Android-Glide-从服务器下载图片至指定SD路径中

1.先封装一个SDFileHelper方法，通过Glide图片加载库保存服务器上的图片

String filePath = Environment.getExternalStorageDirectory() + File.separator + "A1";，自定义图片保存的位置

public class SDFileHelper {

    private Context context;

    public SDFileHelper() {
    }

    public SDFileHelper(Context context) {
        super();
        this.context = context;
    }

    //Glide保存图片
    public void savePicture(final String fileName, String url){
        Glide.with(context).load(url).asBitmap().toBytes().into(new SimpleTarget<byte[]>() {
            @Override
            public void onResourceReady(byte[] bytes, GlideAnimation<? super byte[]> glideAnimation) {
                try {
                    savaFileToSD(fileName,bytes);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    //往SD卡写入文件的方法
    public void savaFileToSD(String filename, byte[] bytes) throws Exception {
        //如果手机已插入sd卡,且app具有读写sd卡的权限
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            String filePath = Environment.getExternalStorageDirectory() + File.separator + "A1";
            File dir1 = new File(filePath);
            if (!dir1.exists()){
                dir1.mkdirs();
            }
            filename = filePath+ "/" + filename;
            //这里就不要用openFileOutput了,那个是往手机内存中写数据的
            FileOutputStream output = new FileOutputStream(filename);
            output.write(bytes);
            //将bytes写入到输出流中
            output.close();
            //关闭输出流
            Toast.makeText(context, "图片已成功保存到"+filePath, Toast.LENGTH_SHORT).show();
        } else Toast.makeText(context, "SD卡不存在或者不可读写", Toast.LENGTH_SHORT).show();
    }

}

2.在事件中调用

public class MainActivity extends AppCompatActivity {
private String url = "http://www.vorin.cn/storage/oilImage/test/tim1.jpeg";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn = (Button)findViewById(R.id.btn_get);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SDFileHelper helper = new SDFileHelper(MainActivity.this);
                helper.savePicture("tim1.jpeg", url);
            }
        });
    }
}

3.若要加载大量图片

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn = (Button)findViewById(R.id.btn_get);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //100要换掉
                for (int i = 1; i < 100; i++) {
                    String url = "http://www.vorin.cn/storage/oilImage/test/tim" + i + ".jpeg";
                    //取得最后一个/的下标
                    int index = url.lastIndexOf("/");
                    //将字符串转为字符数组
                    char[] ch = url.toCharArray();
                    //根据 copyValueOf(char[] data, int offset, int count) 取得最后一个字符串
                    String informationId = String.copyValueOf(ch, index + 1, ch.length - index - 1);
                    SDFileHelper helper = new SDFileHelper(MainActivity.this);
                    helper.savePicture(informationId, url);
                }
            }
        });
    }
}
上述中i要通过接口获取jsons数据统计文件数量，会在下篇中讲到