findByAll（）,findBy{columnName}在Spring data jpa中不起作用

Question

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.SpringBoot.model.User;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {

    User findByUsername(String username);
}

@Service
public class UserServiceImp {

    UserRepository userRepository;

    public List<User> getAllUsers() throws Exception {
        return (List<User>) userRepository.findAll();
    }

    public User getUserById(String username) throws Exception {
        System.out.println("in service imp class ***************************");
        return userRepository.findByUsername(username);
    }

    public void addUsers(User user) throws Exception {
        userRepository.save(user);

    }
}

@Entity
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String username;
    private String name;
    private int userCode;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getUserCode() {
        return userCode;
    }

    public void setUserCode(int userCode) {
        this.userCode = userCode;
    }
}

我的控制器

package com.SpringBoot.controller;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.SpringBoot.model.User;
import com.SpringBoot.service.Userservice;

@RestController
public class UserController {

    @Autowired
    UserServiceImp userservice;

    @PostMapping("/user/add")
    public void addUsers(@RequestBody User user) {
        try {
            userservice.addUsers(user);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @GetMapping("/user/{id}")
    public User getUserById(@PathVariable("id") String username) {
        User user = null;
        try {
            System.out.println("***************  " + username);
            user = userservice.getUserById(username);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    }


    @GetMapping(value = "/users")
    public List<User> getAllUser() {
        List<User> user = new ArrayList<User>();
        System.out.println("***************  ");
        try {
            user = userservice.getAllUsers();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    }
}

我的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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.test.junit</groupId>
    <artifactId>SpringBoot</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.4</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Answer 1

不确定您使用的是哪个数据库，但例如在Postgres中，术语“user”是一个保留的关键字。它将只在提供引号的名称时与hibernate一起工作：

@Table(name="\"user\"")

小心大小写。

您可以在https://bootify.io创建一个小项目，它将为您提供一个正在运行的配置。