Java

Amazon AWS EC2 Security Group and S3 Bucket Configuration

Amazon AWS EC2  Security Group and S3 Bucket configuration

Read our previous post : How to Create And Configure Amazon EC2 Free tier account

Amazon AWS is an awesome cloud service, It is worth writing a post on AWS service and its usage.

It is very easy to create an AWS account and use it, but most people will struck when its matter of security. Amazon setup is little bit complicated for security configuration. Please follow the steps given below to enable security group in your amazon cloud service.

Steps For Amazon EC2 Security Group:

Step 1: Go to your EC2 Service as shown in the image below

EC2

EC2

Step 2: Go to the section Security Group

Amazon Security Group

Amazon Security Group

 

Step 3: Enter Group Details 

Amazon Security group details

Amazon Security group details

 

Step 4: Add following rules 

Inbound

  • Rule 1

 Type : HTTP

 Protocol : TCP

 Port Range : 80

 Source : 0.0.0.0/0

  • Rule 2

 Type : All traffic

 Protocol : All traffic

 Port Range : All traffic

 Source : Your Ip Address ( search in google What Is My IP, copy paste the same IP here )

  • Rule 3

 Type : SSH

 Protocol : TCP

 Port Range : 22

 Source : Your Security Group Id

  • Rule 4

 Type : MYSQL

 Protocol : TCP

 Port Range : Mysql port ( 3306 )

 Source : Your Security Group Id

Outbound

  • Rule 1

 Type : HTTP

 Protocol : TCP

 Port Range : 80

 Source : 0.0.0.0/0

  • Rule 2

 Type : All traffic

 Protocol : All traffic

 Port Range : All traffic

 Source : Your Ip Address ( search in google What Is My IP, copy paste the same IP here )

  • Rule 3

 Type : MYSQL

 Protocol : TCP

 Port Range : Mysql port ( 3306 )

 Source : Your Security Group Id

Amazon S3 Bucket configuration

Step 1 : Go to Administration and Security from Amazon Services

Amazon S3 : IAM

Amazon S3 : IAM

 

Step 2 : Select Group from the IAM page

Step 3: Create new group, Give any name for the group

Step 4: The most important step is to set Policy type for the S3 bucket.

For file upload/download, Select AmazonEC2FullAccess

If this is done then your Amazon S3 is ready for use.

Step 5: Go to S3 service from the main menu

There create new bucket. Set permissions to your bucket as per your need.

File Upload to Amazon S3 bucket in Java 

Code Sample :

private static String bucketName = “”; //Give your YourS3Bucket name
private static String keyName = “”; // Give SomeKey

public final static String FOLDER_PATH = “TestFolder”;

public final static String rootServerURL = “”; //Your S3 Bucket Path => Your Amazon Instance / BucketName

BasicAWSCredentials awsCreds = new BasicAWSCredentials(“AccessKey”, “SecretKey”);

AmazonS3 s3client = new AmazonS3Client(awsCreds);

PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, keyName, fileObject);
putObjectRequest.withCannedAcl(CannedAccessControlList.PublicRead); // Read Permission for all
s3client.putObject(putObjectRequest);

Lambda Expressions in java – A Java 8 feature

What are Lambda Expression – Java 8 new feature?

Lambda expressions refers to what we had anonymous classes in the older versions of java.

So the very next straight forward thing comes to our mind, if already java is having anonymous classes why a replacement for the same is needed?

Why are Lambda Expressions needed, even if anonymous classes already exist?

The answer goes very simple, Lambda expressions when used makes our code more lighter as compared to when we use anonymous classes.

For Example:

Consider there is a class called Person
To sort the Person class by name if we use anonymous class we have to use the following code

Collections.sort(list, new Comparator() {
  @Override
  public int compare(Person p1, Person p2) {
       return p1.getName().compareTo(p2.getName());
  }
 });

But if we use Lambda expressions it will reduce to just 1 line, as show below,

Collections.sort(list, (Person p1, Person p2) -> p1.getName().compareTo(p2.getName()));

reduces lot of bulky codes.

Lets Discuss one example in detail:

We all are aware of Service Oriented Architecture if not please go through the tutorial 

Calling services will always be time consuming (in general all network calls are considered slow), so we handle those requests asynchronously. If the call is asynchronous then in order to get the response from the service we expect a call back to be called which will return us the result.

