Freemarker 实战: 代码生成器

时间 2019-11-08

标签 freemarker 实战代码成器栏目 FreeMarker 繁體版

原文原文链接

Freemarker 实战: 代码生成器

在上一节介绍了 Freemarker的一些基础的用法，那么在这一节呢，经过简易代码生成器来实际感觉下Freemarker在开发中的魅力java

这里只是生成MySQL的代码，其余数据库的话能够自行扩展mysql

开发环境

Maven管理， Freemarker + MyBatis 整合开发git

生成的代码架构：SSM框架redis

Maven 配置spring

<parent>
    <artifactId>x_utils</artifactId>
    <groupId>com.sanq.product.x_utils</groupId>
    <version>1.0-SNAPSHOT</version>
</parent>
<!--依赖-->
<dependencies>
  <dependency>
      <groupId>com.sanq.product.x_utils</groupId>
      <artifactId>util_common</artifactId>
      <version>1.0-SNAPSHOT</version>
  </dependency>
  <dependency>
      <groupId>com.sanq.product.x_utils</groupId>
      <artifactId>util_redis</artifactId>
      <version>1.0-SNAPSHOT</version>
  </dependency>
  <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
  </dependency>
  <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
  </dependency>
  <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <scope>runtime</scope>
  </dependency>
  <dependency>
      <groupId>org.freemarker</groupId>
      <artifactId>freemarker</artifactId>
  </dependency>
  <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId> logback-classic</artifactId>
  </dependency>
</dependencies>

<build>
  <finalName>generate</finalName>
  <!--这里配置是为了在打包的时候 这些文件不会被忽略-->
  <resources>
      <resource>
          <directory>src/main/java</directory>
          <includes>
              <include>**/*.properties</include>
              <include>**/*.xml</include>
              <include>**/*.ftl</include>
          </includes>
          <filtering>false</filtering>
      </resource>
      <resource>
          <directory>src/main/resources</directory>
          <includes>
              <include>**/*.properties</include>
              <include>**/*.xml</include>
              <include>**/*.ftl</include>
          </includes>
          <filtering>false</filtering>
      </resource>
  </resources>
</build>
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关于配置中 x_utils, 你们能够查看代码：代码查看,sql

题外话数据库

X_Util模块描述安全

Common 对开发中常常使用的一些工具类进行封装

Redis 对Redis的操做进行封装

GenerateCode 代码生成器的源代码（早期开发, 只是修改ftl文件,没有修改FreemarkerUtil,能够参考）

pom.xml配置完成bash

Mybatis 配置

在config.properties中配置数据源等session

# 数据源的配置
driver = com.mysql.jdbc.Driver
url = jdbc:mysql:///test?useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true
username = root
password = root


#table_schema 
# 由于在查询表的时候须要提供库名， 因此在这里配置
table_schema = test

# 生成的文件包名
packageName = com.sanq.product.freemarker
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mybatis.xml配置

<?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>

  <!--加载config文件-->
	<properties resource="config.properties"/> 
  <!--别名-->
	<typeAliases>  
	    <typeAlias alias="tables" type="com.sanq.product.generate.entity.Tables" />
	    <typeAlias alias="fields" type="com.sanq.product.generate.entity.Fields" />
	</typeAliases> 

  <!--数据源-->
	<environments default="development">
		<environment id="development">
			<transactionManager type="jdbc"></transactionManager>
			<dataSource type="POOLED">
				<property name="driver" value="${driver}" />
				<property name="url" value="${url}" />
				<property name="username" value="${username}" />
				<property name="password" value="${password}" />
			</dataSource>
		</environment>
	</environments>
  <!--mapper映射配置--->
	<mappers>
		<mapper resource="com/sanq/product/generate/mappers/TableMapper.xml" />
		<mapper resource="com/sanq/product/generate/mappers/FieldMapper.xml" />
	</mappers>
</configuration>
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mybatis.xml配置完成

