Freemarker 實戰: 代碼生成器

時間 2019-11-08

標籤 freemarker 實戰代碼成器欄目 FreeMarker 简体版

原文原文鏈接

Freemarker 實戰: 代碼生成器

在上一節介紹了 Freemarker的一些基礎的用法，那麼在這一節呢，經過簡易代碼生成器來實際感覺下Freemarker在開發中的魅力java

這裏只是生成MySQL的代碼，其餘數據庫的話能夠自行擴展mysql

開發環境

Maven管理， Freemarker + MyBatis 整合開發git

生成的代碼架構：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>
<!--依賴-->
<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>
  <!--這裏配置是爲了在打包的時候 這些文件不會被忽略-->
  <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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關於配置中 x_utils, 你們能夠查看代碼：代碼查看,sql

題外話數據庫

X_Util模塊描述安全

Common 對開發中常常使用的一些工具類進行封裝

Redis 對Redis的操做進行封裝

GenerateCode 代碼生成器的源代碼（早期開發, 只是修改ftl文件,沒有修改FreemarkerUtil,能夠參考）

pom.xml配置完成bash

Mybatis 配置

在config.properties中配置數據源等session

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


#table_schema 
# 由於在查詢表的時候須要提供庫名， 因此在這裏配置
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>

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

  <!--數據源-->
	<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

具體實現

由於開發環境中沒有和Spring整合，因此在使用的時候就不能經過Spring來管理，須要寫個工具類來獲取SqlSession

工具類咱們採用單例模式來實現，單例模式的雙重校驗鎖，靜態內部類和枚舉都是線程安全, 推薦使用

這裏採用雙重校驗鎖的形式

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
  //這裏是獲取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

關於FreemarkerUtil這裏再也不給出，在freemarker入門中已經提供

開發要規範，在表中字段會存在下劃線因此在這裏咱們須要把下劃線去掉而且將下劃線跟隨的首字母大寫。

這裏使用靜態內部類

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();
  }

  //替換字符串中指定字符，並將緊跟在它後面的字母大寫
  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;
  }

  //將首字母大寫
  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

以上都是工具類，下面纔是重點

所謂的代碼生成只不過是偷懶的一種方式，由於在開發過程當中， CRUD方法一遍遍的寫，毫無技術性可言，因此咱們就經過代碼生成器來生成這些方法，簡化咱們的開發過程，讓咱們可以更加專一於業務的操做。

不過代碼生成只是其中的一種方式，也能夠經過BaseService， BaseMapper來封裝。這個就因人而異了。

Freemarker方面，重點給你們展現下entity.ftl和mapper.ftl, 其餘的都是按照本身的習慣來寫就能夠。

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")} <#--這裏是獲取當前時間， 並格式化-->
    */
  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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在這裏用到了3個指令

string

?cap_first: 將首字母大寫
!"" : 若是爲null或者不存在該屬性就顯示空字符串

if

判斷當前list不爲null and list.size() > 0

list

循環迭代

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> 複製代碼

這裏和上面是同樣的，不過須要注意的是 ftl文件中若是有包含 # 這種特殊字符，須要對其進行轉義纔會成功輸出

${r"#{" + field.javaField + "}"} 複製代碼

到此 ftl文件也已經完成，下面進行正文

查詢全部表的sql 使用這個

SHOW TABLE STATUS
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這裏咱們須要如下字段 property爲實體Tables中的屬性

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

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下來查詢表的字段

SELECT  * FROM information_schema.COLUMNS where TABLE_NAME = 'tb_users' AND table_schema = 'test' order by column_key desc;
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這裏須要注意在查詢表字段的時候須要咱們以前在config.properties配置的schema加上，否則它會查詢出全部庫中表名爲tb_users的字段.

這裏咱們須要如下字段 property爲實體Fields中的屬性

<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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下面是在實體中的操做

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();

  //這裏是對錶名進行轉換 換成Java命名規範的名稱
  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() {
    /** 處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;
  }

  //轉換成java類型
  public String getJavaType() {

    /** 處理字段類型 */
    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中書寫執行程序推薦使用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();

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

      if(tables != null && tables.size() > 0) {
          /**獲取表中全部的字段*/
          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

      //劃分文件生成目錄
      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";

      //將數據傳遞給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());

      //這裏生成文件
      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， 若是文件夾不存在， 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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