Springboot2中如何集成pagehelper

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>

  <parent>

    <groupId>org.springframework.boot</groupId>

    <artifactId>spring-boot-starter-parent</artifactId>

    <version>2.2.1.RELEASE</version>

    <relativePath/> <!-- lookup parent from repository -->

  </parent>

  <groupId>qinfeng.zheng</groupId>

  <artifactId>learn-pagequery</artifactId>

  <version>0.0.1-SNAPSHOT</version>

  <name>learn-pagequery</name>

  <description>Demo project for Spring Boot</description>

  <properties>

    <java.version>1.8</java.version>

  </properties>

  <dependencies>

    <dependency>

      <groupId>org.springframework.boot</groupId>

      <artifactId>spring-boot-starter-web</artifactId>

    </dependency>

    <dependency>

      <groupId>org.mybatis.spring.boot</groupId>

      <artifactId>mybatis-spring-boot-starter</artifactId>

      <version>1.3.2</version>

    </dependency>

    <dependency>

      <groupId>mysql</groupId>

      <artifactId>mysql-connector-java</artifactId>

      <version>5.1.47</version>

      <scope>runtime</scope>

    </dependency>

    <dependency>

      <groupId>org.springframework.boot</groupId>

      <artifactId>spring-boot-starter-test</artifactId>

      <scope>test</scope>

      <exclusions>

        <exclusion>

          <groupId>org.junit.vintage</groupId>

          <artifactId>junit-vintage-engine</artifactId>

        </exclusion>

      </exclusions>

    </dependency>

    <dependency>

      <groupId>com.github.pagehelper</groupId>

      <artifactId>pagehelper-spring-boot-starter</artifactId>

      <version>1.2.12</version>

    </dependency>

  </dependencies>

  <build>

    <plugins>

      <plugin>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-maven-plugin</artifactId>

      </plugin>

    </plugins>

  </build>

</project>

public class Country implements Serializable {

  private static final long serialVersionUID = 6569081236403751407L;

  private int  id;

  private String countryname;

  private String countrycode;

  public int getId() {

    return id;

  }

  public void setId(int id) {

    this.id = id;

  }

  public String getCountryname() {

    return countryname;

  }

  public void setCountryname(String countryname) {

    this.countryname = countryname;

  }

  public String getCountrycode() {

    return countrycode;

  }

  public void setCountrycode(String countrycode) {

    this.countrycode = countrycode;

  }

}

@Mapper

public interface CountryMapper {

  @Select("select * from country")

  List<Country> findAll();

}

@RestController

public class CountryController {

  @Autowired

  private CountryMapper countryMapper;

  @GetMapping("/findAll")

  public List<Country> findAll(@RequestParam(defaultValue = "1") Integer pageNum, @RequestParam(defaultValue = "20") Integer pageSize) {

    PageHelper.startPage(pageNum, pageSize);

    List<Country> countries = countryMapper.findAll();

    Page page = (Page) countries;

    System.out.println("每页展示条数：" + page.getPageSize());

    System.out.println("总条数：" + page.getTotal());

    System.out.println("当前页：" + page.getPageNum());

    System.out.println("总页数：" + page.getPages());

    return countries;

  }

}

drop table country if exists;

create table country (

 id int primary key auto_increment,

 countryname varchar(32),

 countrycode varchar(2)

);

insert into country (id, countryname, countrycode) values(1,'Angola','AO');

insert into country (id, countryname, countrycode) values(2,'Afghanistan','AF');

insert into country (id, countryname, countrycode) values(3,'Albania','AL');

insert into country (id, countryname, countrycode) values(4,'Algeria','DZ');

insert into country (id, countryname, countrycode) values(5,'Andorra','AD');

insert into country (id, countryname, countrycode) values(6,'Anguilla','AI');

insert into country (id, countryname, countrycode) values(7,'Antigua and Barbuda','AG');

insert into country (id, countryname, countrycode) values(8,'Argentina','AR');

insert into country (id, countryname, countrycode) values(9,'Armenia','AM');

insert into country (id, countryname, countrycode) values(10,'Australia','AU');

insert into country (id, countryname, countrycode) values(11,'Austria','AT');

insert into country (id, countryname, countrycode) values(12,'Azerbaijan','AZ');

insert into country (id, countryname, countrycode) values(13,'Bahamas','BS');

insert into country (id, countryname, countrycode) values(14,'Bahrain','BH');

insert into country (id, countryname, countrycode) values(15,'Bangladesh','BD');

insert into country (id, countryname, countrycode) values(16,'Barbados','BB');

insert into country (id, countryname, countrycode) values(17,'Belarus','BY');

insert into country (id, countryname, countrycode) values(18,'Belgium','BE');

