瑞吉外卖员工管理业务开发-自学笔记

文章目录

新增员工
- 需求分析
- 代码开发
员工信息分页查询
- 需求分析
- 代码开发
启用、禁用员工账号
- 需求分析
- 代码开发
编辑员工信息

新增员工

需求分析

后台系统中可以管理员工信息，通过新增员工来添加后台系统用户，点击【添加员工】按钮跳转到新增页面

代码开发

页面发生ajax请求，将新增员工页面中输入的数据以json的形式提交到服务端
服务端Controller接收页面提交的数据并调用Service将数据进行保存
Service调用Mapper操作数据库，保存数据

    /**
     * 新增员工
     * @param employee
     * @return
     */
     @PostMapping()
     public R<String> save(HttpServletRequest request,@RequestBody Employee employee){
         log.info("新增员工，员工信息：{}",employee.toString());
         // 设置初始密码123456，需要进行md5加密处理
         employee.setPassword(DigestUtils.md5DigestAsHex("123456".getBytes()));
         employee.setCreateTime(LocalDateTime.now());
         employee.setUpdateTime(LocalDateTime.now());
         //获得当前登录用户的id
         Long empId = (Long) request.getSession().getAttribute("employee");
         employee.setCreateUser(empId);
         employee.setUpdateUser(empId);

         employeeService.save(employee);
         return R.success("新增员工成功！");
     }
}

目前还存在一个问题，就是如果在新增员工时输入的账号已经存在，由employee表中对该字段加入了唯一约束，此时程序会抛出异常

2022-06-23 18:46:03.052 ERROR 28140 --- [nio-8080-exec-5] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DuplicateKeyException: 
### Error updating database.  Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry 'zhangsan' for key 'idx_username'
### The error may exist in com/itheima/reggie/mapper/EmployeeMapper.java (best guess)
### The error may involve com.itheima.reggie.mapper.EmployeeMapper.insert-Inline
### The error occurred while setting parameters
### SQL: INSERT INTO employee  ( id, username, name, password, phone, sex, id_number,  create_time, update_time, create_user, update_user )  VALUES  ( ?, ?, ?, ?, ?, ?, ?,  ?, ?, ?, ? )
### Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry 'zhangsan' for key 'idx_username'
; Duplicate entry 'yingying' for key 'idx_username'; nested exception is java.sql.SQLIntegrityConstraintViolationException: Duplicate entry 'yingying' for key 'idx_username'] with root cause

java.sql.SQLIntegrityConstraintViolationException: Duplicate entry 'yingying' for key 'idx_username'
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ClientPreparedStatement.execute(ClientPreparedStatement.java:370) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:497) ~[druid-1.1.23.jar:1.1.23]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
	at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59) ~[mybatis-3.5.6.jar:3.5.6]
	at com.sun.proxy.$Proxy74.execute(Unknown Source) ~[na:na]
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:47) ~[mybatis-3.5.6.jar:3.5.6]
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74) ~[mybatis-3.5.6.jar:3.5.6]
	at com.baomidou.mybatisplus.core.executor.MybatisSimpleExecutor.doUpdate(MybatisSimpleExecutor.java:56) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117) ~[mybatis-3.5.6.jar:3.5.6]
	at com.baomidou.mybatisplus.core.executor.MybatisCachingExecutor.update(MybatisCachingExecutor.java:85) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:197) ~[mybatis-3.5.6.jar:3.5.6]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:184) ~[mybatis-3.5.6.jar:3.5.6]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:426) ~[mybatis-spring-2.0.5.jar:2.0.5]
	at com.sun.proxy.$Proxy55.insert(Unknown Source) ~[na:na]
	at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:271) ~[mybatis-spring-2.0.5.jar:2.0.5]
	at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.execute(MybatisMapperMethod.java:60) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy$PlainMethodInvoker.invoke(MybatisMapperProxy.java:148) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
	at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
	at com.sun.proxy.$Proxy58.insert(Unknown Source) ~[na:na]
	at com.baomidou.mybatisplus.extension.service.IService.save(IService.java:63) ~[mybatis-plus-extension-3.4.2.jar:3.4.2]
	at com.baomidou.mybatisplus.extension.service.IService$$FastClassBySpringCGLIB$$f8525d18.invoke(<generated>) ~[mybatis-plus-extension-3.4.2.jar:3.4.2]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.3.6.jar:5.3.6]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) ~[spring-aop-5.3.6.jar:5.3.6]
	at com.itheima.reggie.service.impl.EmployeeServiceImpl$$EnhancerBySpringCGLIB$$e1d647ef.save(<generated>) ~[classes/:na]
	at com.itheima.reggie.controller.EmployeeController.save(EmployeeController.java:100) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.6.jar:5.3.6]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:652) ~[tomcat-embed-core-9.0.45.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.6.jar:5.3.6]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.45.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at com.itheima.reggie.filter.LoginCheckFilter.doFilter(LoginCheckFilter.java:48) ~[classes/:na]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.6.jar:5.3.6]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.6.jar:5.3.6]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1707) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.45.jar:9.0.45]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131]

