SQL:　Java 连接 MySQL

1. 开发环境

- java: Eclipse

- MySQL 5.7

- MySQL Connect/J

具体的开发环境搭建就不在这里赘述。

 2.  Java连接Mysql步骤

将Eclipse 项目中加入jar (connector J): 项目属性 -> Java Biuld Path -> add external JARs....



准备MySQL, 

<span style="font-size:18px;">mysql> create database mydb;
Query OK, 1 row affected (0.00 sec)

mysql> use mydb;
Database changed
mysql> create table test_tbl
-> (id serial,
-> name varchar(20) not null);
Query OK, 0 rows affected (0.10 sec)

mysql> desc test_tbl;
+-------+---------------------+------+-----+---------+----------------+
| Field | Type                | Null | Key | Default | Extra          |
+-------+---------------------+------+-----+---------+----------------+
| id    | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment |
| name  | varchar(20)         | NO   |     | NULL    |                |
+-------+---------------------+------+-----+---------+----------------+
2 rows in set (0.04 sec)

mysql></span>

Java 程序：
我建了两个类， DBHelper.java 和 Test.java

DBHelper.java 文件如下：

<span style="font-size:18px;">package SQL.Demo;
import java.sql.*;
import static java.lang.System.out;

public class DBHelper {
public static final String driver = "com.mysql.jdbc.Driver";
//url指向要访问的数据库
public  Connection conn = null;
public  PreparedStatement pstmt = null;
public  Statement stmt = null;
public  ResultSet res = null;

public void Connect(String url, String user, String passward){

try {
// 利用forname 实现动态加载类
Class.forName(driver);
conn = DriverManager.getConnection(url, user, passward);
stmt = conn.createStatement();
} catch (ClassNotFoundException e)
{
e.printStackTrace();
} catch (SQLException e){
e.printStackTrace();
}

}

public void Close(){
try {
if (!conn.isClosed())
conn.close();
}
catch (SQLException e){
e.printStackTrace();
}
}

public void Excute(String sql){
try{
stmt.execute(sql);
}catch (SQLException e){
e.printStackTrace();
}
}

public void ExcuteQuery(String sql){
try{
res = stmt.executeQuery(sql);
}catch (SQLException e){
e.printStackTrace();
}
}

public void ExcutePreparedStmt(String sql){
try {
pstmt = conn.prepareStatement(sql);
res = pstmt.executeQuery(sql);

}catch (SQLException e){
e.printStackTrace();
}

}

public void PrintResult(){
System.out.println("------result-------");
try {
ResultSetMetaData resdata = res.getMetaData();
int i;
// 打印结果的字段
for ( i = 0; i < resdata.getColumnCount(); i++){
//out.println("colum count = " + resdata.getColumnCount());
String columnname = resdata.getColumnName(i+1);
System.out.print(columnname + "\t\t");
}
// 打印结果的数据（除字段外）
out.println();
while(res.next()){
for (i = 0; i < resdata.getColumnCount(); i++){
String s = res.getString(i+1);
System.out.print(s + "\t\t");
}
out.println();
}

}
catch (SQLException e){
e.printStackTrace();
}
}

}</span>

Test.java 文件（程序）如下：

package SQL.Demo;

public class Test {

public static void main(String[] args){
//驱动程序

//"jdbc:mysql://127.0.0.1:3306/scutcs";
String url = "jdbc:mysql://localhost:3306/mydb";
//数据的用户和密码
String user = "andrew";
String pwd = "andrew123";

//DBHelper db1  = new DBHelper();
DBHelper db1 = new DBHelper();
db1.Connect(url, user, pwd);
String sql = "Insert into test_tbl (name) values ('Andrew'); ";
db1.Excute(sql);
db1.Excute("Insert into test_tbl (name) values ('Ray'); ");
db1.Excute("Insert into test_tbl (name) values ('Fenny'); ");
db1.ExcuteQuery("select * from test_tbl");
db1.PrintResult();
db1.Close();

}

}

运行结果如下：



注意：由于我们没有配置SSL所以，出现WARN: Establishing SSL ....

SSL 配置，请自行百度。