使用http请求框架把服务器的文件下载到本地(Andriod-async-http)

1

准备3个jar包httpcore-4.4.3.jar，android-async-http-1.4.8.jar，httpclient-4.3.6.jar
链接：https://pan.baidu.com/s/1CK1NPfHBtppF-lxR-RcUmQ
密码：f16a

2

MainActivity

package com.example.xeonrnc.download_demo;
 
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.FileAsyncHttpResponseHandler;
import org.apache.http.Header;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
 
public class MainActivity extends AppCompatActivity {
    //指定要下载的文件的url
    String url="http://192.168.43.173:8080/my_upload/pic/22.png";
    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            "android.permission.READ_EXTERNAL_STORAGE",
            "android.permission.WRITE_EXTERNAL_STORAGE"
    };
    public static void verifyStoragePermissions(Activity activity) {
 
        try {
            //检测是否有写的权限
            int permission = ActivityCompat.checkSelfPermission(activity,
                    "android.permission.WRITE_EXTERNAL_STORAGE");
            if (permission != PackageManager.PERMISSION_GRANTED) {
                // 没有写的权限，去申请写的权限，会弹出对话框
                ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn=(Button)findViewById(R.id.download);
        verifyStoragePermissions(this);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                uploadClick();
            }
        });
    }
 
 
 
    public void uploadClick(){
        AsyncHttpClient client=new AsyncHttpClient();
        client.get(url, new FileAsyncHttpResponseHandler(this) {
            @Override
            public void onFailure(int i, Header[] headers, Throwable throwable, File file) {
 
            }
 
            @Override
            public void onSuccess(int i, Header[] headers, File file) {
                System.out.println(file.getAbsolutePath());
                //将下载的文件保存到本地sdcard的picture文件夹，并重命名为abc.png
                File path=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES+"/abc.png");
                try {
                    InputStream in=new FileInputStream(file);
                    OutputStream out=new FileOutputStream(path);
                    byte[] bytes=new byte[100];
                    int len=-1;
                    while((len=in.read(bytes))!=-1){
                        out.write(bytes,0,len);
                    out.flush();
                }
                out.close();
                in.close();
            }catch (FileNotFoundException e){
                e.printStackTrace();
            }catch (IOException e){
                e.printStackTrace();
                }
                System.out.println();
            }
        });
 
 
    }
}

AndroidManifest.xml

activity_main.xml