The following example demonstrates rather tries to simulate such a scenario,
Consider the following class “ThreadCallableClass” which will make the call to service,

//CallBack.java
package com.dhi.callback;

@FunctionalInterface
public interface CallBack {
	void operationCompelte(String args);
}


//ThreadCallableClass.java

package com.dhi.thread;

import java.util.concurrent.Callable;

import com.dhi.callback.CallBack;

public class ThreadCallableClass implements Callable<String>{
	
	public ThreadCallableClass(CallBack callBack) {
		this.callBack = callBack;
	}

	CallBack callBack;

	String str;
	
	public String getStr() {
		return str;
	}

	public void setStr(String str) {
		this.str = str;
	}
	
	@Override
	public String call() throws Exception {
		System.out.println("service is getting called with the value: " + str);
		//code to call the service to fetch some details
		callBack.operationCompelte(str);
		return "return " + str;
	}

}

//MAIN.JAVA

package com.dhi.main;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import com.dhi.thread.ThreadCallableClass;

public class MainClass {

	public static void main(String[] args) {
		List<String> list = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			list.add("dhi" + i);
		}

		ArrayBlockingQueue<Runnable> arrayBlockingQueue = new ArrayBlockingQueue<Runnable>(
				1000);
		ExecutorService executorService = new ThreadPoolExecutor(10, 100, 20,
				TimeUnit.SECONDS, arrayBlockingQueue);
		for (String eachStr : list) {
			ThreadCallableClass callable = new ThreadCallableClass((String test1) -> {System.out.println(" call back getting called for the service for "+ test1);});
			callable.setStr(eachStr);
			executorService.submit(callable);
		}
		System.out.println("after thread pool");
		executorService.shutdown();
	}

}

//Person.java
package com.dhi.main;

import java.io.Serializable;

public class Person implements Serializable{
	
	String name;
	String mob;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getMob() {
		return mob;
	}
	public void setMob(String mob) {
		this.mob = mob;
	}

}


Download Code
DhiJava8LambdaFeature

Spring3 Issue with java8

Spring3 Issue with java8

Most common problem every one face during upgrading java to java8

Problem: All is well in your java spring3 web application, suddenly you start getting,







java.lang.IllegalArgumentException
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.core.type.classreading.SimpleMetadataReader.(SimpleMetadataReader.java:52)
at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80)
at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101)
at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230)
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4961)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5455)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)


			




Solution:

This issue is due to update of java to java 8, Following are the solutions for the same,

  1. You still intend to use java8 then spring must be upgraded to 4 or
  2. Change back the version of java to java7.

Steps to change in eclipse,

  1. Right click on the project and goto properties.
  2. Select “Java Build Path”.
  3. Goto “Libraries” tab.
  4. Select JRE System Lib (sometimes the name will mislead, it will be showing java7 but internally it will be pointing to java8).
  5. Click on “Edit” button present on the right side.
  6. Select “Alternate JRE” and click on “Installed JRE”.
  7. Click on “Add” è “Standard VM”.
  8. Click on “Directory” and select the JRE7 home.
  9. An entry for jre7 will be present, check the check box present against jre7.
  10. Click “Ok”
  11. Click on “Finish”.
  12. Click “Ok” again.
  13. Click on “Project” menu and then “Clean”
  14. Wait till the build completes.

You are good with all now again.

Jersey ClientHandlerException : A message body writer for Java type, class org.json.JSONObject, and MIME media type,

lientHandlerException: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json,

com.sun.jersey.api.client.ClientHandlerException: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json, was not found
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:149)
    at com.sun.jersey.api.client.Client.handle(Client.java:648)
    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:670)
    at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74)
    at com.sun.jersey.api.client.WebResource$Builder.post(WebResource.java:563)
    at com.knowledgecess.test.service.impl.TestServiceImpl.getQuestions(TestServiceImpl.java:48)
    at com.knowledgecess.test.action.TestAction.demotest(TestAction.java:70)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:511)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:432)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1653)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json, was not found
    at com.sun.jersey.api.client.RequestWriter.writeRequestEntity(RequestWriter.java:288)
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler._invoke(URLConnectionClientHandler.java:204)
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:147)
    ... 74 more
knowledgecess







Solution :
Just find jsonInput, second parameter for post() in the below code add toString to jsoninput data

ClientResponse clientResponse = webResource
                .accept(MediaType.APPLICATION_JSON)
                .type(MediaType.APPLICATION_JSON)
                .post(ClientResponse.class, jsonInput);

FIX –

ClientResponse clientResponse = webResource
.accept(MediaType.APPLICATION_JSON)
.type(MediaType.APPLICATION_JSON)
.post(ClientResponse.class, jsonInput.toString());

Java Jar files; Java Libraries; JSON lib;

Java Jar files and Uses

JAR:  aopalliance-repackaged-2.2.0.jar 

Usage: aop alliance will be internally used by

Note : Google Guice Core is a powerful library released by Google for dependency injection, this works with java 6 and above ( download )

JAR:  apache-mime4j-0.6.jar

Usage: apache mime will be used for mime message parsing. This jar internally used by 

  • commons-io
  • commons-logging
  • junit like testing libraries
  • log4j 

JAR : commons-io

Usage – commons io provides utility classes, stream implementations, file filters,file comparators, endian transformation classes

