用JDBC访问大段文本数据

用JDBC访问大段文本数据

 

public class ClobTest {	
	public static void main(String[] args) throws SQLException, IOException, ClassNotFoundException {
		//  create();
		read(); 
	}

	// 从数据库读取大段文本数据，并写入JdbcTest_bak.java文件中
	static void read() throws SQLException, IOException, ClassNotFoundException {
		Connection conn = null;
		PreparedStatement ps = null; 
		ResultSet rs = null;		
		
		try {
			// 1.加载驱动
			Class.forName("com.mysql.jdbc.Driver"); 
			
			// 2.建立连接
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc", "root", "123456");
			
			// 3.创建语句
			ps = conn.prepareStatement("select big_text from clob_test");

			// 4.执行语句
			rs = ps.executeQuery();

			// 5.处理结果
			while (rs.next()) {
				Clob clob = rs.getClob(1); 
				Reader reader = clob.getCharacterStream();

				File file = new File("JdbcTest_bak.java");
				Writer writer = new BufferedWriter(new FileWriter(file));
				char[] buff = new char[1024];				
				for (int i = 0; (i = reader.read(buff)) > 0;) {
					writer.write(buff, 0, i);
				}
				
				writer.close();
				reader.close();
			}
		} finally {
			if(rs != null) rs.close(); rs = null;
			if(ps != null) ps.close(); ps = null;
			if(conn != null) conn.close(); conn = null;
		}
	}	
	
	// 往数据库添加大段文本数据(ClobTest.java文件)
	static void create() throws SQLException, IOException, ClassNotFoundException {
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		
		try {
			// 1.加载驱动
			Class.forName("com.mysql.jdbc.Driver"); 
			
			// 2.建立连接
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc", "root", "123456");
			
			// 3.创建语句
			String sql = "insert into clob_test(big_text) values (?) ";
			ps = conn.prepareStatement(sql);
			
			File file = new File("src/com/jdbc/ClobTest.java");
			Reader reader = new BufferedReader(new FileReader(file));
			
			ps.setCharacterStream(1, reader, (int) file.length());
			
			// 4.执行语句
			int i = ps.executeUpdate();
			reader.close();

			System.out.println("i=" + i);
		} finally {
			if(rs != null) rs.close(); rs = null;
			if(ps != null) ps.close(); ps = null;
			if(conn != null) conn.close(); conn = null;
		}
	}
}