CODEWITHSUNDEEP
javacode-generation
Amira Elsayed Ismail
Amira Elsayed Ismail

Reputation: 9414

How to build simple code generator in java

I want to build a simple code generator in java that can take database connection string and then create the model layer for each table in database , I don't know how can I do that , so if any one has any tutorial or links that may help me complete this task i will be thankful

Thanks in Advance

I have found a good example on code project that can take the database and make a good code generation for the tables in database , but unfortunately it is written in C# and also generate C# code

I don't know if it right to generate C# code and then convert them to java using any conversion software , or the right thing is to try to modify it to generate java classes instead of C# classes

by the way the link for the example is http://www.codeproject.com/KB/codegen/TierGenerator.aspx

I need your advice as soon as you can

Thanks in Advance

Upvotes: 8

Views: 36992

Answers (4)

Andreas Dolk
Andreas Dolk

Reputation: 114817

For quick and simple code generator: Just write the java source code into a StringBuilder and dump its content to a .java file. I never used third party libs for simple autogenerators:

StringBuilder sourceBuilder = new StringBuilder();
sourceBuilder.append("package com.example.beans;\n\n");
sourceBuilder.append("import java.util.*;\n\n");
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("\t\tthis.")
               .append(dbField.getType)
               .append(" = ")
               .append(dbField.getType)
               .append(";\n\t}");

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

Upvotes: 13

lgu
lgu

Reputation: 2460

Don't reinvent the wheel, use an existing code generator. Telosys Tools does this kind of job : http://www.telosys.org/

It's an open source project, so you can also look inside if you want to reuse the generator engine (it works with Velocity templates)

Upvotes: 2

Stephen C
Stephen C

Reputation: 719446

If you want to implement your own code generator ...

In my experience ... using a template-based tool like Velocity or FreeMarker or JET reduces the effort in writing and maintaining source code generators.

Here are some relevant links:

Doing code generation using StringBuilder / String concatenation, is a lot of work (for a non-trivial code-generation task) and tends to give you a pile of code that is hard to read and hard to maintain. It is also more difficult to generate well-formatted (e.g, properly indented, line-wrapped) code, if that is relevant to your use-case.

Upvotes: 18

xflorian
xflorian

Reputation: 365

Minuteproject is designed to meet this requirement. It reads database metadata, optionally (but in reality extremely useful) enrich the model and generate for any text based language (ex: java, c#, php, jsf, html, js etc...) You can benefit out of the box of shipped solutions (JPA2, Openxava, Primefaces)

But also you can:

  • create additional artifacts (your own that match your architecture/design);
  • decide there naming convention;
  • if there are model, package, application, table, column, view specific;
  • any artifact can find information on other artifacts if they want to correctly reference them.

Upvotes: 1

Related Questions