Android离线缓存的实例代码
android做到一定程度，需要考虑缓存的问题，不信可以掏出手机看看淘宝等一些app是否无网的情况下还可以浏览，不过大部分app并没有考虑到这些问题，解决Android的缓存有哪些方法呢
1.IO流读写文件
2.数据库
3.LruCache和DiskLruCache
个人比较喜欢sd卡文件读写的方式，原因自己可以去分析。
（1）权限
<uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permissionandroid:name="android.permission.INTERNET"></uses-permission> <uses-permissionandroid:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission> <!--在SDCard中创建与删除文件权限--> <uses-permissionandroid:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> <!--往SDCard写入数据权限--> <uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
（2）判断网络连接的状态，有什么用呢？自己想
if(isNetworkAvailable(MainActivity.this)){
Toast.makeText(getApplicationContext(),"当前有可用网络！",Toast.LENGTH_LONG).show();
}else{
Toast.makeText(getApplicationContext(),"当前wu可用网络！",Toast.LENGTH_LONG).show();
}
publicbooleanisNetworkAvailable(Activityactivity)
{
Contextcontext=activity.getApplicationContext();
//获取手机所有连接管理对象（包括对wi-fi,net等连接的管理）
ConnectivityManagerconnectivityManager=(ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
if(connectivityManager==null)
{
returnfalse;
}
else
{
//获取NetworkInfo对象
NetworkInfo[]networkInfo=connectivityManager.getAllNetworkInfo();
if(networkInfo!=null&&networkInfo.length>0)
{
for(inti=0;i<networkInfo.length;i++)
{
System.out.println(i+"===状态==="+networkInfo[i].getState());
System.out.println(i+"===类型==="+networkInfo[i].getTypeName());
//判断当前网络状态是否为连接状态
if(networkInfo[i].getState()==NetworkInfo.State.CONNECTED)
{
returntrue;
}
}
}
}
returnfalse;
}
（3）端口写入数据
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
FilesdCardDir=Environment.getExternalStorageDirectory();//获取SDCard目录
FilesaveFile=newFile(sdCardDir,"itcast.txt");
FileOutputStreamoutStream=newFileOutputStream(saveFile);
outStream.write(result.getBytes());
outStream.close();
}
（4）读取数据
FilesdCardDir=Environment.getExternalStorageDirectory();//获取SDCard目录
FilesaveFile1=newFile(sdCardDir,"itcast.txt");
BufferedReaderbr=null;
try{
br=newBufferedReader(newFileReader(saveFile1));
Stringreadline="";
StringBuffersb=newStringBuffer();
while((readline=br.readLine())!=null){
System.out.println("readline:"+readline);
sb.append(readline);
}
Stringstr=sb.toString();
(5)部分完整demo1
if(isNetworkAvailable(MainActivity.this)){
Toast.makeText(getApplicationContext(),"当前有可用网络！",Toast.LENGTH_LONG).show();
}else{
Toast.makeText(getApplicationContext(),"当前wu可用网络！",Toast.LENGTH_LONG).show();
FilesdCardDir=Environment.getExternalStorageDirectory();//获取SDCard目录
FilesaveFile1=newFile(sdCardDir,"itcast.txt");
BufferedReaderbr=null;
try{
br=newBufferedReader(newFileReader(saveFile1));
Stringreadline="";
StringBuffersb=newStringBuffer();
while((readline=br.readLine())!=null){
System.out.println("readline:"+readline);
sb.append(readline);
}
Stringstr=sb.toString();
JSONObjectjsonObject=newJSONObject(str);
JSONArrayjsonArray=jsonObject.getJSONArray("data");
for(inti=0;i<jsonArray.length();i++){
JSONObjectobject=jsonArray.getJSONObject(i);
Stringtitle=object.getString("name");
Stringcontent=object.getString("description");
Stringurl=object.getString("picSmall");
domainBeannewsInfo=newdomainBean(title,content,url);
//Stringpath=Environment.getExternalStorageDirectory()+"/"+name;
//ObjectOutputStreamout=newObjectOutputStream(newFileOutputStream(path));
//out.writeObject(newsInfo);
list.add(newsInfo);
//新建适配器
beanAdapter=newBeanAdapter(list,MainActivity.this);
//配置适配器
xListView.setAdapter(beanAdapter);
br.close();
}
}catch(IOExceptione){
e.printStackTrace();
}catch(JSONExceptione){
e.printStackTrace();
}
}
(6)部分完整demo2
publicStringlogoutPost(StringURL){
Stringresult="";
try{
Stringdata=URLEncoder.encode("UTF-8");
//+"&password="+URLEncoder.encode(password,"UTF-8");//传递的数据
URLurl=newURL(URL);
//2、url.openConnection()打开网络链接
HttpURLConnectionconn=(HttpURLConnection)url.openConnection();
//3、设置请求的方式
conn.setRequestMethod("POST");
conn.setDoInput(true);//发送POST请求必须设置允许输出
conn.setDoOutput(true);//发送POST请求必须设置允许输入
conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
conn.setRequestProperty("Charset","utf-8");
conn.setRequestProperty("Content-Length",String.valueOf(data.getBytes().length));
//5、获取输出流
OutputStreamos=conn.getOutputStream();
os.write(data.getBytes());
os.flush();
BufferedReaderin=newBufferedReader(newInputStreamReader(conn.getInputStream()));
Stringline;
while((line=in.readLine())!=null){result+="\n"+line;}
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
FilesdCardDir=Environment.getExternalStorageDirectory();//获取SDCard目录
FilesaveFile=newFile(sdCardDir,"itcast.txt");
FileOutputStreamoutStream=newFileOutputStream(saveFile);
outStream.write(result.getBytes());
outStream.close();
}
}catch(UnsupportedEncodingExceptione){
e.printStackTrace();
}catch(ProtocolExceptione){
e.printStackTrace();
}catch(MalformedURLExceptione){
e.printStackTrace();
}catch(IOExceptione){
e.printStackTrace();
}
returnresult;
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。