我正在使用Tomcat 7，MySql Workbench 5.2.27，JSF 2.0，这个异常来自我的网页（Trip Record.xhtml）的ManagedBean（TripTableBean.java）。每当我在浏览其他网页后点击进入Trip Record.xhtml，它就会出现。原谅我可怕的代码......
TripTableBean.java
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:114)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at Database.DBController.readRequest(DBController.java:21)
at Database.TripTableBean.retrieve(TripTableBean.java:389)
at Database.TripTableBean.<init>(TripTableBean.java:69)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:188)
at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:102)
at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:409)
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:269)
at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:244)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:116)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:71)
at org.apache.el.parser.AstValue.getTarget(AstValue.java:94)
at org.apache.el.parser.AstValue.getType(AstValue.java:82)
at org.apache.el.ValueExpressionImpl.getType(ValueExpressionImpl.java:176)
at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:98)
at org.primefaces.component.datatable.DataTable.isLazy(DataTable.java:904)
at org.primefaces.component.datatable.DataTableRenderer.encodeMarkup(DataTableRenderer.java:177)
at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:103)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1763)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1756)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:401)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:964)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:304)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
异常发起的方法 :( TripTableBean.java:389）指向rs2 = db.readRequest（dbQuery2）;
public void retrieve() throws SQLException, NamingException {
t = new ArrayList<TripSearchy>();
ResultSet rs = null;
ResultSet rs2 = null;
ResultSet rs3 = null;
DBController db = new DBController();
db.setUp();
//SQL: change select statement here
String dbQuery = "select * from (trip inner join agency on trip.id=agency.trip_id inner join tourguide on trip.id=tourguide.trip_id inner join accommodation on trip.id=accommodation.trip_id)";
rs = db.readRequest(dbQuery);
try{
while(rs.next()){
//add to list
id = rs.getInt("trip.id");
name = rs.getString("trip.name");
startDate = rs.getString("trip.startDate");
endDate = rs.getString("trip.endDate");
costOfTrip = rs.getString("trip.costOfTrip");
maxNoOfParticipants = rs.getString("trip.maxNoOfParticipants");
closingDateOfApplication = rs.getString("trip.closingDateOfApplication");
instructions = rs.getString("trip.instructions");
psea = rs.getString("trip.psea");
fasop = rs.getString("trip.fasop");
ktpiop = rs.getString("trip.ktpiop");
opId = rs.getInt("trip.overseasprogramme_id");
overseasProgramme = rs.getString("trip.overseasProgrammeName");
tourGuideName = rs.getString("tourguide.name");
tourGuideContact = rs.getString("tourguide.contact");
companyName = rs.getString("agency.companyName");
agentName = rs.getString("agency.agentName");
agentContact = rs.getString("agency.agentContact");
airlineChoice = rs.getString("agency.airlineChoice");
placeOfLodging = rs.getString("accommodation.placeOfLodging");
startDateOfLodging = rs.getString("accommodation.startDate");
endDateOfLodging = rs.getString("accommodation.endDate");
String dbQuery2 = "Select * from tripstaff where trip_id = '" + id + "'";
rs2 = db.readRequest(dbQuery2);
String lec;
ArrayList<String> dbQueryM = new ArrayList<String>();
while (rs2.next()){
lec = rs2.getString("tripstaff.lecturer_id");
dbQueryM.add("Select * from lecturer where id = '" + lec + "'");
}
ArrayList<NypStaff> nsf = new ArrayList<NypStaff>();
for (int i = 0; i < dbQueryM.size(); i++){
rs3 = db.readRequest(dbQueryM.get(i));
if (rs3.next()){
NypStaff temp = new NypStaff();
//set values retrieved from database into attributes
temp.setName(rs3.getString("lecturer.name"));
temp.setEmail(rs3.getString("lecturer.email"));
temp.setContact(rs3.getString("lecturer.contact"));
nsf.add(temp);
}
}
try {
Calendar c = Calendar.getInstance();
Calendar c2 = Calendar.getInstance();
Calendar c3 = Calendar.getInstance();
Calendar c4 = Calendar.getInstance();
Calendar c5 = Calendar.getInstance();
try {
c.setTime(formatter.parse(startDate));
c2.setTime(formatter.parse(endDate));
c3.setTime(formatter.parse(startDateOfLodging));
c4.setTime(formatter.parse(endDateOfLodging));
c5.setTime(formatter.parse(closingDateOfApplication));
}
catch (ParseException e1) {
