JavaWeb学习笔记之数据库连接

JDBC MySql 数据库连接

公共类 ConnetionFactory 代码如下

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ConnectionFactoryTest {
private final String dbDriver = "com.mysql.jdbc.Driver";
private final String url = "jdbc:mysql://localhost:3306/xmu_cs";
private final String userName = "root";
private final String password ="root";

private ResultSet rs = null;
private Statement stmt = null;
private Connection conn = null;

//创建加载数据库驱动的方法
public ConnectionFactoryTest(){
try {
Class.forName(dbDriver).newInstance();//系统自动加载数据库驱动
System.out.println("数据库驱动加载成功！");
} catch (Exception e) {
// TODO: handle exception
System.out.println("数据库加载失败");
}
}
//创建数据库连接的方法
public boolean createConnection(){
try {
conn = (Connection) DriverManager.getConnection(url, userName, password);
conn.setAutoCommit(true);
System.out.println("数据库连接成功！");
return true;
} catch (Exception e) {
// TODO: handle exception
System.out.println(e.getMessage());
System.out.println("数据库连接失败！");
return false;
}
}

//创建查询语句的方法
public ResultSet executeQuery(String sql){
try {
if(conn == null){
createConnection();
}
stmt = conn.createStatement();
try {
rs = stmt.executeQuery(sql);
return rs;
} catch (Exception e) {
// TODO: handle exception
System.out.println(e.getMessage());
return null;
}
} catch (Exception e) {
// TODO: handle exception
System.out.println(e.getMessage());
return null;
}
}

//创建执行更新操作的方法
public boolean executeUpdate(String sql){
if(conn == null){
createConnection();
}
try {
stmt = conn.createStatement();
stmt.executeUpdate(sql);
return true;
} catch (Exception e) {
// TODO: handle exception
System.out.println(e.getMessage());
return false;
}
}

//创建关闭数据库连接的方法
public void closeConnection(){
if(null != rs){
try {
rs.close();
System.out.println("结果集关闭成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(null != stmt){
try {
stmt.close();
System.out.println("Statement关闭成功！！");
} catch (Exception e) {
// TODO: handle exception
}
}
if(null !=conn){
try{
conn.close();
System.out.println("数据库连接关闭成功！");
}catch(SQLException e){
e.printStackTrace();
}
}
}
}

编写jUnit测试类，代码如下：

public class dbConnectionTest {
private ResultSet rs = null;
private static ConnectionFactoryTest cf = new ConnectionFactoryTest();
@BeforeClass
public static void setUpBeforeClass() throws Exception {
cf.createConnection();
}

@AfterClass
public static void tearDownAfterClass() throws Exception {
cf.closeConnection();
}

@Test
public void testQuery() throws SQLException {
String sql = "select * from test";
rs = cf.executeQuery(sql);
while(rs.next()){
System.out.println("id:"+rs.getString("id")+" | name:"+rs.getString("name"));
}

}

}

结果如下：

数据库驱动加载成功！
数据库连接成功！
id:1 | name:test1
id:2 | name:test2
结果集关闭成功！
Statement关闭成功！！
数据库连接关闭成功！