=?");
       pstmt.setInt(1, picID); // 传入要取的图片的ID
       rs = pstmt.executeQuery();
       rs.next();
       file = new File(outfilename);
       if (!file.exists()) {
        file.createNewFile(); // 如果文件不存在，则创建
       }
       fos = new FileOutputStream(file);   //得到文件输出流
       is = rs.getBinaryStream("img");    //从数据库中得到文件二进制流
       int size = 0;
      
       while ((size = is.read(Buffer)) != -1) { //读到buffer 中缓存
            //System.out.println(size); //打印buffer大小
            fos.write(Buffer, 0, size); //写入到文件输出流中
       }
    } catch (Exception e) {
            System.out.println( e.getMessage());
    } finally {
       // 关闭用到的资源
           fos.close();
           rs.close();
           pstmt.close();
           conn.close();
    }
    }
    public static void main(String[] args) {
        if (!args[0].equals(null))
        {
            try {
               GetImg gi=new GetImg();
               gi.blobRead(args[0], 1);
            } catch (Exception e) {
                System.out.println("[Main func error: ]" + e.getMessage());
            }
        }   
        else{
            System.out.println("Warnning: Please type your store path and filename!");
        }
    }
}





JAVA从数据库读取图片数据并保存到本地的方法
                                      

//从数据表tablepicture中读字段picture

Sql="Select picture From tablepicture"；
Rs = Stmt.executeQuery(Sql);
while (Rs.next())
{
   java.io.InputStream long_out = Rs.getBinaryStream("Picture");
    if (long_out != null)
     {
      byte[] long_buf=new byte[8192];
      int len=0;
      java.io.FileOutputStream long_file = new java.io.FileOutputStream("E:/tomcatx/webapps/ROOT/upfile/instrumentimages/"+Rs.getString("pictureid")+".jpg");
       while((len = long_out.read(long_buf))>0)
       long_file.write(long_buf,0,len);
       long_file.close();
       long_out.close();
       }
      }
  Rs.close();