Context的方法
getCacheDir
getFilesDir
getExternalCacheDir
getCacheDir
getFilesDir
getExternalCacheDir
getExternalFilesDir
特点1：无需权限将assets中的图片文件保存到sdcard或内存中（当然资源是从网络下载需添加网络权限）
特点2：随着应用卸载缓存数据也一并删除
如果不想应用卸载也将相关资源卸载请保存到除此之外的其他目录
目录结构
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="cn.weimei.tiankong.com.fileproject.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:id="@+id/textView" />
<ImageView
android:id="@+id/iv"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_below="@+id/textView" />
<WebView
android:id="@+id/web"
android:layout_width="match_parent"
android:layout_height="200dp"
android:layout_below="@+id/iv" />
</RelativeLayout>
MainActivity.java
package cn.weimei.tiankong.com.fileproject;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.webkit.WebView;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* 调用方法=打印的路径
* getCacheDir=/data/user/0/cn.weimei.tiankong.com.fileproject/cache
* getFilesDir=/data/user/0/cn.weimei.tiankong.com.fileproject/files
* getExternalCacheDir=/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/cache
* getExternalFilesDir=/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/files
* 这几个方法存储无需权限
*/
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private ImageView iv;
private InputStream in;
private WebView web;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
printdifrentPath();
initView();
//setImageViewByInputStrim();
//loadImageByWebView();
//saveAndLoadImgCacheDir();
//saveAndLoadImgExternalCacheDir();
//saveAndLoadFilesDir();
//saveAndLoadExtranalFileDir();
saveSdcardOrDataDir();
}
/**
* 初始化视图
*/
private void initView() {
iv = (ImageView) findViewById(R.id.iv);
web = (WebView) findViewById(R.id.web);
}
/**
* 将assets目录的图片加载到imageView中
*/
private void setImageViewByInputStrim() {
try {
in = getAssets().open("12345.png");
} catch (IOException e) {
e.printStackTrace();
}
iv.setImageBitmap(BitmapFactory.decodeStream(in));
}
/**
* 将assets目录的图片加载到WebView中
*/
private void loadImageByWebView() {
web.loadUrl("file:///android_asset/12345.png");
}
/**
* 调用方法=打印的路径
* getCacheDir=/data/user/0/cn.weimei.tiankong.com.fileproject/cache
* getFilesDir=/data/user/0/cn.weimei.tiankong.com.fileproject/files
* getExternalCacheDir=/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/cache
* getExternalFilesDir=/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/files
* 这几个方法存储无需权限
*/
public void printdifrentPath() {
Log.d(TAG, "getCacheDir=" + getCacheDir());
Log.d(TAG, "getFilesDir=" + getFilesDir());
Log.d(TAG, "getExternalCacheDir=" + getExternalCacheDir());
Log.d(TAG, "getExternalFilesDir=" + getExternalFilesDir(null));
}
/**
* 将assets目录的图片保存到/data/user/0/cn.weimei.tiankong.com.fileproject/cache目录下并显示在imageView中
*/
public void saveAndLoadCacheDir() {
try {
InputStream in = getAssets().open("12345.png");
File filepath = getCacheDir();//getCacheDir
File fileOut = new File(filepath.getPath(), "savecachedir.png");
FileOutputStream os = new FileOutputStream(fileOut);
byte[] buffer = new byte[1024];
int count = 0;
while ((count = in.read(buffer)) > 0) {
os.write(buffer, 0, count);
}
//加载文件保存在cachedir的图片
iv.post(new Runnable() {
@Override
public void run() {
FileInputStream fileIs = null;
try {//getCacheDir
File loadFile = new File(getCacheDir().getPath() + "/savecachedir.png");
Log.d(TAG, "run: getCacheDir--path=" + loadFile.getPath());
fileIs = new FileInputStream(loadFile);
iv.setImageBitmap(BitmapFactory.decodeStream(fileIs));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 将assets目录的图片保存到/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/cache目录下并显示在imageView中
*/
public void saveAndLoadExternalCacheDir() {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
