MyBatis的逆向工程和分頁插件

逆向工程

自己生成mybatis執行時所需要的xml，接口，和實體類

第一步：在pow.xml中引入依賴文件

<dependency>
  <groupId>org.mybatis.generator</groupId>
  <artifactId>mybatis-generator-core</artifactId>
  <version>1.3.2</version>
</dependency>

<dependency>
  <groupId>org.mybatis.generator</groupId>
  <artifactId>mybatis-generator-maven-plugin</artifactId>
  <version>1.3.6</version>
</dependency>

<!--導入mybatis架包-->
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis</artifactId>
  <version>3.4.6</version>
</dependency>

然後在pluginManagement的標籤下面加

<plugins>
  <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
  </plugin>
  <!--mybatis-generator插件-->
  <plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.5</version>
    <!--指定資源文件的路徑-->
    <configuration>
      <configurationFile>src\main\resources\generatorConfig.xml</configurationFile>
      <verbose>true</verbose>
      <overwrite>true</overwrite>
    </configuration>
    <!--此插件需要依賴的jar包資源-->
    <dependencies>
      <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.44</version>
      </dependency>
    </dependencies>
  </plugin>
</plugins>

2.新建
com.xx.model—實體類
com.xx.mapper—映射類
的兩個包，裏面不用新建類

3.新建mybatis的配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
 <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/test?characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <mapper resource="com/ywy/model/UserMapper.xml"></mapper>
    </mappers>
</configuration>

還有新建generatorConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
        
<generatorConfiguration>
    <context id="testTables" targetRuntime="MyBatis3">
        <commentGenerator>
            <!-- 是否去除自動生成的註釋 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true" />
        </commentGenerator>
        
        <!--數據庫連接的信息：驅動類、連接地址、用戶名、密碼 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://127.0.0.1:3306/test"
                        userId="root"
                        password="123456">
        </jdbcConnection>
        
        <!-- <jdbcConnection driverClass="oracle.jdbc.driver.OracleDriver"
            connectionURL="jdbc:oracle:thin:@127.0.0.1:1521:orcl"
            userId="scott"
            password="wcy675600920">
        </jdbcConnection> -->
        
        <!-- 默認false，把JDBC DECIMAL 和 NUMERIC 類型解析爲 Integer，爲 true時把JDBC DECIMAL 和
            NUMERIC 類型解析爲java.math.BigDecimal -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>
        
        <!-- targetProject:生成PO類的位置 -->
        <javaModelGenerator targetPackage="com.ywy.model"
                            targetProject="src/main/java">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
            <!-- 從數據庫返回的值被清理前後的空格 -->
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        
        <!-- targetProject:mapper映射文件生成的位置 -->
        <sqlMapGenerator targetPackage="com.ywy.model"
                         targetProject="src/main/java">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
        </sqlMapGenerator>
        
        <!-- targetPackage：mapper接口生成的位置 -->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.ywy.mapper"
                             targetProject="src/main/java">
            <!-- enableSubPackages:是否讓schema作爲包的後綴 -->
            <property name="enableSubPackages" value="false" />
        </javaClientGenerator>
        
        <!-- 指定數據庫表 -->
        <table tableName="user" schema="" enableCountByExample="false"
               enableDeleteByExample="false" enableUpdateByExample="false"
               enableSelectByExample="false" selectByExampleQueryId="false">
        </table>
        
        <!-- 有些表的字段需要指定java類型
         <table schema="" tableName="">
            <columnOverride column="" javaType="" />
        </table> -->
    </context>
</generatorConfiguration>

然後最後一步

分頁插件

第一步：在pom.xml中導入依賴

<!--mybatis的分頁查詢插件-->
<dependency>
  <groupId>com.github.pagehelper</groupId>
  <artifactId>pagehelper</artifactId>
  <version>3.4.2</version>
</dependency>

<dependency>
  <groupId>com.github.jsqlparser</groupId>
  <artifactId>jsqlparser</artifactId>
  <version>0.9.1</version>
</dependency>

第二步：在mybatis的配置文件中加

<!--分頁的配置-->
<plugins>
    <plugin interceptor="com.github.pagehelper.PageHelper">
    <!--配置方言-->
        <property name="dialect" value="mysql"/>
    </plugin>
</plugins>

第三步：用分頁

//在查詢的前面設置PageHelper.startPage(當前頁數,每頁顯示多少行);
PageHelper.startPage(1,2);
List<User> list = umapper.findAllUser();
for (User user : list) {
    System.out.println(user);
}

PageInfo<User> info=new PageInfo<User>(list);
int i=info.getTotal();//獲取最大行數，裏面還有很多方法