Spring boot 入門（二）：Spring boot集成MySql,Mybatis和PageHelper插件

時間 2019-11-13

標籤 spring boot 入門集成 mysql mybatis pagehelper 插件欄目 Spring 简体版

原文原文鏈接

　　上一篇文章，寫了如何搭建一個簡單的Spring boot項目，本篇是接着上一篇文章寫得：Spring boot入門：快速搭建Spring boot項目（一），主要是spring boot集成mybatis和pagehelpercss

關於mybatis和pagehelper的介紹，能夠自行博客，網上不少相似的博客，這裏，我直接上代碼和項目搭建教程。html

1.配置文件：在配置文件application.yml中配置MySql數據庫鏈接池和Mybatis掃描包以及PageHelper分頁插件前端

 1 mybatis:
 2   mapper-locations: classpath:mapper/*.xml
 3   type-aliases-package: com.tswc.edu.entity
 4 
 5 mapper:
 6   mappers:
 7   - com.tswc.edu.util.MyMapper
 8   not-empty: false
 9   identity: MYSQL
10   #identity: SQLSERVER
11 
12 pagehelper:
13   helperDialect: MYSQL
14   reasonable: true
15   supportMethodsArguments: true
16   params: count=countSql
17 
18 spring:
19   datasource:
20     type: com.alibaba.druid.pool.DruidDataSource
21     driverClassName: com.mysql.jdbc.Driver
22     url: jdbc:mysql://127.0.0.1:3306/edu?useUnicode=true&characterEncoding=utf8
23     username: root
24     password: 123456
25     initialSize: 1
26     minIdle: 3
27     maxActive: 20
28     # 配置獲取鏈接等待超時的時間
29     maxWait: 60000
30     # 配置間隔多久才進行一次檢測，檢測須要關閉的空閒鏈接，單位是毫秒
31     timeBetweenEvictionRunsMillis: 60000
32     # 配置一個鏈接在池中最小生存的時間，單位是毫秒
33     minEvictableIdleTimeMillis: 30000
34     validationQuery: select 'x'
35     testWhileIdle: true
36     testOnBorrow: false
37     testOnReturn: false
38     # 打開PSCache，而且指定每一個鏈接上PSCache的大小
39     poolPreparedStatements: true
40     maxPoolPreparedStatementPerConnectionSize: 20
41     # 配置監控統計攔截的filters，去掉後監控界面sql沒法統計，'wall'用於防火牆
42     filters: stat,wall,slf4j
43     # 經過connectProperties屬性來打開mergeSql功能；慢SQL記錄
44     connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
45     # 合併多個DruidDataSource的監控數據
46     #useGlobalDataSourceStat: true

同時，須要在pom.xml中添加相應的jar包依賴,若是存在jar包沒法下載，能夠手動下載，而後放到相應的jar包文件夾中java

***********************************這裏面須要注意Spring boot和mybatis的jar包之間的版本，sping boot2+要求高版本，eg：spring boot2+不能識別pagehelper1.2如下的版本mysql

 1  <!--mybatis -->
 2         <dependency>
 3             <groupId>mysql</groupId>
 4             <artifactId>mysql-connector-java</artifactId>
 5             <version>5.1.6</version>
 6         </dependency>
 7         <dependency>
 8             <groupId>org.mybatis</groupId>
 9             <artifactId>mybatis</artifactId>
10             <version>3.4.4</version>
11         </dependency>
12 
13         <dependency>
14             <groupId>org.mybatis.spring.boot</groupId>
15             <artifactId>mybatis-spring-boot-starter</artifactId>
16             <version>1.1.1</version>
17         </dependency>
18         <!--druid -->
19         <dependency>
20             <groupId>com.alibaba</groupId>
21             <artifactId>druid</artifactId>
22             <version>1.0.28</version>
23         </dependency>
24 
25         <!--mapper-->
26         <dependency>
27             <groupId>tk.mybatis</groupId>
28             <artifactId>mapper-spring-boot-starter</artifactId>
29             <version>2.1.0</version>
30         </dependency>
31         <!--pagehelper,Spring boot2.0+只能設備pagehelper1.2+-->
32         <dependency>
33             <groupId>com.github.pagehelper</groupId>
34             <artifactId>pagehelper-spring-boot-starter</artifactId>
35             <version>1.2.5</version>
36         </dependency>

2：代碼部分git

（1）.更新入口主文件，主要增長了一些註解，github

　　此處須要注意@MapperSca的引用，這裏有2個可引用的包，分別是tk.mybatis.spring.annotation.MapperScan和org.mybatis.spring.annotation.MapperScan;web

　　tk.mybatis.spring.annotation.MapperScan：爲mubatis帶的mapper掃描文件，org.mybatis.spring.annotation.MapperScan爲spring自帶的掃描文件，在低版本的mybatis上，2個包能夠隨意使用，可是Spring boot2+後，增長了一些特性（建議閱讀spring boot2+的底層代碼，加深理解），致使只能使用高版本的mtbatis，同時spring自帶的MapperScan也沒法使用，因此使用sping boot2+後，須要引用高版本的mybatis，同時這裏只能使用mybatis的MapperScan的掃描包；spring在後期更新中，應該也會使其可以用於boot中spring

 1 @ServletComponentScan
 2 @MapperScan(basePackages = "com.tswc.edu.mapper")
 3 @SpringBootApplication
 4 public class EduApplication {
 5 
 6     public static void main(String[] args) {
 7         SpringApplication.run(EduApplication.class, args);
 8     }
 9 
10 }

　　若是在項目正常，啓動，可是在使用mybatis時，報此類錯誤：sql

　　後臺錯誤：沒法獲取實體類對應的表名!

