package com.learning.example.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpDownloader {
	
	private URL url = null; 
	
	/**
	 * 根据URL下载文件,前提是这个文件当中的内容是文本,函数的返回值就是文本当中的内容
	 * 1.创建一个URL对象
	 * 2.通过URL对象,创建一个HttpURLConnection对象
	 * 3.得到InputStream
	 * 4.从InputStream当中读取数据
	 * @param urlStr
	 * @return
	 */
	public String download(String urlStr){
		StringBuffer sb = new StringBuffer();
		String line = null;
		BufferedReader buffer = null;
		try {
			url = new URL(urlStr);
			HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();
			buffer = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
			while( (line = buffer.readLine()) != null){
				sb.append(line);
			}
			
		} 
		catch (Exception e) {
			e.printStackTrace();
		}
		finally{
			try {
				buffer.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return sb.toString();
	}

	/**
	 * 
	 * @param urlStr
	 * @param path
	 * @param fileName
	 * @return 
	 * 		-1:文件下载出错
	 * 		 0:文件下载成功
	 * 		 1:文件已经存在
	 */
	public int downFile(String urlStr, String path, String fileName){
		InputStream inputStream = null;
		try {
			FileUtils fileUtils = new FileUtils();
			
			if(fileUtils.isFileExist(path + fileName)){
				return 1;
			} else {
				inputStream = getInputStreamFromURL(urlStr);
				File resultFile = fileUtils.write2SDFromInput(path, fileName, inputStream);
				if(resultFile == null){
					return -1;
				}
			}
		} 
		catch (Exception e) {
			e.printStackTrace();
			return -1;
		}
		finally{
			try {
				inputStream.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return 0;
	}
	
	/**
	 * 根据URL得到输入流
	 * @param urlStr
	 * @return
	 */
	public InputStream getInputStreamFromURL(String urlStr) {
		HttpURLConnection urlConn = null;
		InputStream inputStream = null;
		try {
			url = new URL(urlStr);
			urlConn = (HttpURLConnection)url.openConnection();
			inputStream = urlConn.getInputStream();
			
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return inputStream;
	}
}