注: 此方法使用简单,但是没有分页读取数据,适合数据量不大情况下的报表
原文:
http://www.hibernate.org/79.html
Using JasperReports with Hibernate
This section will demonstrate a couple of ways to use the results of a Hibernate query as the datasource of a report in JasperReports.
When the Hibernate query returns a simple collection of objects, The JRBeanCollectionDataSource class in the JasperReports library will work fine.
--------------------------------------------------------------------------------------------------------
List cats = session.find("from eg.Cat");
Map parameters = new HashMap();
parameters.put("Title", "The Cat Report");
InputStream reportStream = this.class.getResourceAsStream("/the-cat-report.xml");
JasperDesign jasperDesign = JasperManager.loadXmlDesign(reportStream);
JasperReport jasperReport = JasperManager.compileReport(jasperDesign);
JRBeanCollectionDataSource ds = new JRBeanCollectionDataSource(cats);
JasperPrint jasperPrint = JasperManager.fillReport(jasperReport, parameters, ds);
JasperManager.printReportToPdfFile(jasperPrint, "the-cat-report.pdf");
--------------------------------------------------------------------------------------------------------
However, when the Hibernate query returns tuples of objects (each tuple as an array, each array as an element in the returned List), things get a little tricky. Jasper needs a way to reference each object in the array by a field name. This class is a good solution, but at this time you are required to pass an array of field names matching the results of the query.
--------------------------------------------------------------------------------------------------------
public class HibernateQueryResultDataSource implements JRDataSource {
private String[] fields;
private Iterator iterator;
private Object currentValue;
public HibernateQueryResultDataSource(List list, String[] fields) {
this.fields = fields;
this.iterator = list.iterator();
}
public Object getFieldValue(JRField field) throws JRException {
Object value = null;
int index = getFieldIndex(field.getName());
if (index > -1) {
Object[] values = (Object[])currentValue;
value = values[index];
}
return value;
}
public boolean next() throws JRException {
currentValue = iterator.hasNext() ? iterator.next() : null;
return (currentValue != null);
}
private int getFieldIndex(String field) {
int index = -1;
for (int i = 0; i < fields.length; i++) {
if (fields
.equals(field)) {
index = i;
break;
}
}
return index;
}
}
--------------------------------------------------------------------------------------------------------
Now running your report would look something like this:
--------------------------------------------------------------------------------------------------------
List cats = session.find("select cat.type, cat.birthdate, cat.name from eg.DomesticCat cat");
Map parameters = new HashMap();
parameters.put("Title", "The Cat Report");
InputStream reportStream = this.class.getResourceAsStream("/the-cat-report.xml");
JasperDesign jasperDesign = JasperManager.loadXmlDesign(reportStream);
JasperReport jasperReport = JasperManager.compileReport(jasperDesign);
String[] fields = new String[] { "type", "birthdate", "name"};
HibernateQueryResultDataSource ds = new HibernateQueryResultDataSource(cats, fields);
JasperPrint jasperPrint = JasperManager.fillReport(jasperReport, parameters, ds);
JasperManager.printReportToPdfFile(jasperPrint, "the-cat-report.pdf");
--------------------------------------------------------------------------------------------------------
Another, alternate implementation, from Erik Romson:
--------------------------------------------------------------------------------------------------------
public class HibernateQueryResultDataSource implements JRDataSource
{
private static final transient Logger logger =
Logger.Factory.getInstance(HibernateQueryResultDataSource.class);
protected HashMap fieldsToIdxMap=new HashMap();
protected Iterator iterator;
protected Object currentValue;
List values;
public HibernateQueryResultDataSource(List list, String query)
{
int start =query.indexOf("select ");
int stop =query.indexOf(" from ");
Assertion.assertTrue(
(start!=-1) &&
(stop!=-1),
"The query "+
query+
" must be of the form select x,x from ..."
);
start+="select".length();
String parameters=query.substring(start,stop);
parameters=parameters.trim();
Assertion.assertTrue(
parameters.length()>0,
"The query "+
query+
" seems to be weird"
);
StringTokenizer tokenizer=new StringTokenizer(parameters,",");
int idx=0;
while( tokenizer.hasMoreTokens() )
{
String parameter=tokenizer.nextToken();
fieldsToIdxMap.put( parameter.trim(), new Integer(idx) );
idx++;
}
values=list;
this.iterator = list.iterator();
}
public Object getFieldValue(JRField field) throws JRException
{
String fieldName=field.getName().replace('_','.');
//JasperReports does not allow '.' in field names, so we
//use '_' for nested properties instead and must convert here
//(comment added by kbrown)
Integer idxInt=(Integer) fieldsToIdxMap.get(fieldName);
if (idxInt==null)
{
Assertion.fail(
"The field \""+
fieldName+
"\" did not have an index mapping. Should be one off "+
fieldsToIdxMap.keySet()
);
}
Object[] values = (Object[]) currentValue;
Assertion.assertTrue(
idxInt.intValue()
"The index from field "+
fieldName+
" was illegal"
);
Object value= values[ idxInt.intValue() ];
if ( logger.isDebugEnabled() )
{
logger.debug("fetched value "+value+" from field "+fieldName);
}
return value;
}
public boolean next() throws JRException
{
currentValue = iterator.hasNext() ? iterator.next() : null;
return currentValue != null;
}
public List getValues()
{
return values;
}
}
--------------------------------------------------------------------------------------------------------
Using JasperReports with Hibernate
This section will demonstrate a couple of ways to use the results of a Hibernate query as the datasource of a report in JasperReports.
