小编Har*_*ara的帖子

当我尝试使用JPA使用hibernate进行bean验证时,会发生以下异常:

Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: Chapter11] Unable to build EntityManagerFactory
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:915)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:890)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:57)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
at example.test.Test.main(Test.java:18)

Caused by: org.hibernate.HibernateException: Error applying BeanValidation relational constraints
at org.hibernate.cfg.beanvalidation.BeanValidationIntegrator.applyRelationalConstraints(BeanValidationIntegrator.java:219)
at org.hibernate.cfg.beanvalidation.BeanValidationIntegrator.integrate(BeanValidationIntegrator.java:126)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:306)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1744)
at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:94)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:905)
... 5 more

Caused by: java.lang.reflect.InvocationTargetException
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 org.hibernate.cfg.beanvalidation.BeanValidationIntegrator.applyRelationalConstraints(BeanValidationIntegrator.java:208)
... 10 more
Caused by: java.lang.NoClassDefFoundError: javax/validation/ParameterNameProvider
at org.hibernate.validator.HibernateValidator.createGenericConfiguration(HibernateValidator.java:41)
at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:269)
at javax.validation.Validation.buildDefaultValidatorFactory(Validation.java:111)
at org.hibernate.cfg.beanvalidation.TypeSafeActivator.getValidatorFactory(TypeSafeActivator.java:521)
at …

今天我发现,对于Java中的并发性我们有很好的框架Akka,我也发现,有一个反应式编程框架就像在应用程序中RxJava执行一样multithreading.但我还是很困惑!为什么两者都优于Java Concurrency框架？

如今响应式编程是成熟的话题,大多数语言都支持Functional Reactive Programing像Netflix有关的API提供Reactive programming了一种以上的语言.Rxjava是用于API之一java,scala等等.根据RxJava他们内部使用演员为维护multithreading和Akka也使用Actors了multithreading编程.

那么,它们之间的区别Akka和Reactive Programming方法之间的区别是Java Concurrency什么？

我正在尝试使用spring-security-oauth2.0基于Java的配置.我的配置已完成,但是当我在tomcat上部署应用程序并点击/oauth/token访问令牌的url时,会Oauth生成以下错误:

<oauth>
<error_description>Full authentication is required to access this resource</error_description>
<error>unauthorized</error>
</oauth>

我的配置在Git中心,请点击链接

代码很大,所以请参考git.我正在使用chrome postman客户端发送请求.以下是我的要求.

POST /dummy-project-web/oauth/token HTTP/1.1
Host: localhost:8081
Cache-Control: no-cache
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials&client_id=abc%40gmail.com&client_secret=12345678 

错误就像,URL是安全的Oauth,但在配置中,我给予访问此URL的所有权限.这个问题究竟是什么？

我正在尝试创建一个maven多模块项目.项目创建成功,但当我尝试使用一个模块作为另一个模块的依赖项时,它会生成异常.当我使用eclipse创建模块时,我选择打包为jar,但是当创建模块时,在子pom.xml中没有提及包装标签,我手动将包装标签作为jar插入.以下是我的父母pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.netsol</groupId>
<artifactId>empirecl</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
-------------------------
<modules>
    <module>empirecl-web</module>
    <module>empirecl-dao</module>
    <module>empirecl-service</module>
    <module>empirecl-api</module>
</modules>

道儿童模块:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>com.netsol</groupId>
    <artifactId>empirecl</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <relativePath>../pom.xml</relativePath>
</parent>
<artifactId>empirecl-dao</artifactId>
<packaging>jar</packaging>
<name>empirecl-dao</name>
------------------------

服务子模块:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>com.netsol</groupId>
    <artifactId>empirecl</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <relativePath>../pom.xml</relativePath>
</parent>
<artifactId>empirecl-service</artifactId>
<packaging>jar</packaging>
<name>empirecl-service</name>

<dependencies>
    <dependency>
        <groupId>com.netsol</groupId>
        <artifactId>empirecl-dao</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <type>jar</type>
    </dependency>
------------------------------------------

Dao模块maven清理并安装成功,但是当我尝试使用服务模块时,它将生成以下异常:

[ERROR] Failed to execute goal on project empirecl-service: Could not resolve dependencies for project com.netsol:empirecl-service:jar:0.0.1-SNAPSHOT: Failed to collect …

我试图在java中使用lambda表达式创建一个示例,我正在使用官方JDK8.我的例子运行成功.但是当我试图检查编译器如何将lambda表达式转换为字节代码时,这让我有些困惑.以下是我的例子的代码: -

public class LambdaTest {
    public Integer lambdaBinaryOpertor(BinaryOperator<Integer> binaryOperator) {
        return binaryOperator.apply(60, 72);
    }

    public static void main(String[] args) {
        LambdaTest test = new LambdaTest();
        BinaryOperator<Integer> binaryOperator = (a, b) -> a*b;
        System.out.println("Additon using Lambda BinaryOperator: "+test.lambdaBinaryOpertor(binaryOperator));
    }
}

在这个文章,他们关于如何编译的lambda表达式转换成字节码讨论.根据该文档,lambda表达式转换为static方法和lambda表达式声明的位置,具有lambda static方法的引用.以下示例位于文章中:

//Source code
class A {
    public void foo() {
        List<String> list = ...
        list.forEach( s -> { System.out.println(s); } );
    }
} 

//After compile above code "translate code " 
class A {
    public …

正如我们在Java 8中所知,引入了功能接口的概念.功能接口有一种abstract方法,可以使用多种默认或静态方法.

但为什么Functional接口只有一个抽象方法呢？如果Interface有多个抽象方法,为什么这不是一个功能接口？

@Embedded注释技术和@OneToOne注释技术有什么区别,因为在嵌入式中,java类在类中包含"Has a"关系,并且在@Embedded注释的帮助下,我们坚持在数据库中有一个对象.在OneToOne关系中,我们还坚持在数据库中拥有一个对象.

我对Spring安全性中的URL模式有点混淆.因为,在servlet核心http安全性中,/和/*url模式用于指定一个或多个目录./用于一个目录,/*用于许多目录.但是在Spring-security中,/**还介绍了/**url-pattern在安全性方面的主要目的是什么.

什么是javax.validationjava ee中的包,如何在JPA 2.0中使用它？我想通过@NotNull注释验证我的Enity .我的JPA实现是Hibernate:

public class Employee implements Serializable , EmployeeDetail {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    private int id;

    private String name;

    private long salary;
    ...

在MongoDb中,当我尝试修改集合中的现有文档时,它会生成以下异常: javascript execution failed : can't save a DBQuery object at src/mongo/shell/collection.js

在mongoDb shell中,我执行以下操作:

 > var doc1 = db.users.find({name:"Harmeet"})
 > doc1.color = "Blue"
 > db.users.save(doc1)

当调用save方法时异常thow.