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List<Map<String,Object>> to org.json.JSONObject?

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问题 List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); Map<String, Object> map = new HashMap<String, Object>(); map.put("abc", "123456"); map.put("def", "hmm"); list.add(map); JSONObject json = new JSONObject(list); try { System.err.println(json.toString(2)); } catch (JSONException e) { e.printStackTrace(); } What's wrong with this code? The output is: {"empty": false} 回答1: public String listmap_to_json_string(List<Map<String, Object>> list) { JSONArray json_arr=new JSONArray(

@PreDestroy never called on @ViewScoped

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I have a @ViewScoped bean that has a method with an @PreDestroy annotation that should make sure some remote connections are closed. However, the method is not called when the user navigates away. Is there anything one can do wrong? Do I have to register anything anywhere in order to make it work? It's a simple public method ( void ) that throws no exception. I'm using JSF 2 (MyFaces) with Tomcat 7.0.12. Could it be a problem with Tomcat? UPDATE The @PostConstruct annotation works fine. BalusC This is a known issue and unfortunately not trivial to solve without letting all the navigation take

Spring - set a property only if the value is not null

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问题 When using Spring, is it possible to set a property only if the value passed is not null? Example: <bean name="myBean" class="some.Type"> <property name="abc" value="${some.param}"/> </bean> The behavior I'm looking for is: some.Type myBean = new some.Type(); if (${some.param} != null) myBean.setAbc(${some.param}); The reason I need this is since abc has a default value which I don't want to override with a null . And the Bean I am creating is not under my source control - so I cannot change

Easy way of populating Javabeans based on request parameters

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I have a simple person class: package simpleApp.entities; public class Person { private String name; private String secondname; public void setSecondname(String cognome) { this.secondname = cognome; } public String getSecondname() { return secondname; } public void setName(String nome) { this.name = nome; } public String getName() { return name; } } and a simple html page: <html> <body> <form action="/simpleApp/person/" method="POST"> name: <input type="text" name="name"><br> second name: <input type="text" name="secondname"><br> <input type="submit"> </form> </body> </html> and a simple

How can I turn off extra logging?

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问题 I have a Java service that uses Spring and CXF. The code is from a previous developer and I'm providing maintenance, but I'm seeing this in the logs -------------------------------------- Apr 16, 2013 1:44:11 PM org.apache.cxf.interceptor.AbstractLoggingInterceptor log INFO: Inbound Message ---------------------------- ID: 33 Address: /MyApplication/endpoint Encoding: UTF-8 Http-Method: POST Content-Type: application/x-www-form-urlencoded Headers: {content-type=[application/x-www-form

Using a Stateful Session Bean to track an user's session

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it's my first question here and I hope that I'm doing it right. I need to work on a Java EE project, so, before starting, I'm trying to do something simple and see if I can do that. I'm stuck with Stateful Session Beans . Here's the question : How can I use a SFSB to track an user's session? All the examples that I saw, ended up in "putting" the SFSB into a HttpSession attribute. But I don't understand why! I mean, if the bean is STATEFUL, why do I have to use the HttpSession to keep it? Isn't an EJB Container's task to return the right SFSB to the client? I've tried with a simple counter bean

Difference between managed bean and backing bean

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I came across the terms "managed bean" and "backing bean" in several forums. Many people think both are the same. But, there seems to be a slight difference. Can any one help me to understand the exact difference between these two terms? Changing my initial answer - there is no meaningful difference between the two. The tutorial says that backing beans are later declared as managed beans. So, to summarize: a backing bean is the class out of context a managed bean is the backing bean whenever it is declared to be used with the JSF managed bean facility. I've never actually used the term

redirect from jsf?

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问题 I am working on application with jsp, jstl and jsf for my college project, thats being said, I am as well very new to jsf. Everything is going great so far. However, I seems to have a problem figuring out how to do redirect from managed bean to page with dinamyc parameters. For example article.jsp?article_id=2 Can somebody tell me how it is done ? I been trying to use somethinng like FacesContext.getCurrentInstance().getExternalContext().dispatch("faces/article.jsp2?article_id=" + articleId);

How do I print a list of strings contained within another list in iReport?

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问题 I am creating a simple reporting program using java and iReport (from jasper), which is supposed to create a report in pdf showing PCs with their IP address, their location, whether it's idle or not at the moment (handled by another system), and a list of projects it is currently attached to (managed elsewhere, too). I'm using iReport for this matter, and have created a dummy collection generating class as follows: public class PCReports { public static java.util.Collection PC_collection;

ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/mail/MessagingException

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I am getting a strange ClassFormatError when using the javaMail api to send email on my spring mvc web app. Below is my mail-cfg.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/mvc http://www.springframework