小编Kha*_*han的帖子

从数据库中读取学生对象时出现此错误.

org.springframework.beans.BeanInstantiationException:无法实例化[java.lang.Long]:找不到默认构造函数; 嵌套异常是java.lang.NoSuchMethodException:java.lang.Long.()org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107)

完整堆栈跟踪:

org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>()
org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107)

Student.java

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>()
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause

org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>()
    org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:775)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:368)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:172)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause

java.lang.NoSuchMethodException: java.lang.Long.<init>()
    java.lang.Class.getConstructor0(Class.java:3082) …

studentService.js

   app.factory('saveStudentService',['$http','$scope',function ($http,$scope) { 
            var studentData = {};
            studentData.save = function(jsondata){
                var action = "student";
                var method = "POST";
                $http({
                    url: action,
                    method: method,
                    headers: {'Content-Type': 'application/json'},
                    data: jsondata
                }).success(function(data, status, headers, config) {
                    toastr.success(status +' : Data has been submitted successfully ');
                }).error(function(data, status, headers, config) {
                    toastr.error(status + ' : Data has not been submitted successfully ');
                });
            };
            return studentData;
        }]);

我收到了这个错误

angular.js:13642Error: [$injector:unpr] http://errors.angularjs.org/1.5.6/$injector/unpr?p0=%24scopeProvider%20%3C-%20%24scope%20%3C-%20saveStudentService
    at Error (native)
    at https://ajax.googleapis.com/ajax/libs/angularjs/1.5.6/angular.min.js:6:412

如果来自studentService.js,则删除$ scope,即

app.factory('saveStudentService',['$http',function ($http) { 

此代码工作正常,并没有在控制台中收到任何错误消息.

以下是studentController.js文件,该文件来自此studentService. …

java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
    org.springframework.security.crypto.password.DelegatingPasswordEncoder$UnmappedIdPasswordEncoder.matches(DelegatingPasswordEncoder.java:236)
    org.springframework.security.crypto.password.DelegatingPasswordEncoder.matches(DelegatingPasswordEncoder.java:196)
    org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter$LazyPasswordEncoder.matches(WebSecurityConfigurerAdapter.java:593)

我的代码工作正常,现在我已将弹簧安全版本从4.0更改为5.0,它无法正常工作

正如我读过的那样，如果自定义对象需要成为地图的键，则需要覆盖 hashcode 和 equals 方法，但在我的情况下，它可以在不覆盖它的情况下工作。有人能告诉我出了什么问题吗？

    Map<Student,Integer> map = new HashMap<>();
    Student s1=new Student(1,"A");
    Student s2=new Student(2,"B");
    Student s3=new Student(3,"C");

    map.put(s1,1);
    map.put(s2,2);
    map.put(s1,3);

    for(Student s:map.keySet()) {
        System.out.println(map.get(s) + "->" + s.id + " " +s.name);
    }

正确的输出：

3-> 1A

2-> 2 B