mybatis逆向工程与分页在springboot中的应用及遇到坑

最近在项目中应用到springboot与mybatis，在进行整合过程中遇到一些坑，在此将其整理出来，便于以后查阅与复习。

 项目运行环境为：eclispe+jdk1.8+maven

搭建spring boot环境

首先建立maven project,在生成的pom文件中加入依赖，代码如下：

<parent>
 <groupid>org.springframework.boot</groupid>
 <artifactid>spring-boot-starter-parent</artifactid>
 <version>1.5.2.release</version>
 <relativepath/> <!-- lookup parent from repository -->
</parent>
<properties>
 <project.build.sourceencoding>utf-8</project.build.sourceencoding>
 <project.reporting.outputencoding>utf-8</project.reporting.outputencoding>
 <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-test</artifactid>
 </dependency>
 <dependency>
  <groupid>org.mybatis.spring.boot</groupid>
  <artifactid>mybatis-spring-boot-starter</artifactid>
  <version>1.3.0</version>
 </dependency>
 <dependency>
  <groupid>mysql</groupid>
  <artifactid>mysql-connector-java</artifactid>
  <scope>runtime</scope>
 </dependency>
 <!--分页插件-->
 <dependency>
   <groupid>com.github.pagehelper</groupid>
   <artifactid>pagehelper-spring-boot-starter</artifactid>
   <version>1.2.1</version>
 </dependency>
 <!-- alibaba的druid数据库连接池 -->
 <dependency>
  <groupid>com.alibaba</groupid>
  <artifactid>druid</artifactid>
  <version>1.0.29</version>
 </dependency>
</dependencies>
<build>
 <plugins>
  <plugin>
   <groupid>org.springframework.boot</groupid>
   <artifactid>spring-boot-maven-plugin</artifactid>
  </plugin>
  <!-- mybatis generator 自动生成代码插件 -->
  <plugin>
   <groupid>org.mybatis.generator</groupid>
   <artifactid>mybatis-generator-maven-plugin</artifactid>
   <version>1.3.2</version>
   <configuration>
    <configurationfile>${basedir}/src/main/resources/generator/generatorconfig.xml</configurationfile>
    <overwrite>true</overwrite>
    <verbose>true</verbose>
   </configuration>
  </plugin>
 </plugins>
</build>

配置好依赖后进行maven install,此时注意的坑：

 坑一：启动maven install报错：

[error] failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.release:repackage (default) on project springboot-mybatis: execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.release:repackage failed: unable to find main class -> [help 1]
[error]
[error] to see the full stack trace of the errors, re-run maven with the -e switch.
[error] re-run maven using the -x switch to enable full debug logging.
[error]
[error] for more information about the errors and possible solutions, please read the following articles:
[error] [help 1] http://cwiki.apache.org/confluence/display/maven/pluginexecutionexception

报错原因是没有启动类

 解决方法:编写启动类main.java正常运行！

@springbootapplication
public class main {
 public static void main(string[] args) {
  springapplication.run(main.class, args);
 }
}

坑二：启动maven install报错：

[error] failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project springboot-mybatis: compilation failure
[error] no compiler is provided in this environment. perhaps you are running on a jre rather than a jdk?
[error] -> [help 1]
[error]
[error] to see the full stack trace of the errors, re-run maven with the -e switch.
[error] re-run maven using the -x switch to enable full debug logging.
[error]
[error] for more information about the errors and possible solutions, please read the following articles:
[error] [help 1] http://cwiki.apache.org/confluence/display/maven/mojofailureexception

报错原因：项目的java环境与电脑环境不符合，例如我的新建项目运行环境为j2se-1.5,报错是在我将其改为jre1.8之后

 解决方案：

 右键项目——build path——configure build path——libraries——双击jre system libraries如下图所示：

选择alternate jre 如2处的下拉框只有jre，点击3处的install jres，依次经过add——standard vm——next——directory,选择本机的jdk位置点击finish

在install jres位置将默认勾选更改jdk,如下图所示，并保存。

再次maven install项目正常。如下所示：

[info] build success
[info] ------------------------------------------------------------------------
[info] total time: 3.351 s
[info] finished at: 2018-09-05t21:20:48+08:00
[info] final memory: 23m/181m
[info] ------------------------------------------------------------------------

在src/main/resources新建文件：application.yml，内容如下所示：

server:
 port: 8080
spring:
 datasource:
  name: test
  url: jdbc:mysql://localhost:3306/test
  username: root
  password: 123456
  driver-class-name: com.mysql.jdbc.driver
## 该配置节点为独立的节点
mybatis:
 mapper-locations: classpath:mapper/*.xml
#pagehelper分页插件
pagehelper:
 helperdialect: mysql
 reasonable: true
 supportmethodsarguments: true
 params: count=countsql