insert into country (id, countryname, countrycode) values(19,'Belize','BZ');

insert into country (id, countryname, countrycode) values(20,'Benin','BJ');

insert into country (id, countryname, countrycode) values(21,'Bermuda Is.','BM');

insert into country (id, countryname, countrycode) values(22,'Bolivia','BO');

insert into country (id, countryname, countrycode) values(23,'Botswana','BW');

insert into country (id, countryname, countrycode) values(24,'Brazil','BR');

insert into country (id, countryname, countrycode) values(25,'Brunei','BN');

insert into country (id, countryname, countrycode) values(26,'Bulgaria','BG');

insert into country (id, countryname, countrycode) values(27,'Burkina-faso','BF');

insert into country (id, countryname, countrycode) values(28,'Burma','MM');

insert into country (id, countryname, countrycode) values(29,'Burundi','BI');

insert into country (id, countryname, countrycode) values(30,'Cameroon','CM');

insert into country (id, countryname, countrycode) values(31,'Canada','CA');

insert into country (id, countryname, countrycode) values(32,'Central African Republic','CF');

insert into country (id, countryname, countrycode) values(33,'Chad','TD');

insert into country (id, countryname, countrycode) values(34,'Chile','CL');

insert into country (id, countryname, countrycode) values(35,'China','CN');

insert into country (id, countryname, countrycode) values(36,'Colombia','CO');

insert into country (id, countryname, countrycode) values(37,'Congo','CG');

insert into country (id, countryname, countrycode) values(38,'Cook Is.','CK');

insert into country (id, countryname, countrycode) values(39,'Costa Rica','CR');

insert into country (id, countryname, countrycode) values(40,'Cuba','CU');

insert into country (id, countryname, countrycode) values(41,'Cyprus','CY');

insert into country (id, countryname, countrycode) values(42,'Czech Republic','CZ');

insert into country (id, countryname, countrycode) values(43,'Denmark','DK');

insert into country (id, countryname, countrycode) values(44,'Djibouti','DJ');

insert into country (id, countryname, countrycode) values(45,'Dominica Rep.','DO');

insert into country (id, countryname, countrycode) values(46,'Ecuador','EC');

insert into country (id, countryname, countrycode) values(47,'Egypt','EG');

insert into country (id, countryname, countrycode) values(48,'EI Salvador','SV');

insert into country (id, countryname, countrycode) values(49,'Estonia','EE');

insert into country (id, countryname, countrycode) values(50,'Ethiopia','ET');

insert into country (id, countryname, countrycode) values(51,'Fiji','FJ');

insert into country (id, countryname, countrycode) values(52,'Finland','FI');

insert into country (id, countryname, countrycode) values(53,'France','FR');

insert into country (id, countryname, countrycode) values(54,'French Guiana','GF');

insert into country (id, countryname, countrycode) values(55,'Gabon','GA');

insert into country (id, countryname, countrycode) values(56,'Gambia','GM');

insert into country (id, countryname, countrycode) values(57,'Georgia','GE');

insert into country (id, countryname, countrycode) values(58,'Germany','DE');

insert into country (id, countryname, countrycode) values(59,'Ghana','GH');

insert into country (id, countryname, countrycode) values(60,'Gibraltar','GI');

insert into country (id, countryname, countrycode) values(61,'Greece','GR');

insert into country (id, countryname, countrycode) values(62,'Grenada','GD');

insert into country (id, countryname, countrycode) values(63,'Guam','GU');

insert into country (id, countryname, countrycode) values(64,'Guatemala','GT');

insert into country (id, countryname, countrycode) values(65,'Guinea','GN');

insert into country (id, countryname, countrycode) values(66,'Guyana','GY');

insert into country (id, countryname, countrycode) values(67,'Haiti','HT');

insert into country (id, countryname, countrycode) values(68,'Honduras','HN');

insert into country (id, countryname, countrycode) values(69,'Hongkong','HK');

insert into country (id, countryname, countrycode) values(70,'Hungary','HU');

insert into country (id, countryname, countrycode) values(71,'Iceland','IS');

insert into country (id, countryname, countrycode) values(72,'India','IN');

insert into country (id, countryname, countrycode) values(73,'Indonesia','ID');

insert into country (id, countryname, countrycode) values(74,'Iran','IR');

insert into country (id, countryname, countrycode) values(75,'Iraq','IQ');

insert into country (id, countryname, countrycode) values(76,'Ireland','IE');

insert into country (id, countryname, countrycode) values(77,'Israel','IL');

insert into country (id, countryname, countrycode) values(78,'Italy','IT');

insert into country (id, countryname, countrycode) values(79,'Jamaica','JM');

