jasperreports自定义数据源

使用的是jasperreports-5.6.0版本的包。

需求:  报表由一个基本Basic对象和一个集合类CustomList对象组成

问题：jasperreports没有提供类似可用的datasource类

解决方法：自定义一个DataSource实现JRDataSource接口即可

仿照JRBeanCollectionDataSource写了一个ReportDataSource，同样使其继承JRAbstractBeanDataSource，代码如下：

public class ReportDataSource extends JRAbstractBeanDataSource {    /**     *     */    private Collection<?> data;    private Iterator<?> iterator;    private Object currentBean;    private Object basicData;//基本数据    /**     *     */    public ReportDataSource(Object basicData,Collection<?> beanCollection)    {        this(basicData,beanCollection, true);    }    /**     *     */    public ReportDataSource(Object basicData,Collection<?> beanCollection, boolean isUseFieldDescription)    {        super(isUseFieldDescription);        this.basicData = basicData;        this.data = beanCollection;        if (this.data != null)        {            this.iterator = this.data.iterator();        }    }    /**     *     */    public boolean next()    {        boolean hasNext = false;        if (this.iterator != null)        {            hasNext = this.iterator.hasNext();            if (hasNext)            {                this.currentBean = this.iterator.next();            }        }        return hasNext;    }    /**     *     */    public Object getFieldValue(JRField field) throws JRException    {        if(field.getName().contains("basic.")){            return getBeanProperty(basicData,field.getName().split("\\.")[1]);        }        return getFieldValue(currentBean, field);    }    /**     *     */    public void moveFirst()    {        if (this.data != null)        {            this.iterator = this.data.iterator();        }    }    /**     * Returns the underlying bean collection used by this data source.     *     * @return the underlying bean collection     */    public Collection<?> getData()    {        return data;    }    /**     * Returns the total number of records/beans that this data source     * contains.     *     * @return the total number of records of this data source     */    public int getRecordCount()    {        return data == null ? 0 : data.size();    }    /**     * Clones this data source by creating a new instance that reuses the same     * underlying bean collection.     *     * @return a clone of this data source     */    public ReportDataSource cloneDataSource()    {        return new ReportDataSource(basicData,data);    }

上面代码是修改JRBeanCollectionDataSource的，仅仅变动了几行代码而已，在jrmxl文件中就可以使用basic.属性名来标识Basic对象的属性了。

值得注意的是，如果CustomList为空，则无法输出报表，如果需要，可以在ReportDataSource构造器中增加  判断集合是否为空的代码，如果为空则初始化其长度为1的集合