本文实例为大家分享了asynctask异步类实现网页内容放大缩小的详细代码，供大家参考，具体内容如下
webactivity.java:
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package com.supermario.filemanager;
import java.io.file;
import java.io.fileinputstream;
import java.io.filenotfoundexception;
import java.io.ioexception;
import org.apache.http.protocol.http;
import android.app.activity;
import android.app.alertdialog;
import android.content.dialoginterface;
import android.content.dialoginterface.onclicklistener;
import android.os.asynctask;
import android.os.bundle;
import android.view.view;
import android.webkit.websettings;
import android.webkit.webview;
import android.widget.relativelayout;
import android.widget.zoomcontrols;
public class webactivity extends activity {
//网页浏览器
private webview webview;
//进度条布局和网页内容主体布局
private relativelayout loadinglayout,weblayout;
//放大缩小控制器
private zoomcontrols zoomcontrols;
@override
protected void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.web);
//初始化页面组件
webview = (webview)findviewbyid(r.id.webkit);
loadinglayout = (relativelayout)findviewbyid(r.id.loadinglayout);
weblayout = (relativelayout)findviewbyid(r.id.weblayout);
zoomcontrols = (zoomcontrols)findviewbyid(r.id.zoomcontrols);
websettings websettings = webview.getsettings();
//设置可以使用js脚本
websettings.setjavascriptenabled(true);
//执行异步进程
new myasynctask().execute("");
}
private void reading(){
string filepath = getintent().getstringextra("filepath");
if (filepath != null) {
//读取文件
webview.loaddata(readwebdatatostringfrompath(filepath, new filereadoverback() {
@override
public void filereadover() {
}
}), "text/html", http.utf_8);
} else {
new alertdialog.builder(webactivity.this).settitle("出错了").setmessage("获取文件路径出错!").setpositivebutton("返回", new onclicklistener() {
@override
public void onclick(dialoginterface dialog, int which) {
webactivity.this.finish();
}
});
}
}
//将网页数据读取到一个字符串变量中
private string readwebdatatostringfrompath(string path,final filereadoverback filereadoverback){
file file = new file(path);
stringbuffer stringbuffer = new stringbuffer();
try {
//读取文件内容
fileinputstream inputstream = new fileinputstream(file);
byte[] bytes = new byte[1024];
int readcount = 0;
while ((readcount = inputstream.read(bytes)) > 0) {
stringbuffer.append(new string(bytes, 0, readcount));
}
filereadoverback.filereadover();
} catch (filenotfoundexception e) {
return "文件不存在!";
} catch (ioexception e) {
return "文件读取错误!";
}
return stringbuffer.tostring();
}
interface filereadoverback{
void filereadover();
}
//异步处理类
class myasynctask extends asynctask<string, string, string>{
//首先执行的函数
@override
protected void onpreexecute() {
super.onpreexecute();
loadinglayout.setvisibility(view.visible);
weblayout.setvisibility(view.gone);
}
//后台执行
@override
protected string doinbackground(string... params) {
reading();
return null;
}
@override
protected void onpostexecute(string result) {
super.onpostexecute(result);
//设置载入进度条隐藏
loadinglayout.setvisibility(view.gone);
//设置浏览器内容可见
weblayout.setvisibility(view.visible);
// 放大按钮
zoomcontrols.setonzoominclicklistener(new view.onclicklistener() {
//将网页内容放大
@override
public void onclick(view v) {
webview.zoomin();
}
});
// 缩小按钮
zoomcontrols.setonzoomoutclicklistener(new view.onclicklistener() {
//将网页内容缩小
@override
public void onclick(view v) {
webview.zoomout();
}
});
}
}
}
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移动技术网。
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