用jdbc访问二进制类型的数据

jhlishero

1、创建数据表（MYSQL数据库）
create table big_blob (     id int(10),      blob_txt blob); 
2、JdbcUtils工具类
package com.sunrex;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;/** * 东南西北风 * @author Administrator * */public final class JdbcUtils {private static Connection conn = null;/* 访问数据库的url*/private final static String DATABASE_URL = "jdbc:mysql://localhost:3306/study?useUnicode=true&characterEncoding=UTF8";private final static String DATABASE_USERNAME = "root";private final static String DATABASE_PASSWORD = "root";static {try {Class.forName("com.mysql.jdbc.Driver");conn = DriverManager.getConnection(DATABASE_URL, DATABASE_USERNAME, DATABASE_PASSWORD);} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}}private JdbcUtils(){}public static Connection getConnection() {return conn;}public static void close(Connection conn, Statement stmt, ResultSet rs) {try {if(rs!=null) rs.close();} catch (SQLException e) {e.printStackTrace();} finally {try {if(stmt!=null)stmt.close();} catch (SQLException e) {e.printStackTrace();} finally {try {if(conn!=null) conn.close();} catch (SQLException e) {e.printStackTrace();}}}}} 
3、二进制文件操作类
package com.sunrex.demo06;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;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.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import com.sunrex.JdbcUtils;/** * 用jdbc访问二进制类型的数据 * 在数据库中，经常需要用到大字段类型， * 如oracle中long/blob/clob, * sqlserver中text/image， * mysql中的text/longtext/clob/blob。  */public class BlobTest {public static void main(String[] args) throws Exception {//insert();read(1);}/** * 添加数据 * @throws Exception */public static void insert() throws Exception {Connection conn = null;PreparedStatement pstmt = null;ResultSet rs = null;try {conn = JdbcUtils.getConnection();//---注意：如果数据库中设置的是blob类型字段，二进制的最大容量不能超过64KString sql = "insert into big_blob (id, blob_txt) values (?, ?)";pstmt = conn.prepareStatement(sql);pstmt.setInt(1, 1);//使用字节流，读取文本信息File file = new File("blob.jpg");InputStream is = new BufferedInputStream(new FileInputStream(file));pstmt.setBinaryStream(2, is, (int)file.length());//填充二进制流is.close();pstmt.executeUpdate();} finally {JdbcUtils.close(conn, pstmt, rs);}}/** * 读取数据 * @param id */private static void read(int id) throws Exception {Connection conn = null;PreparedStatement pstmt = null;ResultSet rs = null;try {conn = JdbcUtils.getConnection();//---注意：如果数据库中设置的是blob类型字段，二进制的最大容量不能超过64KString sql = "select blob_txt from big_blob where id=?";pstmt = conn.prepareStatement(sql);pstmt.setInt(1, id);rs =pstmt.executeQuery();while(rs.next()) {////读取方法一：//Blob blob = rs.getBlob("blob_txt");//InputStream is = blob.getBinaryStream();//输入流//读取的方法二：InputStream is = rs.getBinaryStream("blob_txt");byte[] bytes = new byte[1024];//输出流File file = new File("blob_bak.jpg");OutputStream os = new BufferedOutputStream(new FileOutputStream(file));for(int i=0; (i=is.read(bytes))>0;) {os.write(bytes, 0, i);}os.close();is.close();}} finally {JdbcUtils.close(conn, pstmt, rs);}}}