开发者使用JasperReport——不同数据源之自定义数据源

前言

    前面讲解了一些JasperReport给我们提供的一些实现好的数据源，当然如果我们有自己的特殊需要，还可以自定义数据源。

 

正题

跟之前的一样，我们要生成报表需要以下几个步骤：

1.引入jar包，请看《静态文本报表》 。

2.新建报表模版：

跟我们前一篇的AircraftReport报表模版是一样的，请参见《不同数据源之Map数据源》；

 

3.编译报表模版，请看《静态文本报表》。

4.编写自定义数据源ListOfArraysDataSource：

 

package com.dan.jasper;

import java.util.List;

import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRField;
import net.sf.jasperreports.engine.JRRewindableDataSource;

import org.apache.commons.lang.ArrayUtils;

/**
 * 自定义数据源
 * @author zdd
 *
 */
public class ListOfArraysDataSource implements JRRewindableDataSource {

	private List<String[]> listOfArrays;
	private String[] fieldNames;
	private int index = -1;
	
	public ListOfArraysDataSource(List<String[]> listOfArrays){
		this.listOfArrays = listOfArrays;
	}
	
	@Override
	public Object getFieldValue(JRField jrField) throws JRException {
		int fieldIndex = ArrayUtils.indexOf(fieldNames, jrField.getName());
		if (fieldIndex == ArrayUtils.INDEX_NOT_FOUND){
			throw new JRException("Invalid field" + jrField.getName());			
		}
		
		return listOfArrays.get(index)[fieldIndex];
	}

	@Override
	public boolean next() throws JRException {
		index++;
		boolean returnVal = true;
		if (index >= listOfArrays.size()){
			returnVal = false;
		}
		return returnVal;
	}

	@Override
	public void moveFirst() throws JRException {
		index = 0;
	}

	public List<String[]> getListOfArrays() {
		return listOfArrays;
	}

	public void setListOfArrays(List<String[]> listOfArrays) {
		this.listOfArrays = listOfArrays;
	}

	public String[] getFieldNames() {
		return fieldNames;
	}

	public void setFieldNames(String[] fieldNames) {
		this.fieldNames = fieldNames;
	}

	public int getIndex() {
		return index;
	}

	public void setIndex(int index) {
		this.index = index;
	}

}

 

5.编写servlet:

 

package com.dan.servlet;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.jasperreports.engine.JRDataSource;
import net.sf.jasperreports.engine.JasperRunManager;

import com.dan.jasper.ListOfArraysDataSource;

/**
 * 使用自定义数据源填充
 * @author zdd
 *
 */
public class CustomDataSourceReportServlet extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 2174316885912562306L;

	/**
	 * 创建数据源
	 * @return
	 */
	private JRDataSource createReportDataSource(){
		String[] headers = {"ID","NAME","SEX"};
		ListOfArraysDataSource dataSource;
		List<String[]> reportRows = initializeListOfArrays();
		dataSource = new ListOfArraysDataSource(reportRows);
		dataSource.setFieldNames(headers);
		return dataSource;		
	}
	
	private List<String[]> initializeListOfArrays(){
		List<String[]> reportRows = new ArrayList<String[]>();
		String[] row1 = {"1","rebecca1","female"};
		String[] row2 = {"2","rebecca2","female"};
		String[] row3 = {"3","rebecca3","female"};
		String[] row4 = {"4","rebecca4","female"};
		reportRows.add(row1);
		reportRows.add(row2);
		reportRows.add(row3);
		reportRows.add(row4);
		return reportRows;
	}
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		 
		ServletOutputStream servletOutputStream = resp.getOutputStream();
		
		InputStream reportStream = getServletConfig().getServletContext().getResourceAsStream("/WEB-INF/classes/reports/AircraftReport.jasper");
		
 		
		try{
			JRDataSource dataSource = createReportDataSource();
			JasperRunManager.runReportToPdfStream(reportStream, servletOutputStream, new HashMap(),dataSource);
			
			resp.setContentType("application/pdf");
			servletOutputStream.flush();
			servletOutputStream.close();
		}catch(Exception e){
			StringWriter stringWriter = new StringWriter();
			PrintWriter printWriter = new PrintWriter(stringWriter);
			e.printStackTrace(printWriter);
			resp.setContentType("text/plain");
			resp.getOutputStream().print(stringWriter.toString());
		}
	}

}

6.配置web.xml，就是配置servlet

 

7.运行项目

看一下我的运行结果：

小结：

  通过这么多不同数据源的介绍我们不难看到，其实所有的数据源都是对于接口JRDataSource 的一个实现，只不过是JasperReport把我们常用到的数据源形式提前帮我们写好了，我们所需要进行的二次开发就是在其基础上再进行优化和美化。