读取/更新Oracle数据库blob字段代码,Java代码库,德仔网

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【Java】读取/更新Oracle数据库blob字段

作者:瑞祺 / 发布于2017/3/29/ 592

1. 读取BLOB字段
import oracle.sql.BLOB;
ResultSet rs = ps.executeQuery(sql);
BLOB blob = (BLOB) rs.getBlob("content");
String s = blobToString(blob);

2. blobToString()方法
private String blobToString(BLOB blob) throws SQLException, UnsupportedEncodingException {
        long BlobLength; // BLOB字段长度
        int i = 1; // 循环变量
        byte[] bytes; // BLOB临时存储字节数组
        String newStr = ""; // 返回字符串

        byte[] msgContent = blob.getBytes(); // BLOB转换为字节数组
        BlobLength = blob.length();  //获取BLOB长度  
        if (msgContent == null || BlobLength == 0) //如果为空，返回空值  
        {
            return "";
        } else {
            while (i <= BlobLength) //循环处理字符串转换，每次1024；Oracle字符串限制最大4k 
            {
                bytes = blob.getBytes(i, 1024);
                i = i + 1024;
                newStr = newStr + new String(bytes);
            }
        }
        return newStr;
    }
3. update BLOB字段
    public void insertData(String task_name, String tast_target) {
        int num = 0;
        String hql = "insert into table values(sequence_id.nextval,?,EMPTY_BLOB()) returning id into ?";

        try {
            Connection conn = GlobalData.getConnection();
            OraclePreparedStatement ops = (OraclePreparedStatement) conn.prepareStatement(hql);
            ops.setString(1, task_name);
            ops.registerReturnParameter(2, OracleTypes.NUMBER);

            num = ops.executeUpdate();
            ResultSet rset = ops.getReturnResultSet(); // rest is not null
            long id = 0;
            while (rset.next()) {
                id = rset.getLong(1);
                System.out.println("Insert returnning: " + id);
            }

            //更新blob字段
            Statement bst = conn.createStatement();
            ResultSet bset = bst.executeQuery("select tast_target from table  where id=" + id + " FOR UPDATE");

            BLOB blob = null;
            while (bset.next()) {
                blob = ((OracleResultSet) bset).getBLOB(1);
            }
            final java.io.BufferedOutputStream out = new java.io.BufferedOutputStream(blob.getBinaryOutputStream());//输出流
            ByteArrayInputStream streamTemp = null;//输入流
            try {
                streamTemp = new ByteArrayInputStream(tast_target.getBytes("ISO-8859-1"));
            

} catch (UnsupportedEncodingException ex) {
                Logger.getLogger(OracleGenelDaoImpl.class  

.getName()).log(Level.SEVERE, null, ex);
            }

            byte[] buffer = new byte[1024];//缓冲区

            int length = -1;
            try {
                while ((length = streamTemp.read(buffer)) != -1) {
                    out.write(buffer, 0, length);
                }
                streamTemp.close();
                out.close();
            

} catch (IOException ex) {
                Logger.getLogger(OracleGenelDaoImpl.class  

.getName()).log(Level.SEVERE, null, ex);
            }
            conn.commit();
            ops.close();
            bst.close();
        

} catch (SQLException ex) {
            Logger.getLogger(OracleGenelDaoImpl.class  

.getName()).log(Level.SEVERE, null, ex);
        }
    }

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