GVKun编程网logo

java – Autowired在Custom Constraint验证器中给出Null值（java当中实现验证的是什么）

10

最近很多小伙伴都在问java–Autowired在CustomConstraint验证器中给出Null值和java当中实现验证的是什么这两个问题，那么本篇文章就来给大家详细解答一下，同时本文还将给你拓

最近很多小伙伴都在问java – Autowired在Custom Constraint验证器中给出Null值和java当中实现验证的是什么这两个问题，那么本篇文章就来给大家详细解答一下，同时本文还将给你拓展002-Struts2的action中@Autowired注入service为NULL、@Autowired注解在非Controller中注入为null、@Autowired配合@PostConstruct注入问题、@Compenent,@Autowired,@PostConstruct自实现等相关知识，下面开始了哦！

本文目录一览：

java – Autowired在Custom Constraint验证器中给出Null值（java当中实现验证的是什么）

java – Autowired在Custom Constraint验证器中给出Null值（java当中实现验证的是什么）

我对Spring来说是全新的,我已经在SO上找到了一些问题的答案.以下是链接：

Spring 3.1 Autowiring does not work inside custom constraint validator

Autowiring a service into a validator

Autowired Repository is Null in Custom Constraint Validator

我有一个Spring项目,我想在其中使用Hibernate Validator进行对象验证.基于我在网上阅读的内容和一些论坛,我试图注入验证器如下：

@Bean
  public Validator validator() {
    return new LocalValidatorfactorybean().getValidator();
  }

但无论我在哪里使用

@Autowired
Validator validator;

它采用了Spring的验证器实现而不是Hibernate的验证器.我无法弄清楚如何准确地注入Hibernate验证器并简单地将其自动装配到其他类中,所以我使用了一个便宜的技巧,现在我的Java Config看起来像这样

@Bean
      public Validator validator() {
        // ValidatorImpl is Hibernate's implementation of the Validator
        return new ValidatorImpl();
      }

(我真的很感激,如果有人能指出我如何避免以这种Hacky方式获得Hibernate Validator的正确方向)

但是让我们来看看主要问题：

这是自定义验证定义

@Target( { METHOD,FIELD,ANNOTATION_TYPE,CONSTRUCTOR,ParaMETER } )
@Retention(RUNTIME)
@Constraint(validatedBy = EmployeeValidator.class)
@Documented
public @interface EmployeeValidation {
String message() default "{constraints.employeeConstraints}";
public abstract Class

我的自定义验证器

public class EmployeeValidator implements ConstraintValidator

在上面的Custom Constraint Validator中,我得到employeeService null.我知道Spring启动时没有实例化ConstraintValidator的任何实现,但我认为添加ValidatorImpl()实际上会解决这个问题.但事实并非如此.

现在我陷入了一个非常hacky的解决方法,我不想继续这样的代码.有人可以帮助我解决我的情况.

附：这些是我在Java Config文件中的导入：

import org.hibernate.validator.HibernateValidator; 
import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.context.MessageSource; 
import org.springframework.context.annotation.Bean; 
import org.springframework.context.annotation.ComponentScan; 
import org.springframework.context.annotation.Configuration; 
import org.springframework.context.annotation.PropertySource; 
import org.springframework.context.support.ReloadableResourceBundleMessageSource; 
import org.springframework.core.env.Environment; 
import org.springframework.validation.Validator; 
import org.springframework.validation.beanvalidation.LocalValidatorfactorybean; 
import org.springframework.web.servlet.LocaleResolver; 
import org.springframework.web.servlet.ViewResolver; 
import org.springframework.web.servlet.config.annotation.EnableWebMvc; 
import org.springframework.web.servlet.config.annotation.InterceptorRegistry; 
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport; 
import org.springframework.web.servlet.i18n.CookieLocaleResolver; 
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor; 
import org.springframework.web.servlet.view.InternalResourceViewResolver;
最佳答案
我希望解决方案可以帮助某人：

@Bean
public Validator validator () {

    ValidatorFactory validatorFactory = Validation.byProvider( HibernateValidator.class )
        .configure().constraintValidatorFactory(new SpringConstraintValidatorFactory(autowireCapablebeanfactory))
        .buildValidatorFactory();
    Validator validator = validatorFactory.getValidator();

    return validator;
}

使用SpringConstraintValidatorFactory初始化验证器以便注入工作并将验证器实现提供为Hibernate.class以下列方式工作：

>您的项目将由您选择的图书馆验证
>您的自定义验证器将能够使用Spring的功能,同时通过Hibernate执行验证.

