POI实现一个通用的Excel读取模板

    POI是Apache基金会的提供的java实现的一套用于读取Excel、Word、PPT等文档的库，在实际项目中可能 很多地方都会用到Excel的读取，比如Excel的导入，我们不可能每个地方都单独实现一套Excel的读取方法，这时候就需要封装一个通用的类，只要有读取Excel的地方就调用该方法就可以了，下面我们就来实现它。
    首先，为了提高可扩展性，也为了方便扩展到譬如Word、PPT这类文档，我们需要抽象出一个Template类，通过工厂方法来构建不同的Template。
    然后，实现每个不同的Template，在实现过程中，我们还可以设置Listener，这样只要实现了该监听器，就能得到当前读取到的值，方便扩展。
    OK，下面请看具体的代码：
    import java.io.InputStream;
import java.io.Serializable;
import java.util.List;

import cn.sunsharp.poi.bean.Filter;

/**
* The template of POI.
* All template must inherit this class.
* @author lynn
*
*/
public abstract class Template {

protected List<Filter> filters;
protected boolean ignore = false;

public void setFilters(List<Filter> filters) {
this.filters = filters;
}

public List<Filter> getFilters() {
return filters;
}

public boolean isIgnore() {
return ignore;
}

public void setIgnore(boolean ignore) {
this.ignore = ignore;
}

/**
* parse the excel、ppt、word etc.
* it is a abstract method.
* you can implement it.
* @param inputStream
* @return
* @throws Exception
*/
public abstract List<Serializable> parse(InputStream inputStream)throws Exception;

public abstract void parse(InputStream inputStream,TemplateListener listener)throws Exception;
}

import java.io.InputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import cn.sunsharp.poi.bean.Excel;
import cn.sunsharp.poi.bean.ExcelFilter;
import cn.sunsharp.poi.bean.Filter;

class ExcelTemplate extends Template {

@Override
public List<Serializable> parse(InputStream inputStream) throws Exception {
OPCPackage pkg = null;
List<Serializable> list = new ArrayList<Serializable>();
try{
pkg = OPCPackage.open(inputStream);
XSSFWorkbook workbook = new XSSFWorkbook(pkg);
int sheetNum = workbook.getNumberOfSheets();
XSSFSheet sheet = null;
XSSFRow row = null;
XSSFCell cell = null;
Excel excel = null;
for (int i = 0; i < sheetNum; i++) {
sheet = workbook.getSheetAt(i);
if(null == sheet){
continue;
}
for (int j = 0,rowNum = sheet.getLastRowNum(); j <= rowNum; j++) {
row = sheet.getRow(j);
if(null == row){
continue;
}
for (int k = 0,cellNum = row.getLastCellNum(); k <= cellNum; k++) {
cell = row.getCell(k);
if(null == cell){
continue;
}
excel = new Excel();
excel.setSheetName(sheet.getSheetName());
excel.setSheetIndex(i);
excel.setCell(k);
excel.setRow(j);
excel.setValue(cell.toString());
list.add(excel);
}
}
}
}finally{
if(null != pkg){
pkg.close();
}
}
return filterData(list);
}

@Override
public void parse(InputStream inputStream,
TemplateListener listener) throws Exception {
if(null == listener){
throw new NullPointerException("listener must not be null.");
}
List<Serializable> data = parse(inputStream);
int size = 0;
if(null != data && (size = data.size()) > 0){
Excel excel = null;
for (int i = 0; i < size; i++) {
excel = (Excel)data.get(i);
listener.callback(excel);
}
}
}

/**
* ignore为true，则不读取filter指定的数据，为false则读取filter指定的数据
* filter为空，则ignore参数失效，即读取所有数据
* filter参数中,sheetIndex为空，则读取所有sheet，row为空，则读取所有row,cell为空，则读取所有cell
*/
private List<Serializable> filterData(List<Serializable> list){
List<Serializable> data = new ArrayList<Serializable>();
int size = 0;
if(null != list && (size = list.size()) > 0){
Excel excel = null;
if(null != filters && filters.size() > 0){
for (int i = 0; i < size; i++) {
excel = (Excel)list.get(i);
for (Filter item : filters) {
ExcelFilter filter = (ExcelFilter)item;
Integer sheetIndex = filter.getSheetIndex();
Integer row = filter.getRow();
Integer cell = filter.getCell();
if(ignore){
if(null != sheetIndex && sheetIndex.intValue() == excel.getSheetIndex()){
continue;
}
if(null != row && row.intValue() == excel.getRow()){
continue;
}
if(null != cell && cell.intValue() == excel.getCell()){
continue;
}
data.add(excel);
}else{
//如果三个都有值
if(null != sheetIndex && null != row && null != cell){
if(sheetIndex.intValue() == excel.getSheetIndex() && row.intValue() == excel.getRow() && cell.intValue() == excel.getCell()){
data.add(excel);
}
}
//如果sheetIndex没有值，row和cell有值
if(null == sheetIndex && null != row && null != cell){
if(row.intValue() == excel.getRow() && cell.intValue() == excel.getCell()){
data.add(excel);
}
}
//如果row没有值，sheetIndex和cell有值
if(null == row && null != sheetIndex && null != cell){
if(sheetIndex.intValue() == excel.getSheetIndex() && cell.intValue() == excel.getCell()){
data.add(excel);
}
}
//如果cell没有值，sheetIndex和row有值
if(null == cell && null != sheetIndex && null != row){
if(sheetIndex.intValue() == excel.getSheetIndex() && row.intValue() == excel.getRow()){
data.add(excel);
}
}
//如果只有sheetIndex有值
if(null == row && null == cell && null != sheetIndex){
if(sheetIndex.intValue() == excel.getSheetIndex()){
data.add(excel);
}
}
//如果只有row有值
if(null == cell && null == sheetIndex && null != row){
if(row.intValue() == excel.getRow()){
data.add(excel);
}
}
//如果只有cell有值
if(null == sheetIndex && null == row && null != cell){
if(cell.intValue() == excel.getCell()){
data.add(excel);
}
}
}
}
}
}else{
data.addAll(list);
}
}
return data;
}

