1、导入dmdbms/drivers/jdbc下面的驱动包,根据jdk选择

2、代码如下
更新

import java.io.*;
import java.sql.*;
import dm.jdbc.*;

public class ClobReplace {
	public static void main(String args[]){
		// 定义 DM JDBC 驱动串
	     String jdbcString = "dm.jdbc.driver.DmDriver";
	    // 定义 DM URL 连接串
	     String urlString = "jdbc:dm://localhost:5236";
	    // 定义连接用户名
	     String userName = "SYSDBA";
	    // 定义连接用户口令
	     String password = "SYSDBA";
	    // 定义连接对象
	     Connection conn = null;
	    // 定义 SQL 语句执行对象
	     PreparedStatement pstate = null;

	        try {
	            //1.加载 JDBC 驱动程序
	            System.out.println("Loading JDBC Driver...");
	            Class.forName(jdbcString);
	            //2.连接 DM 数据库
	            System.out.println("Connecting to DM Server...");
	            conn = DriverManager.getConnection(urlString, userName, password);
	//------------------------------------------------------------------------------------------
	            //1.修改大字段信息:  
	            String sql_insert = "update TEST_BIG_DATA set txt=? where id=1;";
	            pstate = conn.prepareStatement(sql_insert);
	            //加载图片为输入流
	            String filePath = "D:\\1.jpg";
	            File file = new File(filePath);
	            String filePath2 = "D:\\新建文本文档.txt";
	            File file2 = new File(filePath2);
	            InputStream in = new BufferedInputStream(new FileInputStream(file));
	            InputStream in2 = new BufferedInputStream(new FileInputStream(file));
	            BufferedReader reader = new BufferedReader(
	                new InputStreamReader(new FileInputStream(file2),"UTF-8"));
	            pstate.setClob(1, reader);
	            pstate.executeUpdate();
	//-------------------------------------------------------------------------------------------
	        } catch (ClassNotFoundException e) {
	            e.printStackTrace();
	        } catch (SQLException e) {
	            e.printStackTrace();
	        } catch (FileNotFoundException e) {
	            e.printStackTrace();
	        } catch (UnsupportedEncodingException e) {
	            e.printStackTrace();
	        } finally {
	            try {
	                pstate.close();
	                conn.close();
	            } catch (SQLException e) {
	                e.printStackTrace();
	            }
	        }
	    }

	}

插入

import java.sql.*;
import dm.jdbc.*;
import java.io.*;

public class TestClob{

public void TestClob(){}

public static void main(String args[]){
	// 定义 DM JDBC 驱动串
     String jdbcString = "dm.jdbc.driver.DmDriver";
    // 定义 DM URL 连接串
     String urlString = "jdbc:dm://localhost:5236";
    // 定义连接用户名
     String userName = "SYSDBA";
    // 定义连接用户口令
     String password = "SYSDBA";
    // 定义连接对象
     Connection conn = null;
    // 定义 SQL 语句执行对象
     PreparedStatement pstate = null;

        try {
            //1.加载 JDBC 驱动程序
            System.out.println("Loading JDBC Driver...");
            Class.forName(jdbcString);
            //2.连接 DM 数据库
            System.out.println("Connecting to DM Server...");
            conn = DriverManager.getConnection(urlString, userName, password);
//------------------------------------------------------------------------------------------
            //1.插入大字段信息:  
            String sql_insert = "INSERT INTO TEST_BIG_DATA (\"photo\","
                + "\"describe\",\"txt\")VALUES(?,?,?);";
            pstate = conn.prepareStatement(sql_insert);
            //加载图片为输入流
            String filePath = "D:\\DM8特点.jpg";
            File file = new File(filePath);
            String filePath2 = "D:\\达梦产品简介.txt";
            File file2 = new File(filePath2);
            InputStream in = new BufferedInputStream(new FileInputStream(file));
            InputStream in2 = new BufferedInputStream(new FileInputStream(file));
            BufferedReader reader = new BufferedReader(
                new InputStreamReader(new FileInputStream(file2),"UTF-8"));
            //1.绑定 stream 流信息到第一个?
            pstate.setBinaryStream(1, in);
            //2.绑定 Inputstream 对象到第二个?这里
            pstate.setBlob(2, in2);
            //3.绑定 Reader 对象到第三个?
            pstate.setClob(3, reader);
            pstate.executeUpdate();
//-------------------------------------------------------------------------------------------
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } finally {
            try {
                pstate.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}

查询

import java.io.*;
import java.sql.*;
import dm.jdbc.*;

public class ReadClob{


public static void main(String args[]){

try{

	Class.forName("dm.jdbc.driver.DmDriver"); 
	//创建数据库连接
	Connection conn = DriverManager.getConnection("jdbc:dm://127.0.0.1:5236/DMSERVER","SYSDBA", "SYSDBA");
	//创建statement对象
	Statement stat = conn.createStatement();

	boolean defaultCommit = conn.getAutoCommit();
	conn.setAutoCommit(false);
	String sql1="select content from NEWS";
	PreparedStatement ps1=conn.prepareStatement(sql1);

	ResultSet rs1=ps1.executeQuery();

while (rs1.next()){

		Clob clob=rs1.getClob(1);

BufferedReader in=new BufferedReader(clob.getCharacterStream());

StringWriter out=new StringWriter();

int c;

while((c=in.read())!=-1){

out.write(c);

}

String content=out.toString();

System.out.println (content);//输出CLOB内容 }

} 


}catch(Exception e){e.printStackTrace();

}
}
}

详细文档可参考：https://eco.dameng.com/docs/zh-cn/start/index.html