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jdbc总结

jdbc
1.    连接数据库的步骤:
1)       注册驱动
2)       建立连接
3)       创建语句
4)       执行语句
5)       处理结果
6)       释放资源(注意关闭的顺序)
实例//1.注册驱动
     
[java]
 DriverManager.registerDriver(newcom.mysql.jdbc.Driver()); 
       
       System.setProperty("jdbc.drivers", "com.mysql.jdbc.Driver"); 
       
        Class.forName("com.mysql.jdbc.Driver");//推荐方式 
         
       //2.建立连接 
        
        String url = "jdbc:mysql:localhost:3306/jdbc"; 
        String user = "root"; 
        String password = "mysql"; 
Connection conn = DriverManager.getConnection(url,user,password); 
       
       //3.创建语句 
       Statement st = conn.createStatement(); 
       
       //4.执行语句 
       ResultSet rs = st.executeQuery("select * from user"); 
       //5.处理结果 
       while(rs.next()){//按行来遍历 
System.out.println(rs.getObject(1) + "\t" + rs.getObject(2) + "\t" +rs.getObject(3) + "\t" + rs.getObject(4)); 
       } 
       //6.释放资源(注意关闭的顺序) 
       rs.close(); 
       st.close(); 
       conn.close(); 

2.    注意在jdbc中的sql注入问题,解决的办法是使用PreparedStatement :PreparedStatement ps = null;// 利用PreparedStatement而不用Statement是因为PreparedStatement能够对输入的内容进行过滤,除去sql的关键字,防止此问题。
3.    数据库中对大文本的写入和读取:clob类的处理
[java]
public class ClobTest { 
  
    /**
     * @param args
     * @throws Exception
     */ 
    public static void main(String[] args) throws Exception { 
       //create(); 
        read(); 
    } 
     //数据库的读取操作 
    static void read() throws SQLException, Exception { 
       Connection conn = null; 
       Statement st = null; 
       ResultSet rs = null; 
       try { 
           conn = JdbcUtils.getConnection(); 
           // 3.创建语句 
           st = conn.createStatement(); 
           // 4.执行语句 
           rs = st.executeQuery("select big_text from clob_test"); 
           // 5.处理结果 
           while (rs.next()) {// 按行来遍历 
              Reader reader = rs.getCharacterStream(1); 
              Filefile = newFile("CRUD_bak.java"); 
              Writerwriter = 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 { 
           JdbcUtils.free(rs, st, conn); 
       } 
    } 
    
    //数据库的创建操作 
    static void create() throws SQLException, IOException { 
       Connection conn = null; 
       PreparedStatement ps = null; 
       ResultSet rs = null; 
       try { 
           conn = JdbcUtils.getConnection(); 
  
           // 3.创建语句 
           String sql = "insertinto clob_test(big_text) values(?)"; 
           ps = conn.prepareStatement(sql); 
           File file = new File("src/com/lcq/jdbc/CRUD.java"); 
           Reader reader = newBufferedReader(newFileReader(file)); 
           //传递大块的文本文档 
           ps.setCharacterStream(1,reader, file.length()); 
           int i = ps.executeUpdate(); 
           reader.close(); 
           System.out.println("i = " + i); 
           
       } finally { 
           JdbcUtils.free(rs, ps, conn); 
       } 
    } 


4.    问题blob类型读取二

补充:软件开发 , Java ,
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