HTML缓存思路探究(版本一)
探究背景:作为一名安卓新手，要实现这个是过程是比较简单的，因为思路需要在网上寻找，各项细节技术都比较不熟练，不过经过一整天的探究，总算是有了点成果
整体思路：
1.首先通过jsoup下载html,保存在本地，关于保存路径挺纠结的，后来参考了
http://www.cnblogs.com/freeliver54/archive/2011/09/16/2178910.html文档，使用安卓自带的
openFileOutput和openFileInput在
//读文件在./data/data/com.tt/files/下面存取我们的html文件
代码如下package com.example.htmlcache;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.apache.http.util.EncodingUtils;
import android.content.Context;
//http://www.cnblogs.com/freeliver54/archive/2011/09/16/2178910.html
// http://www.th7.cn/web/html-css/201410/62906.shtml
public class FileUtils {
Context context;
public FileUtils(Context context) {
super();
this.context = context;
}
public void writeFileData(String fileName,String message){
try{
FileOutputStream fout =context.openFileOutput(fileName, Context.MODE_PRIVATE);
byte [] bytes = message.getBytes();
fout.write(bytes);
fout.close();
}
catch(Exception e){
e.printStackTrace();
}
}
public String readFileData(String fileName){
String res="";
try{
FileInputStream fin = context.openFileInput(fileName);
int length = fin.available();
byte [] buffer = new byte[length];
fin.read(buffer);
res = EncodingUtils.getString(buffer, "UTF-8");
fin.close();
}
catch(Exception e){
e.printStackTrace();
}
return res;
}
}
2.当我们请求一个url,如何映射到本地文件呢，这里就要用到SQLite数据库保存我们的URL,另外我们在存储html文件名时使用
固定名称+id的方式，这样当我们请求一个url时候，首先查找数据库是否有对应的记录，从而加载本地文件
package com.example.htmlcache;
import java.io.IOException;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import android.content.Context;
public class ParseHtmlService {
Context context;
String cachePage ="cacgePage";
public ParseHtmlService(Context context) {
super();
this.context = context;
}
public String getHtmlByUrl(String url, String news_title,
String news_date) {
String data="";
int id = DBOpenHelper.getInstance(context).queryId(url);
if(id != -1){
//读取本地html
data = new FileUtils(context).readFileData(cachePage+id+".html");
return data;
}
Boolean flag = false;
Document document = null;
data = "<body>" +
"<center><h2 style='font-size:16px;'>" + news_title + "</h2></center>";
data = data + "<p align='left' style='margin-left:10px'>"
+ "<span style='font-size:10px;'>"
+ news_date
+ "</span>"
+ "</p>";
data = data + "<hr size='1' />";
try {
document = Jsoup.connect(url).timeout(9000).get();
String body = document.getElementsByTag("body").html();
if(body.length()>10){
flag = true;
}else{
body="数据加载失败";
}
data+=body;
data = data + "</body>";
} catch (IOException e) {
e.printStackTrace();
data = "数据加载异常" + "</body>";
}
if(flag){
long rowId = DBOpenHelper.getInstance(context).insert(url);
new FileUtils(context).writeFileData(cachePage+rowId+".html", data);
}
return data;
}
}
3.那么如何缓存图片呢，这里的解决方案是使用webview查看一下，这样webview自身会对图片进行缓存的
package com.example.htmlcache;
import android.content.Context;
import android.os.AsyncTask;
import android.webkit.WebSettings;
import android.webkit.WebView;
public class MyAsnycTask extends AsyncTask<String, String, String> {
WebView webView;
Context context;
@Override
protected String doInBackground(String... urls) {
String htmls = new ParseHtmlService(context).getHtmlByUrl(urls[0],urls[1],urls[2]);
return htmls;
}
public MyAsnycTask(WebView webView, Context context) {
super();
this.webView = webView;
this.context = context;
}
@Override
protected void onPostExecute(String htmls) {
super.onPostExecute(htmls);
if(webView != null){
webView.loadDataWithBaseURL (null, htmls, "text/html", "utf-8",null);
}else{
WebView wv = new WebView(context);
WebSettings settings = wv.getSettings();
settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
settings.setAppCacheEnabled(true);
wv.loadDataWithBaseURL (null, htmls, "text/html", "utf-8",null);
}
}
}
DEMO下载地址:http://pan.baidu.com/s/1jGj98SA