数据库连接类
public class sqlserver4{
public static Connection conn = null;
public static ResultSet rs = null;
public static DriverManager dm = null;
public static Statement stmt = null;
public static String info = new String("数据库连接对象为空");
private String ClassName = "org.gjt.mm.mysql.Driver";
private String url="jdbc:mysql://localhost:3306/dbname";
private String dbuser="test";
private String dbpassword=""; public sqlserver4() {
try{
Class.forName(ClassName).newInstance();
}
catch (Exception e) { info = "加载数据库类错误";
System.out.println("classexc:"+e.getMessage());
}
try{
conn= DriverManager.getConnection(url,dbuser,dbpassword);
}
catch (Exception e) { info = "数据库连接对象创建错误";
System.out.println("connexc:"+e.getMessage());}
try{
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
}
catch (Exception e) { info = "数据库缓存对象创建错误";
System.out.println("stmtexc:"+e.getMessage());}
}
}
调用并执行sql的方法在另一个类sessionBean中
public String login(String u,String p){//登陆
try {
String sql = "SELECT czy_bh,czy_mm FROM czk_czy WHERE czy_bh='"+u+"'";
rs = sqlserver4.stmt.executeQuery(sql);
System.out.println("execute!");
if (!rs.next()){
info = u+":登录名不正确";
return "1"; }
password = rs.getString(2).trim();
if (!password.equals(p)){
info = "密码不正确";
return "2";//密码不正确
}
s_name = rs.getString(2).trim();
s_id = u;
}
catch (Exception e){System.out.println("e:"+e.getMessage());}
return "0";
}
异常捕捉为Null,为什么不执行我的sql,在"if (!rs.next()){"的输出语句也并没有执行,这是为什么呢,之前我在sessionBean类中将sqlserver4实例化之后执行没有问题!这两个类在同一个包当中,应该不用实例化可以直接调用的呀!
静待回复,谢谢!
public class sqlserver4{
public static Connection conn = null;
public static ResultSet rs = null;
public static DriverManager dm = null;
public static Statement stmt = null;
public static String info = new String("数据库连接对象为空");
private String ClassName = "org.gjt.mm.mysql.Driver";
private String url="jdbc:mysql://localhost:3306/dbname";
private String dbuser="test";
private String dbpassword=""; public sqlserver4() {
try{
Class.forName(ClassName).newInstance();
}
catch (Exception e) { info = "加载数据库类错误";
System.out.println("classexc:"+e.getMessage());
}
try{
conn= DriverManager.getConnection(url,dbuser,dbpassword);
}
catch (Exception e) { info = "数据库连接对象创建错误";
System.out.println("connexc:"+e.getMessage());}
try{
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
}
catch (Exception e) { info = "数据库缓存对象创建错误";
System.out.println("stmtexc:"+e.getMessage());}
}
}
调用并执行sql的方法在另一个类sessionBean中
public String login(String u,String p){//登陆
try {
String sql = "SELECT czy_bh,czy_mm FROM czk_czy WHERE czy_bh='"+u+"'";
rs = sqlserver4.stmt.executeQuery(sql);
System.out.println("execute!");
if (!rs.next()){
info = u+":登录名不正确";
return "1"; }
password = rs.getString(2).trim();
if (!password.equals(p)){
info = "密码不正确";
return "2";//密码不正确
}
s_name = rs.getString(2).trim();
s_id = u;
}
catch (Exception e){System.out.println("e:"+e.getMessage());}
return "0";
}
异常捕捉为Null,为什么不执行我的sql,在"if (!rs.next()){"的输出语句也并没有执行,这是为什么呢,之前我在sessionBean类中将sqlserver4实例化之后执行没有问题!这两个类在同一个包当中,应该不用实例化可以直接调用的呀!
静待回复,谢谢!
解决方案 »
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