Java 存储和读取 oracle CLOB 类型字段的实用方法

Posted 2020-08-11

 

package oracle.clob; 

import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileReader; 
import java.io.IOException; 
import java.io.Reader; 
import java.io.StringReader; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import oracle.jdbc.driver.OracleDriver; 
import oracle.sql.CLOB; 

public class ClobTest { 
    String url = "jdbc:oracle:thin:@192.168.2.157:1521:orcl"; 
    String user = "xj"; 
    String pwd = "xj"; 
    String text = "这是要插入到CLOB里面的数据"; 

    
    private void clobImport() throws ClassNotFoundException, SQLException { 
        // TODO Auto-generated method stub 
        DriverManager.registerDriver(new OracleDriver()); 
        Connection conn = DriverManager.getConnection(url, user, pwd);// 得到连接对象 
        String sql = "insert into clob_test(id,str) values (‘1‘,?)";// 要执行的SQL语句 

        PreparedStatement stmt = conn.prepareStatement(sql);// 加载SQL语句 
        // PreparedStatement支持SQL带有问号？，可以动态替换？的内容。 
        Reader clobReader = new StringReader(text); // 将 text转成流形式 
        stmt.setCharacterStream(1, clobReader, text.length());// 替换sql语句中的？ 
        int num = stmt.executeUpdate();// 执行SQL 
        if (num > 0) { 
            System.out.println("ok"); 
        } else { 
            System.out.println("NO"); 
        } 
        stmt.close(); 
        conn.close(); 
    } 

    private void clobExport() throws ClassNotFoundException, SQLException, 
            IOException { 
        // TODO Auto-generated method stub 
        CLOB clob = null; 
        String sql = "select * from clob_test where id=1"; 
        DriverManager.registerDriver(new OracleDriver()); 
        Connection conn = DriverManager.getConnection(url, user, pwd);// 得到连接对象 
        PreparedStatement stmt = conn.prepareStatement(sql); 
        ResultSet rs = stmt.executeQuery(); 
        String id = ""; 
        String content = ""; 
        if (rs.next()) { 
            id = rs.getString("id");// 获得ID 
            clob = (oracle.sql.CLOB) rs.getClob("str"); // 获得CLOB字段str 
            // 注释： 用 rs.getString("str")无法得到 数据 ，返回的 是 NULL; 
            content = ClobToString(clob); 
        } 
        stmt.close(); 
        conn.close(); 
        // 输出结果 
        System.out.println(id); 
        System.out.println(content); 
    } 

    // 将字CLOB转成STRING类型 
    public String ClobToString(CLOB clob) throws SQLException, IOException { 

        String reString = ""; 
        Reader is = clob.getCharacterStream();// 得到流 
        BufferedReader br = new BufferedReader(is); 
        String s = br.readLine(); 
        StringBuffer sb = new StringBuffer(); 
        while (s != null) {// 执行循环将字符串全部取出付值给StringBuffer由StringBuffer转成STRING 
            sb.append(s); 
            s = br.readLine(); 
        } 
        reString = sb.toString(); 
        return reString; 
    } 

    
    // TODO Auto-generated method stub 
    public static void main(String[] args) throws IOException, 
            ClassNotFoundException, SQLException { 
        // TODO Auto-generated method stub 
        ClobTest clobtest = new ClobTest(); 
        // read file 
        FileReader _frd = new FileReader(new File("D:\\DOS.txt")); 
        BufferedReader _brd = new BufferedReader(_frd); 
        String _rs = _brd.readLine(); 
        StringBuffer _input = new StringBuffer(); 
        while (_rs != null) { 
            _input.append(_rs); 
            _rs = _brd.readLine(); 
        } 
        // System.out.println(_input.toString()); 
        // 输入测试 
        clobtest.text = _input.toString(); 
        clobtest.clobImport(); 
        // 输出测试 
        // clobtest.clobExport(); 
    } 

}