基於Ant+Velocity的簡單代碼生成器的思路與實現

（原文：http://www.javaeye.com/topic/30893）
在SSH項目中，我們應用了service layer模式，所以針對一個模塊，它就存在pojo、dao、daoImpl、service、serviceImpl，再到struts中的action、form。假設設計是面向數據庫的，針對一個數據庫表，那麼就要產生7個java文件，如果還要做異常處理，那麼就是8個java文件。如果數據庫有50個表，那麼就是50*8＝400個java文件。工程不小。

至於爲什麼要用service layer模式，論壇上已有討論http://www.javaeye.com/topic/29867

然而我們都知道，web中出現最多的操作是CURD，這400個java文件中有多少代碼是重複的？幾乎佔了80%甚至更多。編寫這樣重複的代碼是很枯燥無味的，而且如果是由不同人負責不同的模塊的分工方式，程序員編碼的風格是各不相同（雖然可能有規範約束，但是最後出來的東西還是避免不了的帶有程序員個人風格的）。

所以爲了節省時間和精力，便做一個程序來生成程序。
只要配置好你的項目名，你的模塊名，模塊路徑，就可以在幾秒之內完成一個模塊的CURD代碼，同時你可以自定義模板。

這是工具的大概設計思路：

由ant處理編譯、生成目錄的工作，velocity處理程序模板，contentEngine爲核心處理程序。

產生的目錄結構和代碼路徑：
模塊名
--子模塊1
----model
------businessobject
------dao
--------hibernate
----service
------impl
----view
------action
------form
----Exception
--子模塊2
...
其中model/businessobject中是pojo和hbm.xml，這個由hibernate工具根據數據庫表產生。

我們假設模塊名爲course，子模塊名爲table，類名爲CourseMember。因篇幅問題，我們只看一個daoImpl的例子。

首先我們利用建立一個daoImpl的模板
ObjectDaoHibernateImpl.vm

代碼

${package_Hibernate}
${import_SQLException}
${import_List}
${import_HibernateCallback}
${import_HibernateObjectRetrievalFailureException}
${import_HibernateDaoSupport}
${import_HibernateException}
${import_Query}
${import_Session}
${import_ObjectNameDao}
${import_ObjectName}
${import_Finder}
${import_Page}
${import_Criteria}
${import_Projections}

/**
 * The Hibernate implementation of the <code>${ObjectName}Dao</code>.
 *
 * @author ${Author}
 * @see ${ObjectName}Dao
 */
public class ${ObjectName}DaoHibernateImpl extends HibernateDaoSupport implements ${ObjectName}Dao {
    /**
     * Default constructor.
     */
    public ${ObjectName}DaoHibernateImpl() {
        super();
    }

    /**
     * @see ${ObjectName}Dao#save${ObjectName}(${ObjectName})
     */
    public ${ObjectName} save${ObjectName}(${ObjectName} ${objectname}) {
        this.getHibernateTemplate().save(${objectname});
        return ${objectname};
    }

    /**
     * @see ${ObjectName}Dao#get${ObjectName}(String)
     */
    public ${ObjectName} get${ObjectName}(String id) {
        return (${ObjectName})this.getHibernateTemplate().load(${ObjectName}.class, id);
    }

    /**
     * @see ${ObjectName}Dao#update${ObjectName}(${ObjectName})
     */
    public void update${ObjectName}(${ObjectName} ${objectname}) {
        this.getHibernateTemplate().update(${objectname});
    }

    /**
     * @see ${ObjectName}Dao#delete${ObjectName}(${ObjectName})
     */
    public void delete${ObjectName}(${ObjectName} ${objectname}) {
        this.getHibernateTemplate().delete(${objectname});
    }

    /**
     * @see ${ObjectName}Dao#getAll${ObjectName}s()
     */
    public List getAll${ObjectName}s() {
        return getHibernateTemplate().executeFind(new HibernateCallback() {
            public Object doInHibernate(Session session)
                throws HibernateException, SQLException {

