我對gwt相當陌生,並且找出與mysql數據庫的連接讓我難堪。由於很少有直接的教程,所以我在這裏討論了另一個stackoverflow問題。到數據庫的GWT/Mysql/Java連接
http://stackoverflow.com/questions/8335322/java-gwt-mysql-connection-refused/8388422#8388422
雖然我不明白。很少有東西,這個項目並沒有使用GAE,而只是GWT,就像之前在其他問題中所回答的那樣。是的,我可以通過另一個示例程序連接到我的數據庫,因此數據庫的鏈接已打開。我還將我的mysql驅動程序導入到/ WEB-INF/lib中,並將其添加到我的java構建路徑中。這個問題的癥結在於,我不知道爲什麼我不能連接,而且我的控制檯沒用,如果任何人都可以看到蝙蝠,我做錯了那將是太棒了,或者如果有的話是一種打印出更好的錯誤信息的方法,以及我不知道如何查看服務器端資源的控制檯(我在某處讀到可能存在更多錯誤,然後顯示什麼內容? ) 謝謝。
這裏是我的GreetingServiceImpl.java相關代碼
private final Connection connect() {
String driver = "com.mysql.jdbc.Driver";
String dblink = "jdbc:mysql://localhost:3306/";
String dbname = "gwttest";
String dbuser = "user";
String dbpass = "test";
try {
Class.forName(driver).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Connection conn = null;
try {
conn = DriverManager.getConnection(dblink + dbname, dbuser, dbpass);
} catch (SQLException e) {
System.err.println("mysql connection error: ");
e.printStackTrace();
}
return conn;
}
這裏是我的helloserver.java相關代碼
Button b = new Button("test");
vPanel.add(b);
b.addClickHandler(new ClickHandler() {
@Override
public void onClick(ClickEvent event) {
GreetingServiceAsync testservice= (GreetingServiceAsync) GWT.create(GreetingService.class);
testservice.echo("test", new AsyncCallback<String>() {
@Override
public void onFailure(Throwable caught) {
// TODO Auto-generated method stub
vPanel.add(new Label("error"));
//vPanel.add(new Label(caught.printStackTrace());
caught.printStackTrace();
}
@Override
public void onSuccess(String result) {
// TODO Auto-generated method stub
vPanel.add(new Label(result));
}
});
}
});
這裏是錯誤消息我已經在運行,點擊按鈕(收到除了「錯誤」,這在我的HTML彈出)
com.google.gwt.user.client.rpc.StatusCodeException: 404 <html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/>
<title>Error 404 NOT_FOUND</title>
</head>
<body><h2>HTTP ERROR: 404</h2><pre>NOT_FOUND</pre>
<p>RequestURI=/helloserver/greet</p><p><i><small><a href="http://jetty.mortbay.org/">Powered by Jetty://</a></small></i></p><br/>
</body>
</html>
at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:209)
at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287)
at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:338)
at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:219)
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:571)
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:279)
at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:242)
at sun.reflect.GeneratedMethodAccessor23.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:293)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:547)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
at java.lang.Thread.run(Unknown Source)
你是對的,我改變了web.xml文件,並忘記將它改回來。我恢復了原來的狀態,我的問題解決了。 – john 2013-02-27 15:45:49