Question

我的配置是：应用服务器：Weblogic 10gR3 数据库：Oracle 10g IDE：Netbeans Java：版本7

从游泳池获取连接时我遇到异常。我已经使用try资源来避免错误关闭连接和语句的负担。

这是堆栈跟踪。

[INFO] 2016-06-24 19:01:08,304 org.nmdc.incentivepackage.databaseFiles.DepositMDao checkData 184 - Executing query SELECT count(*) count FROM dep_m
[INFO] 2016-06-24 19:01:08,304 org.nmdc.incentivepackage.databaseFiles.DepositMDao checkData 188 - Executing query SELECT count(*) count FROM dep_m
[INFO] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.databaseFiles.DepositMDao checkData 194 - Relinquish Database connection ...
[INFO] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.databaseFiles.DepositMDao checkData 206 - return 1###success###
[INFO] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.controllerFiles.CheckDepositMDataController processRequest 35 - result 1###success###   .........save
[INFO] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.controllerFiles.CheckDepositMDataController processRequest 46 - update deposit master table 
[INFO] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.controllerFiles.GetDepositMDataController processRequest 33 - Fetching deposit master data 
[ERROR] 2016-06-24 19:01:08,320 org.nmdc.incentivepackage.databaseFiles.DepositMDao getDepositMData 239 - Exception 
java.sql.SQLException: Connection has already been closed.
at weblogic.jdbc.wrapper.PoolConnection.checkConnection(PoolConnection.java:55)
at weblogic.jdbc.wrapper.Connection.preInvocationHandler(Connection.java:92)
at weblogic.jdbc.wrapper.Connection.createStatement(Connection.java:441)
at org.nmdc.incentivepackage.databaseFiles.DepositMDao.getDepositMData(DepositMDao.java:219)
at org.nmdc.incentivepackage.controllerFiles.GetDepositMDataController.processRequest(GetDepositMDataController.java:35)
at org.nmdc.incentivepackage.controllerFiles.GetDepositMDataController.doPost(GetDepositMDataController.java:74)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3498)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(Unknown Source)
at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2180)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2086)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1406)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)

提供连接对象的DBUtility类是

public class DBUtility {
  private static Connection conn;
  private static Context ctx ;
  final static Logger logger = LoggerFactory.getLogger(DBUtility.class);

  public DBUtility() {
    ctx = null;            
    conn = null;        
  }

  public static Connection getConnection() throws Exception {
    if (conn != null)
         return conn;
    else {            
           //Hashtable ht = new Hashtable();
          // ht.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
         //  ht.put(Context.PROVIDER_URL,"t3://localhost:7001"); //weblogic server        
          try {                  
            ctx = new InitialContext();
            javax.sql.DataSource ds = (javax.sql.DataSource) ctx.lookup ("incentivepool");
            conn = ds.getConnection();                
          }
          catch(Exception e) {
             logger.error("Error in establishing connection...",e);
          }
   }

   return conn;
   }
}

抛出异常的类是

ublic class DepositMDao extends HttpServlet {

private  Connection connection = null; 
final static Logger log = LoggerFactory.getLogger(DepositMDao.class); 
private String deposit,category,period,query;
private float amount;
private String errors,status;
private int errorCount;
private Statement statement;
private ResultSet rs;
JSONObject jobject; 

public DepositMDao() throws Exception {
   // connection = DBUtility.getConnection();
    if(connection != null) {
      log.info("Received Database connection ...");
    }
    errors ="";
    status = "success";
    errorCount =0;  
    statement = null;
}  
 public String checkData() throws SQLException {
    int count=0;
    query = "SELECT count(*) count FROM dep_m" ;
    log.info("Executing query "+query);
    try ( Connection connection = DBUtility.getConnection();
        Statement statement = connection.createStatement(); 
       ) {           
        log.info("Executing query "+query);
        try (ResultSet rs = statement.executeQuery(query)) {                    
            if(rs.next()) {
                count = rs.getInt("count");
            }              
         }
        log.info("Relinquish Database connection ...");
    } catch(Exception ex) {
        errorCount++;
        errors = errors + " "+ex.getMessage();
        log.error("Exception ",ex);         
    }     

    if(errorCount == 0) {
        status = "success";          
     } else {
        status = "failure";          
     }   
     log.info("return "+count+"###"+status + "###"+errors);
     return count+"###"+status + "###"+errors;
}

public List<DepositMBean> getDepositMData() throws SQLException {

 List<DepositMBean> depositList = new ArrayList();
 DepositMBean depositBean;
 String dep14,dep11C,dep11B;
 depositBean = null;
 depositList = null;   
 query = "SELECT c_dep14,c_dep11C,c_dep11B FROM dep_m ";     
 try ( Connection connection1 = DBUtility.getConnection();
        Statement statement1 = connection1.createStatement(); 
       ) 
    {           
        log.info("Executing query "+query);
        try (ResultSet rs1 = statement1.executeQuery(query)) {
            while (rs1.next()) { 
                depositBean = new DepositMBean();
                dep14 = rs1.getString("c_dep14"); 
                dep11C = rs1.getString("c_dep11C"); 
                dep11B = rs1.getString("c_dep11B");

                depositBean.setcDep14(dep14);
                depositBean.setcDep11B(dep11B);
                depositBean.setcDep11C(dep11C);            
                depositList.add(depositBean);            
            }    
            depositBean.display();
            log.info("Relinquish Database connection ...");
        } 
    } catch(Exception ex ) {
      log.error("Exception ",ex);         
  }  
 return depositList;     
}

服务器上的池配置是：

Answer 1

因为连接是静态对象，这意味着只能存在一个连接实例。

if (conn != null && !conn.isClosed())
     return conn;

所以第一次调用它是有效但第二次没有，因为连接已经关闭。

如果关闭，则需要重新创建连接

lab <- c("Prog->Makro", "Prog->Prog",  "Prog->Prog",  "Prog->Prog", "Makro->Makro", "Makro->Makro", "Makro->Makro", "Makro->Makro", "Makro->Makro", "Apop->Apop")

lab <- unlist(strsplit(lab, "->"))[seq(1, length(lab), 2)]
 [1] "Prog"  "Prog"  "Prog"  "Prog"  "Makro" "Makro" "Makro" "Makro" "Makro" "Apop"  "Prog"  "Makro"

lab <- unlist(strsplit(lab, "->"))
lab[seq(1, length(lab), 2)]
 [1] "Prog"  "Prog"  "Prog"  "Prog"  "Makro" "Makro" "Makro" "Makro" "Makro" "Apop"  "Prog"  "Makro"
[13] "Makro" "Makro" "Makro" "Makro" "Makro" "Makro" "Prog"  "Granu" "Apop"  "Makro" "Makro" "Makro"

java.sql.SQLException：第一次数据库查询后，连接已被关闭

1 个答案: