Java 服务类Spring引导中出现空指针异常

你好。。我正在尝试创建一个spring boot web应用程序，在该应用程序中，我必须在spring boot的用户详细信息中找到用户，但在使用测试时出现错误。以下是我的配置：

用户类别：

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "USERS")
public class User implements Serializable {

  /**
     * 
     */
    private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue(strategy= GenerationType.IDENTITY)
  @Column(name = "USERNAME")
  private String username;

  @Column(name = "PASSWORD", nullable = false)
  private String password;

  @Column(name = "ENABLED", nullable = false)
  private boolean enabled;

  public User() {
    super();
    // TODO Auto-generated constructor stub
}

public User(String username, String password, boolean enabled, Set<Authorities> authorities, Customer customer) {
    super();
    this.username = username;
    this.password = password;
    this.enabled = enabled;
    this.authorities = authorities;
    this.customer = customer;
}

@OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
  private Set<Authorities> authorities = new HashSet<>();

  @OneToOne(cascade = CascadeType.ALL)
    private Customer customer;
  //Getter and Setter methods

public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public boolean isEnabled() {
    return enabled;
}

public void setEnabled(boolean enabled) {
    this.enabled = enabled;
}

public Set<Authorities> getAuthorities() {
    return authorities;
}

public void setAuthorities(Set<Authorities> authorities) {
    this.authorities = authorities;
}

public Customer getCustomer() {
    return customer;
}

public void setCustomer(Customer customer) {
    this.customer = customer;
}

}

因此，我运行的测试如下： 用户详细信息测试：

package com.vishal.project;

import static org.junit.Assert.assertNotNull;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.GenericApplicationContext;

import org.springframework.security.core.userdetails.UserDetailsService;

import com.vishal.project.entities.User;
import com.vishal.project.services.UserService;



public class UserDetailsTest {

    private static Logger logger = LoggerFactory.getLogger(UserDetailsTest.class);

    private GenericApplicationContext ctx;
    private UserDetailsService userDetailsService;
    private UserService userService;

    @Before
    public void SetUp() {
        ctx = new AnnotationConfigApplicationContext(OnlineBookShoppeApplication.class);
        userDetailsService = ctx.getBean(UserDetailsService.class);
        logger.info("starting to run tests now............");
        assertNotNull(userDetailsService);
    }   
        @Test
        public void testfindByUsername() {
             User user = userService.findByUsername("admin");
             String Username = user.getUsername();
             logger.info("Username=" + Username);

        }

        @After
         public void teardown() {
            ctx.close();
        }

    }

但是得到一个n错误，比如：

java.lang.NullPointerException
    at com.vishal.project.UserDetailsTest.testfindByUsername(UserDetailsTest.java:37)
    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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)

用户服务接口：

package com.vishal.project.services;

import com.vishal.project.entities.User;

public interface UserService {

    User findByUsername(String username);
    User save (User user);

}

---

非常感谢您的帮助…

您的

userService

字段为

null

，因为您尚未为其赋值。您的测试似乎没有使用您的

userDetailsService

字段，因此您可以删除它，然后替换此行：

userDetailsService = ctx.getBean(UserDetailsService.class);

为此：

userService = ctx.getBean(UserService.class);

---

java:37哪一行？要么userService为null，要么user为null谢谢先生。现在我得到了这个错误，它说没有quaorg.springframework.beans.factory.NoSuchBeanDefinitionException：没有可用的'com.vishal.project.services.UserService'类型的合格bean，但我已经为UserService定义了UserdetailsServiceImpl。刚刚在问题中添加了服务方法

userDetailsService = ctx.getBean(UserDetailsService.class);

userService = ctx.getBean(UserService.class);