如何在java中构建简单的代码生成器

StringBuilder sourceBuilder = new StringBuilder();
sourceBuilder.append("package com.example.beans;nn");
sourceBuilder.append("import java.util.*;nn");
sourceBuilder.append("public class MyBean {");

for (DBField dbField:getFieldsFromDatabaseModel) {  // this DBField class is pure fiction!
  // bean attribute
  sourceBuilder.append("tprivate ")
               .append(dbField.getType)
               .append(toFieldName(dbField.getName()))
               .append(" = null;n");

  // setter method
  sourceBuilder.append("tpublic void ")
               .append(toSetterName(dbField.getName()))
               .append("(");
               .append(dbField.getType)
               .append(toFieldName(dbField.getName()))
               .append(")n")
               .append("ttthis.")
               .append(dbField.getType)
               .append(" = ")
               .append(dbField.getType)
               .append(";nt}");

   // getter method ...
sourceBuilder.append("t}n}n");