殺雞用牛刀之用velocity根據數據庫表生成javabean

一直想找一個東東根據數據庫生成實體，具有以下功能：
1，可以根據參數定義實體的父類和接口。

2，能夠去除父類中或接口中已經定義的屬性和方法。

經谷哥和度娘后，滿足自己個性化要求的很難找到，於是殺雞用牛刀，操起了velocity這樣的模板引擎，幸好velocity並不算太重。

為了達到可配置化，使用了兩個配置文件--參數文件和模板文件。

思路：

1，在xml文件中定義四個參數（生成文件路徑，包路徑，父類名稱，接口名稱）；

2，寫一個javabean的模板文件。

3，調用參數和模板文件生成javabean文件。

以下為關鍵代碼：

1，xml中參數定義

<!--
以下為生成javabean模板涉及的參數
-->
<beantemplet name="default">
<param name="genDirPath" rem="生成java文件的路徑">
src/entitybean/
</param>
<param name="templetFilePath" rem="模板文件的路徑">
src/cfg/beanTemplet.vm
</param>
<param name="packagePath" rem="包路徑">
entitybean
</param>
<param name="superClass" rem="所繼承的父類">
bean.EntityObject
</param>
<param name="implInterface" rem="所實現的接口,本參數可重復,重復時表示實現多個接口">
</param>
</beantemplet>

2, velocity語法的javabean模板文件

##類型定義
#macro(typeof $field)
#if($field.startsWith("s") || $field.startsWith("t"))String##
#elseif($field.startsWith("i"))Integer##
#elseif($field.startsWith("n"))BigDecimal##
#elseif($field.startsWith("b"))Integer##
#else String##
#end
#end
##首字母大寫
#macro(initUpperCase $field)
$field.toUpperCase().substring(0,1)$field.substring(1)##
#end
##類名稱簡寫，去掉類名前面的類路徑
#macro(shortName $fullClassName)
#set($index = $fullClassName.lastIndexOf(".") + 1)
$fullClassName.substring($index)##
#end

package $vm.packagePath;

import java.math.BigDecimal;
#if($vm.superClass)
import $vm.superClass;
#end
#if($vm.interfaces)
#foreach($itf in $vm.interfaces)
import $itf;##
#end
#end

public class $vm.className ##
#if($vm.superClass)extends #shortName($vm.superClass)##
#end
#if($vm.interfaces)
#foreach($itf in $vm.interfaces)
#if($foreach.count < 2) implements ##
#end##
#shortName($itf)##
#if( $foreach.hasNext ),##
#end
#end
#end{

#if($vm.fields)
#foreach($field in $vm.fields)
private #typeof($field) $field;
#end
#end

#if($vm.fields)
#foreach($field in $vm.fields)

public void set#initUpperCase($field)(#typeof($field) $field){
 this.$field = $field;
}

public #typeof($field) get#initUpperCase($field)(){
 return this.$field;
}
#end
#end

#if($vm.tableName)##
public String getTableName(){
 return "$vm.tableName";
}
#end

#if($vm.unImplMethods)
#foreach($method in $vm.unImplMethods)
$method
#end
#end

}

3,生成javabean文件代碼

public class BeanGennerator2 {
 String genDirPath = null;
 String templetFilePath = null;
 String packagePath = null;
 String superClass = null;
 String[] implInterface = null;
 
 public String getGenDirPath() {
  return genDirPath;
 }

 public void setGenDirPath(String genDirPath) {
  this.genDirPath = genDirPath;
 }

 public String getTempletFilePath() {
  return templetFilePath;
 }

 public void setTempletFilePath(String templetFilePath) {
  this.templetFilePath = templetFilePath;
 }

 public String getPackagePath() {
  return packagePath;
 }

 public void setPackagePath(String packagePath) {
  this.packagePath = packagePath;
 }

 public String getSuperClass() {
  return superClass;
 }

 public void setSuperClass(String superClass) {
  this.superClass = superClass;
 }

 public String[] getImplInterface() {
  return implInterface;
 }

 public void setImplInterface(String[] implInterface) {
  this.implInterface = implInterface;
 }

 public BeanGennerator2(){
  setDefaultFromCfgFile();
 }
 
 /**
  * 從配置文件中設置默認參數
  */
 private void setDefaultFromCfgFile(){
  String[] params = null;
  params = ConfigHelper.instance().getBeanTempletParams("genDirPath");
  if(0 < params.length){
   genDirPath = params[0];
  }
  params = ConfigHelper.instance().getBeanTempletParams("templetFilePath");
  if(0 < params.length){
   templetFilePath = params[0];
  }
  params = ConfigHelper.instance().getBeanTempletParams("packagePath");
  if(0 < params.length){
   packagePath = params[0];
  }
  params = ConfigHelper.instance().getBeanTempletParams("superClass");
  if(0 < params.length){
   superClass = params[0];
  }
  implInterface = ConfigHelper.instance().getBeanTempletParams("implInterface");
  
