JDBC常用API小结

建立数据库链接的三种方式：

package com.victor_01;
 
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
 
import org.junit.Test;
 
public class Test1 {
	private String url = "jdbc:mysql://192.168.244.144:3306/test";
	private String user = "root";
	private String password = "123456";
 
	@Test
	public void test1() throws Exception {
		Driver driver = new com.mysql.jdbc.Driver();
		Properties prop = new Properties();
		prop.setProperty("user", user);
		prop.setProperty("password", password);
		Connection conn = driver.connect(url, prop);
		System.out.println(conn);
	}
 
	@Test
	public void test2() throws SQLException{
		Driver driver = new com.mysql.jdbc.Driver();
		DriverManager.registerDriver(driver);
		Connection conn = DriverManager.getConnection(url, user, password);
		System.out.println(conn);
	}
 
	@Test
	public void test3() throws Exception {
		Class.forName("com.mysql.jdbc.Driver");
		Connection conn = DriverManager.getConnection(url, user, password);
		System.out.println(conn);
 
	}
 
}

推荐使用第三种，其实第二种和第三种本质上是一种，后者是前者的优化版。

JDBC接口核心的API

 JDBC接口核心的API
                java.sql.*   和  javax.sql.*
 
            |- Driver接口： 表示java驱动程序接口。所有的具体的数据库厂商要来实现此接口。
                |- connect(url, properties):  连接数据库的方法。
                        url: 连接数据库的URL
                            URL语法： jdbc协议:数据库子协议://主机:端口/数据库
                            user： 数据库的用户名
                            password： 数据库用户密码
            |- DriverManager类： 驱动管理器类，用于管理所有注册的驱动程序
                |-registerDriver(driver)  : 注册驱动类对象
                |-Connection getConnection(url,user,password);  获取连接对象
 
            |- Connection接口： 表示java程序和数据库的连接对象。
                    |- Statement createStatement() ： 创建Statement对象
                    |- PreparedStatement prepareStatement(String sql)  创建PreparedStatement对象
                    |- CallableStatement prepareCall(String sql) 创建CallableStatement对象
 
            |- Statement接口： 用于执行静态的sql语句
                    |- int executeUpdate(String sql)  ： 执行静态的更新sql语句（DDL，DML）
                    |- ResultSet executeQuery(String sql)  ：执行的静态的查询sql语句（DQL）
 
                |-PreparedStatement接口：用于执行预编译sql语句
                        |- int executeUpdate() ： 执行预编译的更新sql语句（DDL，DML）
                        |-ResultSet executeQuery()  ： 执行预编译的查询sql语句（DQL）
 
                    |-CallableStatement接口：用于执行存储过程的sql语句（call xxx）
                            |-ResultSet executeQuery()  ： 调用存储过程的方法
 
            |- ResultSet接口：用于封装查询出来的数据
                    |- boolean next() ： 将光标移动到下一行
                    |-getXX() : 获取列的值

Statement接口

package com.victor_01;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
import org.junit.Test;
 
public class Demo2 {
	private String url = "jdbc:mysql://192.168.244.144:3306/test";
	private String user = "root";
	private String password = "123456";
 
	@Test
	public void Test1() {
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(url, user, password);
			stmt = conn.createStatement();
 
			String sql = "drop table if exists jdbc_test";
			int result = stmt.executeUpdate(sql);
			System.out.println("Drop table:" + result);
 
			sql = "create table jdbc_test(id int,name varchar(10))";
			result = stmt.executeUpdate(sql);
			System.out.println("Create result:" + result);
 
			sql = "insert into jdbc_test values(1,'hello')";
			result = stmt.executeUpdate(sql);
			System.out.println("Insert result:" + result);
 
			int id = 2;
			String name = "world";
			sql = "insert into jdbc_test values(" + id + ",'" + name + "')";
			result = stmt.executeUpdate(sql);
			System.out.println("Insert result2:" + result);
 
			name = "java";
			sql = "update jdbc_test set name='" + name + "' where id=" + id
					+ "";
			result = stmt.executeUpdate(sql);
			System.out.println("Update result:" + result);
 
			sql = "select * from jdbc_test";
			rs = stmt.executeQuery(sql);
			while (rs.next()) {
				System.out
						.println(rs.getInt("id") + " " + rs.getString("name"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (rs != null) {
				try {
					rs.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			if (stmt != null)
				try {
					stmt.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			if (conn != null)
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
		}
 
