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关于Android中几个常用文件路径的介绍

外部存储，内部存储的区别

Internal storage: 

总是可用的 

这里的文件默认只能被我们的app所访问。 

当用户卸载app的时候，系统会把internal内该app相关的文件都清除干净。 

Internal是我们在想确保不被用户与其他app所访问的最佳存储区域。 

External storage: 

并不总是可用的，因为用户有时会通过USB存储模式挂载外部存储器，当取下挂载的这部分后，就无法对其进行访问了。 

是大家都可以访问的，因此保存在这里的文件可能被其他程序访问 

当用户卸载您的应用时，只有在您通过 getExternalFilesDir() 将您的应用的文件保存在目录中时，系统才会从此处删除您的应用的文件 

External是在不需要严格的访问权限并且希望这些文件能够被其他app所共享或者是允许用户通过电脑访问时的最佳存储区域。 

常见的获取文件路径方法，对应的绝对路径

getCacheDir().getAbsolutePath()：

/data/data/packagename/cache

getFilesDir().getAbsolutePath()：

/data/data/packagename/files

以上为内存存储路径,以下为外部存储路径

getExternalCacheDir().getAbsolutePath()：

可以作为外部缓存的路径,卸载app时，会自动删除文件 

/storage/emulated/0/Android/data/packagename/cache

Environment.getExternalStorageDirectory().getAbsolutePath()：

/storage/emulated/0

Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsolutePath())：

/storage/emulated/0/DCIM

getExternalFilesDir(Environment.DIRECTORY_PICTURES).getAbsolutePath：

/storage/emulated/0/Android/data/packagename/files/Pictures

获取文件夹下所有文件：

File[] files = new File(path).listFiles();

示例代码如下：package com.leixiansheng.fileandpath;

import android.os.Environment;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;

import android.widget.TextView;

import java.io.File;

import java.util.List;

public class MainActivity extends AppCompatActivity {

private static final String TAG = "MainActivity";

private TextView fileAbsolutePath;

private String path = "";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

fileAbsolutePath = findViewById(R.id.file_path);

String cacheDir = getCacheDir().getAbsolutePath();

String filesDir = getFilesDir().getAbsolutePath();

String externalFilesDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES).getAbsolutePath();

String externalCacheDir = getExternalCacheDir().getAbsolutePath();

String externalStorageDirectory = Environment.getExternalStorageDirectory().getAbsolutePath();

String externalStoragePublicDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsolutePath();

String externalStorageState = Environment.getExternalStorageState();

path = externalStorageDirectory + File.separator + "Test" + File.separator;

fileAbsolutePath.setText("cacheDir:" + cacheDir + "n" + "n"

+ "filesDir:" + filesDir + "n" + "n"

+ "externalFilesDir:" + externalFilesDir + "n" + "n"

+ "externalCacheDir:" + externalCacheDir + "n" + "n"

+ "externalStorageDirectory:" + externalStorageDirectory + "n" + "n"

+ "externalStoragePublicDirectory:" + externalStoragePublicDirectory + "n" + "n"

+ "externalStorageState:" + externalStorageState + "n" + "n"

+ "path:" + path);

getFileList(path);

Log.i(TAG,"cacheDir:" + cacheDir + "n"

+ "filesDir:" + filesDir + "n"

+ "externalFilesDir:" + externalFilesDir + "n"

+ "externalCacheDir:" + externalCacheDir + "n"

+ "externalStorageDirectory:" + externalStorageDirectory + "n"

+ "externalStoragePublicDirectory:" + externalStoragePublicDirectory + "n"

+ "externalStorageState:" + externalStorageState + "n"

+ "path:" + path);

}

//获取文件夹下的所有文件名

public void getFileList(String path) {

File[] files = new File(path).listFiles();

if (files == null) {

return;

}

for (int i = 0; i < files.length; i++) {

Log.i(TAG,files[i].getName());

}

}

}

注意：获取外部文件记得给权限！<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.leixiansheng.fileandpath">

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

<application

android:allowBackup="true"

android:icon="@mipmap/ic_launcher"

android:label="@string/app_name"

android:roundIcon="@mipmap/ic_launcher_round"

android:supportsRtl="true"

android:theme="@style/AppTheme">

<activity android:name=".MainActivity">

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

</application>

</manifest>打印Log 

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test3.txt

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test1.txt

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test5.txt

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test2.txt

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test4.txt

01-29 11:13:46.945 16689-16689/com.leixiansheng.fileandpath I/MainActivity: test6.txt

01-29 11:13:46.946 16689-16689/com.leixiansheng.fileandpath I/MainActivity: cacheDir:/data/data/com.leixiansheng.fileandpath/cache

filesDir:/data/data/com.leixiansheng.fileandpath/files

externalFilesDir:/storage/emulated/0/Android/data/com.leixiansheng.fileandpath/files/Pictures

externalCacheDir:/storage/emulated/0/Android/data/com.leixiansheng.fileandpath/cache

externalStorageDirectory:/storage/emulated/0

externalStoragePublicDirectory:/storage/emulated/0/DCIM

externalStorageState:mounted

path:/storage/emulated/0/Test/