Java 从oracle 11g xe获取Blob文件时创建的空文件

下面给出了两个程序

1> 将blob文件存储到数据库中

及

2> 从数据库检索blob文件

1。将blob文件存储到数据库中

package jdbc;

import java.net.URL;
import java.sql.*;
import java.io.*;
import java.util.Properties;



public class Storing_Image {

public static void main(String[] args) throws Exception{

    Properties p = new Properties();
    p.put("user", "system");
    p.put("password", "password");

    URL url = Storing_Clob.class.getResource("/images/bunny.jpg");
    File file = new File(url.toURI());
    FileInputStream fis = new FileInputStream(file);

    DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

    Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe",p);

    PreparedStatement pstmt = con.prepareStatement("insert into myblob(BLOB_FILE) values(?)");

 pstmt.setBinaryStream(1, fis, (byte)file.length());

    System.out.println("Length of string: "+file.length());
    System.out.println("No of rows affected: "+pstmt.executeUpdate());
    con.close();
}
}

import java.sql.*;
import java.util.Properties;
import java.io.*;

public class Retrieving_Image {

public static void main(String[] args) throws Exception{

    Properties p = new Properties();
    p.put("user", "system");
    p.put("password", "password");

    DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
    Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe",p);

    PreparedStatement pstmt = con.prepareStatement("select BLOB_FILE from myblob",ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);

    ResultSet rs = pstmt.executeQuery();

    rs.first();

        InputStream is = rs.getBinaryStream(1);

    FileOutputStream fos = new FileOutputStream("H:/result1.jpg");


    while(((byte) is.read())!=-1)
    {
        fos.write((byte) is.read());
    }

    fos.close();
    con.close();
 }
}

myblob表只有一个Blob数据类型的列

插入表后，我执行以下命令：-

select * from myblob;

它给出了以下输出：-

我猜这是表中图片的字节值

2.从数据库检索Blob文件（图像）

package jdbc;

import java.net.URL;
import java.sql.*;
import java.io.*;
import java.util.Properties;



public class Storing_Image {

public static void main(String[] args) throws Exception{

    Properties p = new Properties();
    p.put("user", "system");
    p.put("password", "password");

    URL url = Storing_Clob.class.getResource("/images/bunny.jpg");
    File file = new File(url.toURI());
    FileInputStream fis = new FileInputStream(file);

    DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

    Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe",p);

    PreparedStatement pstmt = con.prepareStatement("insert into myblob(BLOB_FILE) values(?)");

 pstmt.setBinaryStream(1, fis, (byte)file.length());

    System.out.println("Length of string: "+file.length());
    System.out.println("No of rows affected: "+pstmt.executeUpdate());
    con.close();
}
}

import java.sql.*;
import java.util.Properties;
import java.io.*;

public class Retrieving_Image {

public static void main(String[] args) throws Exception{

    Properties p = new Properties();
    p.put("user", "system");
    p.put("password", "password");

    DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
    Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe",p);

    PreparedStatement pstmt = con.prepareStatement("select BLOB_FILE from myblob",ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);

    ResultSet rs = pstmt.executeQuery();

    rs.first();

        InputStream is = rs.getBinaryStream(1);

    FileOutputStream fos = new FileOutputStream("H:/result1.jpg");


    while(((byte) is.read())!=-1)
    {
        fos.write((byte) is.read());
    }

    fos.close();
    con.close();
 }
}

这将提供以下输出：-

正如您所看到的，这是一个空白图像，即0kb。

---

我正在使用Oracle11gXe和ojdbc6_g.jar驱动程序

你试过fos.flush（）吗；关闭前？@ThrashBean是的。它不会改变任何东西。您是否进行了一些调试并检查while循环是否已执行或

is.read（）

是否在第一次读取时停止？再看看@bellabax我做了如下工作：

int counter=0；while（（is.read（））！=-1）{System.out.println（“计数器是：+（++计数器））；fos.write（（字节）是.read（））；}

它给我以下输出：-

计数器是：1计数器是：2计数器是：3计数器是：4计数器是：5计数器是：6计数器是：7计数器是：8计数器是：9计数器是：10

请用我提供的sql cmd输出图像告诉它。thnks。