insert into country (id, countryname, countrycode) values(80,'Japan','JP');

insert into country (id, countryname, countrycode) values(81,'Jordan','JO');

insert into country (id, countryname, countrycode) values(82,'Kampuchea (Cambodia )','KH');

insert into country (id, countryname, countrycode) values(83,'Kazakstan','KZ');

insert into country (id, countryname, countrycode) values(84,'Kenya','KE');

insert into country (id, countryname, countrycode) values(85,'Korea','KR');

insert into country (id, countryname, countrycode) values(86,'Kuwait','KW');

insert into country (id, countryname, countrycode) values(87,'Kyrgyzstan','KG');

insert into country (id, countryname, countrycode) values(88,'Laos','LA');

insert into country (id, countryname, countrycode) values(89,'Latvia','LV');

insert into country (id, countryname, countrycode) values(90,'Lebanon','LB');

insert into country (id, countryname, countrycode) values(91,'Lesotho','LS');

insert into country (id, countryname, countrycode) values(92,'Liberia','LR');

insert into country (id, countryname, countrycode) values(93,'Libya','LY');

insert into country (id, countryname, countrycode) values(94,'Liechtenstein','LI');

insert into country (id, countryname, countrycode) values(95,'Lithuania','LT');

insert into country (id, countryname, countrycode) values(96,'Luxembourg','LU');

insert into country (id, countryname, countrycode) values(97,'Macao','MO');

insert into country (id, countryname, countrycode) values(98,'Madagascar','MG');

insert into country (id, countryname, countrycode) values(99,'Malawi','MW');

insert into country (id, countryname, countrycode) values(100,'Malaysia','MY');

insert into country (id, countryname, countrycode) values(101,'Maldives','MV');

insert into country (id, countryname, countrycode) values(102,'Mali','ML');

insert into country (id, countryname, countrycode) values(103,'Malta','MT');

insert into country (id, countryname, countrycode) values(104,'Mauritius','MU');

insert into country (id, countryname, countrycode) values(105,'Mexico','MX');

insert into country (id, countryname, countrycode) values(106,'Moldova, Republic of','MD');

insert into country (id, countryname, countrycode) values(107,'Monaco','MC');

insert into country (id, countryname, countrycode) values(108,'Mongolia','MN');

insert into country (id, countryname, countrycode) values(109,'Montserrat Is','MS');

insert into country (id, countryname, countrycode) values(110,'Morocco','MA');

insert into country (id, countryname, countrycode) values(111,'Mozambique','MZ');

insert into country (id, countryname, countrycode) values(112,'Namibia','NA');

insert into country (id, countryname, countrycode) values(113,'Nauru','NR');

insert into country (id, countryname, countrycode) values(114,'Nepal','NP');

insert into country (id, countryname, countrycode) values(115,'Netherlands','NL');

insert into country (id, countryname, countrycode) values(116,'New Zealand','NZ');

insert into country (id, countryname, countrycode) values(117,'Nicaragua','NI');

insert into country (id, countryname, countrycode) values(118,'Niger','NE');

insert into country (id, countryname, countrycode) values(119,'Nigeria','NG');

insert into country (id, countryname, countrycode) values(120,'North Korea','KP');

insert into country (id, countryname, countrycode) values(121,'Norway','NO');

insert into country (id, countryname, countrycode) values(122,'Oman','OM');

insert into country (id, countryname, countrycode) values(123,'Pakistan','PK');

insert into country (id, countryname, countrycode) values(124,'Panama','PA');

insert into country (id, countryname, countrycode) values(125,'Papua New Cuinea','PG');

insert into country (id, countryname, countrycode) values(126,'Paraguay','PY');

insert into country (id, countryname, countrycode) values(127,'Peru','PE');

insert into country (id, countryname, countrycode) values(128,'Philippines','PH');

insert into country (id, countryname, countrycode) values(129,'Poland','PL');

insert into country (id, countryname, countrycode) values(130,'French Polynesia','PF');

insert into country (id, countryname, countrycode) values(131,'Portugal','PT');

insert into country (id, countryname, countrycode) values(132,'Puerto Rico','PR');

insert into country (id, countryname, countrycode) values(133,'Qatar','QA');

insert into country (id, countryname, countrycode) values(134,'Romania','RO');

insert into country (id, countryname, countrycode) values(135,'Russia','RU');

insert into country (id, countryname, countrycode) values(136,'Saint Lueia','LC');

insert into country (id, countryname, countrycode) values(137,'Saint Vincent','VC');

insert into country (id, countryname, countrycode) values(138,'San Marino','SM');

insert into country (id, countryname, countrycode) values(139,'Sao Tome and Principe','ST');

