Spring Boot starter--jdbctemplate usage and related issues resolution

1, in the Pom.xml file to introduce the corresponding dependency

    <!--MySQL Dependency -    <Dependency>        <groupId>Mysql</groupId>        <Artifactid>Mysql-connector-java</Artifactid>        <version>5.1.42</version>    </Dependency>        <!--jdbc Dependency -    <Dependency>        <groupId>Org.springframework.boot</groupId>        <Artifactid>Spring-boot-starter-jdbc</Artifactid>    </Dependency>

2. Create Grade Class

public class Grade {    private int id;    Private String Gradenm;    private int teacherid;        public int getId () {        return ID;    }    public void setId (int id) {        this.id = ID;    }    Public String Getgradenm () {        return gradenm;    }    public void Setgradenm (String gradenm) {        this.gradenm = gradenm;    }    public int Getteacherid () {        return teacherid;    }    public void Setteacherid (int teacherid) {        This.teacherid = Teacherid;    }}

View Code

3. Create Gradedao

import java.sql.resultset;import Java.sql.sqlexception;import Javax.annotation.resource;import Org.springframework.jdbc.core.beanpropertyrowmapper;import Org.springframework.jdbc.core.jdbctemplate;import Org.springframework.jdbc.core.rowmapper;import Org.springframework.stereotype.repository;import        Com.wyl.bean.Grade, @Repositorypublic class gradedao{@Resource private JdbcTemplate jdbctemplate;        Public Grade Findbygradenm (string gradenm) {string-sql = "SELECT * from Grade where grade_nm= '" + gradenm + "'"; rowmapper   <grade> rm = new Beanpropertyrowmapper<>   (grade.class);    Return Jdbctemplate.queryforobject (SQL,RM); }/*    
* You must manually encapsulate the grade class yourself, because Springboot encapsulates a column in the database as an object by default
* / class Graderowmapper implements RowMapper     <Grade> {@Override public Grade Maprow (ResultSet rs, int rowNum) throws SQLException {//TODO            auto-generated method Stub Grade Grade = new Grade ();            Grade.setgradenm (rs.getstring ("grade_nm"));            Grade.setid (Rs.getint ("id"));            Grade.setteacherid (Rs.getint ("teacher_id"));        return grade; }    }}

4. Create Gradeservice

ImportJavax.annotation.Resource;ImportOrg.springframework.stereotype.Service;ImportCom.wyl.bean.Grade;ImportCom.wyl.dao.GradeDAO;/*** Gradeservice class, call method in Gradedao **/@Service Public classGradeservice {@ResourcePrivateGradedao Gradedao;  PublicGrade fingbygradenm (String gradenm) {returnGradedao.findbygradenm (GRADENM); }}

5. Create Gradecontroller

ImportJavax.annotation.Resource;Importorg.springframework.web.bind.annotation.RequestMapping;ImportOrg.springframework.web.bind.annotation.RestController;ImportCom.wyl.bean.Grade;ImportCom.wyl.service.GradeService; @RestController Public classJpacontroller {@ResourcePrivateGradeservice Gradeservice; @RequestMapping ("/finfbygradenm")     PublicGrade finfbygradenm (String gradenm) {System.out.println ("Finfbygradenm"); return Gradeservice.fingbygradenm (GRADENM); }}

