如何解决Class.forName“ com.mysql.jdbc.Driver”newInstance
那么这个简单的方法呢?
java.sql.Driver d=new com.mysql.jdbc.Driver();
我也想知道为什么您要用这种方式连接数据库?最好让服务器对其进行管理。
首先context.xml
像这样配置(如果您使用的是tomcat):
<context>
<Resource name="_ds" auth="Container" type="javax.sql.DataSource"
maxActive="128" maxIdle="32" username="_admin" password="qwerty" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://127.0.0.1:3306/dbname"/>
</context>
然后,简单地从servlet / etc中的该资源获取连接,如下所示:
public void init() {
try {
_ds = (DataSource) InitialContext.lookup("java:/comp/env/_ds");
} catch (Exception ex) {
}
}
private javax.sql.DataSource _ds;
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
try {
/*String driver = "com.mysql.jdbc.Driver";
con = null;
String username = "";
String password = "";
Class.forName("com.mysql.jdbc.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/dbName", "root", "password");*/
Connection con=_ds.getConnection();
Statement st = con.createStatement();
ResultSet mar = st.executeQuery("SELECT * FROM table");
Gson gson = new GsonBuilder().create();
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
con.close();
} catch (SQLException e) {
String message = e.getMessage();
}
顺便说一句,不要忘记在<CATALINA_BASE>/lib
文件夹中编写MySQL JDBC驱动程序jar 文件。
解决方法
我在Netbeans
7.2上遇到此错误,它说ClassNotFoundexception和InstantationException。我真的在这个问题上陷入困境。请帮助我。
protected void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {
try {
String driver = "com.mysql.jdbc.Driver";
con = null;
String username = "";
String password = "";
Class.forName("com.mysql.jdbc.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/dbName","root","password");
Statement st = con.createStatement();
ResultSet mar = st.executeQuery("SELECT * FROM table");
Gson gson = new GsonBuilder().create();
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
} catch (SQLException e) {
String message = e.getMessage();
}
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