Android--从本地相册获取图片并显示

很多博客讲这部分内容会和其他的混在一起讲，看起来会比较费劲，为了更方便的调用，特意写了如何从本地获取图片以及 显示这部分代码。

1、布局文件：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="com.example.choose_photo.MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="choose"
        android:id="@+id/choose"/>
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/imageview"/>

</android.support.constraint.ConstraintLayout>

2、Maintivity

package com.example.choose_photo;

import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {
    private Button button;
    private ImageView imageView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.choose);
        imageView = (ImageView) findViewById(R.id.imageview);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(Intent.ACTION_PICK, null);
                intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "image/*");
                startActivityForResult(intent, 2);


            }
        });
    }
    protected void onActivityResult(int requestCode, int resultCode, Intent data){
        if (requestCode == 2) {
            // 从相册返回的数据
            if (data != null) {
                // 得到图片的全路径
                Uri uri = data.getData();
                imageView.setImageURI(uri);
          }
        }
    }

}

3、权限

 <uses-feature
        android:name="android.hardware.camera"
        android:required="true"
        />

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="com.miui.whetstone.permission.ACCESS_PROVIDER"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-feature android:name="android.hardware.camera.autofocus" />