openCSV读写CSV文件

        openCSV是一款简单的用于解析CSV文件的java类库，它封装了CSV格式文件的读写操作，可将文件与java对象进行自动映射，自定义分隔符，使用转义符等。

在使用时有几点需要注意下：

        1、       生成的csv文件用EXCEL打开时，总是产生乱码，但是用NOTEPAD++打开时，显示正常。这是因为导出的文件是UTF-8不含BOM格式编码的，为了要让EXCEL正确的显示，需要手动的给将要输出的内容加上BOM标识。

        2、       可通过@ CsvBindByName和@ CsvBindByPosition来CSV文件字段与对象属性进行映射。@ CsvBindByName是根据表头的名称来映射；@CsvBindByPosition是根据文件中字段的位置来映射。当2个注解一起使用时则基于位置的方式有效。因此如果写文件时即想指定顺序又想加表头的话需手动写表头。

        3、       在读CSV文件时需要注意BOM字符，因为在写文件时为了能在Excel里打开增加了UTF-8 BOM标识，读文件时第一列会读不出来。这种情况的解决方法是使用apache commons io提供的BOMInputStream。

        代码示例如下

public class Person {

	private String name;

	private int age;

	private int sex;

	private String phone;

	private String address;

	public String getName() {
		return name;
	}

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

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public int getSex() {
		return sex;
	}

	public void setSex(int sex) {
		this.sex = sex;
	}

	public String getPhone() {
		return phone;
	}

	public void setPhone(String phone) {
		this.phone = phone;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public String toString() {
		return ":"+name + ";" + age + ";" + sex + ";" + phone + ";" + address;
	}
}

public class WriteCSV {

	public void writeCSV2(List<Person> dataList, String finalPath) {
		try {
			Writer writer = new FileWriter(finalPath);
			// 手动加上BOM标识
			writer.write(new String(new byte[] { (byte) 0xEF, (byte) 0xBB, (byte) 0xBF }));

			// 设置显示的顺序
			String[] columnMapping = { "name", "age", "sex", "phone", "address" };
			ColumnPositionMappingStrategy<Person> mapper = 
					new ColumnPositionMappingStrategy<Person>();
			mapper.setType(Person.class);
			mapper.setColumnMapping(columnMapping);

			// 写表头
			CSVWriter csvWriter = new CSVWriter(writer, CSVWriter.DEFAULT_SEPARATOR,
					CSVWriter.NO_QUOTE_CHARACTER);
			String[] header = { "姓名", "年龄", "性别", "手机", "住址" };
			csvWriter.writeNext(header);

			StatefulBeanToCsv beanToCsv = new StatefulBeanToCsvBuilder(writer)
					.withMappingStrategy(mapper)
					.withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
					.withSeparator(CSVWriter.DEFAULT_SEPARATOR)
					.withEscapechar('\\').build();
			beanToCsv.write(dataList);
			csvWriter.close();
			writer.close();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (CsvDataTypeMismatchException e) {
			e.printStackTrace();
		} catch (CsvRequiredFieldEmptyException e) {
			e.printStackTrace();
		}
		System.out.println(finalPath + "数据导出成功");
	}

	public void readCSV2(String finalPath) {
		try {
			// 使用BOMInputStream自动去除UTF-8中的BOM
			Reader reader = new InputStreamReader(new BOMInputStream(
					new FileInputStream(finalPath)), "utf-8");
			CSVReader csvReader = new CSVReader(reader, CSVWriter.DEFAULT_SEPARATOR,
					CSVWriter.NO_QUOTE_CHARACTER);

			// 列名的映射
			HeaderColumnNameTranslateMappingStrategy<Person> strategy = 
					new HeaderColumnNameTranslateMappingStrategy<Person>();
			strategy.setType(Person.class);
			Map<String, String> columnMapping = new HashMap<String, String>();
			columnMapping.put("姓名", "name");
			columnMapping.put("年龄", "age");
			columnMapping.put("性别", "sex");
			columnMapping.put("手机", "phone");
			columnMapping.put("住址", "address");
			strategy.setColumnMapping(columnMapping);

			CsvToBean<Person> csvToBean = new CsvToBean<Person>();

			List<Person> list = csvToBean.parse(strategy, csvReader);

			for (Person p : list) {
				System.out.println(p.toString());
			}
			csvReader.close();
			reader.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		List<Person> dataList = new ArrayList<Person>();
		Person person1 = new Person();
		person1.setName("張三");
		person1.setSex(1);
		person1.setAge(55);
		person1.setPhone("13911111111");
		person1.setAddress("北京海淀区");
		dataList.add(person1);
		Person person2 = new Person();
		person2.setName("小美");
		person2.setSex(0);
		person2.setAge(20);
		person2.setPhone("13911112222");
		person2.setAddress("北京西城区");
		dataList.add(person2);
		Person person3 = new Person();
		person3.setName("小明");
		person3.setSex(1);
		person3.setAge(25);
		person3.setPhone("13933333333");
		person3.setAddress("北京海淀区");
		dataList.add(person3);

		WriteCSV writer = new WriteCSV();
		String finalPath2 = "D:/bbb.csv";
		writer.writeCSV2(dataList, finalPath2);
		writer.readCSV2(finalPath2);
	}
}