 }

 /**
  * 生成javabean文件
  * @param tableGetter
  * @param tableCodes
  * @throws Exception
  */
 @SuppressWarnings("unchecked")
 void genBeanFile(ITableGetter tableGetter,String[] tableCodes) throws Exception{
  VelocityEngine ve = new VelocityEngine();
  ve.init();  

  Template vt = ve.getTemplate(getTempletFilePath());

  VelocityContext context = new VelocityContext();

  String[] superFields = getSuperFields(getSuperClass());
  String[] unImplMethods = getUnImplMethods(getImplInterface());

  @SuppressWarnings("rawtypes")
  Map map = new ConcurrentHashMap();
  if(null != getPackagePath()){
   map.put("packagePath", getPackagePath());
  }
  if(null != getSuperClass()){
   map.put("superClass", getSuperClass());
  }
  if(null != getImplInterface() && 0 < getImplInterface().length){
   map.put("interfaces", getImplInterface());
  }
  if(null != unImplMethods && 0 < unImplMethods.length){
   map.put("unImplMethods", unImplMethods);
  }
//  map.put("superFields", superFields);

  List<Table> list = tableGetter.getTables(tableCodes);
  for(Table t:list){
   String tableName = t.getScode();
   String className = CommTool.initialUpperCase(BeanTool.tableCode2ClassName(tableName.toLowerCase()));
   String[] fields = getFields(getThisFields(t),superFields);
   map.put("tableName",tableName);
   map.put("className",className);
   map.put("fields", fields);
   context.put("vm", map);
   StringWriter sw = new StringWriter();
   vt.merge( context, sw );

//   writeToFile(className,sw.toString());
   System.out.print(sw);
  }
 }
 
 /**
  * 取本類中不包含父類中已經聲明的屬性
  * @param thisFields
  * @param superFields
  * @return
  */
 private String[] getFields(String[] thisFields,String[] superFields){
  if(null == thisFields){
   return new String[0];
  }
  if(null == superFields || 0 >= superFields.length){
   return thisFields;
  }
  
  List<String> thisList = new ArrayList<String>();
  Set<String> superFieldSet = new HashSet<String>(Arrays.asList(superFields));
  for(String field:thisFields){
   if(!superFieldSet.contains(field)){
    thisList.add(field);
   }
  }
  return thisList.toArray(new String[0]);
 }
 
 /**
  * 取表t中所有的屬性
  * @param t
  * @return
  */
 private String[] getThisFields(Table t) {
  // TODO Auto-generated method stub
  return BeanTool.vosFieldValues(t.getColumns().toArray(new Column[0]),"scode");
 }

 /**
  * 取父類中聲明的屬性
  * @param superClass2
  * @return
  */
 private String[] getSuperFields(String superClass2) {
  // TODO Auto-generated method stub
  List<String> list = new ArrayList<String>();
  Class cls = null;
  try {
   cls = Class.forName(superClass2);
  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  if(null != cls){
   Field[] fieldList = cls.getDeclaredFields();
   for(Field f: fieldList){
    String name = f.getName();
    if(!list.contains(name)){
     list.add(name);
    }
   }
  }
  
  return list.toArray(new String[list.size()]);
 }
 
 private String[] getUnImplMethods(String[] implInterface2) {
  // TODO Auto-generated method stub
  List<String> list = new ArrayList<String>();
  if(null != implInterface2){
   String str = " abstract ";
   StringBuffer buf = new StringBuffer();
   try{
    for(String itf : implInterface2){
     Class cls = Class.forName(itf);
     Method[] methods = cls.getMethods();
     
     for(Method m:methods){
      buf.append(m.toGenericString());
      if(m.getReturnType().isPrimitive()){
       buf.append("{\r\n    return 0;\r\n}");
      }else if(buf.indexOf(" void ")>0){
       buf.append("{\r\n\r\n}\r\n");
      }else {
       buf.append("{\r\n    return null;\r\n}");
      }
      
      int index = buf.indexOf(str);
      list.add(buf.replace(index, index+str.length(), " ").toString());
     }
     
//     list.add(buf.toString());
    }
    
   }catch(ClassNotFoundException e){
    
   }
  }
  return list.toArray(new String[list.size()]);
 }

 private void writeToFile(String fileName, String content) throws IOException  {
  // TODO Auto-generated method stub
  FileWriter fw =null;
  BufferedWriter bufWriter = null;
  String filePath = this.getGenDirPath()+fileName+".java";
  try {
   fw = new FileWriter(filePath);
   bufWriter = new BufferedWriter(fw);
   bufWriter.append(content).flush();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }finally{
   if(null != bufWriter)
    bufWriter.close();
   if(null != fw)
    fw.close();
  }  
 }
 
}