具体实现

由于开发环境中没有和Spring整合，因此在使用的时候就不能经过Spring来管理，须要写个工具类来获取SqlSession

工具类咱们采用单例模式来实现，单例模式的双重校验锁，静态内部类和枚举都是线程安全, 推荐使用

这里采用双重校验锁的形式

DaoSupport.java

public class DaoSupport {
  private DaoSupport() {}
  private static DaoSupport instance;

  public static DaoSupport getInstance() {
    if(null == instance) {
      synchronized (DaoSupport.class) {
        if(null == instance) 
          instance = new DaoSupport();
      }
    }
    return instance;
  }

  private static final String RESOURCE = "mybatis.xml"; //配置文件
  //这里是获取SqlSession
  public SqlSession getSession(){
      SqlSession session = null;
      try{
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder()	//
            .build(Resources.getResourceAsReader(RESOURCE));
        session = sessionFactory.openSession();
      }catch(Exception ex){
          ex.printStackTrace();
      }
      return session;
  }
}
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DaoSupport完成

关于FreemarkerUtil这里再也不给出，在freemarker入门中已经提供

开发要规范，在表中字段会存在下划线因此在这里咱们须要把下划线去掉而且将下划线跟随的首字母大写。

这里使用静态内部类

StringUtil.java

public class StringUtil {
  private StringUtil() {}

  public static String getInstance() {
    return Holder.INSTANCE;
  }

  private static class Holder {
    public static final StringUtil INSTANCE  = new StringUtil();
  }

  //替换字符串中指定字符，并将紧跟在它后面的字母大写
  public String replaceChar(String strVal, String tag) {
    StringBuffer sb = new StringBuffer();  
    sb.append(strVal.toLowerCase());  
    int count = sb.indexOf(tag);  
    while(count!=0){  
        int num = sb.indexOf(tag,count);  
        count = num+1;  
        if(num!=-1){  
          char ss = sb.charAt(count);  
          char ia = (char) (ss - 32);  
          sb.replace(count,count+1,ia+"");  
        }  
    }  
    String ss = sb.toString().replaceAll(tag,"");  
    return ss;
  }

  //将首字母大写
  public String firstUpperCase(String strVal) {
    StringBuffer sb = new StringBuffer();
    if(null != strVal && !"".equals(strVal)) {
      sb.append(String.valueOf(strVal.charAt(0)).toUpperCase());
      for(int i = 1; i < strVal.length(); i++) {
        sb.append(strVal.charAt(i));
      }
    }
    return sb.toString();
  }
}
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StringUtil.java完成

以上都是工具类，下面才是重点

所谓的代码生成只不过是偷懒的一种方式，由于在开发过程当中， CRUD方法一遍遍的写，毫无技术性可言，因此咱们就经过代码生成器来生成这些方法，简化咱们的开发过程，让咱们可以更加专一于业务的操做。

不过代码生成只是其中的一种方式，也能够经过BaseService， BaseMapper来封装。这个就因人而异了。

Freemarker方面，重点给你们展现下entity.ftl和mapper.ftl, 其余的都是按照本身的习惯来写就能够。

entity.ftl

package ${entityPackage!""};

import java.io.Serializable;
import java.util.*;
import java.math.BigDecimal;
import org.springframework.format.annotation.DateTimeFormat;

public class ${table.javaName?cap_first!""}  implements Serializable {

  /**
    *	version: ${table.comment!""}
    *----------------------
    * 	author:sanq.Yan
    * 	date:${nowDate?string("yyyy-MM-dd")} <#--这里是获取当前时间， 并格式化-->
    */
  private static final long serialVersionUID = 1L;

  <#if table.fields?? && table.fields?size gt 0>
  <#list table.fields as field>
  /**${field.columnComment!""}*/
  <#if field.javaType == "Date">
  @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
  </#if>
  private ${field.javaType!""} ${field.javaField!""};
  </#list>
  </#if>

  <#if table.fields?? && table.fields?size gt 0>
  <#list table.fields as field>
  public ${field.javaType!""} get${field.javaField?cap_first!""}() {
    return ${field.javaField};
  }
  public void set${field.javaField?cap_first!""}(${field.javaType!""} ${field.javaField!""}) {
    this.${field.javaField!""} = ${field.javaField!""};
  }

  </#list>
  </#if>
}

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在这里用到了3个指令

string

?cap_first: 将首字母大写
!"" : 若是为null或者不存在该属性就显示空字符串

if

判断当前list不为null and list.size() > 0

list

循环迭代

mybatis.ftl

<select id="findById" resultMap="${table.javaName}Map"
      parameterType="<#list table.fields as field><#if field.columnKey == "PRI">${field.javaType}</#if></#list>">
  SELECT
  <include refid="${table.name}_columns"/>
  FROM ${table.name} ${table.name?substring(0,1)}
  WHERE
  <#list table.fields as field>
      <#if field.columnKey == "PRI">
          ${table.name?substring(0,1)}.${field.columnName} = ${r"#{" + field.javaField + "}"} </#if> </#list> LIMIT 1 </select> 复制代码