	}
 
}

PreparedStatement接口

package com.victor_01;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
 
import org.junit.Test;
 
public class Demo3 {
	private String url="jdbc:mysql://192.168.244.144:3306/test";
	private String user="root";
	private String password="123456";
	@Test
	public void PreparedStatementTest() throws Exception{
	   Class.forName("com.mysql.jdbc.Driver");
	   Connection conn=DriverManager.getConnection(url, user, password);
 
	   String sql="insert into jdbc_test(id,name) values(?,?)";
	   PreparedStatement prestmt =conn.prepareStatement(sql);
	   prestmt.setInt(1, 3);
	   prestmt.setString(2,"tom");
	   int result=prestmt.executeUpdate();
	   System.out.println(result);
 
	   sql="update jdbc_test set name=? where id=?";
	   prestmt=conn.prepareStatement(sql);
	   prestmt.setString(1, "steve");
	   prestmt.setInt(2, 3);
	   result=prestmt.executeUpdate();
	   System.out.println(result);
 
	   sql="select * from jdbc_test where id=?";
	   prestmt=conn.prepareStatement(sql);
	   prestmt.setInt(1, 3);
	   ResultSet rs= prestmt.executeQuery();
	   while(rs.next()){
		   System.out.println("id="+rs.getInt(1)+";name="+rs.getString(2));
	   }
	   rs.close();
	   prestmt.close();
	   conn.close();
	   }
 
	}

CallableStatement接口

package com.victor_01;
 
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
 
import org.junit.Test;
 
public class Demo3 {
	private String url="jdbc:mysql://192.168.244.144:3306/test";
	private String user="root";
	private String password="123456";
	@Test
	public void PreparedStatementTest() throws Exception{
	   Class.forName("com.mysql.jdbc.Driver");
	   Connection conn=DriverManager.getConnection(url, user, password);
       String sql="drop procedure findById";
	   Statement stmt=conn.createStatement();
	   int result=stmt.executeUpdate(sql);
	   System.out.println("drop result:="+result);
 
	   sql=" CREATE PROCEDURE findById(IN sid INT) BEGIN select * from jdbc_test where id=sid; end";
	   stmt=conn.createStatement();
	   result=stmt.executeUpdate(sql);
	   System.out.println("create result:="+result);
 
	   //直接调用存储过程
	   sql="call findById(2)";
	   CallableStatement stmt1=conn.prepareCall(sql);
	   ResultSet rs=stmt1.executeQuery();
	   while(rs.next()){
		   System.out.println("id="+rs.getInt(1)+",name="+rs.getString(2));
	   }
 
	   //传参调用存储过程
	   sql="call findById(?)";
	   stmt1=conn.prepareCall(sql);
	   stmt1.setInt(1, 4);
	   rs=stmt1.executeQuery();
	   while(rs.next()){
		   System.out.println("id="+rs.getInt(1)+",name="+rs.getString(2));
	   }
 
	   //带有输出参数的存储过程
	   sql="drop procedure findById1";
	   stmt=conn.createStatement();
	   result=stmt.executeUpdate(sql);
	   System.out.println("drop findById1 result:"+result);
 
	   sql=" CREATE PROCEDURE findById1(IN sid INT,OUT sname VARCHAR(10)) BEGIN select name into sname from jdbc_test where id=sid; end";
	   stmt=conn.createStatement();
	   result=stmt.executeUpdate(sql);
	   System.out.println("create result:="+result);
 
	   sql="call findById1(?,?)";
	   stmt1=conn.prepareCall(sql);
	   stmt1.setInt(1, 4);
	   stmt1.registerOutParameter(2, java.sql.Types.VARCHAR);
	   stmt1.executeQuery(); //注意：结果不是返回到ResultSet中，而是返回到输出参数中。
	   String sname=stmt1.getString(2);
	   System.out.println(sname);
 
	   rs.close();
	   stmt1.close();
	   stmt.close();
	   conn.close();
	   }
 
	}