public String downLoadFromUrl(String urlStr) {
try {
String fileName = getRandomString(20)+".jpg";
String savePath = "/data/back";
// fileName = urlStr.substring(urlStr.lastIndexOf("/")+1);
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
//设置超时间为3秒
conn.setConnectTimeout(3*1000);
//防止屏蔽程序抓取而返回403错误
conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
//得到输入流
InputStream inputStream = conn.getInputStream();
//获取自己数组
byte[] getData = readInputStream(inputStream);
//文件保存位置
File saveDir = new File(savePath);
if(!saveDir.exists()){
saveDir.mkdir();
}
File file = new File(saveDir+File.separator+fileName);
FileOutputStream fos = new FileOutputStream(file);
fos.write(getData);
if(fos!=null){
fos.close();
}
if(inputStream!=null){
inputStream.close();
}
System.out.println("info:"+url+" download success");
String localFile = saveDir+File.separator+fileName;
File fileLocal = new File(localFile);
String retUrl = upload(fileLocal);
fileLocal.delete();
return retUrl;
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
public static byte[] readInputStream(InputStream inputStream) throws IOException {
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while((len = inputStream.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
bos.close();
return bos.toByteArray();
}
//得到输入流
InputStream inputStream = conn.getInputStream();
得到返回字节流
public static byte[] readInputStream(InputStream inputStream) throws IOException {
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while((len = inputStream.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
bos.close();
return bos.toByteArray();
}
读取InputStream，将字节流灌入byte数组，通过ByteArrayOutputStream向Byte数组写入数据，这里的ByteArrayOutputStream无非是起一个合并每次读取byte［］的嫁接功能，也可以不用，自己拼接，只要将InputStream全部压入byte［］即可
File file = new File(saveDir+File.separator+fileName);
FileOutputStream fos = new FileOutputStream(file);
fos.write(getData);
通过FileOutputSteam在本地文件中写入数据
核心：
InputStream－byte［］－OutputStream（FileOutputStream）
byte［］为中介
参考：http://blog.csdn.net/qq_25184739/article/details/51205186
2.输出字节流OutputStream
IO 中输出字节流的继承图可见上图，可以看出：
1. OutputStream是所有的输出字节流的父类，它是一个抽象类。
2. ByteArrayOutputStream、FileOutputStream是两种基本的介质流，它们分别向Byte数组、和本地文件中写入数据。PipedOutputStream是向与其它线程共用的管道中写入数据。
3. ObjectOutputStream和所有FilterOutputStream的子类都是装饰流。