JAR : asm-3.3.jar

Usage : asm jar will be used to analyse the byte code and analyse the frameworks

Note: asm is used by certain code generation libraries like cglib

JAR : gson-2.3.jar 

Usage : gson used to convert java objects into json object. Can be used in struts and springs to convert java objects. ( Documentation )

 JAR : persistence-api-1.0.jar

 Usage : The Java Persistence API provides Java developers with an object/relational mapping facility for managing relational data in Java applications

Dependencies :

  • Servlet-API
  • Javax.inject 

JAR : hk2-api-2.2.0.jar 

Usage : This is called hundred kilobyte kernal for glassfish server, It forma the core glassfish server architecture

 

Hibernate NoSuchBeanDefinitionException : Java Hibernate Exception

Hibernate NoSuchBeanDefinitionException : Java Hibernate Exception

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.cess.service.Employee.EmployeeService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=EmployeeServiceImpl)} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:949) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:818) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:730) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) … 25 more

Solution – 

This issue is a strange issue in hibernate autowire for bean objects, the solution will be as follows but no technical description why so ? 🙂

@Autowired
@Qualifier("EmployeeServiceImpl")
EmployeeService employeeService;  //EmployeeService is an interface


			




Change the above @Qualifier as below 
@Qualifier("employeeServiceImpl")

Note : the only change is instead of capital E in EmployeeServiceImpl, it should be small 'e' employeeServiceImpl
If it is reverse case then do make it Capital .

Hibernate QueryException : could not resolve property:

Hibernate QueryException :  could not resolve property:

org.hibernate.QueryException: could not resolve property: DP of: com.cess.pojo.Customer
at org.hibernate.persister.entity.AbstractPropertyMapping.propertyException(AbstractPropertyMapping.java:67)
at org.hibernate.persister.entity.AbstractPropertyMapping.toType(AbstractPropertyMapping.java:61)
at org.hibernate.persister.entity.AbstractEntityPersister.getSubclassPropertyTableNumber(AbstractEntityPersister.java:1402)
at org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:54)
at org.hibernate.persister.entity.AbstractEntityPersister.toColumns(AbstractEntityPersister.java:1377)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumns(CriteriaQueryTranslator.java:457)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumnsUsingProjection(CriteriaQueryTranslator.java:417)
at org.hibernate.criterion.SimpleExpression.toSqlString(SimpleExpression.java:68)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:357)
at org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:113)
at org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:82)
at org.hibernate.loader.criteria.CriteriaLoader.(CriteriaLoader.java:91)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1577)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
at com.cess.dao.impl.CusomerDaoImpl$1.execute(CustomerDaoImpl.java:77)
at com.cess.framework.TransactionWrapper.run(TransactionWrapper.java:41)
at com.cess.dao.impl.CustomerDaoImpl.getCustomers(CustomerDaoImpl.java:43)
at com.cess.service.impl.CustomerServiceImpl.getCustomers(customerServiceImpl.java:39)
at com.cess.controller.CustomerController.Customers(CustomerController.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:746)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:687)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:822)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1653)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

			




Solution –
Instead of using nested paths directly in Criteria API (unlike HQL), create nested criteria instances and use aliases on each “entity.property”
Example –







Criteria criteria = sessionObject
.createCriteria(Customer.class, "C")
.createAlias("C.department", "D")
.createAlias("D.Section", "S")
.createAlias("S.SubSection", "SB")

SEVERE: Exception sending context initialized event to listener instance of class

SEVERE: Exception sending context initialized event to listener instance of class

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping found. Cannot map '/project' bean method
public java.util.ArrayList com.cess.controller.UserProjectController.UserProject(com.cess.pojo.Class)
to {[/get],methods=[POST],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already '/userinfo' bean method
public java.lang.String com.cess.controller.UserController.userInfo(com.cess.pojo.User) mapped.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1486)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:524)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:461)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:607)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: Ambiguous mapping found. Cannot map '/project' bean method
public java.util.ArrayList com.cess.controller.UserProjectController.UserProject(com.cess.pojo.Class)
to {[/get],methods=[POST],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already '/userinfo' bean method
public java.lang.String com.cess.controller.UserController.userInfo(com.cess.pojo.User) mapped.
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:179)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:145)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:107)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:87)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:150)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1483)
... 22 more

Solution
If your controller class are as follows








			




@Controller("/userinfo")
public class UserController {
@RequestMapping(method=RequestMethod.POST)
 public String userInfo(@RequestBody User user){
 }
}

@Controller("/userproject") 
public class UserProjectController {

@RequestMapping(method=RequestMethod.POST)
  public String userProject(@RequestBody UserProject userProject){
  }
}

//Then Use value Element of @RequestMapping as follows
@Controller
public class UserController {
 
 @RequestMapping(value = "/getuserinfo", method=RequestMethod.POST)
 
  public String userInfo(@RequestBody User user){

  }
}


@Controller
public class UserProjectController {
 //Note value in both controller requestMapping should be different
 
 @RequestMapping(value = "/getuserproject",method=RequestMethod.POST)
  public String userProject(@RequestBody UserProject userProject){

  }
}

Introduction to Struts

Struts is an open source web application framework which will be used to develop the web-
based applications. Struts framework was implemented based on 3 popular design patterns.

