2019-4-22 jdbc学习笔记

jdbc

一.定义：java database connector

二.常用的接口

       java.sql.Driver  驱动

       java.sql.Connection  链接

　　java.sql.Statement    静态处理块

　　java.sql.PreparedStatement   预处理模块

　　java.sql.ResultSet  结果集

　　java.sql.ResultSetMeteData  数据库信息数据集

 

三.使用方法：

　　注意：oracle和mysql的jdbc 的jar包是不一样的

　　1.导入jar包

　　2.编译jar包

 

url=jdbc:oracle:thin:@localhost:1521:ORCL
username=SCOTT
password=root

 

public class DBUtils {
      
private static String url = "";
 private static String username = "";
 private static String password = "";

 static{ 
try { 
//加载驱动
 Class.forName("oracle.jdbc.driver.OracleDriver");
 //通过当前的线程获取类加载器，再获取资源获取器（不然不能读取到相对路径）
 InputStream stream = Thread.currentThread()
 .getContextClassLoader()
 .getResourceAsStream("dao/db.properties");
 //通过properties读取流中的配置信息
 Properties properties = new Properties();
 properties.load(stream);

 url = properties.getProperty("url");
 username = properties.getProperty("username");
 password = properties.getProperty("password");
 } catch (ClassNotFoundException e) { 
 e.printStackTrace();
 } catch (IOException e) { 
 e.printStackTrace();
 }
 }

/**
 * 获取链接的方法
 * @return
 */
 public static Connection getConnection(){ 
 Connection connect = null;
 //创建驱动对象
 Driver driver = new OracleDriver();
 try { 
//将驱动对象加入到驱动对象管理器中
 DriverManager.deregisterDriver(driver);
 //通过驱动对象管理器获取链接
 connect
 = DriverManager
 .getConnection(url,username,password);
 } catch (SQLException e) { 
 e.printStackTrace();
 }
return connect;
 }

/**
 * 获取sql语句传达器
 * @return
 */
 public Statement getStatement(){ 
 Statement st = null;
 try { 
 st = new DBUtils().getConnection().createStatement();
 } catch (SQLException e) { 
 e.printStackTrace();
 }
return st;
 }

/**
 * 获取编译好的PrepareStatement
 * @param psql 带问号的sql语句
 * @param args 与问好相对应的参数
 * @return
 */
 public PreparedStatement getPrepareStatement(String psql,Object... args){ 
 PreparedStatement pst = null;
 //获取链接
 Connection conn = new DBUtils().getConnection();
 try { 
//产生预编译执行器
 pst = conn.prepareStatement(psql);
 for (int i = 0; i < args.length; i++) { 
//给预编译注入参数
 pst.setObject(i+1,args[i]);
 }
 ResultSet resultSet = pst.executeQuery();
 } catch (SQLException e) { 
 e.printStackTrace();
 }
return pst;
 }

/**
 * 释放Connection PrepareStation ResultSet的资源
 * @param conn
 */
 public void release(AutoCloseable... conn){ 
for (int i = 0; i < conn.length; i++) { 
try { 
if(conn[i]!=null){ 
 conn[i].close();
 }
 } catch (Exception e) { 
 e.printStackTrace();
 }
 }
 }

@Test
 /***
 * 测试链接是否成功的方法
 */
 public void test(){ 
 System.out.println(new DBUtils().getConnection());
 }
}

 

    /**
     * 获取表信息数据集
     * @return
     */
    public DatabaseMetaData getDatabaseMetaData(){
        try {
            return DBUtils.getConnection().getMetaData();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    public void getAllTableNames(){
        //获取链接
        Connection connection =
                DBUtils.getConnection();
        try {
            //获取表数据集
            DatabaseMetaData metaData = this.getDatabaseMetaData();
            ResultSet tables = metaData.getTables(null, null, null, new String[]{"TABLE"});
            while(tables.next()){
                //获取表名
                String tableName = tables.getString("TABLE_NAME");
                System.out.println(tableName);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    //输出列名、类型、注释
    public void printColumnInfo(DatabaseMetaData databaseMetaData)throws Exception{
        ResultSet rs = databaseMetaData.getColumns(null, "%", "EMP", "%");
        while(rs.next()){
            //列名
            String columnName = rs.getString("COLUMN_NAME");
            //类型
            String typeName = rs.getString("TYPE_NAME");
            //注释
            String remarks = rs.getString("REMARKS");
            System.out.println(columnName + "--" + typeName + "--" + remarks);
        }
    }

 

//测试基础查询语句
    public void testStatement(){
        Connection conn =
                new DBUtils().getConnection();
        try(Statement statement = conn.createStatement()){
            ResultSet resultSet = statement.executeQuery("SELECT * FROM EMP");
            while(resultSet.next()){
                System.out.print(resultSet.getString("ENAME")+" ");
                System.out.println(resultSet.getInt("SAL"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 当要大量插入数据的时候使用batch更快
     */
    public void testBatch(){
        Connection conn = DBUtils.getConnection();
        try {
            PreparedStatement ps = conn.prepareStatement("INSERT INTO EMPTEMP(NAME,AGE) VALUES(?,?)");
            for (int i = 1; i < 1000; i++) {
                ps.setString(1,"小王"+i);
                ps.setInt(2,i);
                //将当前的指令存储到batch中
                ps.addBatch();
            }
            ps.executeBatch();
            ps.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

 

转载于:https://www.cnblogs.com/w410782823/p/10749678.html