这里和上面是同样的，不过须要注意的是 ftl文件中若是有包含 # 这种特殊字符，须要对其进行转义才会成功输出

${r"#{" + field.javaField + "}"} 复制代码

到此 ftl文件也已经完成，下面进行正文

查询全部表的sql 使用这个

SHOW TABLE STATUS
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这里咱们须要如下字段 property为实体Tables中的属性

<resultMap type="tables" id="tableEntityMap">
		<result column="Name" property="name"/>
		<result column="Comment" property="comment"/>
	</resultMap>

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下来查询表的字段

SELECT  * FROM information_schema.COLUMNS where TABLE_NAME = 'tb_users' AND table_schema = 'test' order by column_key desc;
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这里须要注意在查询表字段的时候须要咱们以前在config.properties配置的schema加上，否则它会查询出全部库中表名为tb_users的字段.

这里咱们须要如下字段 property为实体Fields中的属性

<resultMap type="fields" id="fieldEntityMap">
  <result column="table_name" property="tableName"/>
  <result column="column_name" property="columnName"/>
  <result column="data_type" property="jdbcType"/>
  <result column="column_key" property="columnKey"/>
  <result column="column_comment" property="columnComment"/>
</resultMap>
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下面是在实体中的操做

Tables.java

public class Tables implements Serializable {
  private String name;
  private String comment;

  private String javaName;

  private List<Fields> fields;

  private StringUtil mStringInstance = StringUtil.getInstance();

  //这里是对表名进行转换 换成Java命名规范的名称
  public String getJavaName() {
    int i = this.name.indexOf("_");
    this.javaName = i > 0 ? mStringInstance.replaceChar(this.name , "_") : this.name; 

    return this.javaName;
  }

  //getting and setting
}
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Fields.java

public class Fields implements Serializable {

  private String tableName;

  private String columnName;

  private String javaField;

  private String jdbcType;

  private String javaType;

  private String columnKey;

  private String columnComment;

  private StringUtil mStringInstance = StringUtil.getInstance();

  public String getJavaField() {
    /** 处理字段中的特殊字符 */
    int i = this.columnName.indexOf("_");
    this.javaField = i > 0 ? mStringInstance.replaceChar(this.columnName,
        "_") : this.columnName;

    return this.javaField;
  }

  public void setJavaField(String javaField) {
    this.javaField = javaField;
  }

  //转换成java类型
  public String getJavaType() {

    /** 处理字段类型 */
    if (this.jdbcType.equalsIgnoreCase("varchar")
        || this.jdbcType.equalsIgnoreCase("char")
        || this.jdbcType.equalsIgnoreCase("text")
        || this.jdbcType.equalsIgnoreCase("longtext")) {
      setJavaType("String");
    } else if (this.jdbcType.equalsIgnoreCase("int")
        || this.jdbcType.equalsIgnoreCase("tinyint")
        || this.jdbcType.equalsIgnoreCase("smallint")
        || this.jdbcType.equalsIgnoreCase("mediumint")) {
      setJavaType("Integer");
    } else if (this.jdbcType.equalsIgnoreCase("date")
        || this.jdbcType.equalsIgnoreCase("time")
        || this.jdbcType.equalsIgnoreCase("datetime")
        || this.jdbcType.equalsIgnoreCase("timestamp")) {
      setJavaType("Date");
    } else if (this.jdbcType.equalsIgnoreCase("double")) {
      setJavaType("Double");
    } else if (this.jdbcType.equalsIgnoreCase("long")
        || this.jdbcType.equalsIgnoreCase("bigint")) {
      setJavaType("Long");
    } else if(this.jdbcType.equalsIgnoreCase("decimal")) {
      setJavaType("BigDecimal");
    } else if(this.jdbcType.equalsIgnoreCase("float")) {
      setJavaType("Float");
    }
    return javaType;
  }
  //getting and setting
}

