mybatis根据数据库表结构自动生成实体类，dao，mapper

首先， pom需要引入

 <!-- mysql -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.39</version>
    </dependency>
<!-- mybatis-->
 <dependency>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-core</artifactId>
        <version>1.3.3</version>
    </dependency>

然后是mybatis生成器

import org.mybatis.generator.api.CommentGenerator;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.*;
import org.mybatis.generator.api.dom.xml.XmlElement;
import org.mybatis.generator.config.MergeConstants;
import org.mybatis.generator.config.PropertyRegistry;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

import static org.mybatis.generator.internal.util.StringUtility.isTrue;

/**
 * Mybatis 注释生成器
 */
public class MyCommentGenerator implements CommentGenerator {
    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String currentDateStr;

    public MyCommentGenerator() {
        super();
        properties = new Properties();
        systemPro = System.getProperties();
        suppressDate = false;
        suppressAllComments = false;
        currentDateStr = (new SimpleDateFormat("yyyy-MM-dd")).format(new Date());
    }

    public void addJavaFileComment(CompilationUnit compilationUnit) {
        // add no file level comments by default
        return;
    }

    /**
     * Adds a suitable comment to warn users that the element was generated, and
     * when it was generated.
     */
    public void addComment(XmlElement xmlElement) {
        return;
    }

    public void addRootComment(XmlElement rootElement) {
        // add no document level comments by default
        return;
    }

    public void addConfigurationProperties(Properties properties) {
        this.properties.putAll(properties);

        suppressDate = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_DATE));

        suppressAllComments = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_ALL_COMMENTS));
    }

    /**
     * This method adds the custom javadoc tag for. You may do nothing if you do
     * not wish to include the Javadoc tag - however, if you do not include the
     * Javadoc tag then the Java merge capability of the eclipse plugin will
     * break.
     *
     * @param javaElement the java element
     */
    protected void addJavadocTag(JavaElement javaElement, boolean markAsDoNotDelete) {
        javaElement.addJavaDocLine(" *");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(MergeConstants.NEW_ELEMENT_TAG);
        if (markAsDoNotDelete) {
            sb.append(" do_not_delete_during_merge");
        }
        String s = getDateString();
        if (s != null) {
            sb.append(' ');
            sb.append(s);
        }
        javaElement.addJavaDocLine(sb.toString());
    }

    /**
     * This method returns a formated date string to include in the Javadoc tag
     * and XML comments. You may return null if you do not want the date in
     * these documentation elements.
     *
     * @return a string representing the current timestamp, or null
     */
    protected String getDateString() {
        String result = null;
        if (!suppressDate) {
            result = currentDateStr;
        }
        return result;
    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        sb.append(" ");
        sb.append(getDateString());
        innerClass.addJavaDocLine(sb.toString());
        innerClass.addJavaDocLine(" */");
    }

    public void addEnumComment(InnerEnum innerEnum, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        innerEnum.addJavaDocLine("/**");

        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerEnum.addJavaDocLine(sb.toString());
        innerEnum.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable,
                                IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        field.addJavaDocLine(sb.toString());

        //      addJavadocTag(field, false);

        field.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        field.addJavaDocLine(sb.toString());
        field.addJavaDocLine(" */");
    }

    public void addModelClassComment(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {

    }

    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }

    }

    public void addGetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        method.addJavaDocLine("/**");

        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        sb.setLength(0);
        sb.append(" * @return ");
        sb.append(introspectedColumn.getActualColumnName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        //      addJavadocTag(method, false);

        method.addJavaDocLine(" */");
    }

    public void addSetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }

        method.addJavaDocLine("/**");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        Parameter parm = method.getParameters().get(0);
        sb.setLength(0);
        sb.append(" * @param ");
        sb.append(parm.getName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString());

        //      addJavadocTag(method, false);

        method.addJavaDocLine(" */");
    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {
        if (suppressAllComments) {
            return;
        }

        StringBuilder sb = new StringBuilder();

        innerClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerClass.addJavaDocLine(sb.toString());

        sb.setLength(0);
        sb.append(" * @author ");
        sb.append(systemPro.getProperty("user.name"));
        sb.append(" ");
        sb.append(currentDateStr);

        //      addJavadocTag(innerClass, markAsDoNotDelete);

        innerClass.addJavaDocLine(" */");
    }
}

然后是generator.xml 文件

<?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="my" targetRuntime="MyBatis3">

        <!-- 这里的type里写的是你的实现类的类全路径，即上面那个生成器所在的位置 -->
        <commentGenerator type="org.mybatis.generator.MyCommentGenerator">
        </commentGenerator>
        <!--连接数据库 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://远程地址:3306/数据库名" userId="数据库用户名"
                        password="密码"/>
        <!-- 实体类的地址 targetProject + targetPackage == 生成文件所在位置  根据表结构生成的实体类就在项目的com.common.model中-->
        <javaModelGenerator targetPackage="com.common.model"
                            targetProject="E:\common\src\main\java">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- mapper文件地址 targetProject + targetPackage == 生成文件所在物理位置     生成的.mapper文件就在mybatis文件夹下-->
        <sqlMapGenerator targetPackage="mybatis"
                         targetProject="E:\src\main\resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- dao生成的存放地址 targetProject + targetPackage == 生成文件所在位置  生成的dao接口就在项目的com.dao中-->
        <javaClientGenerator targetPackage="com.dao"
                             targetProject="E:\src\main\java" type="XMLMAPPER">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- tableName 数据库中表的名字    domainObjectName  生成的实体类名字以及加上Dao和Mapper组成的dao和mapper文件的名字 -->
        <table tableName="数据库表的名字" domainObjectName="生成实体类的名字"
               enableCountByExample="false" enableUpdateByExample="false"
               enableDeleteByExample="false" enableSelectByExample="false"
               selectByExampleQueryId="false">
            <property name="useActualColumnNames" value="true"/>
        </table>

    </context>
</generatorConfiguration>

最后是要执行的的类，执行这个类， 就能生成相应的文件了， 执行完可能需要更新下项目才能看出效果

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.exception.InvalidConfigurationException;
import org.mybatis.generator.exception.XMLParserException;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.File;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class MyBatisGeneratorTest {
    public static void main(String[] args) {
        try {
            List<String> warnings = new ArrayList<String>();
            boolean overwrite = true;   

             File configFile = new File("E:\\src\\main\\resource\\generatorConfig.xml");

            ConfigurationParser cp = new ConfigurationParser(warnings);
            Configuration config = cp.parseConfiguration(configFile);
            DefaultShellCallback callback = new DefaultShellCallback(overwrite);
            MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
            myBatisGenerator.generate(null);
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (InvalidConfigurationException e) {
            e.printStackTrace();
        } catch (XMLParserException e) {
            e.printStackTrace();
        }
    }

}