1.在mysq的mydatabasel數據庫中建立一張表
use database;
create table if not exists my_clob_test(
id int primary key auto_increment,
big_text text not null
)charset utf8;
2. 工具類(jdbc鏈接過程代碼)
(1)註冊驅動
(2)創建鏈接
(3)釋放資源
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mysql.jdbc.Statement;
public final class JdbcUtils {
private static String url = "jdbc:mysql://localhost:3306/mydatabase";
private static String user = "root";
private static String password = "123";
private JdbcUtils() {
}
/**
* 註冊驅動
*/
static {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
/**
* 創建鏈接
*
* @return
*/
public static Connection getConnection() {
Connection conn = null;
try {
conn = (Connection) DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
/**
* 釋放資源
*
* @param rs
* @param st
* @param conn
*/
public static void free(ResultSet rs, Statement st, Connection conn) {
// 釋放ResultSet
try {
if (rs != null)
rs.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
// 釋放Statement
try {
if (st != null)
st.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
// 釋放Connection
try {
if (conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
3.運行下面的函數create()向數據庫中插入一條文本數據
/**
* 寫數據到表中
* @param name
* @param birthday
* @param money
* @throws IOException
*/
static void create() throws IOException {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
// 2.創建鏈接
conn = (Connection) JdbcUtils.getConnection();
// 3.建立語句
String sql = "insert into my_clob_test(big_text) values(?)";
ps = (PreparedStatement) conn.prepareStatement(sql);
//將該目錄下的文件內容寫到數據庫的my_clob_test表中
File file = new File("src/cn/itcast/jdbc/JdbcUtilsSing.java");
Reader reader = new BufferedReader(new FileReader(file));
//將「?」代替成數據流
ps.setCharacterStream(1,reader,file.length());
// 4.執行語句
int i = ps.executeUpdate();
reader.close();
System.out.println("i=" + i);
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtils.free(rs, ps, conn); // 關閉資源
}
}
4.運行下面函數read()讀取數據庫中的文本數據,而後將內容寫到當前目錄的copy.java文件中
/**
* 讀取text數據
* @throws IOException
*/
static void read() throws IOException {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
// 2.創建鏈接
conn = (Connection) JdbcUtils.getConnection();
// 3.建立語句
String sql = "select big_text from my_clob_test";
ps = (PreparedStatement) conn.prepareStatement(sql);
// 4.執行語句
rs = ps.executeQuery();
//5.處理結果
while(rs.next()){
// Clob clob = rs.getClob(1);
//Reader reader = clob.getCharacterStream();
//以上兩句語句可使用下面一句代碼代替
Reader reader = rs.getCharacterStream(1);
//封裝數據源
File file = new File("copy.java");
//建立寫數據流
Writer writer =new BufferedWriter(new FileWriter(file));
//建立緩存區
char[] buff = new char[1024];
//讀寫數據方式1
int len=0;
while((len = reader.read(buff))>0){
writer.write(buff,0,len);
}
//讀寫數據方式2
// for(int i = 0;(i = reader.read(buff))>0;){
// writer.write(buff,0,i);
// }
writer.close();
reader.close();
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtils.free(rs, ps, conn); // 關閉資源
}
}
總結:以上幾步實現了(1)創建java與mysql數據庫的鏈接(2)將text數據寫入數據庫(3)讀取數據庫中的text數據