javabeans

问题 Why some times tutorials make beans implement Serializable object and others do not? I know that object should be serialized when I want to send it through a network, so does that prove that each bean used in sessions should implements Serializable objects and beans defined in JSP pages should not since they are not transferred using HTTP requeset 回答1: I know that object should be serialized when I want to send it through a network, so does that prove that each bean used in sessions should

问题 I have created a from which have a text field name 'empId' whose value is set into a bean class through a jsp page using <jsp:setProperty> tag note:empId is of int type in bean class when i write the following code <jsp:setProperty name="mybean" property="empId" value="empId"/> It will work fine but when i write the following code <jsp:setProperty name="mybean" property="empId" value="<%=request.getParameter("empId")%>"/> then it is not working gives the exception JasperException 回答1: Use EL

问题 I have one field which is a composition of two values. This is the field that gets serialized to/from JSON and works great. public String getRevisions() { return revisions; } public void setRevisions(String revisions) { this.revisions = revisions; } I added two helper methods to retrieve the separate values, but I don't want them serialized to JSON. public String getCurrentRevision() { ... return first revision ... } public String getPreviousRevision() { ... return second revision ... } Is

问题 Defining data members in a class that can be publicly accessed/modified var _foo: Int = _ def foo_(foo: Int) = _foo = foo // setter function def foo = _foo // getter function Is it a good practice to convert this using annotation @BeanProperty ? import scala.reflect.BeanProperty @BeanProperty var foo: Int = _ and when to use this annotation and when not to? 回答1: There's some redundancy in your first example, since defining a var already results in the generation of getters and setters. For

问题 I have a JSP page with checkboxes inside an HTML form as below Now while editing user Skill I want to take the comma separated values from the table and populate the checkboxes in JSP. The following code brings the CSV Skills from the database table. List<UserDetails> Skills = new ArrayList<UserDetails>(); pstmt = (PreparedStatement) conn.prepareStatement(strSQL); rs = pstmt.executeQuery(); String strSkills = rs.getString("Skills"); List<String> items = Arrays.asList(strSkills.split("\\s*,\\s

问题 I'm currently trying to use jasper to help me create reports. I have the information and data that I want displayed in this method: private void writeToFile(final List<ScenarioLoadModel> sceneLoadModel) throws Exception { final BufferedWriter bw = new BufferedWriter(new FileWriter("/Uma/nft/result.psv")); for (final ScenarioLoadModel slm : sceneLoadModel) { bw.write(slm.getScenarioId() + PSP + slm.getScenarioId() + PSP + slm.getScenarioConfig().getName() + PSP + slm.getLoad() + PSP + "" + EOL

问题 Hi can i configure gson that he use int instead of double got data like: {fn: chat, data: {roomId: 1, text: "Some brabble"}} I got a PacketClass to deserialize it to: public class DataPacket { private String fn; private Object p; // will be a StringMap } and decode like: DataPacket pkg = gson.fromJson(message, DataPacket.class); for better typehandling i got a data pojo for the DataPacket.p field for example: public class ChatPacket { public int roomId; public String message; public String

问题 I am trying to inject a service into my bean but it is always null . I get the following error: WELD-001000 Error resolving property userBean against base null. Some code snippets: index.xhtml <h:body> Hello from Facelets #{userBean.name} </h:body> userbean.java package beans; import Domain.User; import java.io.Serializable; import javax.enterprise.context.SessionScoped; import javax.inject.Inject; import javax.inject.Named; import service.UserService; @Named @SessionScoped public class

问题 When I run my application, it stops when beans are initializing but doesn't show any logs entries. So I don't know what happened: Log4j.properties log4j.rootLogger=DEBUG, stdout, R log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout org.springframework=DEBUG org.springframework.beans.factory.support=DEBUG log4j.logger.org.springframework.beans.factory.support=DEBUG log4j.logger.org.springframework.beans=DEBUG log4j.category.org

问题 I am stuck at converting Java Bean to Map . There are many resources on the internet, but unfortunately they all treat converting simple beans to Maps. My ones are a little bit more extensive. There's simplified example: public class MyBean { private String firstName; private String lastName; private MyHomeAddress homeAddress; private int age; // getters & setters } My point is to produce Map<String, Object> which, in this case, is true for following conditions: map.containsKey("firstName")