这个怎么运作：
Hibernate的ConstraintValidtorFactory不会初始化任何ConstraintValidator,除非它们被调用但SpringConstraintValidatorFactory通过向它提供AutowireCapablebeanfactory来实现.

编辑
正如@shabyasaschi的一条评论中所提到的,要注入autowireCapablebeanfactory,您可以将方法签名更改为：

Validator validator(final AutowireCapablebeanfactory autowireCapablebeanfactory) {

或者在配置文件中为它添加getter和setter,如下所示：

public AutowireCapablebeanfactory getAutowireCapablebeanfactory() {
        return autowireCapablebeanfactory;
}

public void setAutowireCapablebeanfactory(AutowireCapablebeanfactory autowireCapablebeanfactory) {
        this.autowireCapablebeanfactory = autowireCapablebeanfactory;
}

002-Struts2的action中@Autowired注入service为NULL

002-Struts2的action中@Autowired注入service为NULL

错误代码：只是某个action中的service自动注入失败为NULL

 

解决方法：struts.xml文件中添加如下配置

<constant name="struts.objectFactory.spring.autoWire.alwaysRespect" value="true" />

 

相关说明：

  • struts.objectFactory

设置struts2的对象工厂，默认（struts），类名org.apache.struts2.impl.StrutsObjectFactory，当引入struts2-spring插件之后，则被修改为org.apache.struts2.spring.StrutsSpringObjectFactory
 

  • struts.objectFactory.spring.autoWire 

可选值（name, type, auto, constructor,name）（默认name），设置spring的自动装配方式，只有引入spring插件后才有效。

  • struts.objectFactory.spring.autoWire.alwaysRespect 

（默认false）设置是否总是以自动装配策略创建对象。

@Autowired注解在非Controller中注入为null

@Autowired注解在非Controller中注入为null

/**
 * Created by huangzhenyang on 2017/11/2.
 * Token 工具类
 */
@Component  // 关键1，将该工具类注册为组件，   加粗！！！
public class TokenUtil {
    @Autowired
    private TokenRepository tokenRepository;

    @Autowired
    private TokenService tokenService;

    public static TokenUtil tokenUtil;  // 关键2

    // 关键3
    @PostConstruct
    public void init() {
        tokenUtil = this;
        tokenUtil.tokenRepository = this.tokenRepository;
    }

    tokenUtil .tokenService......

原文链接：https://blog.csdn.net/qq_35056292/article/details/78430777
………………

更新

然后又找到另一个方法 

使用@Autowired 注入 ApplicationContext applicationContext;

TokenService  tokenService = （tokenService）applicationContext.getBean("tokenService");

然后通过tokenService 获取tokenService 中的接口

注：没有测试自己填坑   .0.0.
————————————————

2020-05-07 更新

又发现一种新写法，就是在类中添加@Component注解，把他注册为一个工具类，然后里面的方法不要写成静态方法，在需要用的地方用@Resource

注解注入一下，这样也可以避免在静态方法中使用注入的时候为null的情况

------------------------------------------------------------------------------------------------------------------------

