blob与string类型的相互转换——把stringlexington的数据存进oracle的blob字段中

<div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;">【概述】 <wbr style="word-wrap: break-word;"></wbr></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"><br style="word-wrap: break-word;" /></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"> <wbr style="word-wrap: break-word;">  <wbr style="word-wrap: break-word;"> Oracle的Blob字段比较特殊，他比long字段的性能要好很多，可以用来保存例如图片之类的二进制数据。 <wbr style="word-wrap: break-word;"></wbr></wbr></wbr></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"><br style="word-wrap: break-word;" /></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;">写入Blob字段和写入其它类型字段的方式非常不同，因为Blob自身有一个cursor，你必须使用cursor对 <wbr style="word-wrap: break-word;"></wbr></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"><br style="word-wrap: break-word;" /></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;">blob进行操作，因而你在写入Blob之前，必须获得cursor才能进行写入，那么如何获得Blob的cursor呢？ <wbr style="word-wrap: break-word;"></wbr></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"><br style="word-wrap: break-word;" /></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;">这需要你先插入一个empty的blob，这将创建一个blob的cursor，然后你再把这个empty的blob的cursor <wbr style="word-wrap: break-word;"></wbr></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;"><br style="word-wrap: break-word;" /></span></div><div style="word-wrap: break-word; color: rgb(102, 102, 102); font-family: 宋体, Arial; line-height: 26px;"><span style="font-size:18px;">用select查询出来，这样通过两步操作，你就获得了blob的cursor，可以真正地写入blob数据了。 </span></div>

<pre name="code" class="java">package com.coci.test2;import java.io.OutputStream;import java.io.UnsupportedEncodingException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.Statement;import oracle.sql.BLOB;/** *  * @author Coci * */public class TestBlob {public static void main(String[] args) {// blob内存放的是字节数组// String 的getBytes方法获得该字符串的字节数组(注意编码)，然后存入blob即可String blobStr = "blob";byte[] bytes = null;try {bytes = blobStr.getBytes("utf-8");System.out.println("===" + bytes);} catch (UnsupportedEncodingException e) {e.printStackTrace();}instertData(bytes);// 从数据库中读取Blob类型数据后，要转换成String类型，即转换成InputStream，再从InputStream转成byte[]，再到String即可。// blob转换成String//String result = "";//try {//ByteArrayInputStream msgContent = (ByteArrayInputStream) blob//.getBinaryStream();//byte[] byte_data = new byte[msgContent.available()];//msgContent.read(byte_data, 0, byte_data.length);//result = new String(byte_data);//} catch (SQLException e) {//e.printStackTrace();//}}@SuppressWarnings("deprecation")public static void instertData(byte[] value) {// TODO Auto-generated method stubtry {Class.forName("oracle.jdbc.driver.OracleDriver");String url = "jdbc:oracle:thin:@10.211.19.71:1521:orcl";String username = "yst";String password = "yst";Connection con = DriverManager.getConnection(url, username,password);con.setAutoCommit(false);String sql1 = "insert into testcoci(id,name) values('88',empty_blob())";Statement statement = con.createStatement();boolean b2 = statement.execute(sql1);System.out.println("第一次===" + b2);String sql2 = "select name from testcoci where id=88 for update";PreparedStatement stmt = con.prepareStatement(sql2);ResultSet rs = stmt.executeQuery();OutputStream outStream = null;if (rs.next()) {System.out.println("进来了");BLOB blob = (BLOB) rs.getBlob(1);System.out.println("数据库  blob =" + blob + "=");outStream = blob.getBinaryOutputStream();outStream.write(value, 0, value.length);}outStream.flush();outStream.close();con.commit();con.close();} catch (Exception e) {System.out.println(e.getCause());}}}

<span style="font-size:18px;">这篇博客写的很详细：</span>

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