JDBC

JDBCUtils类中来实现:

public class JDBCUtils {
    
    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;
    
    //加载驱动
    static{
        try {
                        //db.properties是一个配置文件，里面有连接数据库所需要的信息
            InputStream in = JDBCUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties prop = new Properties();    
            prop.load(in);//加载配置文件
            driver = prop.getProperty("driver");
            url = prop.getProperty("url");
            username = prop.getProperty("username");
            password = prop.getProperty("password");
            
            Class.forName(driver);//加载驱动
            
        } catch (Exception e) {
            throw new ExceptionInInitializerError(e);
        }
    }
    
    public static Connection getConnection() throws SQLException{
                
        return DriverManager.getConnection(url, username, password);//获得connection
    }
    
    public static void release(Connection conn, Statement st, ResultSet rs){ //释放资源
        
        if(rs != null){
            try{
                rs.close();
            }catch(Exception e) {
                e.printStackTrace();
            }
            rs = null;
        }
        if(st != null){
            try{
                st.close();
            }catch(Exception e) {
                e.printStackTrace();
            }
            st = null;
        }
        
        if(conn != null){
            try{
                conn.close();
            }catch(Exception e) {
                e.printStackTrace();
            }
            conn = null;
        }    
    }
 
}

JDBC处理大文本
        在MySQL中，大文本是text类型，使用java操作数据库中的大文本需要两个方法setCharacterStream和getCharacterStream，一个是写入数据库的字符流，一个是从数据库中读取的字符流。setCharacterStream(index,Reader,length)有三个参数，Reader表示获取文件的流，length表示文件的长度，index表示参数的索引
        建立数据库

create database test;
use test;
create table testclob
(
   id int primary key auto_increment,
   resume text
);

public class Demo1 {
    
    @Test//向数据库中插入一个文本
    public void add() throws FileNotFoundException {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;
        
        try {
            conn = JDBCUtils.getConnection();  //使用上一节中的JDBCUtils
            String sql = "insert into testclob(resume) values(?)";
            st = conn.prepareStatement(sql); //预处理sql语句
 
            String path = Demo1.class.getClassLoader().getResource("1.txt").getPath();//在工程src目录下存放一个1.txt文件
            File file = new File(path); 
            st.setCharacterStream(1, new FileReader(file), file.length());
            int num = st.executeUpdate(); //执行向数据库中插入
            if(num > 0) {
                System.out.println("插入成功");
            } 
        } catch (SQLException e) {        
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn, st, rs);
        }
    }
    
    @Test //从数据库中读取文本
    public void read() throws IOException {
        Connection conn = null;
        PreparedStatement st = null;
        ResultSet rs = null;
        try {
            conn = JDBCUtils.getConnection();
            String sql = "select resume from testclob where id=?";
            st = conn.prepareStatement(sql);
            st.setInt(1, 1);
            rs = st.executeQuery(); //执行sql语句
            if(rs.next()){
                Reader reader = rs.getCharacterStream("resume"); //获取字段未resume的项，也就是我们刚刚存到数据库的1.txt文件
                char buffer[] = new char[1024];
                int len = 0;
                FileWriter out = new FileWriter("D:\\1.txt"); //写到D盘下
                while((len = reader.read(buffer)) > 0){
                    out.write(buffer, 0, len);
                }
                out.close();
                reader.close();
            }
        } catch (SQLException e) {        
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn, st, rs);
        }
    }
 
}

 

参考：

https://blog.csdn.net/eson_15/article/details/51317001