@Autowired配合@PostConstruct注入问题

@Autowired配合@PostConstruct注入问题

debug时@Autowired注入属性抛出异常，但是在@PostConstruct中却还能注入！这是什么原理？

@Compenent,@Autowired,@PostConstruct自实现

@Compenent,@Autowired,@PostConstruct自实现

本来是想为安卓开发一套可以依赖注入的标签，但是发现安卓很难找到选定包内的java或者class文件。所以只能当做学习参考了，全套代码如下

package com.guanjian.annotion;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Created by Administrator on 2018-06-11.
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Autowired {
}
package com.guanjian.annotion;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Created by Administrator on 2018-06-11.
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface Component {
}
package com.guanjian.annotion;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Created by Administrator on 2018-06-11.
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface PostConstruct {
}
package com.guanjian.util;

import com.guanjian.utils.StringUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 * 类操作工具类
 * Created by Administrator on 2018-06-11.
 */
public final class ClassUtil {
    private static final Logger LOGGER = LoggerFactory.getLogger(ClassUtil.class);

    /**
     * 获取类加载器
     * @return
     */
    public static ClassLoader getClassLoader() {
        return Thread.currentThread().getContextClassLoader();
    }

    /**
     * 加载类
     * @param className
     * @param isInitialized
     * @return
     */
    public static Class<?> loadClass(String className,boolean isInitialized) {
        Class<?> cls;
        try {
            cls = Class.forName(className,isInitialized,getClassLoader());
        } catch (ClassNotFoundException e) {
            LOGGER.error("load class failure",e);
            throw new RuntimeException(e);
        }
        return cls;
    }

    /**
     * 获取制定包名下的所有类
     * @param packageName
     * @return
     */
    public static Set<Class<?>> getClassSet(String packageName) {
        Set<Class<?>> classSet = new HashSet<Class<?>>();
        try {
            Enumeration<URL> urls = getClassLoader().getResources(packageName.replace(".","/"));
            while (urls.hasMoreElements()) {
                URL url = urls.nextElement();
                if (url != null) {
                    String protocol = url.getProtocol();
                    if (protocol.equals("file")) {
                        String packagePath = url.getPath().replaceAll("%20"," ");
                        addClass(classSet,packagePath,packageName);
                    }else if (protocol.equals("jar")) {
                        JarURLConnection jarURLConnection = (JarURLConnection)url.openConnection();
                        if (jarURLConnection != null) {
                            JarFile jarFile = jarURLConnection.getJarFile();
                            if (jarFile != null) {
                                Enumeration<JarEntry> jarEntries = jarFile.entries();
                                while (jarEntries.hasMoreElements()) {
                                    JarEntry jarEntry = jarEntries.nextElement();
                                    String jarEntryName = jarEntry.getName();
                                    if (jarEntryName.endsWith(".class")) {
                                        String className = jarEntryName.substring(0,jarEntryName.lastIndexOf(".")).replaceAll("/",".");
                                        doAddClass(classSet,className);
                                    }
                                }
                            }
                        }
                    }
                }
            }
        } catch (Exception e) {
            LOGGER.error("get class set failure",e);
            throw new RuntimeException(e);
        }
        return classSet;
    }

    private static void addClass(Set<Class<?>> classSet, String packagePath, final String packageName) {
        File[] files = new File(packagePath).listFiles(new FileFilter() {
            public boolean accept(File pathname) {
                return (pathname.isFile() && pathname.getName().endsWith(".class")) || pathname.isDirectory();
            }
        });
        for (File file:files) {
            String fileName = file.getName();
            if (file.isFile()) {
                String className = fileName.substring(0,fileName.lastIndexOf("."));
                if (StringUtil.isNotEmpty(packagePath)) {
                    className = packageName + "." + className;
                }
                doAddClass(classSet,className);
            }else {
                String subPackagePath = fileName;
                if (StringUtil.isNotEmpty(packagePath)) {
                    subPackagePath = packagePath + "/" +subPackagePath;
                }
                String subPackageName = fileName;
                if (StringUtil.isNotEmpty(packageName)) {
                    subPackageName = packageName + "." +subPackageName;
                }
                addClass(classSet,subPackagePath,subPackageName);
            }
        }
    }
    private static void doAddClass(Set<Class<?>> classSet,String className) {
        Class<?> cls = loadClass(className,false);
        classSet.add(cls);
    }
}
package com.guanjian.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Field;