                StringBuffer sb = new StringBuffer(100);
                //sb.append("select distinct ${objectname} ");
                sb.append("SELECT  ${objectname} ");
                sb.append("FROM  ${ObjectName} ${objectname} ");
                sb.append("order by ${objectname}.id");

                Query query = session.createQuery(sb.toString());
                List list = query.list() ;

                return list;
            }
        });
    }



    public Object query(final ${ObjectName} ${objectname},
            final int pageNo, final int maxResult) {
        return getHibernateTemplate().execute(new HibernateCallback() {
            public Object doInHibernate(Session session)
                    throws HibernateException, SQLException {
                Criteria criteria=session.createCriteria(${ObjectName}.class);
                Criteria anothercriteria=session.createCriteria(${ObjectName}.class);
                criteria.setProjection(Projections.rowCount());

    //          if (!${objectname}.get${objectname}Name().equals("")
    //                  && ${objectname}.get${objectname}Name() != null) {
    //              criteria.add(Expression.ilike("contactName","%"+customerContactForm.getContactName()+"%"));
    //              anothercriteria.add(Expression.ilike("contactName","%"+customerContactForm.getContactName()+"%"));
    //          }
                Integer count=(Integer)criteria.uniqueResult();
                List list=anothercriteria.setFirstResult((pageNo-1)*maxResult).setMaxResults(maxResult).list();
                Page page=new Page(count.intValue(), maxResult, pageNo);
                return new Finder(list, page);
            }
        });
    }

    public boolean deleteBybatch(final String[] chxSong) {
    StringBuffer cusIdList = new StringBuffer(200);
    cusIdList.append("delete from ${ObjectName} where ${objectName}No=");
        for (int i = 0; i < chxSong.length; i++) {
            if (i == 0)
                cusIdList.append(chxSong[i]);
            else
                cusIdList.append(" or ${objectName}No=" + chxSong[i]);
        }
        this.getSession().createQuery(cusIdList.toString()).executeUpdate();
        return true;
    }

}

<script type="text/javascript">render_code();</script>
聲明：
1）其中${}是模板語言中的變量，變量的來源一是通過對應的.properties文件，另外是通過參數傳遞。
2）註釋部分因是分頁查詢條件，這個涉及到具體字段，無法預知，所以需要在產生代碼之後程序員根據查詢條件自行修改。另外也涉及到個人項目的分頁方法，這個根據具體情況自定義模板。

 

template.properties
公共屬性文件，是所有template文件（.vm）的變量聲明處，這個會在後面代碼中進行設置。
對於屬性文件，可有兩種方式：
一是針對每一個template模板文件都建立一個屬性文件，優點是在後面ant中設置的參數就少了，而且方便修改。缺點是模板文件數量增多，另外公共部分聲明重複。
二是設定一個公共屬性文件，將特定的變量交給參數傳遞。
我們這裏先用公共屬性文件的方式。

代碼

Author = Cmas R&D Team
import_Arraylist = import java.util.ArrayList;
import_List = import java.util.List;
import_Set = import java.util.Set;
import_FacesException = import javax.faces.FacesException;
import_BeanUtils = import org.apache.commons.beanutils.BeanUtils;
import_Log = import org.apache.commons.logging.Log;
import_LogFactory = import org.apache.commons.logging.LogFactory;
import_SQLException = import java.sql.SQLException;
import_HibernateCallback = import org.springframework.orm.hibernate3.HibernateCallback;
import_HibernateObjectRetrievalFailureException = import org.springframework.orm.hibernate3.HibernateObjectRetrievalFailureException;
import_HibernateDaoSupport = import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import_HibernateException = import org.hibernate.HibernateException;
import_Query = import org.hibernate.Query;
import_Session = import org.hibernate.Session;
import_Map = import java.util.Map;
import_HashMap = import java.util.HashMap;
import_Iterator = import java.util.Iterator;
import_Criteria=import org.hibernate.Criteria;
import_Projections=import org.hibernate.criterion.Projections;
import_DispatchActionSupport=import org.springframework.web.struts.DispatchActionSupport;
import_Action=import org.apache.struts.action.*;
import_HttpServletRequest=import javax.servlet.http.HttpServletRequest;
import_HttpServletResponse=import javax.servlet.http.HttpServletResponse;
import_BeanUtils=import org.apache.commons.beanutils.BeanUtils;
import_DataIntegrity=import org.springframework.dao.DataIntegrityViolationException;