insert into country (id, countryname, countrycode) values(140,'Saudi Arabia','SA');

insert into country (id, countryname, countrycode) values(141,'Senegal','SN');

insert into country (id, countryname, countrycode) values(142,'Seychelles','SC');

insert into country (id, countryname, countrycode) values(143,'Sierra Leone','SL');

insert into country (id, countryname, countrycode) values(144,'Singapore','SG');

insert into country (id, countryname, countrycode) values(145,'Slovakia','SK');

insert into country (id, countryname, countrycode) values(146,'Slovenia','SI');

insert into country (id, countryname, countrycode) values(147,'Solomon Is','SB');

insert into country (id, countryname, countrycode) values(148,'Somali','SO');

insert into country (id, countryname, countrycode) values(149,'South Africa','ZA');

insert into country (id, countryname, countrycode) values(150,'Spain','ES');

insert into country (id, countryname, countrycode) values(151,'Sri Lanka','LK');

insert into country (id, countryname, countrycode) values(152,'St.Lucia','LC');

insert into country (id, countryname, countrycode) values(153,'St.Vincent','VC');

insert into country (id, countryname, countrycode) values(154,'Sudan','SD');

insert into country (id, countryname, countrycode) values(155,'Suriname','SR');

insert into country (id, countryname, countrycode) values(156,'Swaziland','SZ');

insert into country (id, countryname, countrycode) values(157,'Sweden','SE');

insert into country (id, countryname, countrycode) values(158,'Switzerland','CH');

insert into country (id, countryname, countrycode) values(159,'Syria','SY');

insert into country (id, countryname, countrycode) values(160,'Taiwan','TW');

insert into country (id, countryname, countrycode) values(161,'Tajikstan','TJ');

insert into country (id, countryname, countrycode) values(162,'Tanzania','TZ');

insert into country (id, countryname, countrycode) values(163,'Thailand','TH');

insert into country (id, countryname, countrycode) values(164,'Togo','TG');

insert into country (id, countryname, countrycode) values(165,'Tonga','TO');

insert into country (id, countryname, countrycode) values(166,'Trinidad and Tobago','TT');

insert into country (id, countryname, countrycode) values(167,'Tunisia','TN');

insert into country (id, countryname, countrycode) values(168,'Turkey','TR');

insert into country (id, countryname, countrycode) values(169,'Turkmenistan','TM');

insert into country (id, countryname, countrycode) values(170,'Uganda','UG');

insert into country (id, countryname, countrycode) values(171,'Ukraine','UA');

insert into country (id, countryname, countrycode) values(172,'United Arab Emirates','AE');

insert into country (id, countryname, countrycode) values(173,'United Kiongdom','GB');

insert into country (id, countryname, countrycode) values(174,'United States of America','US');

insert into country (id, countryname, countrycode) values(175,'Uruguay','UY');

insert into country (id, countryname, countrycode) values(176,'Uzbekistan','UZ');

insert into country (id, countryname, countrycode) values(177,'Venezuela','VE');

insert into country (id, countryname, countrycode) values(178,'Vietnam','VN');

insert into country (id, countryname, countrycode) values(179,'Yemen','YE');

insert into country (id, countryname, countrycode) values(180,'Yugoslavia','YU');

insert into country (id, countryname, countrycode) values(181,'Zimbabwe','ZW');

insert into country (id, countryname, countrycode) values(182,'Zaire','ZR');

insert into country (id, countryname, countrycode) values(183,'Zambia','ZM');

@GetMapping("/findAll")

  public PageInfo<Country> findAll(@RequestParam(defaultValue = "1") Integer pageNum, @RequestParam(defaultValue = "20") Integer pageSize) {

    PageHelper.startPage(pageNum, pageSize);

    List<Country> countries = countryMapper.findAll();

//    Page page = (Page) countries;

//    System.out.println("每页展示条数：" + page.getPageSize());

//    System.out.println("总条数：" + page.getTotal());

//    System.out.println("当前页：" + page.getPageNum());

//    System.out.println("总页数：" + page.getPages());

    PageInfo<Country> result = new PageInfo<>(countries);

    return result;

  }

private int pageNum; // 当前页码

  private int pageSize; // 每页展示的多少条数据

  private int size;     // 数据总条数

  private int startRow; 

  private int endRow;

  private int pages;   // 总共多少页

  private int prePage;  // 前一页

  private int nextPage; // 后一页

  private boolean isFirstPage;

  private boolean isLastPage;

  private boolean hasPreviousPage;

  private boolean hasNextPage;

  private int navigatePages;

  private int[] navigatepageNums;

  private int navigateFirstPage;

  private int navigateLastPage;