The case of downloading text and picture network programming based on HttpClient for Android

1, Operation effect

2, Implementation steps
1. Create android app DownloadTextImageByHttpClient

2, Main layout file activity main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:tools="http://schemas.android.com/tools"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              android:padding="15dp"
              tools:context="net.lm.ied.download_text_image_by_httpclient.MainActivity">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:gravity="center"
        android:layout_marginBottom="20px"
        android:layout_height="wrap_content">

        <Button
            android:id="@+id/btn_download_text"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:onClick="doDownloadText"
            android:text="@string/download_text"/>

        <Button
            android:id="@+id/btn_download_image"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:onClick="doDownloadImage"
            android:text="@string/download_image"/>

    </LinearLayout>

    <ProgressBar
        android:id="@+id/pb_download_progress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="gone"/>

    <ImageView
        android:id="@+id/iv_image"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:scaleType="fitXY"/>

    <EditText
        android:id="@+id/edt_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:lines="8"
        android:editable="false"
        android:scrollbars="vertical"/>

</LinearLayout>

3. String resource file strings.xml

<resources>
    Download Text and pictures based on HttpClient < / String >
    < string name = "download_text" > Download Text < / String >
    < string name = "Download Image" > Download Image < / String >
</resources>

4. Add support for HttpClient to build.gradle of the module

5. Main interface class MainActivity

package net.lm.ied.download_text_image_by_httpclient;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ProgressBar;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import java.io.IOException;
public class MainActivity extends Activity {

    private final String TAG = "download_text_image";
    private final String SERVER_URL = "http://192.168.183.2:8080/lzy_server";
    private ImageView ivImage;
    private EditText edtText;
    private Bitmap bitmap;
    private String text;
    private ProgressBar pbDownloadProgress;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Using layout resource file to set up user interface
        setContentView(R.layout.activity_main);

        // Get control instance through resource ID
        ivImage = (ImageView) findViewById(R.id.iv_image);
        edtText = (EditText) findViewById(R.id.edt_text);
        pbDownloadProgress = (ProgressBar) findViewById(R.id.pb_download_progress);
    }

    /**
     * Download Image File
     *
     * @param view
     */
    public void doDownloadImage(View view) {
        // Get image file url string
        String strImageUrl = SERVER_URL + "/test.jpg";

        // Create Download Image task
        DownloadImageTask task = new DownloadImageTask();

        // Perform asynchronous tasks
        task.execute(strImageUrl);
    }

    /**
     * Download Image task (asynchronous task)
     */
    private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
        /**
         * What to do before carrying out the task
         */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Make progress bar visible
            pbDownloadProgress.setVisibility(View.VISIBLE);
        }

        /**
         * Work silently in the background
         *
         * @param strings
         * @return
         */

        @Override
        protected Bitmap doInBackground(String... strings) {
            // Get image URL string
            String strImageUrl = strings[0];
            // Define bitmap objects
            Bitmap bitmap = null;

            try {
                // Create http request in GET mode
                HttpGet request = new HttpGet(strImageUrl);
                // Create http client
                HttpClient client = new DefaultHttpClient();
                // Execute http request, return response object
                HttpResponse response = client.execute(request);
                // Judge whether the response is successful (SC: State Code status code)
                if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    // Get response data
                    HttpEntity entity = response.getEntity();
                    // Using bitmap factory to analyze response data and generate bitmap object
                    bitmap = BitmapFactory.decodeStream(entity.getContent());
                } else {
                    Log.d(TAG, "Failed to download image file!");
                }

            } catch (IOException e) {
                e.printStackTrace();
            }

            // Return bitmap object
            return bitmap;
        }

        /**
         * What to do after the task
         *
         * @param bitmap
         */
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            // Let the progress bar disappear
            pbDownloadProgress.setVisibility(View.GONE);
            // Display the bitmap object in the image control
            ivImage.setImageBitmap(bitmap);
        }
    }

    /**
     * Download Text File
     *
     * @param view
     */
    public void doDownloadText(View view) {
        // Define text file URL string
        String strTextUrl = SERVER_URL + "/test.txt";

        // Create Download Text task
        DownloadTextTask task = new DownloadTextTask();
        // Perform asynchronous tasks
        task.execute(strTextUrl);
    }

    /**
     * Download Text task (asynchronous task)
     */
    private class DownloadTextTask extends AsyncTask<String, Void, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Make progress bar appear
            pbDownloadProgress.setVisibility(View.VISIBLE);
        }

        @Override
        protected String doInBackground(String... strings) {
            // Get text file URL string
            String strTextUrl = strings[0];
            // Define text file content
            String content = null;
            try {
                // Define http request for GET mode
                HttpGet request = new HttpGet(strTextUrl);
                // Define http client
                HttpClient client = new DefaultHttpClient();
                // Execute http request, get response object
                HttpResponse response = client.execute(request);
                // Judge whether the response is successful
                if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    // Get response entity
                    HttpEntity entity = response.getEntity();
                    // Convert response entity data to string
                    content = EntityUtils.toString(entity, "UTF-8");
                } else {
                    Log.d(TAG, "Failed to download text file!");
                }

            } catch (IOException e) {
                e.printStackTrace();
            }
            // Return text file content
            return content;
        }

        @Override
        protected void onPostExecute(String content) {
            super.onPostExecute(content);
            // Let the progress bar disappear
            pbDownloadProgress.setVisibility(View.GONE);
            // Let content appear in the text box
            edtText.setText(content);
        }
    }
}

6. Authorize access to the Internet in the project manifest file

7. Start the WebDemo project on the server side (IEDA new project)

8. Launch android app DownloadTextImageByHttpClient

9. End.