blob java_java对blob操作

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.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

import oracle.jdbc.driver.OracleResultSet;

import oracle.sql.BLOB;

/**

* 本类是对oracle数据库进行增删改查操作

* @author LoongHua

*

*/

public class OperateBlobDao {

private Connection conn;

public static Connection getConnection(){

Connection conn=null;

try {

Class.forName("oracle.jdbc.OracleDriver");

conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.6:1521:findata","system","123456");

} catch (Exception e) {

System.out.println("得到数据库连接发生异常");

e.printStackTrace();

}

return conn;

}

public OperateBlobDao(Connection conn){

this.conn=conn;

}

/**

* 想数据中插入一个2进制文章，如图片

* @param fileName 文件名

* @param filePath 文件路径

* @return 是否插入成功

*/

public boolean insert(String fileName, String filePath) {

if(conn==null){

return false;

}

Statement stmt = null;

ResultSet rs = null;

InputStream is = null;

OutputStream os = null;

String query = null;

try {

conn.setAutoCommit(false);

stmt = conn.createStatement();

/*

* 插入所有的数据，插入BLOB字段的列是使用函数empty_blob()，这样系统会创建一个本地化的BLOB数据类型。

*/

query = "insert into aaa(id,name,photo) values (aaa_id.nextval,'"+fileName+"', empty_blob())";

stmt.executeUpdate(query);

/*

*得到刚才插入的记录

*/

query = "select * from aaa where id=(select max(id) from aaa)";

rs = stmt.executeQuery(query);

if (rs.next()) {

// 向BLOB类型变量里插入数据

BLOB blob = ((OracleResultSet)rs).getBLOB("photo");

os = blob.getBinaryOutputStream();

File f = new File(filePath);

is = new FileInputStream(f);

byte[] buffer = new byte[blob.getBufferSize()];

int bytesRead = 0;

while ((bytesRead = is.read(buffer)) != -1) {

os.write(buffer, 0, bytesRead);    }

os.flush();

//清空blob类型

blob = null;

return true;

}

}

catch(Exception e) {

e.printStackTrace();

}

finally {

try {

if(is != null) {

is.close();

}

if(os != null) {

os.close();

}

if(stmt != null) {

stmt.close();

}

if(rs != null) {

rs.close();

}

if(conn != null) {

conn.commit();

}

}

catch(Exception e) {

e.printStackTrace();

}

}

return false;

}

/**

* 用指定的包含文件名的文件路径替换指定名称的文件

* @param fileName 文件名

* @param filePath 包含文件名的文件路径

* @return 是否成功，成功为true，否则为false

*/

public boolean update(String fileName, String filePath){

if(conn==null){

return false;

}

Statement stmt = null;

ResultSet rs = null;

InputStream is = null;

OutputStream os = null;

String query = null;

try {

conn.setAutoCommit(false);

stmt = conn.createStatement();

//记得这里一定要加上 for update 不然会报 blob未锁定错误

/*

* 当然也可以用别的方法更新，比如可以先设置photo字段为empty_blob()

* 然后在向blob插入新的数据，就象对clob操作那篇博客那样做也是可以的。

*/

query="select * from aaa where name='"+fileName+"' for update";

rs=stmt.executeQuery(query);

if(rs.next()){

BLOB blob = ((OracleResultSet) rs).getBLOB("photo");

File f = new File(filePath);

is = new FileInputStream(f);

byte[] buffer=new byte[blob.getBufferSize()];

os = blob.getBinaryOutputStream();

int bytesRead = 0;

while((bytesRead=is.read(buffer))!=-1){

os.write(buffer, 0, bytesRead);    }

os.flush();

blob=null;

return true;

}

}catch(Exception e){

e.printStackTrace();

}

finally{

try {

if(is!=null){

is.close();

}

if(os!=null){

os.close();

}

if(stmt==null){

stmt.close();

}

if(conn!=null){

conn.commit();

}

} catch (Exception e) {

e.printStackTrace();

}

}

return false;

}

/**

* 查询指定文件名的一张图片，如果存在则保存到本机的D盘下

* @param fileName 文件名

* @param filePath 包含文件名的文件路径

*/

public void select(String fileName,String filePath){

if(conn==null){

return ;

}

Statement stmt = null;

ResultSet rs = null;

InputStream is = null;

OutputStream os = null;

String query = null;

try {

conn.setAutoCommit(false);

stmt = conn.createStatement();

query="select * from aaa where name='"+fileName+"'";

rs=stmt.executeQuery(query);

if(rs.next()){

BLOB blob = ((OracleResultSet) rs).getBLOB("photo");

File f = new File(filePath);

os = new FileOutputStream(f);

byte[] buffer=new byte[blob.getBufferSize()];

is = blob.getBinaryStream();

int bytesRead = 0;

while((bytesRead=is.read(buffer))!=-1){

os.write(buffer, 0, bytesRead);    }

os.flush();

blob=null;

}

}catch(Exception e){

e.printStackTrace();

}

finally{

try {

if(is!=null){

is.close();

}

if(os!=null){

os.close();

}

if(stmt==null){

stmt.close();

}

if(conn!=null){

conn.setAutoCommit(true);

}

} catch (Exception e) {

e.printStackTrace();

}

}

}

/**

* 删除指定的文件名的文件

* @param fileName 指定的文件名

* @return 是否成功，成功为true，否则为false

*/

public boolean delete(String fileName){

if(conn==null){

return false;

}

Statement stmt = null;

String query = null;

try {

conn.setAutoCommit(false);

stmt = conn.createStatement();

query="delete from aaa where name='"+fileName+"'";

int row=stmt.executeUpdate(query);

if(row>0){

return true;

}

}catch(Exception e){

e.printStackTrace();

}

finally{

try {

if(stmt==null){

stmt.close();

}

if(conn!=null){

conn.close();

}

} catch (Exception e) {

e.printStackTrace();

}

}

return false;

}

/**

* 关闭数据库

*/

public void close(){

try {

if(conn!=null){

conn.close();

}

} catch (Exception e) {

e.printStackTrace();

}

}

public static void main(String[] args) {

Connection conn=getConnection();

OperateBlobDao obdao=new OperateBlobDao(conn);

//  boolean flag=obdao.insert("123.JPG", "d:/123.JPG");

//  if(flag){

//   System.out.println("插入成功！");

//  }

//  obdao.select("123.JPG", "d:/123.JPG");

//  boolean flag=obdao.delete("123.JPG");

//  if(flag){

//   System.out.println("删除成功！");

//  }

boolean flag=obdao.update("xxgz.pdf", "d:/123.JPG");

if(flag){

System.out.println("更新成功！");

}

obdao.close();

}

}