數據庫連接Java

數據庫選擇了mysql，首先下載MySQL
https://dev.mysql.com/downloads/installer/
選擇下面一個不是web的

然後下載JDBC
https://dev.mysql.com/downloads/connector/j/
還是選下面一個

下載好之後，把jar包放入jdk的lib文件夾中，並在環境變量classpath添加%JAVA_HOME%\lib\mysql-connector-java-5.1.44-bin.jar（對應名稱）
然後就可以打開eclipse啦

1. 首先創建項目，右擊選擇Build Path，configure build path，然後add external JARs,選擇jar包，否則報錯。

2. 可以開始寫啦
   nope，首先要在mysql建庫建表，這裏我的數據庫叫javalinkmysql，表叫test，然後插入了幾行數據。然後就可以開始啦。

import java.sql.*;//導入包
public class DBtest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
          String driver = "com.mysql.jdbc.Driver";
            String url = "jdbc:mysql://127.0.0.1:3306/javalinkmysql?useUnicode=true&characterEncoding=utf-8&useSSL=false";
            String user = "root";
            String password = "1002482382";
            try{
                Class.forName(driver);
                Connection connection = DriverManager.getConnection(url,user,password);
                if(!connection.isClosed()){
                    System.out.println("連接成功");
                }
                Statement statement = connection.createStatement();
                String sql = "select * from test";
                ResultSet result = statement.executeQuery(sql);
                while(result.next()){
                    System.out.print(result.getString("id")+" ");
                    System.out.print(result.getString("name")+" ");
                    System.out.print(result.getString("gender")+" ");
                    System.out.println(result.getString("age"));
                }
                result.close();
                connection.close();
            }catch(Exception e){
                e.printStackTrace();
            }
    }

}

這裏要注意

String url = "jdbc:mysql://127.0.0.1:3306/javalinkmysql?useUnicode=true&characterEncoding=utf-8&useSSL=false";

javalinkmysql是database的名稱，
?useUnicode=true&characterEncoding=utf-8&useSSL=false”
是因爲警告

Sun Sep 10 16:15:13 CST 2017 WARN: Establishing SSL connection without server’s identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn’t set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to ‘false’. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

鏈接成功，顯示數據。