[移动开发]Android从相册获取图片返回路径显示并实现ImageView点击图片放大再次点击缩小返回

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• 作者：Bald programmer

本次案例实现的是动态申请权限打开相册获取图片，并返回图片路径显示到ImageView上，点击图片可以放大，再次点击缩小返回

先看看效果视频

一个?MainActivity类首页，一个showPhoto类（用于显示点击放大后的图片）

一个main布局文件和一个show_photo布局文件

首页在配置清单AndroidMainFest.xml中添加权限和相关代码

<!-- 允许读取手机状态 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<!-- 读取外部存储权限-->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

android:requestLegacyExternalStorage="true"

main.xml布局代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/ImageView"
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:layout_gravity="center"
        android:layout_marginTop="200dp"/>

    <Button
        android:id="@+id/photoSelectButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"
        android:text="获取图片"
        android:textSize="25dp"/>
</LinearLayout>

MainActivity代码

package com.example.csdn;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.content.ContentResolver;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.InputStream;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    //要申请的权限
    private static final String permission[] = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
    };
    ImageView imageView;
    Button photoSelectButton;

    //图片路径
    String photoPath;

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

    private void initView(){
        imageView = findViewById(R.id.ImageView);
        photoSelectButton = findViewById(R.id.photoSelectButton);

        imageView.setOnClickListener(this);
        photoSelectButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.photoSelectButton:
                // 一次请求多个权限, 如果其他有权限是已经授予的将会自动忽略掉
                ActivityCompat.requestPermissions(MainActivity.this,permission,100);
                break;
            case R.id.ImageView:
                Intent intent = new Intent(MainActivity.this,showPhoto.class);
                intent.putExtra("photoPath",photoPath);
                startActivity(intent);
                break;
        }
    }

    /**
     * 请求相册图片处理
     * @param requestCode
     * @param resultCode
     * @param data
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode){
            case 1:
                if (resultCode == RESULT_OK){
                    Uri photoUri = data.getData();
                    photoPath = getPhotoPath(getContentResolver(),photoUri); //获取路径
                    Bitmap bitmap = BitmapFactory.decodeFile(photoPath); //通过路径获取图片
                    imageView.setImageBitmap(bitmap); //展示
                }
                break;
        }
    }

    /**
     * 权限处理
     * @param requestCode
     * @param permissions
     * @param grantResults
     */
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 100){
            Intent photoSelectIntent = new Intent(Intent.ACTION_PICK); //打开相册
            photoSelectIntent.setType("image/*");   //获取本地所有图片
            startActivityForResult(photoSelectIntent,1); //发送请求
        }
    }

    /**
     * 通过Uri获取图片路径
     * @param resolver
     * @param uri 请求资源的Uri
     * @return 图片路径
     */
    public static String getPhotoPath(ContentResolver resolver, Uri uri){
        String[] filePathColumns = {MediaStore.Images.Media.DATA};
        Cursor cursor = resolver.query(uri, filePathColumns, null, null, null);
        cursor.moveToFirst();
        int columnIndex = cursor.getColumnIndex(filePathColumns[0]);
        String imagePath = cursor.getString(columnIndex);
        return imagePath;
    }
}

show_photo.xml布局代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".showPhoto"
    android:background="#000"
    android:id="@+id/ConstrainLayout">

    <ImageView
        android:id="@+id/ImageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

showPhoto类代码

package com.example.csdn;

import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;

public class showPhoto extends AppCompatActivity implements View.OnClickListener {
    ConstraintLayout constraintLayout;
    ImageView imageView;

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

    private void initView(){
        imageView = findViewById(R.id.ImageView);
        constraintLayout = findViewById(R.id.ConstrainLayout);

        //设置监听
        constraintLayout.setOnClickListener(this);
        show();
    }

    private void show(){
        //接收从MainActivity传递过来的图片路径
        String photoPath = getIntent().getStringExtra("photoPath");
        Bitmap bitmap = BitmapFactory.decodeFile(photoPath);
        imageView.setImageBitmap(bitmap);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.ConstrainLayout:
                finish();
                break;
        }
    }
}

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