接下來是ant部分，我們編寫build.xml

build.xml

代碼

<?xml version="1.0" encoding="UTF-8"?>
<project name="cmas" basedir="../" default="all">

    <!-- Project settings -->
    <property name="project.distname" value="cmas" /><!-- 設定項目名 -->
    <property name="project/operationName" value="course/table" /><!-- 設定模塊名，如果有多層以“/”方式擴充，此爲目錄結構變量設定 -->
    <property name="project.operationName" value="course.table" /><!-- 設定模塊名，如果有多層以“.”方式擴充，此爲包結構變量設定 -->
    <property name="ObjectName" value="CourseMember" /><!-- 模塊名類名，大寫 -->
    <property name="objectName" value="courseMember" /><!-- 模塊名變量名，小寫 -->

    <!-- Local system paths -->
    <property file="${basedir}/ant/build.properties" /><!-- 設定ant的一些屬性，這裏我們沒有額外的設置，使用默認 -->
    <property file="${basedir}/${webroot.dir}/template/build.properties" />

    <!--Save_path-->
        <!-- 建立目錄結構 -->
    <mkdir dir="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/model" />
    <mkdir dir="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/service" />
    <mkdir dir="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/view" />
        <!-- 聲明目錄結構變量 -->
    <property name="model.src.dir" location="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/model" />
    <property name="service.src.dir" location="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/service" />
    <property name="view.src.dir" location="${basedir}/JavaSource/com/bnu/${project.distname}/${project/operationName}/view" />

    <property name="overwrite" value="false" />
    <property name="debug" value="true" />
    <property name="webroot.dir" value="${basedir}/WebContent" />
    <property name="webinf.dir" value="${webroot.dir}/WEB-INF" />
    <property name="build.dir" value="build" />

    <!-- 模板文件的聲明，這裏暫時只寫ObjectDaoHibernateImpl -->
    <property name="template.dir" value="${webroot.dir}/template" />
    <property name="ObjectDaoHibernateImpl.template" value="./ObjectDaoHibernateImpl.vm" />
    <property name="template.properties" value="${template.dir}/template.properties" />
        <!--設定classpath，這些包不能少-->
    <property name="classpath" value="${webinf.dir}/classes/" />
    <!-- classpath for JSF 1.1.01 -->
    <path id="compile.classpath">
        <pathelement path="${webinf.dir}/lib/hibernate3.jar" />
        <pathelement path="${webinf.dir}/lib/log4j-1.2.9.jar" />
        <pathelement path="${webinf.dir}/lib/commons-beanutils.jar" />
        <pathelement path="${webinf.dir}/lib/commons-collections.jar" />
        <pathelement path="${webinf.dir}/lib/commons-digester.jar" />
        <pathelement path="${webinf.dir}/lib/commons-logging.jar" />
        <pathelement path="${webinf.dir}/lib/jsf-api.jar" />
        <pathelement path="${webinf.dir}/lib/jsf-impl.jar" />
        <pathelement path="${webinf.dir}/lib/jstl.jar" />
        <pathelement path="${webinf.dir}/lib/standard.jar" />
        <pathelement path="${webinf.dir}/lib/log4j.jar" />
        <pathelement path="${webinf.dir}/lib/velocity-1.4.jar" />
        <pathelement path="${webinf.dir}/lib/velocity-1.4-dev.jar" />
        <pathelement path="${webinf.dir}/classes" />
        <pathelement path="${classpath.external}" />
        <pathelement path="${classpath}" />
    </path>

