当我使用spring boot maven项目mysql-connector并将数据作为post请求插入数据库，但不将数据保存在数据库中时

Question

我有个错误

2021-02-04 10:31:48.341警告6496--[nio-8080-exec-8].w.s.m.s.defaultHandlerExceptionResolver：已解析[org.springframework.http.converter.httpmessagenotreadableException：JSON分析错误：无法构造com.sun.org.apache.xpath.internal.operations.String的实例（尽管至少存在一个创建者）：没有字符串参数构造函数/工厂方法可从字符串值（“[e-mail]”）反序列化；嵌套异常为

   <?xml version="1.0" encoding="UTF-8"?>
    <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>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.4.2</version>
            <relativePath/> <!-- lookup parent from repository -->
        </parent>
    
        <groupId>com.sample</groupId>
        <artifactId>springboot-demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>springboot-demo</name>
        <description>Demo project for Spring Boot</description>
        <properties>
            <java.version>1.8</java.version>
        </properties>
    
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
            </dependency>
    
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

package com.sample.springbootdemo.domain;

import com.sun.org.apache.xpath.internal.operations.String;

import javax.persistence.*;


@Entity // This tells Hibernate to make a table out of this class

@Table(name = "user")
public class UserDTO {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)


    @Column(name = "user_id" )
    private Integer id;

    @Column(name = "first_name",columnDefinition = "varchar(255)")
    private String firstName;

    @Column(name = "last_name",columnDefinition = "varchar(255)")
    private String lastName;

    @Column(name = "age")
    private Integer age;

   @Column(name = "email",columnDefinition = "varchar(255)")
    private String email;



    public Integer getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

     public String getEmail() {
        return email;
    }

   public void setEmail(String email) {
        this.email = email;
    }
}

package com.sample.springbootdemo.controllers;


import com.sample.springbootdemo.domain.UserDTO;

import com.sample.springbootdemo.services.UserServices;
import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController


@RequestMapping(path="/user")
public class User {

    @Autowired
    private UserServices userServices;



    @GetMapping("/all")
    public List<UserDTO> allUsers(){
        return userServices.findAllUsers();
    }

    @PostMapping(path = "/add")
    public String addUser(@RequestBody UserDTO Userdata){
       return userServices.saveUser(Userdata);
    }

}

Answer 1

“String”应该自带java。不要使用导入“com.sun.org.apache.xpath.internal.operations.String”，从您的userDTO中删除该行。