/**
 * 反射工具类
 * Created by Administrator on 2018-06-11.
 */
public final class ReflectionUtil {
    private static final Logger LOGGER = LoggerFactory.getLogger(ReflectionUtil.class);

    /**
     * 创建实例
     * @param cls
     * @return
     */
    public static Object newInstance(Class<?> cls) {
        Object instance;
        try {
            instance = cls.newInstance();
        } catch (Exception e) {
            LOGGER.error("new instance failure",e);
            throw new RuntimeException(e);
        }
        return instance;
    }

    /**
     * 设置成员变量值
     * @param obj
     * @param field
     * @param value
     */
    public static void setField(Object obj, Field field,Object value) {
        try {
            field.setAccessible(true);
            field.set(obj,value);
        } catch (IllegalAccessException e) {
            LOGGER.error("set field failure",e);
            throw new RuntimeException(e);
        }
    }
}
package com.guanjian.util;

import com.guanjian.annotion.Component;

import java.util.HashSet;
import java.util.Set;

/**
 * 类操作助手类
 * Created by Administrator on 2018-06-11.
 */
public final class ClassHelper {
    /**
     * 定义类集合(用于存放所加载的类)
     * @param basePackage
     */
    private static  Set<Class<?>> CLASS_SET;

    /**
     * 扫描所有的包，获取类集合放入CLASS_SET
     * @param basePackage
     */
    public static void setClassSet(String basePackage) {
        CLASS_SET = ClassUtil.getClassSet(basePackage);
    }

    /**
     * 获取应用包名下的所有类
     * @return
     */
    public static Set<Class<?>> getClassSet() {
        return CLASS_SET;
    }

    /**
     * 获取应用包名下所有Comonent类
     * @return
     */
    public static Set<Class<?>> getComponentClassSet() {
        Set<Class<?>> classSet = new HashSet<Class<?>>();
        for (Class<?> cls:CLASS_SET) {
            if (cls.isAnnotationPresent(Component.class)) {
                classSet.add(cls);
            }
        }
        return classSet;
    }

    /**
     * 获取应用包名下所有Bean类
     * @return
     */
    public static Set<Class<?>> getBeanClassSet() {
        Set<Class<?>> beanClassSet = new HashSet<Class<?>>();
        beanClassSet.addAll(getComponentClassSet());
        return beanClassSet;
    }
}
package com.guanjian.util;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * Bean助手类
 * Created by Administrator on 2018-06-11.
 */
public final class BeanHelper {
    /**
     * 定义Bean映射(用于存放Bean类与Bean实例的映射关系)
     */
    private static final Map<Class<?>,Object> BEAN_MAP = new HashMap<Class<?>, Object>();

    /**
     * 获取所有的映射关系
     */
    public static void setBeanMap() {
        Set<Class<?>> beanClassSet = ClassHelper.getBeanClassSet();
        for (Class<?> beanClass:beanClassSet) {
            Object obj = ReflectionUtil.newInstance(beanClass);
            BEAN_MAP.put(beanClass,obj);
        }
    }

    /**
     * 获取Bean映射
     * @return
     */
    public static Map<Class<?>,Object> getBeanMap() {
        return BEAN_MAP;
    }

    /**
     * 获取Bean实例
     * @param cls
     * @param <T>
     * @return
     */
    public static <T> T getBean(Class<T> cls) {
        if (!BEAN_MAP.containsKey(cls)) {
            throw new RuntimeException("Can not get bean by class:" + cls);
        }
        return (T)BEAN_MAP.get(cls);
    }
}
package com.guanjian.util;

import com.guanjian.annotion.Autowired;
import com.guanjian.annotion.PostConstruct;
import com.guanjian.utils.ArrayUtil;
import com.guanjian.utils.CollectionUtil;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Map;