    <!--*****************Build_Dao_Hibernate_Impl*開始創建daoImpl**********************-->
    <!-- define your folder for deployment -->
    <property name="build_daoimpl.dir" value="build_daoimpl" />

    <!-- Check timestamp on files -->
    <target name="build_daoimpl_prepare">
        <tstamp />
    </target>

    <!-- Copy any resource or configuration files -->
    <target name="build_daoimpl_resources">
        <copy todir="${webinf.dir}/classes" includeEmptyDirs="no">
            <fileset dir="JavaSource">
                <patternset>
                    <include name="**/*.conf" />
                    <include name="**/*.properties" />
                    <include name="**/*.xml" />
                </patternset>
            </fileset>
        </copy>
    </target>

    <target name="build_daoimpl_init">
        <!-- Create the time stamp -->
        <tstamp />
        <!-- Create the build directory structure used by compile -->
        <mkdir dir="${model.src.dir}/dao/hibernate" />
    </target>

    <!-- Normal build of application -->
    <target name="build_daoimpl_compile" depends="build_daoimpl_prepare,build_daoimpl_resources,build_daoimpl_init">
        <javac srcdir="${basedir}/JavaSource/com/bnu/exception/" destdir="${webinf.dir}/classes/">
            <classpath refid="compile.classpath" />
        </javac>

        <!--編譯核心java文件contentEngine，這個路徑根據具體情況設定，也可以在前面對其進行統一聲明-->
        <javac srcdir="${basedir}/JavaSource/com/bnu/tools" destdir="${webinf.dir}/classes/">
            <classpath refid="compile.classpath" />
        </javac>
                <!--運行contentEngine，參數設定-->
        <java classname="com.bnu.tools.ContentEngine">
            <classpath refid="compile.classpath" />
            <arg value="DaoImpl" />
            <arg value="${template.dir}" />
            <arg value="${template.properties}" />
            <arg value="${ObjectDaoHibernateImpl.template}" />
            <arg value="package com.bnu.${project.distname}.${project.operationName}.model.dao.hibernate;" />
            <arg value="import com.bnu.${project.distname}.${project.operationName}.model.dao.${ObjectName}Dao;" />
            <arg value="import com.bnu.${project.distname}.${project.operationName}.model.businessobject.${ObjectName};" />
            <arg value="${objectName}" />
            <arg value="${ObjectName}" />
            <arg value="${model.src.dir}/dao/hibernate" />
            <arg value="${ObjectName}DaoHibernateImpl.java" />
        </java>
    </target>

    <!-- Remove classes directory for clean build -->
    <target name="build_daoimpl_clean" description="Prepare for clean build">
        <delete dir="${webinf.dir}/classes" />
        <mkdir dir="${webinf.dir}/classes" />
    </target>

    <!-- Build entire project -->
    <target name="build_daoimpl_build" depends="build_daoimpl_prepare,build_daoimpl_compile" />
    <target name="build_daoimpl_rebuild" depends="build_daoimpl_clean,build_daoimpl_prepare,build_daoimpl_compile" />

    <target name="build_daoimpl" depends="build_daoimpl_build">
        <delete file="${build_daoimpl.dir}/${project.distname}.war" />
        <delete dir="${build_daoimpl.dir}/${project.distname}" />
    </target>

    <target name="clean" description="clean">
        <delete dir="${build.dir}" />
        <delete dir="${webinf.dir}/classes" />
        <delete dir="${dist.dir}" />
    </target>

    <target name="all" description="build all" depends="clean,build_daoimpl">
    </target>
</project>

<script type="text/javascript">render_code();</script>
這裏摘取了daoImpl的聲明段，重要部分已經做了註釋。

核心代碼部分，contentEngine文件。

代碼

package com.bnu.tools;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;

import com.bnu.exception.AppException;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Iterator;
import java.util.Properties;

/**
 *
 * To change the template for this generated type comment go to
 * Window>Preferences>Java>Code Generation>Code and Comments
 */
public class ContentEngine {
    private VelocityContext context = null;

    private Template template = null;

