Android में Picasso लाइब्रेरी के साथ काम कैसे करें?

Square की लोकप्रिय इमेज लोडिंग लाइब्रेरी Picasso का उपयोग करके इमेज लोडिंग, ट्रांसफॉर्मेशन, कॉलबैक, टार्गेट का पूरा ट्यूटोरियल।

निर्भरता जोड़ें

dependencies {
    implementation 'com.squareup.picasso:picasso:2.8'
}

चरण 1: लेआउट

res/layout/activity_main.xml - 9 बटन और एक ImageView:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">
    <Button android:id="@+id/btnDrawable" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignParentStart="true"
        android:layout_centerVertical="true" android:text="Drawable" />
    <ImageView android:id="@+id/imageView" android:layout_width="200dp"
        android:layout_height="200dp" android:layout_centerHorizontal="true"
        android:src="@mipmap/ic_launcher" />
    <Button android:id="@+id/btnPlaceholder" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignBaseline="@id/btnUrl"
        android:layout_alignBottom="@id/btnUrl" android:layout_centerHorizontal="true"
        android:text="Placeholder" />
    <Button android:id="@+id/btnUrl" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignBaseline="@id/btnDrawable"
        android:layout_alignBottom="@id/btnDrawable" android:layout_alignParentEnd="true"
        android:text="URL" />
    <Button android:id="@+id/btnError" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_below="@id/btnDrawable"
        android:layout_alignParentStart="true" android:layout_marginTop="12dp"
        android:text="Error" />
    <Button android:id="@+id/btnCallBack" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignBaseline="@id/btnError"
        android:layout_alignStart="@id/btnPlaceholder" android:text="Callback" />
    <Button android:id="@+id/btnResize" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignBaseline="@id/btnCallBack"
        android:layout_alignBottom="@id/btnCallBack" android:layout_alignParentEnd="true"
        android:text="Resize" />
    <Button android:id="@+id/btnRotate" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_below="@id/btnError"
        android:layout_alignParentStart="true" android:layout_marginTop="12dp"
        android:text="Rotate" />
    <Button android:id="@+id/btnScale" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignStart="@id/btnCallBack"
        android:layout_alignBottom="@id/btnTarget" android:text="Scale" />
    <Button android:id="@+id/btnTarget" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignBaseline="@id/btnRotate"
        android:layout_alignBottom="@id/btnRotate" android:layout_alignParentEnd="true"
        android:text="Targets" />
</RelativeLayout>

चरण 2: MainActivity

src/MainActivity.java:

package app.com.sample;

import androidx.appcompat.app.AppCompatActivity;
import android.graphics.Bitmap;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import com.squareup.picasso.Callback;
import com.squareup.picasso.Picasso;
import com.squareup.picasso.Target;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    ImageView imageView;
    int scaleIndex = 0;
    Button btnDrawable, btnUrl, btnError, btnPlaceholder, btnCallback, btnResize, btnRotate, btnScale, btnTarget;
    private Target customTarget;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initTarget();
    }

    private void initView() {
        imageView = findViewById(R.id.imageView);
        btnDrawable = findViewById(R.id.btnDrawable);
        btnUrl = findViewById(R.id.btnUrl);
        btnPlaceholder = findViewById(R.id.btnPlaceholder);
        btnError = findViewById(R.id.btnError);
        btnCallback = findViewById(R.id.btnCallBack);
        btnResize = findViewById(R.id.btnResize);
        btnRotate = findViewById(R.id.btnRotate);
        btnScale = findViewById(R.id.btnScale);
        btnTarget = findViewById(R.id.btnTarget);

        btnDrawable.setOnClickListener(this);
        btnPlaceholder.setOnClickListener(this);
        btnUrl.setOnClickListener(this);
        btnCallback.setOnClickListener(this);
        btnResize.setOnClickListener(this);
        btnError.setOnClickListener(this);
        btnRotate.setOnClickListener(this);
        btnScale.setOnClickListener(this);
        btnTarget.setOnClickListener(this);
    }

    private void initTarget() {
        customTarget = new Target() {
            @Override public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                imageView.setImageBitmap(bitmap);
            }
            @Override public void onBitmapFailed(Drawable errorDrawable) {
                imageView.setImageDrawable(errorDrawable);
            }
            @Override public void onPrepareLoad(Drawable placeHolderDrawable) {
                imageView.setImageDrawable(placeHolderDrawable);
            }
        };
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btnDrawable:
                Picasso.get().load(R.drawable.image).into(imageView);
                break;
            case R.id.btnPlaceholder:
                Picasso.get().load("www.journaldev.com")
                    .placeholder(R.drawable.placeholder).into(imageView);
                break;
            case R.id.btnUrl:
                Picasso.get().load("https://example.com/image.png")
                    .placeholder(R.drawable.placeholder).into(imageView);
                break;
            case R.id.btnError:
                Picasso.get().load("invalid_url")
                    .placeholder(R.drawable.placeholder)
                    .error(R.drawable.error).into(imageView);
                break;
            case R.id.btnCallBack:
                Picasso.get().load("invalid_url")
                    .error(R.mipmap.ic_launcher)
                    .into(imageView, new Callback() {
                        @Override public void onSuccess() { Log.d("TAG", "onSuccess"); }
                        @Override public void onError(Exception e) {
                            Toast.makeText(MainActivity.this, "Error occurred", Toast.LENGTH_SHORT).show();
                        }
                    });
                break;
            case R.id.btnResize:
                Picasso.get().load(R.drawable.image).resize(200, 200).into(imageView);
                break;
            case R.id.btnRotate:
                Picasso.get().load(R.drawable.image).rotate(90f).into(imageView);
                break;
            case R.id.btnScale:
                // फिट, सेंटर क्रॉप, सेंटर इनसाइड के बीच साइकिल
                if (scaleIndex == 0) {
                    Picasso.get().load(R.drawable.image).fit().into(imageView);
                    Toast.makeText(this, "Fit", Toast.LENGTH_SHORT).show();
                } else if (scaleIndex == 1) {
                    Picasso.get().load(R.drawable.image).resize(200, 200).centerCrop().into(imageView);
                    Toast.makeText(this, "Center Crop", Toast.LENGTH_SHORT).show();
                } else {
                    Picasso.get().load(R.drawable.image).resize(200, 200).centerInside().into(imageView);
                    Toast.makeText(this, "Center Inside", Toast.LENGTH_SHORT).show();
                }
                scaleIndex = (scaleIndex + 1) % 3;
                break;
            case R.id.btnTarget:
                Picasso.get().load("https://example.com/image.png")
                    .placeholder(R.drawable.placeholder)
                    .error(R.drawable.error)
                    .into(customTarget);
                break;
        }
    }
}

Picasso मुख्य विशेषताएं

Picasso vs Glide तुलना

• Picasso: सरल API, छोटा (~100KB), कोई GIF सपोर्ट नहीं (नेटिव)
• Glide: GIF सपोर्ट, लाइफसाइकल इंटीग्रेशन, बड़ा (~500KB)
• दोनों थ्रेड-सेफ, कैशिंग, प्लेसहोल्डर/एरर सपोर्ट करते हैं

नोट

Picasso 2.x में Picasso.with(context) डिप्रिकेटेड है, Picasso.get() उपयोग करें।