其中

### Error updating database.  Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry 'zhangsan' for key 'idx_username'

提示的是“zhangsan”这个用户名Duplicate了，即重复出现。此时我们的程序需要进行异常捕获，通常有两种处理方式

在Controller方法中加入try、catch进行异常捕获

         try {
             employeeService.save(employee);
         }catch (Exception ex){
             R.error("新增员工失败！")
         }
         return R.success("新增员工成功！");

使用异常处理器进行全局异常处理

由于第一种方式在大型项目中需要重复的写很多次，所以推荐使用第二种使用异常处理器进行全局异常处理
1）在common中创建GlobalExceptionHandler类
2）注入@ControllerAdvice、@ResponseBody、@Slf4j注解
3) 在@ControllerAdvice中添加参数annotations，即需要处理的注解
例如：

@ControllerAdvice(annotations = {RestController.class, Controller.class})

4）创建exceptionHandler方法，参数为刚刚报的错误类型：SQLIntegrityConstraintViolationException
5）注入注解@ExceptionHandler,参数同为异常类
6）测试方法能否处理该异常

package com.itheima.reggie.common;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import java.sql.SQLIntegrityConstraintViolationException;

/**
 * 全局异常处理
 */

@ControllerAdvice(annotations = {RestController.class, Controller.class})
@ResponseBody
@Slf4j
public class GlobalExceptionHandler {
    /**
     * 异常处理方法
     * @return
     */
    @ExceptionHandler(SQLIntegrityConstraintViolationException.class)
    public R<String> exceptionHandler(SQLIntegrityConstraintViolationException ex){
        log.error(ex.getMessage());
        return R.error("失败了");
    }
}

如果在输入重复的账号后，看到了提示信息“失败了”，就代表程序没有问题接下来进行具体的功能实现

package com.itheima.reggie.common;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import java.sql.SQLIntegrityConstraintViolationException;

/**
 * 全局异常处理
 */

@ControllerAdvice(annotations = {RestController.class, Controller.class})
@ResponseBody
@Slf4j
public class GlobalExceptionHandler {
    /**
     * 异常处理方法
     * @return
     */
    @ExceptionHandler(SQLIntegrityConstraintViolationException.class)
    public R<String> exceptionHandler(SQLIntegrityConstraintViolationException ex){
        log.error(ex.getMessage());
        // 如果报错中包含了  Duplicate entry
        if(ex.getMessage().contains("Duplicate entry")){
            // 对该错误进行分割，并找到账号信息   、
            // 由于在 Duplicate entry 'zhangsan' for key 'idx_username'中 ‘zhangsan’排在第三为，即下标为2
            String[] split = ex.getMessage().split(" ");
            String msg = split[2] + "已存在";
            return R.error(msg);
        }
        return R.error("未知错误！");
    }
}

员工信息分页查询

需求分析

系统中的员工很多的时候，如果在一个页面中全部展示出来会显得比较乱，不便于查看，所以一般的系统中都会以分页的方式来展示列表数据
页面发送ajax请求，将分页查询参数（page、pageSize 、name）提交到服务器

