先建议一个moduel，先写一个下载图片代码：

public class LoadTest extends AsyncTask<Void,Void,byte[]>{

    public static LoadTest loadtest;

    private byte[] data;

    private String url;
    public setDataL listence;


    public void setDataListence(setDataL l){
        this.listence = l;
    }
    public byte[] getload(){

        return data;
    }

    public void  setUrl(String s){
        this.url = s;
    }
    @Override
    protected byte[] doInBackground(Void... params) {
        try {
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            URL urlimage = new URL(url);
            HttpURLConnection urlconn = (HttpURLConnection) urlimage.openConnection();
            urlconn.setConnectTimeout(5000);
            urlconn.setRequestMethod("GET");
            int sumLenght = urlconn.getContentLength();
            InputStream errorStream = urlconn.getErrorStream();
            int code = urlconn.getResponseCode();
            if (HttpURLConnection.HTTP_OK == code){
                InputStream is = urlconn.getInputStream();
                byte[] buff = new byte[512];
                int len;
                while ((len = is.read(buff))!= -1){
                    outputStream.write(buff,0,len);

                }
                is.close();
                outputStream.flush();
                data = http://www.mamicode.com/outputStream.toByteArray();

            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return data;
    }

    @Override
    protected void onPostExecute(byte[] datainfo) {
        if (null != datainfo){

            listence.getData(datainfo);
        }else {

            super.onPostExecute(datainfo);
        }
    }

    public interface setDataL{
        void getData(byte[] data);
    }

}

打开moduel的gradle：
写入代码：

task makeJar(type: Copy) {
    delete ‘build/libs/myjar.jar‘
    from(‘build/intermediates/bundles/release/‘)
    into(‘build/libs/‘)
    include(‘classes.jar‘)
    rename(‘classes.jar‘, ‘myjar.jar‘)
}
//  在终端执行生成JAR包
//  ./gradlew build
//build.finalizedBy makeJar
//  或者
makeJar.dependsOn(build)
// ./gradlew makeJar

打开终端机Terminal输入命令：gradview makeJar

生成的jar在\build\intermediates\bundles\release目录下。可以看到一个java标志如图：

这样就可以啦，导入其他的项目几可以使用了

demo下载地址：https://github.com/tiaodong/OkHttpTest

测试demo：https://github.com/tiaodong/JarTest

android 简单打jar包