一、直接連接，不封裝到工具類中，主要步驟：
先導包:mysql-connector-java-5.0.8-bin.jar(點擊跳轉到下載界面),放在WebRoot/WEB-INF/lib/下
1.加載驅動//com.MySQL.jdbc.Driver
2.獲取連接 Connection對象
3.獲取用于向數據庫發送SQL的Statement對象
4.執行sql,獲取數據，解析數據
5.關閉連接，釋放資源
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/*協議：子協議://主機:端口/數據庫名*/Stringurl="jdbc:mysql://localhost:3306/jdbctest";//mysql數據庫的用戶名與密碼，安裝時自己設置，一般默認為rootStringuser="root";Stringpassword="root";Connectionconnection=null;Statementstatement=null;ResultSetresultSet=null;try{//1.加載驅動//com.mysql.jdbc.Driver/**DriverManager.registerDriver(new*Driver());用這種方法會加載兩次驅動，也就是說會創建兩個drive對象*/Class.forName("com.mysql.jdbc.Driver");//2.獲取連接connection=DriverManager.getConnection(url,user,password);//3.獲取用于向數據庫發送SQL的Statement對象statement=connection.createStatement();//4.執行sql,獲取數據resultSet=statement.executeQuery("SELECT*FROMusers;");//解析數據while(resultSet.next()){intid=resultSet.getInt("id");Stringname=resultSet.getString("name");Stringpsd=resultSet.getString("password");Stringemail=resultSet.getString("email");Stringbirthday=resultSet.getString("birthday");System.out.println(id+""+name+""+psd+""+email+""+birthday);}}catch(ClassNotFoundExceptione){e.printStackTrace();}catch(SQLExceptione){e.printStackTrace();}finally{//5.關閉連接，釋放資源if(resultSet!=null){try{resultSet.close();}catch(SQLExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}resultSet=null;}if(statement!=null){try{statement.close();}catch(SQLExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}statement=null;}if(connection!=null){try{connection.close();}catch(SQLExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}connection=null;}/* 協議：子協議://主機:端口/數據庫名 */String url = "jdbc:mysql://localhost:3306/jdbctest";// mysql數據庫的用戶名與密碼，安裝時自己設置，一般默認為rootString user = "root";String password = "root";Connection connection = null;Statement statement = null;ResultSet resultSet = null;try { // 1.加載驅動//com.mysql.jdbc.Driver /* * DriverManager.registerDriver(new * Driver());用這種方法會加載兩次驅動，也就是說會創建兩個drive對象 */ Class.forName("com.mysql.jdbc.Driver"); // 2.獲取連接 connection = DriverManager.getConnection(url, user, password); // 3.獲取用于向數據庫發送SQL的Statement對象 statement = connection.createStatement(); // 4.執行sql,獲取數據 resultSet = statement.executeQuery("SELECT * FROM users;"); // 解析數據 while (resultSet.next()) {int id = resultSet.getInt("id");String name = resultSet.getString("name");String psd = resultSet.getString("password");String email = resultSet.getString("email");String birthday = resultSet.getString("birthday");System.out.println(id + " " + name + " " + psd + " " + email+ " " + birthday); }} catch (ClassNotFoundException e) { e.printStackTrace();} catch (SQLException e) { e.printStackTrace();} finally { //5.關閉連接，釋放資源 if (resultSet != null) {try { resultSet.close();} catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace();}resultSet = null; } if (statement != null) {try { statement.close();} catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace();}statement = null; } if (connection != null) {try { connection.close();} catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace();}connection = null; }} |
二、將數據庫連接封裝成一個工具類
這樣做的好處是，在實際開發中，就能做到，改一處即可修改全局。
1.建一個名為db.properties的配置文件，放于src/
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url=jdbc:mysql://localhost:3306/jdbctestusername=rootpassword=rootdriver=com.mysql.jdbc.Driver |
2.工具類：
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importjava.io.IOException;importjava.sql.Connection;importjava.sql.DriverManager;importjava.sql.ResultSet;importjava.sql.SQLException;importjava.sql.Statement;importjava.util.Properties; publicclassJdbcUtil{//私有靜態變量，用以讀取配置文件privatestaticPropertiesconfig=newProperties();static{try{//配置資源文件config.load(JdbcUtil.class.getClassLoader().getResourceAsStream("db.properties"));//加載驅動Class.forName(config.getProperty("driver"));}catch(IOExceptione){e.printStackTrace();}catch(ClassNotFoundExceptione){e.printStackTrace();}}publicstaticConnectiongetConnection(){Connectionconnection=null;try{connection=DriverManager.getConnection(config.getProperty("url"),config.getProperty("username"),config.getProperty("password"));}catch(SQLExceptione){e.printStackTrace();}returnconnection;}//用以關閉連接，釋放資源publicstaticvoidreleaseConn(Connectionconnection,Statementstatement,ResultSetresultSet){if(resultSet!=null){try{resultSet.close();}catch(SQLExceptione){e.printStackTrace();}resultSet=null;}if(statement!=null){try{statement.close();}catch(SQLExceptione){e.printStackTrace();}statement=null;}if(connection!=null){try{connection.close();}catch(SQLExceptione){e.printStackTrace();}connection=null;}} } |
3.使用實例：
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Connectionconnection=null;Statementstatement=null;ResultSetresultSet=null;try{//調用工具類中的靜態方法來獲取連接connection=JdbcUtil.getConnection();statement=connection.createStatement();resultSet=statement.executeQuery("select*fromusers");while(resultSet.next()){intid=resultSet.getInt("id");Stringname=resultSet.getString("name");Stringpsd=resultSet.getString("password");Stringemail=resultSet.getString("email");Stringbirthday=resultSet.getString("birthday");System.out.println(id+""+name+""+psd+""+email+""+birthday); }}catch(Exceptione){e.printStackTrace();}finally{//調用工具類中的靜態方法來關閉連接，釋放資源JdbcUtil.releaseConn(connection,statement,resultSet);} |
希望本文可以對需要的朋友有幫助
原文鏈接：http://www.2cto.com/kf/201702/596389.html