e1.printStackTrace();
}
c.add(Calendar.DATE, 1);
c2.add(Calendar.DATE, 1);
c3.add(Calendar.DATE, 1);
c4.add(Calendar.DATE, 1);
c5.add(Calendar.DATE, 1);
startDate = formatter.format(c.getTime());
endDate = formatter.format(c2.getTime());
startDateOfLodging = formatter.format(c3.getTime());
endDateOfLodging = formatter.format(c4.getTime());
closingDateOfApplication = formatter.format(c5.getTime());
startDated = formatter.parse(startDate);
endDated = formatter.parse(endDate);
startDatedOfLodging = formatter.parse(startDateOfLodging);
endDatedOfLodging = formatter.parse(endDateOfLodging);
closingDatedOfApplication = formatter.parse(closingDateOfApplication);
c.add(Calendar.DATE, -1);
c2.add(Calendar.DATE, -1);
c3.add(Calendar.DATE, -1);
c4.add(Calendar.DATE, -1);
c5.add(Calendar.DATE, -1);
startDate = formatter.format(c.getTime());
endDate = formatter.format(c2.getTime());
startDateOfLodging = formatter.format(c3.getTime());
endDateOfLodging = formatter.format(c4.getTime());
closingDateOfApplication = formatter.format(c5.getTime());
}
catch (ParseException e1) {
e1.printStackTrace();
}
t.add(new TripSearchy (id, opId, overseasProgramme, name, startDated, startDate, endDated, endDate, costOfTrip, ns, nsf, staffName, tourGuideName, tourGuideContact, companyName, agentName, agentContact, airlineChoice, placeOfLodging, startDatedOfLodging, startDateOfLodging, endDatedOfLodging, endDateOfLodging, maxNoOfParticipants, closingDatedOfApplication, closingDateOfApplication, instructions, psea, fasop, ktpiop));
}
}catch (Exception e) {
e.printStackTrace();
}
db.terminate();
}
似乎我已经耗尽了我的连接= \我是否知道如何减少连接使用/增加连接容量？
更新
DBController.java
public class DBController {
private DataSource ds;
Connection con;
public void setUp() throws NamingException{
//connect to database
Context ctx = new InitialContext();
ds = (DataSource)ctx.lookup("java:comp/env/jdbc/it2299");
}
public ResultSet readRequest(String dbQuery){
ResultSet rs=null;
try{
con = ds.getConnection();
Statement stmt = con.createStatement();
rs = stmt.executeQuery(dbQuery);
}
catch(Exception e){e.printStackTrace();}
return rs;
}
public int updateRequest(String dbQuery){
int count=0;
try{
con = ds.getConnection();
Statement stmt = con.createStatement();
count=stmt.executeUpdate(dbQuery);
}
catch(Exception e){e.printStackTrace();}
return count;
}
public void terminate(){
try {con.close();}
catch(Exception e){e.printStackTrace();}
}
}
更新2： 当我的ManagedBean（TripTableBean.java）的范围是ViewScoped时，会发生此异常，当我将其更改为SessionScoped时不会发生此异常。但是，如果它是SessionScoped，我将需要找到一种方法来杀死会话并在我来到这个网页时重新创建一个新的会话，如果不是这个页面上的dataTable将不会从数据库加载更新的更改。
答案 0 :(得分：4)
当你暗示自己时，你的代码太可怕了。您需要确保在try-finally块的 shortest possibe 范围内获取和关闭所有JDBC资源。重写您的代码，使其遵循以下标准JDBC习惯用法：
public List<Entity> list() throws SQLException {
Connection connection = null;
PreparedStatement statement = null;
ResultSet resultSet = null;
List<Entity> entities = new ArrayList<Entity>();
try {
connection = Database.getConnection();
statement = connection.prepareStatement("SELECT id, foo, bar FROM entity");
resultSet = statement.executeQuery();
while (resultSet.next()) {
Entity entity = new Entity();
entity.setId(resultSet.getLong("id"));
entity.setFoo(resultSet.getString("foo"));
entity.setBar(resultSet.getString("bar"));
entities.add(entity);
}
} finally {
if (resultSet != null) try { resultSet.close(); } catch (SQLException ignore) {}
if (statement != null) try { statement.close(); } catch (SQLException ignore) {}
if (connection != null) try { connection.close(); } catch (SQLException ignore) {}
}
return entities;
}
答案 1 :(得分：1)
你有什么连接池设置可以在DBController中发布什么内容？ 提示：db.terminate（）应该在finally {}块中，可能是异常连接丢失。
<强>更新 发布一些可能对您有所帮助的修改，但为了维护起见，请清理代码。寻找已经做出改变的评论。
public class DBController {
private DataSource ds;
private Connection con;// NEW CHANGE
public void setUp() throws NamingException{
//connect to database
Context ctx = new InitialContext();
ds = (DataSource)ctx.lookup("java:comp/env/jdbc/it2299");
con = ds.getConnection(); // NEW CHANGE
}
public ResultSet readRequest(String dbQuery){
ResultSet rs=null;
try{
//REMOVED CODE FROM HERE
Statement stmt = con.createStatement();
rs = stmt.executeQuery(dbQuery);
}
catch(Exception e){e.printStackTrace();}
return rs;
}
public int updateRequest(String dbQuery){
int count=0;
try{
//REMOVED CODE FROM HERE
Statement stmt = con.createStatement();
count=stmt.executeUpdate(dbQuery);
}
catch(Exception e){e.printStackTrace();}
return count;
}
public void terminate(){
try {con.close();}
catch(Exception e){e.printStackTrace();}
}
}
我无法改进代码，但我建议看一下网络上的一些最佳实践以及@BalusC的建议。 请记住：完成后关闭连接对象。