}

import java.io.Serializable;

/**
* template listener
* you can implement this interface to push to your custom class.
* @author lynn
*
*/
public interface TemplateListener {

public void callback(Serializable entity);

}

import cn.sunsharp.poi.enumeration.POI;

public class TemplateFactory {

/**
* via the factory to create template
* @param poi
* @return
*/
public static Template create(POI poi){
switch(poi){
case Excel:
return new ExcelTemplate();
case PPT:
break;
case Word:
break;
case PDF:
break;
}
return null;
}
}

public enum POI {

Excel,PPT,Word,PDF
}

import java.io.Serializable;

/**
* the excel bean.
* @author administrator
*
*/
public class Excel implements Serializable {

private static final long serialVersionUID = -7606795591653370811L;

private String sheetName;

private int sheetIndex;

private int row;

private int cell;

private String value;

public String getSheetName() {
return sheetName;
}

public void setSheetName(String sheetName) {
this.sheetName = sheetName;
}

public int getSheetIndex() {
return sheetIndex;
}

public void setSheetIndex(int sheetIndex) {
this.sheetIndex = sheetIndex;
}

public int getRow() {
return row;
}

public void setRow(int row) {
this.row = row;
}

public int getCell() {
return cell;
}

public void setCell(int cell) {
this.cell = cell;
}

public String getValue() {
return value;
}

public void setValue(String value) {
this.value = value;
}

@Override
public String toString() {
return "Excel [sheetName=" + sheetName + ", sheetIndex=" + sheetIndex
+ ", row=" + row + ", cell=" + cell + ", value=" + value + "]";
}

}

public class Filter {

}

public class ExcelFilter extends Filter {

private Integer sheetIndex;

private Integer row;

private Integer cell;

public static Builder options(){
return new Builder();
}

public static class Builder{

private Integer sheetIndex;

private Integer row;

private Integer cell;

public Builder setSheetIndex(Integer sheetIndex){
this.sheetIndex = sheetIndex;
return this;
}

public Builder setRow(Integer row){
this.row = row;
return this;
}

public Builder setCell(Integer cell){
this.cell = cell;
return this;
}

public ExcelFilter build(){
return new ExcelFilter(this);
}
}

private ExcelFilter(Builder builder){
this.sheetIndex = builder.sheetIndex;
this.row = builder.row;
this.cell = builder.cell;
}

public Integer getSheetIndex() {
return sheetIndex;
}

public Integer getRow() {
return row;
}

public Integer getCell() {
return cell;
}

@Override
public String toString() {
return "ExcelFilter [sheetIndex=" + sheetIndex + ", row=" + row
+ ", cell=" + cell + "]";
}

}

通过以上代码，我们发现，在Template有Filter和ignore两个属性，Filter是过滤器，ignore如果为true，则不读取filter指定的数据，ignore为false，则只读取filter指定的数据，这样就完成了比较优雅的可扩展的Excel读取，我们如果要读取PPT，就构建一个PPTTemplate来实现Template抽象类即可。下面请看测试类：
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import cn.sunsharp.poi.bean.Excel;
import cn.sunsharp.poi.bean.ExcelFilter;
import cn.sunsharp.poi.bean.Filter;
import cn.sunsharp.poi.enumeration.POI;
import cn.sunsharp.poi.template.Template;
import cn.sunsharp.poi.template.TemplateFactory;
import cn.sunsharp.poi.template.TemplateListener;

public class Test implements TemplateListener{

public static void main(String[] args) throws Exception{
new Test().testExcel();
}

private List<String> headers = new ArrayList<String>();

private void testExcel()throws Exception{
String path = "C:\\Users\\administrator.YCSPC017\\Desktop\\农产品行业体系新旧编码对比.xlsx";
Template template = TemplateFactory.create(POI.Excel);
List<Filter> filters = new ArrayList<Filter>();
ExcelFilter filter = ExcelFilter.options()
.setRow(0)
.setSheetIndex(2)
.build();
filters.add(filter);
// filter = ExcelFilter.options()
// .setRow(1)
// .setSheetIndex(1)
// .setCell(1)
// .build();
// filters.add(filter);
template.setFilters(filters);
template.setIgnore(false);
InputStream inputStream = new FileInputStream(path);
template.parse(inputStream,this);
System.out.println(headers);
}

@Override
public void callback(Serializable entity){
Excel excel = (Excel)entity;
headers.add(excel.getValue());
}

}

import java.io.Serializable;

public class Category implements Serializable{

private static final long serialVersionUID = 2348166129263260641L;
private String name;

private String id;

public String getId() {
return id;
}

public void setId(String id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "Category [name=" + name + ", id=" + id + "]";
}

}

如果有问题，可以给我留言哦！