至此springboot环境搭建完毕！

逆向工程应用

首先应该注意到在pom文件中有配置逆向工程xml文件的位置：src/main/resources/generator/generatorconfig.xml

因而在src/main/resources下新建generator文件夹，并建立generatorconfig.xml文件，代码如下：

<?xml version="1.0" encoding="utf-8"?>
<!doctype generatorconfiguration public "-//mybatis.org//dtd mybatis generator configuration 1.0//en" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorconfiguration>
 <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包-->
 <classpathentry location="e:\plugins\maven\repo\mysql\mysql-connector-java\5.1.41\mysql-connector-java-5.1.41.jar"/>
 <context id="db2tables" targetruntime="mybatis3">
  <commentgenerator>
   <property name="suppressdate" value="true"/>
   <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
   <property name="suppressallcomments" value="true"/>
  </commentgenerator>
  <!--数据库链接url，用户名、密码 -->
  <jdbcconnection driverclass="com.mysql.jdbc.driver" connectionurl="jdbc:mysql://localhost/test" userid="root" password="123456">
  </jdbcconnection>
  <javatyperesolver>
   <property name="forcebigdecimals" value="false"/>
  </javatyperesolver>
  <!-- 生成pojo类的位置-->
  <javamodelgenerator targetpackage="com.luis.entity" targetproject="src/main/java">
   <property name="enablesubpackages" value="true"/>
   <property name="trimstrings" value="true"/>
  </javamodelgenerator>
  <!-- 生成映射文件的包名和位置-->
  <sqlmapgenerator targetpackage="mapper" targetproject="src/main/resources">
   <!-- enablesubpackages 是否让schema作为包的后缀-->
   <property name="enablesubpackages" value="false"/>
  </sqlmapgenerator>
  <!-- 生成mapper接口的位置-->
  <javaclientgenerator type="xmlmapper" targetpackage="com.luis.mapper" targetproject="src/main/java">
   <!-- enablesubpackages 是否让schema作为包的后缀-->
   <property name="enablesubpackages" value="false"/>
  </javaclientgenerator>
  <!-- 指定数据库表 -->
  <table schema="" tablename="user"></table>
 </context>
</generatorconfiguration>

根据个人环境将配置文件中的配置进行更改，如数据库密码，包名，对应数据库表

 所用的数据库表如下：

drop table if exists `user`;
create table `user` (
 `id` bigint(20) not null,
 `name` varchar(255) not null,
 `age` int(4) not null,
 primary key (`id`)
) engine=innodb default charset=utf8;
insert into `user` values ('1', 'wanger', '22');
insert into `user` values ('2', 'zhangsan', '18');
insert into `user` values ('3', 'lisi', '23');
insert into `user` values ('4', 'wangwu', '21');

配置完成后，右键项目，选择run as——maven build——在下面两处分别填入：

goals: mybatis-generator:generate -e
 profiles: generatorconfig.xml

如下图所示：

出现如下所示，代码生成成功，刷新项目即可。

[info] generating example class for table user
[info] generating record class for table user
[info] generating mapper interface for table user
[info] generating sql map for table user
[info] saving file usermapper.xml
[info] saving file userexample.java
[info] saving file user.java
[info] saving file usermapper.java
[info] ------------------------------------------------------------------------
[info] build success
[info] ------------------------------------------------------------------------

需要注意的是：逆向工程生成的代码不会覆盖，因而不能重复多次生成。

 此处也有个小坑，逆向工程的代码生成后，启动项目会报如下错误：

***************************
application failed to start
***************************

description:

field usermapper in com.luis.service.impl.userserviceimpl required a bean of type 'com.luis.mapper.usermapper' that could not be found.

action:

consider defining a bean of type 'com.luis.mapper.usermapper' in your configuration.

解决方案：

1、给生成的mapper接口文件前加注解：@mapper 即可解决。但需要给每一个mapper文件前加，繁琐，因而有第二种类

解决办法

2、在启动类前加@mapperscan({"com.luis.mapper"})，其中com.luis.mapper为mapper文件的所在位置。

 参考自：

分页应用

逆向工程已经生成了entity类，及dao层的mapper接口与*mapper.xml文件，因而/只用编写service层与web层。

 首先在userservice中编写接口，代码如下：

public interface userservice {
 user selectbyname(string name);
 list<user> findalluser(int pagenum, int pagesize);
}

在userserviceimpl文件进行实现，代码如下所示：

@service
public class userserviceimpl implements userservice {
 @autowired
 private usermapper usermapper;
 @override
 public user selectbyname(string name) {
  userexample example = new userexample();
  criteria criteria = example.createcriteria();
  criteria.andnameequalto(name);
  list<user> users = usermapper.selectbyexample(example);
  if (users != null && users.size() > 0) {
   return users.get(0);
  }
  return null;
 }
 /**
  * pagenum 开始页数
  * pagesize 每页显示的数据条数
  */
 @override
 public list<user> findalluser(int pagenum, int pagesize) {
  //将参数传给方法实现分页
  pagehelper.startpage(pagenum, pagesize);
  userexample example = new userexample();
  list<user> list = usermapper.selectbyexample(example);
  return list;
 }
}

最后在controller层对查询结果进行接收，usercontroller代码如下：

@controller
@restcontroller
public class usercontroller {
 @autowired
 private userservice userservice;
 @requestmapping("/test")
 public user queruserbyname() {
  user user = userservice.selectbyname("luis");
  system.out.println(user.tostring());
  return user;
 }
 @requestmapping("/list")
 public list<user> queruser() {
  list<user> list = userservice.findalluser(1, 2);
  //获取分页信息
  pageinfo<user> pageinfo = new pageinfo<>(list);
  system.out.println("total:" + pageinfo.gettotal());
  system.out.println("pages:" + pageinfo.getpages());
  system.out.println("pagesize:" + pageinfo.getpagesize());
  return list;
 }
}

测试

此前在项目编写过程中已经对可能出现的错误进行了总结，最后，对项目的功能进行测试，通过加@restcontroller注解将数据传输到浏览器中。

 测试mybatis与springboot，浏览器输入，浏览器输出：

{"id":1,"name":"wanger","age":22}

分页测试，浏览器输入，浏览器输出：

[{"id":1,"name":"wanger","age":22},{"id":2,"name":"zhangsan","age":18}]

eclipse输出：

total:4
pages:2
pagesize:2

项目搭建完毕，具体代码参见github

总结

以上所述是小编给大家介绍的mybatis逆向工程与分页在springboot中的应用，希望对大家有所帮助