  • MVC design pattern.
  • Front Controller design pattern.
  • Application Controller design pattern.

MVC design pattern :-

There are 3 layers in MVC Design pattern

I.  Presentation Layer

II.  Controller Layer

III.  Model Layer

Capture1

I Presentation Layer :-

It contains the presentation logic and can be implemented with JSP or with any other presentation frameworks like flex, velocity etc. Struts Presentation Layer contains following components.

1)     JSPs/HTMLs
2)      Struts custom tags
3)      Form Beans
4)      Message Bundles

1)     JSPs/HTMLs:

In struts presentation layer JSPs will be used to display the data to the client and also used to receive the input data from the client.

2)      Struts custom tags:

Apache has implemented various custom tags for the struts based application development and are categorized as follows.

  • Html tag libraries
  • Bean tag libraries
  • Logic tag libraries
  • Tiles tag libraries
  • Template tag libraries
  • Nested tag libraries
  1. Form Beans:

Form bean is a simple java bean styled class which stores the data. When we are writing the form bean java class, the bean class must be a subclass of one of the following.

  • ActionForm
  • DynaActionForm
  • ValidatorForm
  • DynaValidatorForm
  • ValidatorActionForm
  • DynaValidatorActionForm

 

  1. Message Bundles:

Message Bundles are nothing but property files which contain key value pair. Mainly message bundles will be used to achieve i18n (internationalization).

II Controller Layer :-

The Controller portion of the application is focused on receiving requests from the client (typically a user running a web browser), deciding what business logic function is to be performed, and then delegating responsibility for producing the next phase of the user interface to an appropriate View component. Following are the various components which we use in struts controller layer.   

   i)   ActionServlet

   ii)  RequestProcessor

   iii)  Action class

 i) ActionServlet:

ActionServlet is the one and only servlet for the entire struts application which is implemented based on Front controller design pattern and this servlet is loaded during server startup time. ActionServlet is responsible for receiving all incoming request and delegating to RequestProcessor. It also initialize the struts-config.xml file.

 ii)  RequestProcessor

RequestProcessor is responsible for processing all incoming request. It is implemented on Application Controller Design pattern. RequestProcessor is responsible for identifying the incoming action class and its form bean, it is also responsible for managing life cycle of form bean. After getting response, it manages to return to corresponding jsp by using ActionForward.

iii)  Action class

Action Class is the beginning of application’s business logic.

III Model Layer : –

Since there are no predefined components for model layer in struts like presentation layer and controller layer, so struts will not deal with model layer. But struts allows us to make use of any of the following model layer.

i)    Simple JDBC component

ii)   DAO + Hibernate

iii)  DAO + JDBC

iv)  Spring

v)   Web services     etc…

STRUTS FLOW

Capture1flow diagram showing struts flow

Steps for the flow         

  • When we submit the request after entering value in jsp form, request will be submitted to ActionServlet which is configured in web.xml.
  • This ActionServlet is responsible for initializing struts-config.xml and this struts-config.xml file is     configured in web.xml.
  • ActionServlet delegates the request to RequestProcessor
  • RequestProcessor takes the incoming request uri and tries to find the matching <action> tag in struts-config.xml. If no matching action is found, then client will get “cannot retrieve mapping for action”.
  • Once matching action is found for the incoming request uri, then corresponding “name” will be taken and tries to find the corresponding <form-bean> under <form-beans> configuration. If no matching <form-bean> is found then client will get the error called “cannot retrieve definition for form beans”.
  •  Once matching is found, RequestProcessor is responsible for managing form-bean life cycle.
  •  RequestProcessor takes the <action> “type” which is Action java class and create the instance    for the first time. With that Action class instance, execute() method  will be called.
  •  Once execute() method is completed ActionForward will be returned to RequestProcessor with      the forward name associated with the ActionForward object and RequestProcessor will try to  identify corresponding <forward> inside struts-config.xml file.
  •  Once the forward is found then its path will be taken and will be forwarded to the client.
  •   RequestProcessor takes the <action> “type” which is Action java class and create the instance     for the first time. With that Action class instance, execute() method  will be called.
  •  Once execute() method is completed ActionForward will be returned to RequestProcessor with  the forward name associated with the ActionForward object and RequestProcessor will try to  identify corresponding <forward> inside struts-config.xml file.
  •  Once the forward is found then its path will be taken and will be forwarded to the client.