I have a web application that executes on tomcat 6.

I have a MysqlDb class that uses a BasicDataSource from a spring JDBC.

so far I've used the following bean configuration in web.xml:

<bean id="MysqlDb" class="com.xpogames.gamesisland.mysql.MysqlDb">
    <property name="idDataSource" ref="idDataSource"/>
 </bean>

and I had the following setter function:

  public void setidDataSource(BasicDataSource ds) {
    this._dataSource=(DataSource)ds;
    this._simpleJdbcTemplate = new SimpleJdbcTemplate(_dataSource);
    this._jdbcTemplate = new JdbcTemplate(_dataSource);
 }

I want to convert my class to use static functions, so I created an empty pri开发者_JS百科vate constructor so the class won't explicitly instantiated by callers.

besides that I changed the setidDataSource function to a static function, but when I try to do that I get the following error:

Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'idDataSource' of bean class [com.xpogames.gamesisland.mysql.MysqlDb]: Bean property 'idDataSource' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?

is there a way to resolve this issue in web.xml or do I need to manually fetch the ServletContext

ServletContext servletContext = this.getServletContext();
this._context = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);

and fetch the bean from there and just remove the lines i printed here from web.xml ?

For one, you've declared the setter setidDataSource. It should be setIdDataSource. The first letter of a property must be a capital letter after the word set.

Also, a setter method must not be static but an instance method.

Spring-beans are by default singletons, you do not need to implement your class as a singleton as long as you use the bean from the context. The simplest answer to your question is getting the bean from the context after setting the datasource in the context, but I thought you want to stay away from the context.

Static setters for class are of course possible (they would just set static property for all instances), but in IoC pattern (which is used in spring), bean is instance, and term "property of bean" always means "property of instance of class" - consider it as limitation of given IoC implementation.

I understand know that I had a bad implementation idea. I still need a constructor, so building a class with static functions and static init is a bad idea, and trying to execute a static setter from a bean is not logical and impossible.

Instead I changed the class to be a singleton class, so I will be able to use it anywhere in my application and it will be constructed only once.

thanks for all the information.

update

I still don't know if that's a good method, but at least it works.

in my red-web.xml (consider it as spring applicationContext.xml), I have the following:

 <bean id="MysqlDb" class="com.xpogames.gamesisland.mysql.MysqlDb" init-method="getInstance">
    <property name="idDataSource" ref="idDataSource"/>
 </bean>

Here it creates a MysqlDb bean and configure it to use the getInstance() init method if MysqlDb Class. i made sure to have a setidDataSource() function in mysqlDb class for the datasource to be properly set.

<bean id="web.handler" class="com.xpogames.gamesisland.Application">
    <property name="MysqlDb" ref="MysqlDb"/>
</bean>

Here, I create the main bean of my application and I made sure to have the function setMysqlDb for the MysqlDb class to be set from the bean configuration.

So far mysqlDb acts as a singelton class because it's constructor is protected and it creates the instance only once:

public static MysqlDb getInstance() {
    if (instance == null) {
        instance = new MysqlDb();
    }
    return instance;
}

The problem that I encountered was that in other parts of my application whenever I used getInstance(), the MysqlDb class would come up and all the variables that where set with setidDataSource where null.

so resolve that issue I created another function called setInstance in mysqlDb:

public static void setInstance(MysqlDb db) { instance=db; }

this is my main setMysqlDb function in my main application:

public void setMysqlDb(MysqlDb db) {
    this._mysqlDb=db;
    /* it seems that without forcing a setInstance on the class, whenever other classes
     * would try to getInstance(), variables that are supposed to be configured by the bean
     * would be empty. this resolves that issue
     */
    MysqlDb.setInstance(db);
}

so this configuration works. it's obviously not the recommended or best solution! but it seems that I need to read and learn further before I come up with a better solution.