sunsy

项目里用到了jasperreport，平时都是用ireport来设计好报表模板直接使用就好了，但是碰到动态表头等情况就比较麻烦了，而且有些报表可能仅是针对一个数据表或者说一个实体对象的操作，对于这种报表一个个设计JRXML也比较麻烦，尝试了一下编程的方式来生成报表，只是个简单的测试。在网上找一些资料发现纯编程来写报表的相关内容很少，也是看了相关的API后才写了个例子。

ReportProcess.java是一个简单的用来构造、编译并导出报表的类。

package jasper.test;

import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;

import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperExportManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.JasperReport;
import net.sf.jasperreports.engine.design.JRDesignBand;
import net.sf.jasperreports.engine.design.JRDesignExpression;
import net.sf.jasperreports.engine.design.JRDesignField;
import net.sf.jasperreports.engine.design.JRDesignStaticText;
import net.sf.jasperreports.engine.design.JRDesignTextField;
import net.sf.jasperreports.engine.design.JasperDesign;

public class ReportProcess {

	public static void main(String[] args) {
		try {
			JasperReport jp = getJasperReport();
			InputStream in = new FileInputStream(
					"src/test/java/jasper/test/Data.csv");// 换成自己目录
			CsvDataSource csvDataSource = new CsvDataSource(
					new InputStreamReader(in));
			in.close();

			JasperPrint jpr = JasperFillManager.fillReport(jp, null,
					csvDataSource);
			JasperExportManager.exportReportToHtmlFile(jpr, "c:/test.html");//　写的时候随便指定了个查看的目录
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static JasperReport getJasperReport() throws JRException {
		JasperDesign design = new JasperDesign();
		design.setName("testReport");

		JRDesignBand title = new JRDesignBand();
		title.setHeight(50);
		JRDesignStaticText titleText = new JRDesignStaticText();
		titleText.setText("test report");
		titleText.setX(230);
		titleText.setFontSize(20);
		titleText.setHeight(50);
		titleText.setWidth(100);
		title.addElement(titleText);
		design.setTitle(title);

		String[] headers = { "name", "age", "gender", "like" };
		JRDesignBand columnHeader = new JRDesignBand();
		columnHeader.setHeight(30);

		JRDesignBand detail = new JRDesignBand();
		detail.setHeight(30);

		for (int i = 0; i < headers.length; i++) {
			// add column headers
			JRDesignStaticText staticText = new JRDesignStaticText();
			staticText.setText(headers[i]);
			staticText.setFontSize(16);
			staticText.setHeight(30);
			staticText.setWidth(50);
			staticText.setX(50 * i);
			columnHeader.addElement(staticText);

			// define fields
			JRDesignField field = new JRDesignField();
			field.setName(headers[i]);
			field.setValueClass(String.class);
			design.addField(field);

			// add text fields for displaying fields
			JRDesignTextField textField = new JRDesignTextField();
			JRDesignExpression expression = new JRDesignExpression();
			expression.setText("$F{" + headers[i] + "}");
			expression.setValueClass(String.class);
			textField.setExpression(expression);
			textField.setFontSize(14);
			textField.setHeight(30);
			textField.setWidth(50);
			textField.setX(50 * i);
			detail.addElement(textField);
		}
		design.setColumnHeader(columnHeader);
		design.setDetail(detail);

		return JasperCompileManager.compileReport(design);
	}

}

CsvDataSource.java是摘自JASER例子里的一个数据源实现，有现成的做例子的时候就拿来用了，用这个比较简单，不用写数据库那一堆。

package jasper.test;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.Reader;
import java.util.List;

import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRField;
import net.sf.jasperreports.engine.JRRewindableDataSource;
import au.com.bytecode.opencsv.CSVReader;

/**
 * 
 * 这个类摘自JASPER带的一个例子里的CSV数据源实现。
 * 
 */
public class CsvDataSource implements JRRewindableDataSource {
	private CSVReader csvReader;
	private List rows;
	private int currentRowIndex = -1;
	private int currentColIndex = 0;
	private int totalRows;

	public CsvDataSource(Reader reader) {
		try {
			csvReader = new CSVReader(reader);
			rows = csvReader.readAll();
			totalRows = rows.size();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public boolean next() throws JRException {
		boolean retVal = true;

		currentRowIndex++;
		currentColIndex = 0;

		if (currentRowIndex >= totalRows) {
			retVal = false;
		}

		return retVal;
	}

	public Object getFieldValue(JRField arg0) throws JRException {
		String value = null;
		String[] currentRow = (String[]) rows.get(currentRowIndex);

		value = currentRow[currentColIndex];
		currentColIndex++;

		return value;
	}

	public void moveFirst() throws JRException {
		currentRowIndex = 0;
		currentColIndex = 0;
	}
}

Data.csv里的数据。

jim,12,male,basketball
lily,13,female,dancing
david,23,male,swimming
su,23,female,running

结果大致是这个样子。

                  test report  
 name    age   gender   like  
 jim     12    male     basketb  
 lily    13    female   dancing  
 david   23    male     swimmi
 su      23    female   running 

这里就是个实验性的代码，但至少可以知道，我们可以通过一些手段来编程处理JASPER的报表。可以写得更完善一些，动态获取表头个数与内容，写QUERY查询，填充报表。
比如一张表有一部分表头是不定的，那就可以在程序中追加表头定义，追加字段定义等。