我在网上搜索了N天,几乎没有关于线程安全的解决办法,同样的问题Redis就很好解决,改了一个网上找来的工具类,请懂的大神帮我修改一下或者给点指导意见.我现在的想法就是加了synchronized关键字,但是总觉得还是有问题,非常感谢!
class MySQLUtil {
private static final String driver = "com.mysql.jdbc.Driver";
private static final String url = "jdbc:mysql://192.168.31.103:3306/";
private static final String character = "?useUnicode=true&characterEncoding=utf8";
private static final String ssl = "&useSSL=false";
private static final String user = "root";
private static final String password = "111111";
private static Connection connection = null;
private static Statement statement = null;
private static PreparedStatement ps = null;
private static ResultSet rs = null;
boolean TestConnection(String db) {
try {
Class.forName(driver);
Connection connection = DriverManager.getConnection(url + db + character + ssl, user, password);
if (!connection.isClosed()) {
CloseConnection();
return true;
}
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
synchronized private void ConnectToDB(String db) {
try {
Class.forName(driver);
Connection connection = DriverManager.getConnection(url + db + character + ssl, user, password);
if (!connection.isClosed()) {
statement = connection.createStatement();
}
} catch (Exception e) {
e.printStackTrace();
}
}
synchronized private void CloseConnection() {
try {
if (rs != null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps != null) {
ps.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
synchronized void ModifyData(String db, String data) {
ConnectToDB(db);
try {
statement.execute(data);
} catch (SQLException e) {
e.printStackTrace();
} finally {
CloseConnection();
}
}
synchronized List ReadData(String db, String data) {
List<String> list = new ArrayList<>();
int count;
ConnectToDB(db);
try {
rs = statement.executeQuery(data);
ResultSetMetaData rsmd;
rsmd = rs.getMetaData();
count = rsmd.getColumnCount();
while (rs.next()) {
for (int i = 1; i <= count; i++) {
String label = rsmd.getColumnLabel(i);
list.add(label);
String value = rs.getString(i);
list.add(value);
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
CloseConnection();
}
return list;
}
}
为了保证连接间数据独立(非共享),我猜你想实现连接池:
稍微修改了下,可能会好一些,建议还是听上面那哥们的,使用成熟的数据库连接池,没必要重复造轮子
使用单例,保证数据库连接的唯一性
修改
synchronized
关键字的用法,提高效率增加
volatile
关键字,提高稳定性没必要同步吧, 多个连接也没关系啊。
数据库自己有锁的。
你也可以直接用连接池。
多谢大家的回答,我把代码改了一下,请大家帮我看看有没有问题了,主要是没做过java,我的处理方式就是:除了常量外,没有类成员变量,全部用参数和返回值传递,所有变量都在方法里申明