Android开发探秘之四:利用Intent实现数据传递

在Android开发过程中,很多人都熟悉Intent,这是个用于在多个View之间共享数据的类。本节主要是继承上节,通过点选ListView中的文本,把文本中的URL加载到一个新的页面上,并且打印出来。为了方便,我先把上一节的代码重新贴一下,因为在上一节后,代码做了少许修改:

Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
Codetry {
doc = Jsoup.parse(new URL("http://www.51yam.com"), 5000);
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
} final List<Map<String, String>> list = new ArrayList<Map<String, String>>();
Elements es = doc.getElementsByClass("subnav"); for (int i=0;i<es.size();i++) {
Element e = es.get(i); int count = e.getElementsByTag("a").size();
for(int j=0;j<count;j++)
{
Map<String, String> map = new HashMap<String, String>();
Element ex = e.getElementsByTag("a").get(j);
map.put("title", ex.text());
map.put("href", "http://www.51yam.com/"+ex.attr("href"));
list.add(map);
} } ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(new SimpleAdapter(this, list, android.R.layout.simple_list_item_2,
new String[] { "title","href" }, new int[] {
android.R.id.text1,android.R.id.text2
}));

实现的效果如下:

Android开发探秘之四:利用Intent实现数据传递

然后我们需要做的就是当点击ListView中的项目的时候,程序会将每个话题下面的URL链接发送到新的页面显示:

下面是当点击ListView项目的时候,利用Intent传递数据的方法:

Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
CodelistView.setOnItemClickListener(new OnItemClickListener(){

			@Override
public void onItemClick(AdapterView<?> parent, View v, int position,long id) {
//Toast.makeText(getApplicationContext(), (TextView), duration) System.out.println("position:"+position);
System.out.println("id:"+id); //Toast.makeText(_GetWebResoureActivity.this, list.get(position).get("href"), Toast.LENGTH_SHORT).show();
Intent intent = new Intent(v.getContext(),topicdetails.class);
intent.putExtra("src", list.get(position).get("href"));
startActivityForResult(intent,0);
} });

在子页面“topicdetails.java”中,我们可以通过如下的方式来接收传递过来的值:

Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
Codepackage com.android.web;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.EditText;
import java.lang.Object; public class topicdetails extends Activity { private EditText editText; @Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.topiccontent);
editText = (EditText)this.findViewById(R.id.editText); String srcUrl = getIntent().getStringExtra("src");
editText.setText(srcUrl); }
}

当然,一定不要忘记了在AndroidManifest.xml文件中添加Activity映射(黄色背景部分):

Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
Code<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.web"
android:versionCode=""
android:versionName="1.0" > <uses-sdk android:minSdkVersion="" /> <!-- 加入访问网络的权限 -->
<uses-permission android:name="android.permission.INTERNET" /> <application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name="._GetWebResoureActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".topicdetails"></activity>
</application> </manifest>

这样当一切工作准备完毕后,运行程序,点击ListView 的Item,我们成功地跳转到了子页面:

Android开发探秘之四:利用Intent实现数据传递

以下是所有的源码:

Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
主页面源码package com.android.web;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.lang.Object; import org.apache.http.util.ByteArrayBuffer;
import org.apache.http.util.EncodingUtils;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements; import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast; public class _GetWebResoureActivity extends Activity { Document doc; @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main); findViewById(R.id.button1).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
load();
}
});
} protected void load() { try {
doc = Jsoup.parse(new URL("http://www.51yam.com"), 5000);
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
} final List<Map<String, String>> list = new ArrayList<Map<String, String>>();
Elements es = doc.getElementsByClass("subnav"); for (int i=0;i<es.size();i++) {
Element e = es.get(i); int count = e.getElementsByTag("a").size();
for(int j=0;j<count;j++)
{
Map<String, String> map = new HashMap<String, String>();
Element ex = e.getElementsByTag("a").get(j);
map.put("title", ex.text());
map.put("href", "http://www.51yam.com/"+ex.attr("href"));
list.add(map);
} } ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(new SimpleAdapter(this, list, android.R.layout.simple_list_item_2,
new String[] { "title","href" }, new int[] {
android.R.id.text1,android.R.id.text2
}));
listView.setOnItemClickListener(new OnItemClickListener(){ @Override
public void onItemClick(AdapterView<?> parent, View v, int position,long id) {
//Toast.makeText(getApplicationContext(), (TextView), duration) System.out.println("position:"+position);
System.out.println("id:"+id); //Toast.makeText(_GetWebResoureActivity.this, list.get(position).get("href"), Toast.LENGTH_SHORT).show();
Intent intent = new Intent(v.getContext(),topicdetails.class);
intent.putExtra("src", list.get(position).get("href"));
startActivityForResult(intent,0);
} }); } /**
* @param urlString
* @return
*/
public String getHtmlString(String urlString) {
try {
URL url = null;
url = new URL(urlString); URLConnection ucon = null;
ucon = url.openConnection(); InputStream instr = null;
instr = ucon.getInputStream(); BufferedInputStream bis = new BufferedInputStream(instr); ByteArrayBuffer baf = new ByteArrayBuffer(500);
int current = 0;
while ((current = bis.read()) != -1) {
baf.append((byte) current);
}
return EncodingUtils.getString(baf.toByteArray(), "gbk");
} catch (Exception e) {
return "";
}
}
}
Android开发探秘之四:利用Intent实现数据传递Android开发探秘之四:利用Intent实现数据传递
子页面源码package com.android.web;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.EditText;
import java.lang.Object; public class topicdetails extends Activity { private EditText editText; @Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.topiccontent);
editText = (EditText)this.findViewById(R.id.editText); String srcUrl = getIntent().getStringExtra("src");
editText.setText(srcUrl); }
}
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