6. Testing

Org.springframework.beans.factory.BeanCreationException:Error creating bean with Name ' Org.springframework.boot.autoconfigure.liquibase.liquibaseautoconfiguration$liquibaseconfiguration ': Invocation of Init method failed; Nested exception is java.lang.IllegalStateException:Cannot find changelog location:class path resource [db/changelog/db . Changelog-master.yaml] (please add changelog or check your liquibase configuration) at Org.springframework.beans.facto Ry.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization ( initdestroyannotationbeanpostprocessor.java:137) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization (abstractautowirecapablebeanfactory.java:409) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean ( Abstractautowirecapablebeanfactory. java:1620) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean ( abstractautowirecapablebeanfactory.java:555) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean ( abstractautowirecapablebeanfactory.java:483) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.abstractbeanfactory$1.getobject (abstractbeanfactory.java:306) ~[ Spring-beans-4.3.8.release.jar:4.3.8.release] At Org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton ( defaultsingletonbeanregistry.java:230) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean (abstractbeanfactory.java:302) ~[ Spring-beans-4.3.8.release.jar:4.3.8.release] At Org.springframework.beans.factory.support.AbstractBeanFactory.getBeAn (abstractbeanfactory.java:197) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons ( defaultlistablebeanfactory.java:761) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization ( abstractapplicationcontext.java:866) ~[spring-context-4.3.8.release.jar:4.3.8.release] at Org.springframework.context.support.AbstractApplicationContext.refresh (abstractapplicationcontext.java:542) ~[ Spring-context-4.3.8.release.jar:4.3.8.release] At Org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh ( embeddedwebapplicationcontext.java:122) ~[spring-boot-1.5.3.release.jar:1.5.3.release] at Org.springframework.boot.SpringApplication.refresh (springapplication.java:737) [Spring-boot-1.5.3.release.jar : 1.5.3.RELEASE] at Org.springframework.boot.SpringApplication.refreshContext (springapplication.java:370) [Spring-boot-1.5.3.release.jar:1.5.3.release] at Org.springframework.boot.SpringApplication.run ( springapplication.java:314) [Spring-boot-1.5.3.release.jar:1.5.3.release] at Org.springframework.boot.SpringApplication.run (springapplication.java:1162) [Spring-boot-1.5.3.release.jar : 1.5.3.RELEASE] at Org.springframework.boot.SpringApplication.run (springapplication.java:1151) [ Spring-boot-1.5.3.release.jar:1.5.3.release] at Com.wyl.App.main (app.java:16) [Classes/:na] at Sun.reflect.NativeMe THODACCESSORIMPL.INVOKE0 (Native Method) ~[na:1.8.0_60] at Sun.reflect.NativeMethodAccessorImpl.invoke ( nativemethodaccessorimpl.java:62) ~[na:1.8.0_60] at Sun.reflect.DelegatingMethodAccessorImpl.invoke ( delegatingmethodaccessorimpl.java:43) ~[na:1.8.0_60] at Java.lang.reflect.Method.invoke (method.java:497) ~[na : 1.8.0_60] at Org.springframework.boot.devtools.restart.RestartLauncher.run (restartlauncher.java:49) [ Spring-boot-devtools-1.5.3.release.jar:1.5.3.release]cauSed by:java.lang.IllegalStateException:  cannot find changelog location:class path resource [db/changelog/ DB.CHANGELOG-MASTER.YAML] (please add changelog or check your liquibase configuration)     At Org.springframework.util.Assert.state (assert.java:70) ~[spring-core-4.3.8.release.jar:4.3.8.release "at ORG.SPR ingframework.boot.autoconfigure.liquibase.liquibaseautoconfiguration$ Liquibaseconfiguration.checkchangelogexists (liquibaseautoconfiguration.java:92) ~[ Spring-boot-autoconfigure-1.5.3.release.jar:1.5.3.release] at Sun.reflect.NativeMethodAccessorImpl.invoke0 ( Native Method) ~[na:1.8.0_60] at Sun.reflect.NativeMethodAccessorImpl.invoke (nativemethodaccessorimpl.java:62) ~[na : 1.8.0_60] at Sun.reflect.DelegatingMethodAccessorImpl.invoke (delegatingmethodaccessorimpl.java:43) ~[na:1.8.0_60 ] at Java.lang.reflect.Method.invoke (method.java:497) ~[na:1.8.0_60 "at Org.springframework.beans.factory.annotatio N.initdestroyannotationbeanpostprocessor$lifecycleelement.invoke (Initdestroyannotationbeanpostprocessor.java : 366) ~[spring-beans-4.3.8.release.jar:4.3.8.release] at Org.springframework.beans.factory.annotation.initdestroyannotationbeanpostprocessor$lifecyclemeTadata.invokeinitmethods (initdestroyannotationbeanpostprocessor.java:311) ~[spring-beans-4.3.8.release.jar : 4.3.8.RELEASE] At Org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization (initdestroyannotationbeanpostprocessor.java:134) ~[spring-beans-4.3.8.release.jar:4.3.8.release] ... Common frames omitted

This test occurs because Db.changelog-master.yaml files are required in liquibase .

Workaround:

1. Add the following code to the Application.properties:

Liquibase.change-log=classpath:/liquibase/db.changelog.xml

　　2. Create the /liquibase/db.changelog.xml directory under the Src/main/resource package, and the contents of Db.changelog.xml are as follows:

<?XML version= "1.0" encoding= "UTF-8"?><Databasechangelogxmlns= "http://www.liquibase.org/xml/ns/dbchangelog/1.9"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "http://www.liquibase.org/xml/ns/dbchangelog/1.9 http://www.liquibase.org/xml/ns/dbchangelog/dbchange Log-1.9.xsd ">    <ChangeSetID= "1"author= "Jim">        <createtableTableName= "UserAccount">            <columnname= "userid"type= "bigint">                <ConstraintsPrimaryKey= "true" />            </column>            <columnname= "Accountstate"type= "varchar (255)" />            <columnname= "Expireddate"type= "datetime" />            <columnname= "username"type= "varchar (255)" />        </createtable>        <AdduniqueconstraintTableName= "UserAccount"ColumnNames= "username"ConstraintName= "username" />    </ChangeSet>    <ChangeSetID= "2"author= "Jim">        <AddColumnTableName= "UserAccount">            <columnname= "Gender"type= "varchar (1)"value= "M">                <ConstraintsNullable= "false" />            </column>        </AddColumn>    </ChangeSet></Databasechangelog>   

After the test results are resolved:

　　

Spring Boot starter--jdbctemplate usage and related issues resolution