    // private String properties = null ;

    /**
     *
     * @param properties
     * @throws Exception
     */
    public void init(String properties) throws Exception {
        if (properties != null && properties.trim().length() > 0) {
            Velocity.init(properties);
        } else {
            Velocity.init();
        }
        context = new VelocityContext();
    }

    public void init(Properties properties) throws Exception {

        Velocity.init(properties);
        context = new VelocityContext();
    }

    /**
     *
     * @param key
     * @param value
     */
    public void put(String key, Object value) {
        context.put(key, value);
    }

    /**
     * 設置模版
     *
     * @param templateFile
     *            模版文件
     * @throws AppException
     */
    public void setTemplate(String templateFile) throws AppException {
        try {
            template = Velocity.getTemplate(templateFile);
        } catch (ResourceNotFoundException rnfe) {
            rnfe.printStackTrace();
            throw new AppException(" error : cannot find template "
                    + templateFile);
        } catch (ParseErrorException pee) {
            throw new AppException(" Syntax error in template " + templateFile
                    + ":" + pee);
        } catch (Exception e) {
            throw new AppException(e.toString());
        }

    }

    /**
     * 設置模版
     *
     * @param templateFile
     *            模版文件
     * @throws AppException
     */
    public void setTemplate(String templateFile, String characterSet)
            throws AppException {
        try {
            template = Velocity.getTemplate(templateFile, characterSet);
        } catch (ResourceNotFoundException rnfe) {
            rnfe.printStackTrace();
            throw new AppException(" error : cannot find template "
                    + templateFile);
        } catch (ParseErrorException pee) {
            throw new AppException(" Syntax error in template " + templateFile
                    + ":" + pee);
        } catch (Exception e) {
            throw new AppException(e.toString());
        }

    }

    /**
     * 轉換爲文本文件
     */
    public String toText() throws AppException {
        StringWriter sw = new StringWriter();
        try {
            template.merge(context, sw);
        } catch (Exception e) {
            throw new AppException(e.toString());
        }
        return sw.toString();
    }

    /**
     *
     * @param fileName
     */
    public void toFile(String fileName) throws AppException {
        try {
            StringWriter sw = new StringWriter();
            template.merge(context, sw);

            PrintWriter filewriter = new PrintWriter(new FileOutputStream(
                    fileName), true);
            filewriter.println(sw.toString());
            filewriter.close();
        } catch (Exception e) {
            throw new AppException(e.toString());
        }

    }

    public static void main(String[] args) {
        ContentEngine content = new ContentEngine();
        try {
            Properties p = new Properties();

            Properties varp = new Properties();

            String path = args[1];

            p.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, path);
            p.setProperty(Velocity.RUNTIME_LOG, path + "velocity.log");

            content.init(p);

            FileInputStream in = new FileInputStream(args[2]);
            varp.load(in);

            content.setTemplate(args[3], "gb2312");

            Iterator it = varp.keySet().iterator();
            String key = "";
            String value = "";
            while (it.hasNext()) {
                key = (String) it.next();
                value = varp.getProperty(key);
                content.put(key, value);
            }

            if (args[0].equals("DaoImpl")) {
                content.put("package_Hibernate", args[4]);
                content.put("import_ObjectNameDao", args[5]);
                content.put("import_ObjectName", args[6]);
                content.put("objectname", args[7]);
                content.put("ObjectName", args[8]);
                content.toFile(args[9] + '/' + args[10]);//導出的路徑，由參數傳遞。
            }
//else 其他情況處理部分，這裏省略。
        } catch (AppException ae) {
            ae.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

<script type="text/javascript">render_code();</script>

 

至此，這個簡單的代碼生成器的代碼就結束了。很顯然它還很弱小，充其量也只是半自動。離完善的代碼生成器還差很遠。拿出來希望對大家有點用處，另外也希望得到各位的指導，大家討論一下代碼生成器的話題。