/**
 * Created by Administrator on 2018-06-11.
 */
public final class IocHelper {
    public static void ioc(){
        //获取所有的Bean类与Bean实例之间的映射关系
        Map<Class<?>,Object> beanMap = BeanHelper.getBeanMap();
        if (CollectionUtil.isNotEmpty(beanMap)) {
            //遍历Bean Map
            for (Map.Entry<Class<?>,Object> beanEntry:beanMap.entrySet()) {
                //从BeanMap中获取Bean类与Bean实例
                Class<?> beanClass = beanEntry.getKey();
                Object beanInstance = beanEntry.getValue();
                //获取Bean类定义的所有成员变量
                Field[] beanFields = beanClass.getDeclaredFields();
                if (ArrayUtil.isNotEmpty(beanFields)) {
                    //遍历Bean Field
                    for (Field beanField:beanFields) {
                        //判断当前Bean Field是否带有Autowired注解
                        if (beanField.isAnnotationPresent(Autowired.class)) {
                            //在Bean Map中获取Bean Field对应的实例
                            Class<?> beanFieldClass = beanField.getType();
                            Object beanFieldInstance = beanMap.get(beanFieldClass);
                            if (beanFieldInstance != null) {
                                //通过反射初始化BeanField的值
                                ReflectionUtil.setField(beanInstance,beanField,beanFieldInstance);
                            }
                        }
                    }
                }
                Method[] beanMethods = beanClass.getMethods();
                if (ArrayUtil.isNotEmpty(beanMethods)) {
                    //遍历method
                    for (Method method:beanMethods) {
                        //判断当前注解是否有PostConstruct注解
                        if (method.isAnnotationPresent(PostConstruct.class)) {
                            try {
                                //执行该方法
                                method.invoke(beanInstance,null);
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }
        }
    }
}
package com.guanjian.manage;

import com.guanjian.util.BeanHelper;
import com.guanjian.util.ClassHelper;
import com.guanjian.util.IocHelper;

/**
 * Created by Administrator on 2018-06-11.
 */
public class Manager {
    public static Object getBean(Class<?> beanClass) {
        return BeanHelper.getBean(beanClass);
    }
    public static void scanAndImp(String basePackage) {
        ClassHelper.setClassSet(basePackage);
        BeanHelper.setBeanMap();
        IocHelper.ioc();
    }
}

测试代码

package com.guanjian.test.compent;

import com.guanjian.annotion.Component;
import com.guanjian.annotion.PostConstruct;

/**
 * Created by Administrator on 2018-06-11.
 */
@Component
public class Test1 {
    private String hello;
    @PostConstruct
    public void init() {
        hello = "你好";
    }
    public void show() {
        System.out.println(hello);
    }
}
package com.guanjian.test.compent;

import com.guanjian.annotion.Autowired;
import com.guanjian.annotion.Component;

/**
 * Created by Administrator on 2018-06-11.
 */
@Component
public class Test2 {
    @Autowired
    private Test1 test1;
    public void show() {
        test1.show();
    }
}
package com.guanjian.test;

import com.guanjian.manage.Manager;
import com.guanjian.test.compent.Test2;

/**
 * Created by Administrator on 2018-06-11.
 */
public class Test {
    public static void main(String[] args) {
        Manager.scanAndImp("com.guanjian.test");
        Test2 test2 = (Test2)Manager.getBean(Test2.class);
        test2.show();
    }
}

关于java – Autowired在Custom Constraint验证器中给出Null值和java当中实现验证的是什么的问题就给大家分享到这里，感谢你花时间阅读本站内容，更多关于002-Struts2的action中@Autowired注入service为NULL、@Autowired注解在非Controller中注入为null、@Autowired配合@PostConstruct注入问题、@Compenent,@Autowired,@PostConstruct自实现等相关知识的信息别忘了在本站进行查找喔。

本文标签：

上一篇java – 在Spring Boot应用程序中扫描不同maven模块/ JAR的组件（springboot扫描外部jar）

下一篇spring – java.lang.IllegalStateException：ApplicationEventMulticaster未初始化 – 在通过上下文组播事件之前调用’refresh’

相关文章