 1 2018-12-14 20:09:25.967 ERROR 29024 --- [nio-8085-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is tk.mybatis.mapper.MapperException: 沒法獲取實體類com.tswc.edu.entity.Index對應的表名!] with root caus 2 
 3 tk.mybatis.mapper.MapperException: 沒法獲取實體類com.tswc.edu.entity.Index對應的表名!
 4     at tk.mybatis.mapper.mapperhelper.EntityHelper.getEntityTable(EntityHelper.java:69) ~[mapper-core-1.1.0.jar:na]
 5     at tk.mybatis.mapper.entity.Example.<init>(Example.java:103) ~[mapper-core-1.1.0.jar:na]
 6     at tk.mybatis.mapper.entity.Example.<init>(Example.java:88) ~[mapper-core-1.1.0.jar:na]
 7     at tk.mybatis.mapper.entity.Example.<init>(Example.java:78) ~[mapper-core-1.1.0.jar:na]
 8     at com.tswc.edu.service.IndexService.getList(IndexService.java:33) ~[classes/:na]
 9     at com.tswc.edu.controller.IndexController.list(IndexController.java:35) ~[classes/:na]
10     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
11     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
12     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
13     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
14     at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
15     at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
16     at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
17     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
18     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
19     at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
20     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
21     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
22     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
23     at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
24     at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
25     at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
26     at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
27     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
28     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
29     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.13.jar:9.0.13]
30     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
31     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
32     at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
33     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
34     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
35     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
36     at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
37     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
38     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
39     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
40     at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
41     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
42     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
43     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
44     at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
45     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
46     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
47     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
48     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
49     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.13.jar:9.0.13]
50     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.13.jar:9.0.13]
51     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.13.jar:9.0.13]
52     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.13.jar:9.0.13]
53     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.13.jar:9.0.13]
54     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.13.jar:9.0.13]
55     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.13.jar:9.0.13]
56     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.13.jar:9.0.13]
57     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:791) [tomcat-embed-core-9.0.13.jar:9.0.13]
58     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) [tomcat-embed-core-9.0.13.jar:9.0.13]
59     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.13.jar:9.0.13]
60     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
61     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
62     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.13.jar:9.0.13]
63     at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]

　　前端錯誤是500

1 Whitelabel Error Page
2 This application has no explicit mapping for /error, so you are seeing this as a fallback.
3 
4 Fri Dec 14 20:09:25 CST 2018
5 There was an unexpected error (type=Internal Server Error, status=500).
6 ???????com.tswc.edu.entity.Index?????!

那麼，就是Mapper掃描包使用有誤

（2）.通用接口mapper：此接口不能被掃描到，不然會報錯，能夠在application.yml中，排除此包的掃描

1 public interface MyMapper<T> extends Mapper<T> {
2     //TODO
3     //FIXME 特別注意，該接口不能被掃描到，不然會出錯
4 }

（3）後臺代碼，控制村層>服務層>接口

 1 @Controller
 2 public class IndexController {
 3     @Autowired
 4     private IndexService indexService;
 5 
 6     @RequestMapping(value = "/index")
 7     public void list(ModelMap modelMap) {
 8         List<Index> list = indexService.getList();
 9         modelMap.put("list", list);
10     }
11 }

 1 @Service
 2 public class IndexService {
 3     @Autowired
 4     private IndexMapper indexMapper;
 5 
 6     public List<Index> getList() {
 7         Example example = new Example(Index.class);
 8         example.setTableName("index_test");
 9         Criteria criteria = example.createCriteria();
10         criteria.andEqualTo("age", 20);
11         return indexMapper.selectByExample(example);
12     }
13 }

1 public interface IndexMapper extends MyMapper<Index> {
2 }

 1 @Table(name = "index_test")
 2 public class Index implements Serializable, IDynamicTableName {
 3     private static final long serialVersionUID = -8709793124943394842L;
 4 
 5     @Transient
 6     private String dynamicTableName;
 7     private String name;
 8     private Integer age;
 9 
10     public String getName() {
11         return name;
12     }
13 
14     public void setName(String name) {
15         this.name = name;
16     }
17 
18     public Integer getAge() {
19         return age;
20     }
21 
22     public void setAge(Integer age) {
23         this.age = age;
24     }
25 
26     @Override
27     public String getDynamicTableName() {
28         return null;
29     }
30 }

　　最後一個類爲實體類，建議在創建實體類的時候，統一加上@Table的註解，方便後期Mybatis的使用，同時也提升了代碼的規範性。固然，若是咱們使用Mybatis的代碼生成器，那麼均會自動加上註解（代碼生成器在後期的博客中會講到）

（4）.前端ftl代碼

 1 <!DOCTYPE html>
 2 <html>
 3 <head lang="en">
 4     <title>Spring Boot Demo - FreeMarker</title>
 5     <link href="/css/index.css" rel="stylesheet" />
 6 </head>
 7 <body>
 8     <table>
 9         <#list list as user>
10         <tr>
11             <td>第${user_index+1}個用戶</td>
12             <td>用戶名：${user.name}</td>
13             <td>年  齡: ${user.age}</td>
14         </tr>
15         </#list>
16     </table>
17 </body>
18 </html>

（5）添加mybatis的空配置文件，因爲spring boot中，數據庫是經過配置文件的形式，因此此文件是空的，可是沒有此文件，mybatis就沒法經過；固然，也能夠經過在此文件做用配置數據庫鏈接池的方式鏈接數據（已過期）

1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD SQL MAP Config 3.1//EN"
3     "http://mybatis.org/dtd/mybatis-3-config.dtd">
4 <configuration>
5   <settings>
6     <setting name="callSettersOnNulls" value="true"/>
7   </settings>
8 </configuration>