SpringBoot+Maven项目实战（5）：集成分页插件

1.添加分页插件依赖

<!--分页插件-->
<dependency>
   <groupId>com.github.pagehelper</groupId>
   <artifactId>pagehelper</artifactId>
   <version>4.1.1</version>
</dependency>

2.编写程序主函数Application

package com.blog;
import com.github.pagehelper.PageHelper;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.tomcat.jdbc.pool.DataSource;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import java.util.Properties;
/**
 * blog
 * Created by yadong.zhang on com.blog.application
 * User：yadong.zhang
 * Date：2016/10/20
 * Time：18:15
 */
/**
 * 1).@SpringBootApplication标注启动配置入口，run()方法会创建一个Spring应用上下文(Application Context)。
 * SpringBoot通过启动内嵌的Servlet容器（默认tomcat）用来处理Http请求。
 * 2).@RestController是特殊的Controller，他的返回值直接作为Http Response的Body部分返回给浏览器
 * 3).Spring WebMvc框架会将Servlet容器里收到的Http请求根据路径分发到对应的@Controller下进行处理。
 */
@SpringBootApplication
@EnableAspectJAutoProxy
@EnableAutoConfiguration
@ComponentScan
//指定扫描的mapper接口所在的包
@MapperScan("com.blog.mapper")
//启动注解事务管理
@EnableTransactionManagement
//@RestController
public class Applaction {
    //    private static final String MAPPER_SCAN_BASE_PACKAGE = "com.blog.mapper";
    private static final String TYPE_ALIASES_PACKAGE = "com.blog.model";
    private static final String MAPPER_LOCATION = "classpath:/mybatis/*.xml";
    @Bean
    @Autowired
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        final SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        // 分页插件
        PageHelper pageHelper = new PageHelper();
        Properties properties = new Properties();
        properties.setProperty("reasonable", "true");
        properties.setProperty("supportMethodsArguments", "true");
        properties.setProperty("returnPageInfo", "check");
        properties.setProperty("params", "count=countSql");
        pageHelper.setProperties(properties);
        //添加插件
        sqlSessionFactoryBean.setPlugins(new Interceptor[]{pageHelper});
        //mybatis.typeAliasesPackage：指定domain类的基包，即指定其在*Mapper.xml文件中可以使用简名来代替全类名（看后边的UserMapper.xml介绍）
        sqlSessionFactoryBean.setTypeAliasesPackage(TYPE_ALIASES_PACKAGE);
        /*
            mybatis.mapperLocations：指定*Mapper.xml的位置
            如果不加会报org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.blog.mapper.MessageMapper.findMessageInfo异常
            因为找不到*Mapper.xml，也就无法映射mapper中的接口方法。
         */
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCATION));
        return sqlSessionFactoryBean.getObject();
    }

    public static void main(String[] args) {
        SpringApplication.run(Applaction.class, args);
    }
}

3.编写Controller

@RequestMapping("/message/{currentPage}")
public String message(@PathVariable("currentPage") Integer currentPage, Model model){
    if(currentPage!= null){
        PageHelper.startPage(currentPage, 10);
    }
    List<Message> messages = messageService.list();
    model.addAttribute("messages", messages);
    return "message";
}

注：比如你的库中一共有20条记录，按照5条一页来分，那就是一共4页数据，在你访问的时候如果指定的“currentPage”大于4，这个插件会按照最大值进行处理，就是说即使你传入个10000，虽不会报错但最多就显示到第4页的数据