java - Fail to connect to mysql when I using spring boot -

i want make web server spring boot, when try connect database, comes errors. here parts of code.

@controller public class backgroundcontroller {  private jdbctemplate jdbctemplate; @requestmapping("/rankinglist") @responsebody public string rankinglist(model model){     string sql="select username,score user;";     list<map<string, object>> list = new arraylist<map<string, object>>();     try {         list = jdbctemplate.queryforlist(sql);     }catch (exception e){         return e.tostring();     }//return "rankinglist"; }  } 

here dependencies in pom.xml;

<dependency>             <groupid>mysql</groupid>             <artifactid>mysql-connector-java</artifactid>         </dependency>         <dependency>             <groupid>org.springframework.boot</groupid>             <artifactid>spring-boot-starter-jdbc</artifactid>         </dependency> 

here parts of application.properties, 'em' name of database;

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/em spring.datasource.username=root spring.datasource.password=qwerty spring.datasource.driver-class-name=com.mysql.jdbc.driver 

here status of database.

connection id:          3 current database:       em current user:           root@localhost ssl:                    not in use using delimiter:        ; server version:         5.7.18-log mysql community server (gpl) protocol version:       10 connection:             localhost via tcp/ip server characterset:    utf8 db     characterset:    utf8 client characterset:    utf8 conn.  characterset:    utf8 tcp port:               3306 

but when url:http://localhost:4908/rankinglist, output java.lang.nullpointerexception.

i want help, , appreciate much.

you should add @autowired private jdbctemplate jdbctemplate;