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在App.java中书写执行程序推荐使用junit

public class App {
  DaoSupport mDaoSupport;
  FreemarkerUtil mFreemarkerUtil;
  StringUtil mStringUtil;
  String mFilePath;
  String mPackName;
  Map<String,Object> mRoot;

  @Before
  public void before() {
      mDaoSupport = DaoSupport.getInstance();
      mFreemarkerUtil = FreemarkerUtil.getInstance();
      mStringUtil = StringUtil.getInstance();
      mFilePath =  PropUtil.getPropVal("packageName").replace(".", File.separator);
      mPackName = PropUtil.getPropVal("packageName");
      mRoot = new HashMap<String, Object>();
  }

  public List<Tables> getTables() {

      String tableSchema = mDaoSupport.getPropVal("table_schema");

      SqlSession session = mDaoSupport.getSession();

      /**获取全部的表*/
      TableMapper tm = session.getMapper(TableMapper.class);
      List<Tables> tables = tm.findAllTables();

      if(tables != null && tables.size() > 0) {
          /**获取表中全部的字段*/
          FieldMapper fm = session.getMapper(FieldMapper.class);
          Map<String,String> map = null;
          for(Tables table : tables) {
              map = new HashMap<String,String>();
              map.put("tableSchema", tableSchema);
              map.put("tableName", table.getName());

              List<Fields> fields = fm.findFieldByTable(map);
              table.setFields(fields);
          }
      }
      return tables;
  }

  @Test
  public void generateCode() {
      List<Tables> tableses = getTables();

      generate(tableses);
  }

  private void generate(List<Tables> tableses) {
      //com.sanq.product.freemarker

      //划分文件生成目录
      String controllerPackage = mFilePath + File.separator + "controller";
      String entityPackage = mFilePath + File.separator + "entity";
      String entityVoPackage = entityPackage + File.separator + "vo";
      String servicePackage = mFilePath + File.separator + "service";
      String serviceImplPackage = mFilePath + File.separator + "service" + File.separator + "impl";
      String mapperPackage = mFilePath + File.separator + "mapper";

      //将数据传递给Freemarker
      mRoot.put("tables", tableses);
      mRoot.put("packageName", mPackName.replace(File.separator,"."));
      mRoot.put("controllerPackage", controllerPackage.replace(File.separator,"."));
      mRoot.put("entityPackage", entityPackage.replace(File.separator,"."));
      mRoot.put("entityVoPackage", entityVoPackage.replace(File.separator,"."));
      mRoot.put("servicePackage", servicePackage.replace(File.separator,"."));
      mRoot.put("serviceImplPackage", serviceImplPackage.replace(File.separator,"."));
      mRoot.put("mapperPackage", mapperPackage.replace(File.separator,"."));
      mRoot.put("nowDate", new Date());

      //这里生成文件
      String tableJavaName;
      for(Tables table : tableses) {

          tableJavaName = mStringUtil.firstUpperCase(table.getJavaName());

          mRoot.put("table", table);

          try {
                generateFile("java/entity.ftl", entityPackage, tableJavaName + ".java");
                generateFile("java/entityVo.ftl", entityVoPackage, tableJavaName + "Vo.java");
                generateFile("java/controller.ftl", controllerPackage, tableJavaName + "Controller.java");
                generateFile("java/mapper.ftl", mapperPackage, tableJavaName + "Mapper.java");
                generateFile("java/mapper_xml.ftl", mapperPackage, tableJavaName + "Mapper.xml");
                generateFile("java/service.ftl", servicePackage, tableJavaName + ".Service.java");
                generateFile("java/service_impl.ftl", serviceImplPackage, tableJavaName + ".ServiceImpl.java");

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    //生成文件， 若是文件夹不存在， 建立
    public void generateFile(String ftl, String path, String fileName) {
        File file = new File("D:"+ File.separator + "tmp" + File.separator + path);
        if (!file.exists())
            file.mkdirs();

        mFreemarkerUtil.out(ftl, mRoot, "D:"+ File.separator + "tmp" + File.separator + path + File.separator + fileName);
    }
}
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到此，代码编写正式完成

生成结果

能够看到代码已经生成成功

实战结束

到此，实战完成。内容不是不少。

好好打磨下这个实战案例，能够基于本身的习惯生成java代码，余下的时间就能够好好的玩耍啦。。。