When the Hibernate query returns a simple collection of objects, The JRBeanCollectionDataSource class in the JasperReports library will work fine.
List cats = session.find("from eg.Cat");
Map parameters = new HashMap();
parameters.put("Title", "The Cat Report");
InputStream reportStream = this.class.getResourceAsStream("/the-cat-report.xml");
JasperDesign jasperDesign = JasperManager.loadXmlDesign(reportStream);
JasperReport jasperReport = JasperManager.compileReport(jasperDesign);
JRBeanCollectionDataSource ds = new JRBeanCollectionDataSource(cats);
JasperPrint jasperPrint = JasperManager.fillReport(jasperReport, parameters, ds);
JasperManager.printReportToPdfFile(jasperPrint, "the-cat-report.pdf");
However, when the Hibernate query returns tuples of objects (each tuple as an array, each array as an element in the returned List), things get a little tricky. Jasper needs a way to reference each object in the array by a field name. This class is a good solution, but at this time you are required to pass an array of field names matching the results of the query.
public class HibernateQueryResultDataSource implements JRDataSource {
private String[] fields;
private Iterator iterator;
private Object currentValue;
public HibernateQueryResultDataSource(List list, String[] fields) {
this.fields = fields;
this.iterator = list.iterator();
}
public Object getFieldValue(JRField field) throws JRException {
Object value = null;
int index = getFieldIndex(field.getName());
if (index > -1) {
Object[] values = (Object[])currentValue;
value = values[index];
}
return value;
}
public boolean next() throws JRException {
currentValue = iterator.hasNext() ? iterator.next() : null;
return (currentValue != null);
}
private int getFieldIndex(String field) {
int index = -1;
for (int i = 0; i < fields.length; i++) {
if (fields
.equals(field)) {
index = i;
break;
}
}
return index;
}
}
Now running your report would look something like this:
List cats = session.find("select cat.type, cat.birthdate, cat.name from eg.DomesticCat cat");
Map parameters = new HashMap();
parameters.put("Title", "The Cat Report");
InputStream reportStream = this.class.getResourceAsStream("/the-cat-report.xml");
JasperDesign jasperDesign = JasperManager.loadXmlDesign(reportStream);
JasperReport jasperReport = JasperManager.compileReport(jasperDesign);
String[] fields = new String[] { "type", "birthdate", "name"};
HibernateQueryResultDataSource ds = new HibernateQueryResultDataSource(cats, fields);
JasperPrint jasperPrint = JasperManager.fillReport(jasperReport, parameters, ds);
JasperManager.printReportToPdfFile(jasperPrint, "the-cat-report.pdf");
--------------------------------------------------------------------------------
Another, alternate implementation, from Erik Romson:
public class HibernateQueryResultDataSource implements JRDataSource
{
private static final transient Logger logger =
Logger.Factory.getInstance(HibernateQueryResultDataSource.class);
protected HashMap fieldsToIdxMap=new HashMap();
protected Iterator iterator;
protected Object currentValue;
List values;
public HibernateQueryResultDataSource(List list, String query)
{
int start =query.indexOf("select ");
int stop =query.indexOf(" from ");
Assertion.assertTrue(
(start!=-1) &&
(stop!=-1),
"The query "+
query+
" must be of the form select x,x from ..."
);
start+="select".length();
String parameters=query.substring(start,stop);
parameters=parameters.trim();
Assertion.assertTrue(
parameters.length()>0,
"The query "+
query+
" seems to be weird"
);
StringTokenizer tokenizer=new StringTokenizer(parameters,",");
int idx=0;
while( tokenizer.hasMoreTokens() )
{
String parameter=tokenizer.nextToken();
fieldsToIdxMap.put( parameter.trim(), new Integer(idx) );
idx++;
}
values=list;
this.iterator = list.iterator();
}
public Object getFieldValue(JRField field) throws JRException
{
String fieldName=field.getName().replace('_','.');
//JasperReports does not allow '.' in field names, so we
//use '_' for nested properties instead and must convert here
//(comment added by kbrown)
Integer idxInt=(Integer) fieldsToIdxMap.get(fieldName);
if (idxInt==null)
{
Assertion.fail(
"The field \""+
fieldName+
"\" did not have an index mapping. Should be one off "+
fieldsToIdxMap.keySet()
);
}
Object[] values = (Object[]) currentValue;
Assertion.assertTrue(
idxInt.intValue()
"The index from field "+
fieldName+
" was illegal"
);
Object value= values[ idxInt.intValue() ];
if ( logger.isDebugEnabled() )
{
logger.debug("fetched value "+value+" from field "+fieldName);
}
return value;
}
public boolean next() throws JRException
{
currentValue = iterator.hasNext() ? iterator.next() : null;
return currentValue != null;
}
public List getValues()
{
return values;
}
}
--------------------------------------------------------------------------------
Using the information from this page I've made a patch to JasperReports 0.6.5. You can find the patch at:
http://www.waltermourao.com.br/JasperReports/jr65_hql.zip
or you can download the full version from:
http://www.waltermourao.com.br/JasperReports/jasperreports-hql-0.6.5.zip
posted on 2006-06-29 19:58
matthew 阅读(1606)
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