代码开发

页面发送ajax请求将分页查询参数(page,pageSize,name)提交到服务器
MP已经为我们提供了分页插件，我们直接使用即可，
在config包下创建MybatisPlusConfig 配置类：

package com.itheima.reggie.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 配置MP的分页插件
 */

@Configuration  
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return  mybatisPlusInterceptor;
    }
}

服务端Controller接收页面提交的数据并调用Service查询数据

先写一个大概的框架，测试一下能否接收到数据，其中的参数都是根据前端发送的请求来设置的。

    @GetMapping("/page")
     public R<Page> page(int page,int PageSize,String name){
        log.info("page = {},PageSize = {}, name = {},page,pageSize,name");
         return null;
     }

Service调用Mapper操作数据库，查询分页数据
Controller将查询到的分页数据响应给页面
页面接收到分页数据并通过ElementUI的Table组件展示到页面上

启用、禁用员工账号

需求分析

在员工管理列表页面，可以对某个员工账号进行启用或者禁用操作。账号禁用的员工不能登录系统，启用后的员工可以正常登录
需要注意的是，只有管理员可以对其他普通用户进行启用、禁用操作，所以普通用户登录系统后启用、禁用按钮不显示

代码开发

页面发送ajax请求，将参数（id,status）提交到服务器
服务端COntroller接收页面提交的数据并调用Service更新数据
Service调用Mapper操作数据库

    /**
     * 根据id修改员工信息
     * @param request
     * @param employee
     * @return
     */
     @PutMapping
    public R<String> update(HttpServletRequest request, @RequestBody Employee employee){
        log.info("employee:{}",employee);

        //获得当前登录用户的id
         Long empId = (Long)request.getSession().getAttribute("employee");
         employee.setUpdateUser(empId);
         employee.setUpdateTime(LocalDateTime.now());

         employeeService.updateById(employee);
         return R.success("修改成功");
     }

现在点击禁用按钮来测试一下会发现，并没有修改禁用状态，这是由于页面中js处理long型数字只能精确到前16位，所以最终通过ajax请求提交给服务器的时候id由1391586184024604674变成了1391586184024604700，导致后端在修改数据的时候id不一致，无法修改数据。
那么如何解决该问题呢？
我们可以在服务端给页面响应json数据时进行处理，将long型数据同意转为String字符串
具体实现步骤：

提供对象转换器JacksonObjectMapper，基于jackson进行java对象到json数据的转换

package com.itheima.reggie.common;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import java.math.BigInteger;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import static com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;

/**
 * 对象映射器:基于jackson将Java对象转为json，或者将json转为Java对象
 * 将JSON解析为Java对象的过程称为 [从JSON反序列化Java对象]
 * 从Java对象生成JSON的过程称为 [序列化Java对象到JSON]
 */
public class JacksonObjectMapper extends ObjectMapper {

    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

    public JacksonObjectMapper() {
        super();
        //收到未知属性时不报异常
        this.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);

        //反序列化时，属性不存在的兼容处理
        this.getDeserializationConfig().withoutFeatures(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);


        SimpleModule simpleModule = new SimpleModule()
                .addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                .addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                .addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)))

                .addSerializer(BigInteger.class, ToStringSerializer.instance)
                .addSerializer(Long.class, ToStringSerializer.instance)
                .addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                .addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                .addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));

        //注册功能模块 例如，可以添加自定义序列化器和反序列化器
        this.registerModule(simpleModule);
    }
}

在WebMVCConfig配置类中扩展Spring mvc的消息转换器，在此消息转换器中使用提供的对象转换器进行java对象到json数据的转换

    /**
     * 扩展mvc框架的消息转换器
     * @param converters
     */
    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        // 创建消息转换器对象
        MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
        // 设置对象转换器，底层使用jackson将java对象转为json
        messageConverter.setObjectMapper(new JacksonObjectMapper());
        // 将上面的消息转换器对象追加到mvc框架的转换器集合中
        // 要是有索引方式的add，将我们自己设置的转换器放到最前面，否则使用的还是原来的转换器
        converters.add(0,messageConverter); 
    }

这里是用消息转换器来调用对象转换器，实现最终的功能，对象转换器只是能转换数据类型，但是需要有人来调用它，才能发挥作用。