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";@Testpublic 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);}@Testpublic 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);}@Testpublic 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APIjava.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";@Testpublic 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";@Testpublic 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";@Testpublic 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();}}