java 获取网络图片

String photoUrl = data.getString("attachment");
String filename = photoUrl.substring(photoUrl.lastIndexOf("/"));

//生成图片链接的url类
URL urlImg = new URL(photoUrl);
HttpURLConnection httpcon =(HttpURLConnection)urlImg.openConnection(); 
httpcon.addRequestProperty("User-Agent","Mozilla / 4.76"); 
InputStream is = httpcon.getInputStream();
//定义字节数组大小
byte[] buffer = new byte[1024];
ByteArrayOutputStream swapStream = new ByteArrayOutputStream();  
int rc = 0;  
while ((rc = is.read(buffer, 0, 100)) > 0) {  
    swapStream.write(buffer, 0, rc);  
}  
buffer = swapStream.toByteArray();
String unit_id=getCommont().getUnit_id();
String destFilePath=Constant.ANNEXPATH+File.separator+getCommon().getOrgan_code()+File.separator+unit_id+File.separator+"JX";
File file=new File(destFilePath);

/**
 *文件路径是否存在 不存在则重新创建     配置路径/区划代码/单位ID/业务类型
 */
if(!file.exists()){
    file.mkdirs();
}
file=null;
/**
 * 文件命名规则:上传时间_附件设置ID
 */
String attach_name=DateTime.toLocaleFileString()+"_"+annexSet.getAnnexSetId()+"."+FileUtil.getExtension(filename);
File fj=new File(destFilePath,attach_name);
if (!fj.exists()){
    fj.createNewFile();
}
try (OutputStream outputStream = new FileOutputStream(fj);) {
    outputStream.write(buffer);
}