csv 檔案是以 

aaa,bbb,ccc

aaa,bbb,ccc

儲存的

這裡的要求是將 List<T> 型別的線性表 轉化成 類似 html 中 table的格式，即第一行是 head 後面是 body

使用註解的效果如下 ：

   

                List<User> users=new ArrayList<User>();
	   	users.add(new User("劉夏楠", 23, "男"));
		users.add(new User("劉夏楠", 23, "男"));
		users.add(new User("劉夏楠", 23, "男"));
		
		writeBeanToCsvFile("D:\\test.csv", users);
		
 

csv檔案：

package bean;

import annotation.csvField;

public class User {
	
	@csvField("姓名")	private String name;
	@csvField("年齡")private Integer age;
	private String sex;
	
	
	public User(String name, Integer age, String sex) {
		super();
		this.name = name;
		this.age = age;
		this.sex = sex;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	
	
}
 

擁有 @csvField 註解的欄位才會被 寫入csv檔案

並且 @csvField 的值作為csv檔案的 title 即 第一行

我們使用反射來達到這個效果

bean 轉 List<String[]> 如下：

private static <T> List<String[]> getStringArrayFromBean(List<T> beans) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
		if(beans.size()<1)
			throw new IllegalArgumentException("長度不能小於1");
		
		List<String[]> result=new ArrayList<String[]>();		
		Class<? extends Object> cls=beans.get(0).getClass();//獲取泛型型別
		Field[] declaredFields=cls.getDeclaredFields();
		List<Field> annoFields=new ArrayList<Field>();		
		for(int i=0;i<declaredFields.length;i++){//篩選出擁有註解的欄位
			csvField anno=declaredFields[i].getAnnotation(csvField.class);//獲取註解
			if(anno!=null)
				annoFields.add(declaredFields[i]);
		}
		String[] title=new String[annoFields.size()];	
		
		for(int i=0;i<annoFields.size();i++){
			title[i]=declaredFields[i].getAnnotation(csvField.class).value();//獲取註解的值
		}
		result.add(title);
		
		for(T each:beans){
			String[] item=new String[annoFields.size()];	
			for(int i=0;i<annoFields.size();i++){
				String fieldName=annoFields.get(i).getName();
				String methodName="get"+fieldName.substring(0,1).toUpperCase()+fieldName.substring(1);
				
					Method method=each.getClass().getMethod(methodName, null);					
					String val=method.invoke(each, null).toString();
					item[i]=val;
			}
			result.add(item);		
		}
		return result;
	}
 

public static <T> void  writeBeanToCsvFile(String csvFilePath,List<T> beans) throws IOException, NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
		File file =new File(csvFilePath);
		if(!file.exists()){		//如果檔案不存在，建立檔案	
				file.createNewFile();		
		}		
		 CsvWriter wr =new CsvWriter(csvFilePath,',', Charset.forName("GBK"));		 
		List<String[]> contents=getStringArrayFromBean(beans);
		 for(String[] each:contents){
			 wr.writeRecord(each);
		 }
		 wr.close();		
	}