Developers use jasperreport to generate reports from data sources

Preface

The first two articles describe how to query databases, but they all interact with databases through Report Templates. That is to say, our query statements and parameter definitions are all written in the templates, so sometimes it is not convenient, so today I will introduce you to interact with the database through servlet, And the template is only responsible for display.

Question

As before, the following steps are required to generate a report:

1. Introduce the jar package. See static text report.

2. Create a report template:

Because servlet is used to interact with the database this time, the query statement is not in our report:

<? Xmlversion = "1.0" encoding = "UTF-8"?>

<Jasperreportxmlns = "http://jasperreports.sourceforge.net/jasperreports"

Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"

Xsi: schemalocation = "http://jasperreports.sourceforge.net/jasperreportshttp://jasperreports.sourceforge.net/xsd/jasperreport.xsd"

Name = "jrresultreport">

<Fieldname = "ID" class = "Java. Lang. Integer"/>

<Fieldname = "name" class = "Java. Lang. String"/>

<Fieldname = "sex" class = "Java. Lang. String"/>

<Pageheader>

<Bandheight = "30">

<Statictext>

<Reportelementx = "0" Y = "0" width = "69" Height = "24"/>

<Textelementverticalalignment = "bottom"/>

<Text> id </text>

</Statictext>

<Statictext>

<Reportelementx = "140" Y = "0" width = "79" Height = "24"/>

<Text> name </text>

</Statictext>

<Statictext>

<Reportelementx = "280" Y = "0" width = "69" Height = "24"/>

<Text> sex </text>

</Statictext>

</Band>

</Pageheader>

<Detail>

<Bandheight = "30">

<Textfield>

<Reportelementx = "0" Y = "0" width = "69" Height = "24"/>

<Textfieldexpressionclass = "Java. Lang. Integer">

$ F {ID}

</Textfieldexpression>

</Textfield>

<Textfield>

<Reportelementx = "140" Y = "0" width = "69" Height = "24"/>

<Textfieldexpressionclass = "Java. Lang. String">

$ F {name}

</Textfieldexpression>

</Textfield>

<Textfield>

<Reportelementx = "280" Y = "0" width = "69" Height = "24"/>

<Textfieldexpressionclass = "Java. Lang. String">

$ F {sex}

</Textfieldexpression>

</Textfield>

</Band>

</Detail>

</Jasperreport>

3. compile the report template. See static text report.

4. Compile servlet:

In this example, the servlet interacts with the database (jrresultsetdatasource Data Source). Therefore, the servlet establishes a connection to the database and a query statement:

Packagecom. Dan. servlet;

 

Importjava. Io. ioexception;

Importjava. Io. inputstream;

Importjava. Io. printwriter;

Importjava. Io. stringwriter;

Importjava. SQL. connection;

Importjava. SQL. drivermanager;

Importjava. SQL. resultset;

Importjava. SQL. statement;

Importjava. util. hashmap;

 

Importjavax. servlet. servletexception;

Importjavax. servlet. servletoutputstream;

Importjavax. servlet. http. httpservlet;

Importjavax. servlet. http. httpservletrequest;

Importjavax. servlet. http. httpservletresponse;

 

Importnet. SF. jasperreports. Engine. jrresultsetdatasource;

Importnet. SF. jasperreports. Engine. jasperrunmanager;

 

/**

* Fill in with jrresultsetdatasource

* @ Author zdd

*

*/

Publicclass dbreportdsservlet extends httpservlet {

 

@ Override

Protectedvoid doget (httpservletrequest req, httpservletresponse resp)

Throwsservletexception, ioexception {

Connectionconnection;

Statementstatement;

Resultsetresultset;

 

Resp. setcontenttype ("application/pdf ");

 

Servletoutputstreamservletoutputstream = resp. getoutputstream ();

 

Inputstreamreportstream = getservletconfig (). getservletcontext (). getresourceasstream ("/WEB-INF/classes/reports/jrresultreport. Jasper ");

 

Stringquery = "select T. ID, T. Name, T. Sex from t_user t ";

 

Try {

Class. forname ("oracle. JDBC. Driver. oracledriver ");

Connection = drivermanager. getconnection ("JDBC: oracle: thin: @ 192.168.24.36: 1521: testreport", "test", "test ");

Statement = connection. createstatement ();

Resultset = statement.exe cutequery (query );

Jrresultsetdatasourceresultsetdatasource = new jrresultsetdatasource (resultset );

Jasperrunmanager. runreporttopdfstream (reportstream, servletoutputstream, newhashmap (), resultsetdatasource );

Resultset. Close ();

Statement. Close ();

Connection. Close ();

Servletoutputstream. Flush ();

Servletoutputstream. Close ();

} Catch (effectione ){

Stringwriterstringwriter = new stringwriter ();

Printwriterprintwriter = new printwriter (stringwriter );

E. printstacktrace (printwriter );

Resp. setcontenttype ("text/plain ");

Resp. getoutputstream (). Print (stringwriter. tostring ());

}

}

 

}

5. configuring web. xml means configuring servlet.

6. Run the project

Let's take a look at my running results:

 

 

Summary:

In fact, so many instances are very simple. The difference between each instance is that they are used in different ways. Other instances are basically similar.