try {
InputStream in = getAssets().open("12345.png");
File filepath = getExternalCacheDir();//getExternalCacheDir
File fileOut = new File(filepath.getPath(), "saveextranalcachedir.png");
FileOutputStream os = new FileOutputStream(fileOut);
byte[] buffer = new byte[1024];
int count = 0;
while ((count = in.read(buffer)) > 0) {
os.write(buffer, 0, count);
}
//加载文件保存在cachedir的图片
iv.post(new Runnable() {
@Override
public void run() {
FileInputStream fileIs = null;
try {//getExternalCacheDir
//这样也可以 File loadFile=new File(getExternalCacheDir().getPath()+"/saveextranalcachedir.png");
File loadFile = new File(getExternalCacheDir().getPath(), "saveextranalcachedir.png");
Log.d(TAG, "run: getExternalCacheDir--path=" + loadFile.getPath());
fileIs = new FileInputStream(loadFile);
iv.setImageBitmap(BitmapFactory.decodeStream(fileIs));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
});
} catch (IOException e) {
e.printStackTrace();
}
} else {
Toast.makeText(this, "sdcard不存在", Toast.LENGTH_SHORT).show();
}
}
/**
* 将assets目录的图片保存到/data/user/0/cn.weimei.tiankong.com.fileproject/files目录下并显示在imageView中
*/
public void saveAndLoadFilesDir() {
try {
InputStream is = getAssets().open("12345.png");
File filepath = getFilesDir();//getFilesDir
File fileOut = new File(filepath.getPath(), "saveandloadfiledir.png");
FileOutputStream os = new FileOutputStream(fileOut);
byte[] buffer = new byte[1024];
int count = 0;
while ((count = (is.read(buffer))) > 0) {
os.write(buffer, 0, count);
}
//加载文件保存在filedir的图片
iv.post(new Runnable() {
@Override
public void run() {
FileInputStream fileIs = null;
try {//getFilesDir
//这样也可以 File loadFile=new File(getFilesDir().getPath()+"/saveandloadfiledir.png");
File loadFile = new File(getFilesDir().getPath() + "/saveandloadfiledir.png");
Log.d(TAG, "run: getExternalCacheDir--path=" + loadFile.getPath());
fileIs = new FileInputStream(loadFile);
iv.setImageBitmap(BitmapFactory.decodeStream(fileIs));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 将assets目录的图片保存到/storage/emulated/0/Android/data/cn.weimei.tiankong.com.fileproject/files目录下并显示在imageView中
*/
public void saveAndLoadExtranalFileDir() {
try {
InputStream is = getAssets().open("12345.png");
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
File outFile = new File(getExternalFilesDir(null).getPath(), "12345.png");
FileOutputStream os = new FileOutputStream(outFile);
int count = 0;
byte[] buffer = new byte[1024];
while ((count = (is.read(buffer))) > 0) {//注意buffer不要忘记了
os.write(buffer, 0, count);
}
iv.post(new Runnable() {
@Override
public void run() {
File loadFile = new File(getExternalFilesDir(null), "12345.png");
try {
Log.d(TAG, "run: getExternalFilesDir--path=" + loadFile.getPath());
FileInputStream is = new FileInputStream(loadFile);
iv.setImageBitmap(BitmapFactory.decodeStream(is));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
});
} else {
Toast.makeText(this, "sdcard不存在", Toast.LENGTH_SHORT).show();
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 如果不存在sdcard就保存到data目录下
*/
public void saveSdcardOrDataDir() {
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
saveAndLoadExternalCacheDir(); //或者saveAndLoadExtranalFileDir();
} else {
saveAndLoadCacheDir(); //或者saveAndLoadFilesDir();
}
}
}
AndroidMenifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.weimei.tiankong.com.fileproject">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
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>源码下载：http://download.csdn.net/detail/u013042707/9645244
作者：u013042707 发表于2016/10/3 17:16:09 原文链接
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